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Hello all; my name is Jon. I have a newly acquired 1983 Yamaha venture 1200 xvz. So to try to explain what I have done here to get myself into the predicament that I am now in...... this is going to be to say the very least embarrassing for me. But the inner auto technician in me wants the damn machine running. Well I purchased this bike hadn’t run in probably a decade or better. That being said I figured need the carbs throughly cleaned..... duh! Well anyways I did pull the carbs off and cleaned out the jet block; that was a new one for me; I currently have a 1982 Yamaha Maxim 650 that I got running from a worse state of being hence my embarrassment. That being said this machine is a completely different animal. Well that being said each I reinstalled the carbs and ..... still not much it would start but stumbles each time I pull the throttle granted this is cold and needs the choke but I thought I could do this with my XJ and my Harley surely this can too.... not so much again I freely admit totally different monster than I am used to. So fast track I finally got the bike to run a bit and got the throttle to respond sorta decently. So I replaced the spark plugs and checked for spark and it was there. I figure still an engine gotta have air; fuel and spark...... anyhow did that changed all four. Bike fired up pretty nicely they were the NGL fine wire iridium for nearly $8 a piece. Did that put the fuel and intake back together and rode it to my in-laws less than a mile away. Noticed immediately that it had a major bog down over 1700 rpm. So much so that I could up shift and engine really didn’t respond to more throttle just stumbled and kept going in its stumble. Fast track couple of weeks later I thought I must have done something wrong on the carbs because I noticed a fuel leak from carb number 4 passenger side front or right front carb. So I took it all apart to look and notice when I cleaned the jet blocks apart I swapped all the bowls around to the wrong spot to the vent tubes faced forward toward the headlight. Then tried starting after being reinstalled with the aide of my beautiful bride small hands; she hates when I say it need it was a “small hand job” but I have far snausages from working on cars and trucks all day. Anyhow she got the throttle return cable hooked to the inner right connection of the carb setup and of course I got the main throttle cable hooked up to the furthest outer and then the choke to the furthest rear connector on the left side behind the carb rack in front of the gas tank. Alright fast forward I had the carbs exposed no intake and tried the choke and no throttle and bike wouldn’t catch. Would the the catch and hiccup and backfire really really liked the back fire which should have been a really good indicator to not do what I did next. Mind you this is without the carb bowl vent tubes connected and routed under tank. I started spraying starting fluid..... stupid I know very stupid especially with the backfiring but I digress. Got it to fire and then stall and a nice mondo humongous back fire then whoosh all of sudden I have an active flame on top of my carb rack and it’s growing. Oh crap not good my wife understandably freaked out called the fire dept.... which I got lucky and put it out before they dispatched the truck but holy crap way too close! Anyhow going from that point to I think I need some serious divine knowledge to be reigned down here!! Please help I will not take things stated offensively assuming they’re going to be constructive also I am expecting to make a giant to do list on systems to check out and clean up.

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First: the CV carbs on the Venture will not perform well with an open intake. The airbox and filter must be fully installed. Closed up.
Second: if the jet block was cruddy, it is likely that the pilot circuits within the carb body are fouled, too. The pilot jet is notorious for being easily blocked.
I suggest that you need to perform a THOROUGH re-cleaning of the carbs, replacing gaskets and O-rings with new.
Attached is a pdf file for an excellent tutorial on cleaning the Mikuni BDS carbs.
 

Vmax Carb Rebuild Guide by NaughtyG.pdf

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Once I pull the carbs again I will go through them throughly; I will have to compile a list of each gasket and seal that I will need to replace. Has anyone dealt with throttle shaft seals on these carburetors or is that an XJ thing?

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These carbs have wire linkages, not a single rod that runs through the adjacent carb body.

Compared to the XJ carbs, ours are a bit more intricate/complicated but much more labor friendly. The K&L rebuild kits are high quality and have everything you'l need for a routine rebuild. Item No. 18-2879V Carb Rep Kit KLY-31 YAM:VMX12

 

Probably already been said, and if you've worked on the XJs you probably already know, but it's worth saying again.

STAY AWAY FROM CHINESE PARTS!!!

