TTrax

Thanks for all the suggestions. I did run the tank down and filled up with fresh gas. I'm sure there is a little B12 still left but I can't imagine it would be enough to damage anything. I will be taking it out again this weekend for a ride. I have been really driving the heck out of it since it is back to running in prime shape. Fuel economy is definitely up, was over 110 miles on that tank when it went down to 1 bar when the best I could get before was around 90-95 miles before it went down to one bar consistently. I am still curious to how this fuel additive solved the problem. I had two theories, but not sure and I guess I will never know without taking the carbs apart again to find. With it running OK I am not touching it at this point. One, is that the B12 caused the desiccated rubber plugs to swell and seal as needed, the other is that I obviously missed some fuel passage or didn't get an emulsion tube cleaned out properly. I looked around with a google search but haven't seen anyone confirm that B12 causes rubber to swell, other than a couple of posts where people theorized that it did. I probably wouldn't have thought twice about it, but after having the carbs off and tinkering with it twice, I am intrigued.

OK thanks for the input. I drove it to work today and ran it around the countryside this afternoon during lunch. Down to 2 bars on the gauge now, will fill up when I get it down some more. Seems like the fuel economy might be better as well now, will do some calculations when I go to fill up. Thanks!

Well, I am afraid to say anything out of fear of jinxing myself. I took the bike out for a short ride for lunch to get a couple more cans of B12 to have on hand in case I need them for the bike or other projects. I took the bike and had been driving very mildly in town. I then went to the gas station and filled up after adding half a can of B12 Chemtool. I took it out and was starting to head out of town. Since the bike was warmed up and I was on the open road I decided to see if the problem was about the same as last time or better/worse. Much to my surprise it launched all the way to redline without a hint of hesitation or bogging. Pulled like a freight train all the way up. I did some mixed driving and tried a few more times. Every time it launched like a Saturn V rocket. Unbelievable. It seems like the carb cleaner had some effect on the carbs, whether it be some varnish or crud I had missed, or if it caused some of the old rubber to swell and seal up as needed. I have no idea, just glad it seems to be working well. Time will tell if the problem is truly resolved. I think I might need to start saving my pennies to have the carbs rebuilt at some point as I am reluctant to believe a fix in a can is going to last long term. Right now I am incredibly grateful it seems to be running right. Now another concern I have is the half can of carb cleaner that is still in the bike. Right now work is keeping me pretty busy so I haven't had much time to take rides. It might be sitting for a week or two before I am going to ride it. Trying to decide if I need to run out that tank and fill with fresh gas with no additive, or if it is OK to leave in the tank for that period of time. If it had that much of a dramatic effect in a 1 month period of sitting there, then I don't want to risk liquifying any rubber plugs or gaskets that are soaking in this mixture. Anyone have any experience with B12 destroying rubber parts in their carbs? Thanks again for all the input, have a good day!

I did send @eusa1 a PM and an email, but I don't think he has had a chance to look at the messages yet. Also, I read through some of the forums and it looks like he works on the second gen only machines? Or maybe I misunderstood. I have been riding the bike a little here and there, might take it to SE Kansas in a couple of weeks. I definitely think there is some funkiness going on with the carbs. A week or two ago I had taken a ride with my wife around some scenic drives nearby. During the trip, I had put in a half can of B12 Chemtool carb cleaner in the tank for a couple of tanks. The bike has sat for this period of time and I decided to go out and take it for a drive. Not sure if it was atmospheric conditions changing (temp and humidity) or if the carb cleaner did something, but now the bike will rev out to around 7K, albeit surging a little on the way up there. At least it isn't a dead bog down like it used to be. I can only theorize that sitting in a warm garage and possibly the fuel additive has caused some dried out rubber component such as the jet block plugs or gaskets to be slightly restored but I can't say for sure. In case Mike doesn't work on the first gen carbs, I had looked around and I did see an outfit out of Texas appears to specialize in working on vintage Japanese motorcycle carbs. Their website is wgcarbs.com. I didn't know if anyone else had any experience with them and the work they have done. It looks like they charge a hefty price to rebuild a set of carbs for this bike. Since I have walked away from working on this thing seriously for a month or so, I am a little more relaxed and might take another stab at it before paying that price. I am almost tempted to just leave it as-is but I'm sure I will do something with it this winter, whether it is having someone else rebuild the carbs or do it myself again. Anyways, I appreciate all the feedback and suggestions everyone has offered, definitely worth the 12 bucks a year to get the help I have received. Hope everyone has a good day and weekend!

