jonclark

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?

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.

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.

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.

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.

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.

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?

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.

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.

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?

Where can I find new gaskets and o-rings for the recleaning/ overhaul? At my local Yamaha dealer? Or another source?

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.