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14 hours ago, jonclark said:

Once I pull the carbs again I will go through them throughly; I will have to compile a list of each gasket and seal that I will need to replace. Has anyone dealt with throttle shaft seals on these carburetors or is that an XJ thing?

Throttle shaft seals seem not to need be ever replaced on the Mikuni BDS34/35. At least, I have never seen them replaced, although some have cautioned about too long carb cleaner soak possibly degrading throttle shaft seals.

Carb parts to replace.xlsx Throttle Shaft Seals and Cleaning.docx

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Thank you both for your very helpful input; and yes  luvmy40 I know all too well of not using the cheap Chinese parts for any Japanese carburetor set up. This weekend after I have pulled the carbs off the bike I will post my cleaning results for everyone. I will also take lots of photos so as to be able to point out any questions or any points of concern that you good folk may have for me.

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Now I am curious as far as what the rubber plugs do on the jet block? But my pilot circuit was very clean on the carburetor and the enrichment well also. And also yes I swapped them around referring to the rubber plugs. The smaller one goes into the pilot circuit and middle one takes the larger of the two or atleast according to the VMAX carburetor cleaning guide that was on the pdf from the forum. I reset my float bowl fuel levels according to the guide. And I also set the air/fuel ratio screws from bottom 2 full turns out each. I am hoping that whatever was causing the problem for the venture came out during this cleaning. I am also planning on removing the spark plugs to make sure the engine is storing excess fuel. Not likely but still worth making sure. 

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The rubber plugs actually seal the bottom of the passageway and prevent the block from sucking gas out of the float bowl. They should fit nice and tight and not be loose at all and if they are loose, they need to be replaced.

There is a place online from Canada that does sell parts for the carbs, Sirius Consolidated Inc and they web address is https://www.siriusconinc.com/search_result.php?make=2&model=Venture Royale&part=All&partno=&x=56&y=16&search=search&start=0 

This link will send you to the catalog for Yamaha Venture parts and you can look through there for different parts including carb parts.

I hope this helps.

Rick F.

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28 minutes ago, cimmer said:

The rubber plugs actually seal the bottom of the passageway and prevent the block from sucking gas out of the float bowl. They should fit nice and tight and not be loose at all and if they are loose, they need to be replaced.

There is a place online from Canada that does sell parts for the carbs, Sirius Consolidated Inc and they web address is https://www.siriusconinc.com/search_result.php?make=2&model=Venture Royale&part=All&partno=&x=56&y=16&search=search&start=0 

This link will send you to the catalog for Yamaha Venture parts and you can look through there for different parts including carb parts.

I hope this helps.

Rick F.

What if these plugs were in the incorrect location ? It appeared that the small plug was supposed to be on the pilot circuit. Would this cause an idle problem or rather a no start problem? 

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Alright an update. I got the carburetors on the bike. Took a bit for the system to prime. Multiple attempts. Then finally got her fired up. Just like some previous times bogged down when throttle up. So I decided to let it warm up. While letting bike warm up; I checked other systems I.e. the ignition system primarily the secondary ignition.

1. Found the insulator over the plug to be slightly leaking could literally feel the current zapping me from the outside while holding the plug against the crankcase this was on the left side sitting on bike. I figured I would check the other three to see if they are all participating, found the second plug not firing on back side of engine. Found the spark plug to be very very very fouled out. Cleaned the plug reconnected to wire;  fired the engine over few time to ensure some spark was coming out of plug and there was. Moved onto the right side just removing plug wires and both made big noticeable difference. 
 

2. once engine was decently at operating temperature I decided why the heck not I’ll do a running vacuum synch on the bike. So with engine still running I methodically disconnected the caps and connected my hoses per each intake manifold and installed on vacuum gauge. And wow yikes way offf! So I went to town...... 2 hours later ..... wait 2 hours what went wrong? Well that is also interesting. Got the left side closed in on each other. Went to right side; got those to close to each other. Then tried to bring each pair together or cylinder 1&2 to 3&4 . Each time I did this I would either bog the engine down so far trying to match them that the engine would literally stall; or the rpm would go so high that the engine was at like 3or 4K rpm. So I couldn’t seem to get all the cylinders perfectly balanced to each other. Oh and when I finally got the vacuum close between each pair the adjustment screw on the right side of the two adjustment screws was completely bottomed out. Which would also send the rpm thru the roof.... but hey this is atleast progress. Engine will start still bogs down most time when hitting the throttle. And also found when I rode it around putting into first the engine Boggs down when letting out the clutch. 
 