I have checked the caps for the sync ports on the carbs, none are cracked and all have the spring clip on them The COPs are being held in place by the plastic covers on top of the valve covers. None of them are touching the valve covers themselves. I am using the factory air cleaner housing and an Emgo air filter that is designed to be an OEM replacement. I had this air filter on for a couple of years now and blowing it out and test driving with it removed made no difference in how the bike performed. I had bought some carb kits from SCI but noticed the box mentioned it was for the Vmax, and I also noticed the needle appeared to have a different profile than the factory one. The needle valve and emulsion tube appeared to be in good condition on each carb so I didn't replace it. I will say the rubber plugs on the bottom of the carbs were rock hard and soaking them in gasoline for a little while didn't seem to make a difference. So this is a possibility too. The gasket between the jet blocks and carb body didn't seem to be tearing so I left those as well without replacement. The small rubber o-rings around the emulsion tubes looked like they had some varnish or white colored substance. I cleaned them up as best as I could but since the carb kits I had received didn't have those as a replacement, I didn't change those out or get too aggressive on cleaning out of fear that I would tear one and have to try to source a replacement. They weren't really tight but not sure how tight they would be from the factory since they are really small diameter rings. I have a local dealership that I might try to see if they will rebuild the carbs right. I looked around online and seen a couple of places that claim to rebuild these carbs but don't know how in depth they would go to do the needed work. Has anyone else around here taken their carbs to have them rebuilt and have they had good luck having it done? Like I said, I am just about done trying to rebuild these things and am considering paying good money to have someone do it right. Let me know if you know of anyone. Thanks and have a good evening!

OK an update on this, sorry for the delay. I was going to get this up and going again the weekend before last but had unexpected company. I went ahead and finished installing the new fuel lines and the fuel pump. I don't know if I had specified but I had switched back to the factory controller and coils (new wires and spark plug caps last year). I went for a test ride, all seemed to be OK around town but hadn't really opened it up to find out if it revved up like it should. Before I got a chance, it started missing on one cylinder. I was really bummed at this point as I figured I had introduced some contamination somewhere between the fuel filter and the carbs and plugged a jet or the screen at the needle valve. Since I had the Ignitech ignition box and COP coils still sitting on the shelf, I figured I would swap them back in and see if it made a difference or not. After installing it back in, I tried to start the bike. As it was cranking, there was a short backfire which sounded like it came through one of the carbs. It did start up but I was disappointed that it still sounded like it was missing. After moping around the shop for a bit and despairing about having to remove the carbs again, I figured I would open the bowl drains to see if one of the carbs were without fuel. All of them drained fuel so I knew at least they were getting fuel supply. Luckily, something caught my eye and I noticed the front right carb's sync cap was gone! I looked around the area and body work and engine and found the cap. I am sure if it was missing during my test drive, it would have disappeared. I can only imagine that the cap was blown off when the backfire through the carb occurred. I reinstalled it and was relieved to find out that the miss was gone and the bike ran fairly decent. I took it on a test drive and it ran about like it had before, but still had the cut-out around 5K RPM. Everything is exactly the same as before. So probably nothing wrong with the original fuel pump and lines. Oh well, another possibility eliminated, but still disappointed the issue isn't resolved. I can't really blame anyone or anything but myself, after two half a**ed attempts at cleaning the carbs. I may be wrong but it really feels like I have a carb issue. Either ignition system seems to work the same (at least at first). Not sure if it is because the original ignition system doesn't have quite the same amount of oomph compared to the Ignitech/COP set up or if there is actually a problem with the original ignition system, but with the Ignitech I have full fire off all 4 cylinders when running. The idle is a little lumpy but I need to do another sync and set the idle speed correctly, right now it is running around 800 to 900 RPM. I took it for a ride today and it ran well enough two up with my wife. I didn't really push it knowing I still had an issue but seemed to run well enough. We ran about 180-200 miles and other than less-than-impressive fuel economy, I didn't notice any issues. The route we took did go through some hills and I was pushing around 70 MPH. While running through this area, I noticed the fuel gauge dropped the first bar after only 27 miles which seems like a new record to me (after the second fill up, 94 miles and 2.8 gallons of gas on the first tank). With the factory ignition system and when I first got the bike, I seem to remember it only dropping a bar after around 45-55 miles. After we slowed down to 65 MPH on flat ground the fuel gauge didn't seem to drop too fast. When we got back to the house, we were down to 1 bar on the gauge and had gone 94 miles. Not as good as I remember but I had set the carb floats so it might be running a bit richer than it had from the PO's settings. Also between my wife and I, we are pushing 450-475 lbs so I know it isn't going to get awesome fuel economy. Also we were running no less than 65 MPH the whole way except in town. At this point, I think I am about ready to just pull the carbs and have someone that knows what they are doing rebuild and set them up right. I am sure I am missing something. I have worked on cars most all my life but haven't run into an issue quite as irritating as this. I am contemplating just driving it like this for awhile until I figure out what I want to do next. Maybe pull the spark plugs after around 1K miles and see if I can see any evidence of running too rich or lean. My wife is getting to the point of trying to have me sell this one off and get something else, I have told her it's not going to be worth much running like it is. I do appreciate all the suggestions and feedback I have gotten so far. Not ready to give up yet, but ready to take a pause at turning wrenches on this thing. Thanks again and hope you all have had a good holiday weekend!

