Yamaha XS 650H Special II Exhaust Problems?

For what it's worth I got a case of MC oil delivered by Walmart.com at a good price, can't remember why but it was freight free? I believe I got the idea from a post on this sight as well. Hope things continue to be a positive learning experience, I'm on my third bike and comparing them to the fairer sex, the more I learn reveals how little I know. :bike:
 
I too was running into the same problem you are having, one side firing while the other was not. Only mine was running on the left and not the right side. I fixed that problem yesterday actually lol. These guys are definitely pointing you in the right direction, it is most likely in your left carb. I found that taking the mix screw, spring, washer and o ring completely out, and then squirting some cleaner thru the holes, followed by compressed air, and also squirting carb cleaner thru the enricher tube followed by compressed air, then doing a bench synch on them fixed my problem. There are plenty of threads on here about bench synching, that got me pretty darn close on the synch. I think these guys have mentioned it already but that little tiny o ring under the washer, spring, and mix screw can cause ALOT of headaches if it is missing, broken, worn, etc. The bike will NOT idle correctly if it is. Take your laptop out in the garage with you, pull up the excellent carb cleaning guide from this site, go to the pilot circuit cleaning section and walk thru it step by step. That fixed my problem, and now my bike is running like a champ. Keep at it, the more you do the more you learn, Im living proof of that lol. Cant thanks these guys enough for all the help.
 
I agree the carb guide is a good thing to take to the garage. I would print it out to take it with me. Taking the lap top to the garage would in my case get the thing dirty and it wouldn't work after.
Leo
 
It did get dirty lol but I prefer to have color pictures and be able to scroll right thru it rather then have to flip pages. Plus Im trying to convice the wife that I need a new laptop, she doesnt have to know Im speeding up its demise!
 
I just have one more question. Since I'm going to assume the cylinder was flooded, making it not fire, it's been about 6-7 months since it last turned on. Does this mean the gas that was in the cylinder leaked down into the oil? In that case I drained the oil already, and it's ready for new oil. Or does this mean when it fires up, it will still be flooded the cylinder won't fire? I'm stumped here.
 
It's rare but a cylinder holding gas CAN bend a rod. :yikes:
Never hurts to crank it over with the plugs out anytime you might have flooded it.
since the gas has washed the oil off the rings and cylinder a squirt of oil in the plug hole is cheap insurance also.
 
Okay! So I got her running today she did not want to start, had to sort of do a 2 stroke method to get her steady. Gas was leaking out the air filter box like crazy, backfire in the left side, right side started to do it after a while (Just the backfiring). Also got new oil in it too. Help!
 
Gas leaking out the filters is a stuck float due to crud or what ever in the float needle seat, or float level to high, or fuel leaking past the oring for the float seat.

Another tip, no fuel with ethanol, or a little as you can find. It attracts water and will cause head ache. Sounds like you really need to read yourself through the carb guide then take those things off and go through them again, piece by piece.
 
CDNTX650 said:
Gas leaking out the filters is a stuck float due to crud or what ever in the float needle seat, or float level to high, or fuel leaking past the oring for the float seat.

Another tip, no fuel with ethanol, or a little as you can find. It attracts water and will cause head ache. Sounds like you really need to read yourself through the carb guide then take those things off and go through them again, piece by piece.
Click to expand...

Yeah. I'll probably have to do that..

ALSO: I rode it around the block a couple times it seemed fine. UNTIL I reved it a bit and it had like a mind of its own, it'd go up to about 4k rpms and then back down and all over.. What is wrong with that?
 
What year is this bike again? Could be airleaks at the carb boots, if pilot jets are half plugged it will be lean, if it has mechanical timing advance it could be stuck. But 1980 and newer should be electronic.

Posted via Mobile
 
CDNTX650 said:
What year is this bike again? Could be airleaks at the carb boots, if pilot jets are half plugged it will be lean, if it has mechanical timing advance it could be stuck. But 1980 and newer should be electronic.

Posted via Mobile
Click to expand...

It is an 1981 xs650H

Also the left cylinder seems to be firing now which is weird, but cool. :p
 
The fuel leaking out is not a good thing, as CDNTX650 said check the float valve.
On it stop leaking that could mean that carb is not getting enough fuel. I would suggest as CDNTX650 said take the carbs off and follow the carb guide, while off, check the flow out of the petcocks. They should flow a good solid stream of fuel. On your 81 it uses vacuum petcocks, so put it in the PRI position.
Leo
 
Alright thanks guys I'll have to pull em off again. Although I'm still unsure whether it is a carb problem, after about 10ish minutes of running, going up and down the street, if I give it a rev the RPMs continue to rise until I have to shut the bike off. I know it's not a stuck throttle cable, because it snaps back and closes back to idle. Thanks again for all the help. :)
 
Generally once the bike warms up, if you blip the throttle and the rpms rise and stay there its a lean condition, its not getting enough fuel. I dont remember if you addressed this already or not, but what size jets are you running and what mods have you done? Plus one or three on going back thru the carbs, get them spotless then do a bench sych, and see where you are at.
 
I have not done any major mods to the actual bike itself, just fix what sticks out to be a problem. And it should be the stock Mikuni BS34 jets in there, I'm not sure on the size but I haven't pulled them off yet to let you know.
 
www.amckayltd.com/carbguide.pdf is a link to the carb guide. This is a good read, I often suggest you read it, print it out, read it. Have it next to you as you work on your carbs. This way you can reference it as you need it.
Having it printed out keeps a lot of crud off your keyboard.
Leo
 
For some reason the motorcycle has been running beautifully I've ridden it around the neighborhood and nothing seems to stick out except doing the carbs when I get the downtime. (It does not leak or have any problems if I start it every day-2 days) I've also crashed it already, not much damage since I got chrome slider bar on the front of the frame, just bent the one left blinker I had on the back, should of tooken that thing off, but damn these 650's are built tough. But I've got about 40 miles on her already.
 
Glad you and the bike are ok. For what its worth, sometimes all these old bikes need are to be ridden lol. Be safe on it, lucky for you that you werent damaged in the wreck. Parts can be replaced, your life cant be.
 

Similar threads

R
Another dead cylinder problem.
Replies
4
Views
596
jpdevol
jpdevol
P
Semi-generic carb theory question
Replies
8
Views
736
Pat D
P
willis
Exhaust squeak.
Replies
4
Views
678
willis
willis
T
First motorcycle and a cylinder not firing.
3 4 5
Replies
84
Views
6K
5twins
5twins
WV Sparky
Throttle stumble just after idle
5 6 7
Replies
124
Views
8K
WV Sparky
WV Sparky
Back
Top