lots going on here. But I will say I am feeling optimistic about Betty; that’s what the wife and I call her “black Betty” . I am wondering if a what appears to be significantly dirty engine air filter would cause issues with any of these? Yes I do plan on replacing it next season just curious about how much of these problems could be attributed to that. Also what about the valve shims not sure with the Venture but I do know that XJ motorcycles will behave a bit eradically when the valve shims are out of spec. Any input is appreciated when constructive.

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When you had the carbs out, did you inspect the slide diaphragms?

My '83 ran like a scalded dog on three cylinders with the valves all out of whack. It popped and back fired like crazy but it idled nice and accelerated strong.

 

I wound up with a mostly new(ish) ignition system as the real problem was two bad coils, 30+ year old wires and caps and a bad ignition module.

 

The valve shims all had to be changed and I eventually rebuilt the carbs, but before that it ran pretty darn nice. Much better after the carbs and valve job, but not terrible before.

 

You weren't trying to rev it with air box off, were you? That dog won't hunt! It'll idle ok, but bog down and die if you open the throttle with the air box open or off.

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15 minutes ago, luvmy40 said:

When you had the carbs out, did you inspect the slide diaphragms?

My '83 ran like a scalded dog on three cylinders with the valves all out of whack. It popped and back fired like crazy but it idled nice and accelerated strong.

 

I wound up with a mostly new(ish) ignition system as the real problem was two bad coils, 30+ year old wires and caps and a bad ignition module.

 

The valve shims all had to be changed and I eventually rebuilt the carbs, but before that it ran pretty darn nice. Much better after the carbs and valve job, but not terrible before.

 

You weren't trying to rev it with air box off, were you? That dog won't hunt! It'll idle ok, but bog down and die if you open the throttle with the air box open or off.

My plan is to replace the coil and the wires this winter. And the diaphragms look really pretty good when I rebuilt the carburetors the looked them over and didn’t see anything obvious I put them up to a light source didn’t see any pin holes. But that doesn’t mean it’s not something else. 
i did not rev the engine with the intake all pulled apart I have heard that it will not run correctly with it off. 
 

There are 2 coils on this bike? Oh boy I suppose I will have to test them out seeing as how I had relatively weak spark on cylinder 1; although I attribute that to a battery that is low on charge. I hooked up battery in bike to my truck while running. I suppose I will test out my coils and replace the wires. Then I will go after the valve shims.

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There are 4 coils on them. You can free up enough slack in the wire harness to "swap" coils with out physically moving them to swing test if you have a dead cylinder. 

When you start on this, you will also want to relocate the CDI box. All the cool kids move them up on top of the air box. It's cooler there and better protected from the elements. Not to mention it makes it much easier to get at if need be.

If you determine the CDI is bad, there is an after market, programable replacement from a Czech company called Ignitech. They are reasonably priced and well worth the money. 

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The spark plug caps are not sealed very well to the wires.  Moisture gets in there and corrodes the copper core spark plug wire.  Usually snipping off a little wire and reinserting the wire into the cap is all that is needed to get the spark back to normal.  Very common issue with these bikes.  

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I will have to “snip” the spark plug wire first to see if that gives a “healthier” spark at the plug. While I do this I will work to relocate the CDI. I am going to put a whole bunch of fun money on the valve shims are a huge part of why my vacuum synch did not produce the usual and highly anticipated results of nice super smooth rev or throttle return; also the bike has I believe something close to 40,000 miles and I am willing to bet the p.o.  did not have this done due to him seeing an engine oil leak from the cam covers. He then parked it for years. My guess is that if the engine isn’t breathing correctly none of my efforts will be worth a damn other than the obvious cleaning things and dealing with the ignition system..... that being said thanks again everyone who has had input to the future success of this bike restoration. Look forward to someday being able to meet and ride with those who would be interested when time comes. I’ll post the results that I get when I work on the bike next.

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Glad to see another XJ’r moving up to the XVZ’s!