OK thanks. Maybe not a problem, the charger indicated 12.5 volts when I first hooked it up but don't remember the battery gurgling like it is when I initially charged it. The only time I ever see the charge level drop on the voltmeter is when I use the brakes.

Another possibility is forming now... I have the battery on the charger since yesterday. It is a "smart" charger and is set for 2 amps. Battery has been charging since yesterday afternoon and this morning the charger is still going at it. I can hear some pretty good bubbling coming from the battery. Wonder if it is possible a battery still has the guts to start an engine but still cause ignition issues? This will be on my list of possible problems if the fuel pump and line replacement doesn't resolve the issue.

Thanks for the insight. I am really hoping it is something related to the fuel inlet system. It's going to get way above my pay grade if it isn't. I got the Mr Gasket 42S in today so I need to get that installed. Wondering if just removing the rear wheel is the best way to get easy access to the fuel lines between the pump and tank, as well as the fuel filter? Not much room to work around there and I don't have the smallest hands. Probably not going out to the garage tomorrow, supposed to be 102°F! Cold front coming in this weekend with possible rain so will be the best time to be out turning the wrenches.

OK thanks. I am supposed to get the fuel pump in today sometime, so will probably try to fit that and new fuel lines up tomorrow or this weekend. I am curious, when your fuel line failed, did it cause the same issue or was it a complete shut down? I ask because I experimented today with my 82 CB750 on the way back to work. I turned off the fuel and rode for what seemed like a couple of miles with no obvious issue. It did finally get to where it would bog down when the throttle was cracked but took quite some time before it would do that. On my Venture, it will instantly bog when you hit 5K, 1st gear on up. In higher gears with enough throttle it seems to bog down somewhere between 5K and 4.5K. I know this is an apple to oranges comparison as the 750 uses a gravity fuel feed and the Venture uses this fuel pump system. Really hoping that fuel pump and lines fixes the issue but have messed with this thing so much I am becoming convinced nothing will resolve it. Just getting frustrated I guess. Another thing I forgot to mention that I tried earlier was removing the air filter and running it. I thought it if was air related it might manifest itself by cutting out at a different RPM but it was exactly the same as before.

