Berdman

Will try the cleaning procedure tonight when I get home. Fingers crossed that's all the issue is. Would really like to not pull the carb off again. Thank you!

I pulled one needle (pilot screw?) completely out last night. The needles are all new, and the carb looked spotless. The guy who rebuilt it soaked it twice in an ultrasonic bath. There might still be some gunk in it?

I'm quite ecstatic! I rode the bike tonight. Had only 3 booms go off and they were minor! Two of them I pushed the start a lil hard, the 3rd was going up a hill in 3rd gear 30/25mph. I ran the carbs dry because I still plan to re jet the pilot. I dont like living on the "edge" of the bang. I hope finding smaller jets wont be too hard to do. Going down one size should be adequate I hope. I will post update as i get to it. Hopfully my findings will help some others also! I noticed the consensus with most is it's running lean, but I found mine running way to rich causing it.

Great 😖. Tomorrow I will try riding it again. Hopfully its lean enough now to be ride able. I will try replacing the pilot jet myself. I'm familiar with carbs. It's just the 4 bank is a little intimidating.

Okay for giggles I turned the pilot screws in. They are fully seated and the bike is idling fine..... I was able to see a vacuum change on cylinder 4 from fully seated to about 1/4 turn. The other cylinders had no change in vacuum. I'm thinking the bike is running way too rich, I forgot the vacuum caps after I pulled guages off and the bike was still idling fine. It was a slight boggy and when I cracked throttle it died a couple times. Is there anyone on here that specializes in these carbs? I already spent 400 to get them rebuilt. I dont think they need a full rebuild again. But I'm just curious if something was rebuilt wrong.

Thanks for the info. I was tinkering around tonight on it. Didnt notice any change in rpm when I adjusted the screws. I did open the pilots up pretty far, seemed to calm the bang in neutral. Thought I was ready to ride. But as soon as I try to start moving the rpm drops and just bang bang bang. So what i have noticed, it only backfired at low rpm(below 1100 according to my guage), I only notice it on cylinders 1&3. There is a small leak at the front and rear of the mufflers. I thought for sure the rear was a drain for water. But the front one looks to be a weld. So next I am going to pull them off and reweld and inspect them. I wouldnt think a pinhole would cause such a bad bang. I'm starting to debate if I might just part this bike out. I'm baffled as to why they would have designed a bike with this issue. Think I am realizing why this bike was abandoned.

Okay I have the new valve shims in, new cover gaskets. All is back together. I synced the carbs. It is hard to get started cold. The backfire is not as bad now. I only get it when I twist throttle too fast. At first I saw flame out of the exhaust, I have turned the pilot screws out one turn. No more flame, just black smoke on backfire. According to the vacuum guages I should be getting higher vacuum. I read somewhere that the only way to adjust the "timing" is to adjust the TPS on the carb. Should I worry about the low vacuum or leave it as is as long as carbs are synced. Should I turn the pilot screws out any more? The bike idles like a champ. It's so close to be ridden. I'm just worried about this backfire to take it out on the road.

The actual caps are still available from partzilla, or any other Yamaha part supplier. $3.47 on partzilla. I just replaced all mine.

Okay, that makes a huge difference! I got a master feeler gauge set goes down to .0015. Front Ex .005 | .006 || .005/6 | .005 IN .0025 | .004 || .003 | .003 IN .004 | .003 || .003 | .003 Ex .005 | .005 || .005 | .005 Cylinder one is TDC when lobes face inwards to each other. Cylinder 2 &4 seem to face outwards? or am I positioning the crank wrong. The 3 that are at minimum. Should I bother adjusting them? Or just leave as is. I am waiting on the valve tool to check the shims still. I was able to pull the covers with out removing the carb! Thank god!

I thought my clymers manual stated intake was .011 to .15. And exhaust was .021 to .025. Is that metric maybe? I will have to look again.

So I have the valve covers pulled. I checked the valve clearances. I cant get the smallest .008 feeler in any. So I am going with I have no clearance at all on any shim. Ordered the tool today. bike has 42k on it. Unsure if the valves have ever been checked before. A little surprised that all of them were so tight.

Thank you for the info! At the moment one of the guages is broken. So looks as I will be buying a new set. That must be what the extra pieces were for in the kit.

I was worried about that! I just replaced the coolant. I wonder if maybe it was residual overflow from letting the air out of system. I really hope that is the case. It's on low side of engine. So if it burped up and ran under the crome cover. I really hope that is the case 😖

I should clarify its the valve cover gasket that is leaking. Not the head gasket.

I have a 96 xvz13. I noticed it was very sensitive to get it into neutral. Fresh oil, new clutch and slave seals. bled out twice. This was the first time I ran the bike. But I would think its just very touchy to find neutral.