I believe you are on the correct path...get those valves clearenced and your carb sync will go smoother.

Just an FYI, it’s not a difficult job (but it’s also a different procedure than the XJ)...the biggest hassle is clearing all plastics out of the way (and putting them back together without breaking all the tabs...ask me how I know). Mom Yam left very little wiggle room in there consequently when I put my valve covers back on, I left a small oil leak in my front gasket (which wasn’t discovered until everything was put back together)...it’s been about 4 years and you’re motivating me to get back in there and fix it!

Also, at least for me...clearencing the valves was much easier with the carbs in the way...but then again, I was cleaning my carbs at the time. 

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16 minutes ago, Patmac6075 said:

Glad to see another XJ’r moving up to the XVZ’s!

I believe you are on the correct path...get those valves clearenced and your carb sync will go smoother.

Just an FYI, it’s not a difficult job (but it’s also a different procedure than the XJ)...the biggest hassle is clearing all plastics out of the way (and putting them back together without breaking all the tabs...ask me how I know). Mom Yam left very little wiggle room in there consequently when I put my valve covers back on, I left a small oil leak in my front gasket (which wasn’t discovered until everything was put back together)...it’s been about 4 years and you’re motivating me to get back in there and fix it!

Also, at least for me...clearencing the valves was much easier with the carbs in the way...but then again, I was cleaning my carbs at the time. 

Which XJ did you start off with? Nice o meet a fellow XJer on this forum; we have another XJer from another forum something tells me that he is on this forum as well. Not sure he goes on another forum by Hogfiddles not sure if you know of him or not.

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I'm also a member at XJBikes.com as was MiCarl. I no longer run an XJ but I logged close to 100K combined miles on my '81 Seca 750 and my '82 Maxim 750.

The Maxim is now owned by another VR member's grandson and from reports, still going strong. The Seca, sadly was sold in pieces sans blown engine as a project base.

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I was pretty active on XJBikes for a while, I had a 550 Seca, a 750 Seca, and a 750 Maxim. I used the same handle over there as I use here...patmac6075. I really enjoyed having a member who stocked and sold just about any wear part you can think of.

But just like over there, there are some really knowledgeable people who are always ready to help...I couldn’t have rebuilt my bike without the input of some really good guys!

BTW, thanks for joining and welcome aboard.

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So finally this evening I was able to do a little bit of work on the bike. As I mentioned previously I was think valve clearances were the culprit behind some really odd carb balancing on vacuum synch. Well I wasn’t able to take off the front valve cover but based off of the rear valves on the intake and the exhaust valves they are significantly out of whack. For the most part the clearances were exceptionally tight a couple of the exhaust shim clearances were approximately .08 mm instead of being between .16-.20 mm clearance.

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Trying to remember when I did my bike...pretty sure every valve shim was out of spec. I was lucky though...I was able to swap around my valves (took forever), but I only ended up needing 3 new shims. Again I’m fortunate to have a bike shop near by that was willing to swap shims at no cost.

Im certain my shims had never been done before I did them.

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1 hour ago, Patmac6075 said:

Trying to remember when I did my bike...pretty sure every valve shim was out of spec. I was lucky though...I was able to swap around my valves (took forever), but I only ended up needing 3 new shims. Again I’m fortunate to have a bike shop near by that was willing to swap shims at no cost.

Im certain my shims had never been done before I did them.

Out of curiosity; prior to having swapped around your valve shims did you have any cold start issues? Even with a nice clean carburetor setup?

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So long ago, and so many small repairs in between...it’s hard to remember.

Right away I bought a brand new AGM battery, and I bought a new heavier duty battery cable set up from a former member (Dingy), I think Skydoc sells something similar. I also swapped my old fuse panel out for a blade setup (see my write up in the maintenance section). While I was in there I pulled my carbs and cleaned them and went after my valves...this was all within the first couple of weeks of owning the bike.

Not exactly sure which of these helped or whether it was a combination of all of them together....

I can tell you this, my bike doesn’t like temps below 45...normally when it’s above 60 it starts pretty quick, but in cooler temps it takes a little more to fire it up and I need to keep the choke (enrichment circuit) on a bit longer.

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