Thanks for the response. The enrichment valves all appear to be fully seated and in their boots. I didn't mess with the idle mixture settings as the machine seems to idle very well, also I didn't want to mess with them out of fear of making the problem worse or creating new problems. The furthest I had the carbs torn down was the jet blocks off and slides and diaphragms out. I had blown through the jets with carb cleaner and compressed air at this point. I left the original gaskets in the carb alone since they didn't tear when I took them apart. I did order carb kits from SCI, but noticed the kits mentioned they were for the vmax, also I noticed the shape of the slide needle was different than what was on the bike currently, so I was hesitant to switch them out. I didn't check the ground on the frame, voltage on the voltmeter is the same as it always shows. I had taken the bike out on a 80 plus mile ride the other day and the battery wasn't low or going dead. Since I had load tested the power and ground to the TCI and power supplies to the ignition coils, I had hoped that would identify a poor ground or power source. I can go back and recheck this. The fuel line between the pump and carb has a red woven fabric on it, assuming this is original? I didn't see any kinks but plan on replacing it when I put the new fuel pump in. If this doesn't fix the problem, then I guess I am going to be getting into the carbs a third time. I don't mind, the biggest problem I have is getting the cables back on the carb. If anyone has some pro tips on this, I would appreciate it. Last time I had put it back together I thought I was going to stretch or break the cables getting the outer sheath back into the saddle/bracket. Maybe I'm doing that wrong. Once again, thanks for taking a look and giving me some ideas. If there is a good write up about setting the mixture screws that I have missed, let me know. Have a good day!

Good evening, I was hoping to figure this one out on my own but I am getting pretty close to the end of my rope. I have been working on it off and on for a year now and not getting anywhere. I was wondering if any one had ever experienced a weak fuel pump or fuel restriction and what the symptoms might be? I have tried about everything I can think of and a few more that I have seen mentioned in the other posts on this site. I will try to remember them all and post them below. First issue I had, my wife and I took a trip that was about 150 miles last June. About 5 minutes into the ride we started getting rained on pretty good and it lasted the rest of the trip. I did notice a few times that the bike seemed to bog down but we were in some really heavy rain. The next day it cleared up and we were back to nice weather. I didn't notice anything different with the bike so I didn't think much more about it. I had read several posts from people who had drown their TCI in heavy rain so it did concern me a little. A few days later I was taking another ride and noticed the bike seemed to surge under hard acceleration. I changed out the spark plug wires and caps, but the issue was the same. I should mention that I also checked the resistance of the ignition coils as well as the pick up coils and all were in spec according to the service manual. At this point I began to worry that I had damaged my TCI in the heavy rain that had occurred earlier. I had been wanting to get the Ignitech TCI for awhile in case this one died, so figured now was the time to do it. I installed it but still noticed I had an intermittent miss at higher engine speeds. Thinking that I had gotten water in one or more ignition coils, I decided to go ahead and switch to a COP set up. I ordered the stick coils from Ignitech and when they came in, I was frustrated to find that the issue was still present. I decided to go ahead and put in new spark plugs. I had seen where some have forgone the resistor type plugs and went with the non resistor type for possible hotter spark. I did this and noticed the engine ran much better at lower engine speeds but seemed to break up at higher engine speeds. Also, the tachometer would jump around quite a bit. The faster the engine speed, the worse the tach would jump and the engine would die down. I switched back to the resistor type plugs and had the engine miss but would rev up and the tach would work. So I went ahead and ordered the correct resistor type plugs for this machine and it seemed to do pretty good. I thought I had it fixed, but still was a little disappointed that it didn't seem to have the power it had when I had bought it 6 years ago. I didn't think too much about it, and didn't mess with it for the rest of last year. This spring I did some maintenance, changed the oil and filter and changed the coolant. I had been reading about how some people had issues with the diaphragms getting holes in them after awhile and how this could cause lackluster acceleration and performance. I decided to go ahead and order new ones (off ebay). Probably not the best quality but when I pulled the old ones out, it was noticed that ALL of them had at least four holes, some had even more. I put in the new diaphragms and took it for a test drive. I was initially thrilled with the off-the -line performance, almost felt as though the front tire was going to come off the ground in first gear. Then the problem I am now fighting became evident... around 4.5 to 5K RPM the machine would completely bog down under hard acceleration. If you let off the throttle, the engine would seem to recover. I can't say that it felt like it misses on a particular cylinder. It just totally bogs out. When it does this, it hangs at around 5K RPM. If you let off it feels like it picks up. Then goose the throttle again and for a split second it starts to accelerate hard then bogs down hard, causing the forks to dive. I thought maybe it was my boost sensor. I ordered a spare off Ebay and swapped it in, but the problem was identical. I decided at this point to go ahead and pull the carbs as I have never gone over them. I admit I should have probably be starting with the simple things such as filters and fuel lines before getting to this point, but I guess I have always done things the hard way. I noticed the main jet on the #2 carb seemed to have a lot of junk in it. I cleaned it out and thought I had found the issue. I went ahead and checked out the jets in the other carbs but found no issues, so blew compressed air as best I could back through the needle valve seats and slapped it all back together, confident I had found the problem. Upon test driving, it seemed to have better power and would rev up higher, but still surged at higher engine speeds. It did seem to rev up a little higher, around 6 to 6.5K rpm but not any higher. I was going to live with it until later, but still bugged me that it wasn't accelerating to red line more smoothly. I went ahead and pulled the spark plugs to see if I could find one that was dirty or sooty compared to the others in case one cylinder was misfiring. All plugs looked the same and this was inconclusive to determine what the issue was. All were clean with no real soot. I did load test the wiring to the TCI and coils to make sure I didn't have a bad connection. All power and ground wires to the TCI and ignition coils would light a spare head light I had laying around for as long as I completed the circuit. I did check the TCI ground wire and it could also light the headlight with no issues. I thought at this point I had been too hasty to put the carbs back together and should have checked several other items, including float settings. I went ahead and pulled the carbs back off and checked the jets again. All checked out OK with no clogging. I did check the floats. I noticed on another post on this height that the correct float height seemed to be about an inch from the top of the float to the body of the carb. Mine were set a little lower (more than an inch) from this, so I set them to the 1 inch setting. I also got a better blowgun with a rubber tip to try to blow more pressurized air back through the needle seats in case any debris had built up in the screens on the fuel inlet to the carbs. I also checked the condition of the slide needle and the bore it fits in and they looked like they are in good condition. The slides were lubed with WD40 and all moved without hanging up. All jets, air and fuel, were blown out and cleaned with carb cleaner. I did have a new fuel filter on hand. I was going to swap it in, but couldn't get to the screw to loosen the clamp that holds the fuel filter. I disconnected the line off the outlet of the fuel filter and fuel came out quite readily so it doesn't seem like it is clogged. I do plan on changing it regardless in the near future as it has been a couple of years since it has been changed. I took it out for a drive again, and was disappointed to find the issue was no better, maybe a little worse. It was back to around 5K RPM max engine speed under a heavy load. It will rev out to almost 7K RPM if you feather it very slowly. Crack open the throttle and it will instantly fall on its face if you are 6K or above. If you hold at 5K and then gun it, it will accelerate for that half second or so, then fall on its face again. I still had my original ignition coils and wiring in the bike for the factory ignition system. I decided to go ahead and swap it back in to see if the problem changed at all. Well, good news and bad news. Bad news is the problem is exactly the same, the good news is there is nothing wrong with my factory TCI and coils. I am pretty sure all that was wrong with the factory ignition system a year ago was a fuel fouled plug. So this is where I am at now. I have an after market fuel pump on its way. The factory one still seems to work but there is little pressure coming from it. There isn't much resistance at all if I cover the end of the fuel line when it is pumping. I see the factory spec is something like 3 psi so maybe this is normal? I did have a longer line and held it up about the height halfway up the windshield. Fuel will come out of the pipe, but not in a column, it just kind of runs out the end without any height to speak of. If I replace this pump, fuel filter, and line and it doesn't fix it, I might be going to the looney bin. I really hope that someone else that has experience with these bikes can give me something else to check. I am sure I have missed a few things that I have checked in the past. Thanks for your help in advance and apologize for the long winded post. I really did try to figure this out without begging for help but have almost exhausted all that I can think of. Praying that this fuel pump and filter resolves it but if not, I am down to either getting rid of the bike and taking a huge hit, or trying to find someone locally that would even touch a bike this old and see if they could figure it out.

OK, well I loaded the COP program and then transferred the timing table over from the file you shared above. Just took it out, seemed to start up very good, no choke needed. Definitely feels like the part throttle response is much better and the top end seems to pull pretty hard compared to the stock curve. Its very close at least so its hard to tell, but just going by the seat of the pants. I tried to listen for any pinging and at least I couldn't hear it anywhere in the rev range, loaded or unloaded. Now for some long term testing and observation to see if the fuel economy improves at all. Over all so far I am liking it a lot. Thanks again for sharing and appreciate all the work everyone has done to make this more refined. Have a good evening!

Thanks for sharing this! I will see if I can move closer to the advance map shown and see how it does. I noticed that the base timing on this map is 5° compared to 10° on the one that came with my module. I wonder if these maps take into account base timing to advance? For example, if your advance is 38° is the total advance actually 48° if your base timing is set for 10?

Last year I ended up getting an Ignitech unit along with COP units and harnesses all from Ignitech directly. I noticed the one they sent out was a v96, not sure if anyone else is running one of these and I'm not sure if there is a difference in the ignition timing map from the v88, from what I can see in the screenshots above. I was pretty easy and plug and play for the most part, except I was running non resistor plugs which really messed with the sparker until I switched back to resistor type plugs. I am also using the original boost sensor. I would have to say the unit coming from Ignitech is very good, but I can say it seems like I have some reduced fuel economy. Also, I was wondering if the timing might be a bit more retarded from the factory TCI because it seems like I feel a little more heat coming off the exhaust while we are riding in windy weather than I remember. Also, WOT power seems to be a little down too, seems like I remember passing someone by downshifting a gear and hammering it, it was like an explosion of power. Now it is still very good but just feels like there is a little less of an edge than I remember. I might not be remembering correctly since we hardly rode at all last year due to many businesses closed and restrictions due to covid. Also, I am reluctant to start messing with the advance curves out of fear of causing more harm than good. I definitely have a problem when I get an idea in my head that something isn't right or the way I remember, I will keep messing with it until I've screwed it up real good. So really fighting the urge to do so. I was curious if anyone still has a copy of some of the changes they have done just to see what others have done with the settings and how it has worked out in real world situations. I know there has to be quite a few miles on some of these units with modified settings with no ill issues (hopefully). Also, I had seen some references to possible dyno testing with some of these settings but was wondering if there were any results, and if there was a reference to which software files produced a certain range of horsepower or calculated mileage. As it stands, I might just keep running the machine with the ignition curve sent to me with the box. It is very good and I really haven't given it much time. All the wind this time of year around here can make any bike seem to have less than stellar fuel mileage. I was just curious to see what other members were running for ignition curves, if willing to share. I have attached the Ignitech files that I received. Thanks! v-max old venture v96.ign v-max old venture with COP coils v96.ign

Yeah that looks awesome! I'm going to have to do some body work on mine in the future. Might consider doing something like this although the PO did a pearl coat paint that is pretty nice as well.

I love the color of that bike! I hope the next owner gets many years of enjoyment out of it. For some reason I have developed a vehicle hoarding complex. I have quite a few vehicles that I should part with but can't seem to pull the trigger on getting rid of any of them.

Prayers for a quick and full recovery.

Prayers for you and your family.

One of the first work trips I made with my current employer was to an assembly center in Edgewood, MD. I work for an agricultural manufacturer and grew up on a small farm. As one of my first jobs, I had to inspect utility tractors coming in from Brazil. We were under the gun to get the inspections done as soon as possible. In my haste, I started the morning by pulling some units into the building from the parking lot. The roll up door into the facility was open part ways and I was eager to get the first machine in to start my day. I remember hurriedly pulling into the building and noticing that the exhaust pipe barely missed clipping the bottom of the part-way opened door. All the sudden I remember thinking "ROPS!!!" right about the time the ROPS frame came in contact with the door, bending it out nicely as the machine passed right through... The manager of the assembly center was known for having a short temper and I was loathe to visit with him to tell him I had damaged his facility. I had grown up around some older farm equipment and a ROPS frame was beyond new technology for any of the machines I grew up with (Allis Chalmers B and WD-45, as well as John Deere G and 830 machines). Fortunately, he had already had some other building issues and had scheduled a contractor to visit and didn't seem to be too concerned about the damage. It might have also been since I spent about 2 hours before he seen the door trying to bend it back into shape as much as possible LOL. Anyways, your post reminded me of that first mistake I made but was glad that the problem didn't conclude with my leave of the company. Hopefully you are doing OK and can chuckle about it in the future!

Yep it's my first post. But rest assured, I have been creeping around the forums entertaining myself with everyone's posts and trying to learn as much as I can about technical stuff and riding in general. Thanks to everyone sharing the pictures, one of my favorite pastimes checking out all the different adventures and awesome places around the country and world!

Here's a few of mine, longest trip I have taken so far. I was a little nervous but the bike held up great, no problems whatsoever! Harrison, Arkansas and nearby locales.