Im getting Cold exhaust from left cylinder. I checked my spark and it looks strong in both, and switched my leads. My compression is 90 in each side. While it was running i pulled the lead from the plug on the left and it kept running with no change what so ever. I pull the right and the motor dies instantly.
-
Enjoy XS650.com? Consider making a donation to help support the site.
XS650.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
Cold exhaust. Back fires. All in the left cylinder.
- Thread starter alex f
- Start date
Don't know if 90 is enough to run reliably. But if it is, you have compression and spark, so the only thing left is carb. Might try revving it high and if it's the pilot circuit that's messed up it should run then.
I figure it may be a carb issue but i feel like it may be unlikely because my jets are all under 100 miles new
I do get a warmer exhaust with sone throttle tho. Also i do need to look into my compression as well. I have ridden it but it deffinatly lacks the power it should have
Spray some carb cleaner around that LH carb and intake see if it revs up. then try a shot in the intake. The most common cause of any problem is the last part you fixed. Not a personal slam just generally true.
DanielBlack
XS650 Junkie
90psi is very far from ideal. 130-150 is normal. My bike also has 85-90psi but runs pretty well albeit not as strong as she could. As I understand it, having even low compression shows that the motor has worn evenly and worked evenly through much of its service. Good news for parts such as the crank when the inevitable motor overhaul comes around.
Until then, I'd follow the experts' advice with a manual or two.
What year? Ignition type? Stock?
Until then, I'd follow the experts' advice with a manual or two.
What year? Ignition type? Stock?
All new jets mean little if the tiny passages from them to the engine are plugged. www.amckayltd.com/carbguide.pdf is our carb bible. read it, print it out, read it. Read it again.
Did I mention the carb guide and to read it?
If not you should.
This is a kinda funny way to express the need to understand your carbs better. The carb guide will help.
A lot of us had the same issues when we first started working on these bikes. We even had the carbs of several time to clean them. Some of us a little slow took 5 or 6 times before we got the clean.
The carb guide has a step by step tear down clean, inspect reassemble and adjust routine. The enricher and idle circuits have very tiny passages that are hard to get clean. Lots of spray can carb cleaner and compressed air is what it takes.
Ultrasonic cleaner work good too. The gallon cans of cab dip work good too but you have to tear them down even further. There are some rubber seal on the throttle shafts that the carb dip can eat away. This causes more problems that can be avoided by the spray cleaners.
Leo
Did I mention the carb guide and to read it?
If not you should.
This is a kinda funny way to express the need to understand your carbs better. The carb guide will help.
A lot of us had the same issues when we first started working on these bikes. We even had the carbs of several time to clean them. Some of us a little slow took 5 or 6 times before we got the clean.
The carb guide has a step by step tear down clean, inspect reassemble and adjust routine. The enricher and idle circuits have very tiny passages that are hard to get clean. Lots of spray can carb cleaner and compressed air is what it takes.
Ultrasonic cleaner work good too. The gallon cans of cab dip work good too but you have to tear them down even further. There are some rubber seal on the throttle shafts that the carb dip can eat away. This causes more problems that can be avoided by the spray cleaners.
Leo
Its an 82 with tci. Pretty much stock.
Bob Kelly III
Ranch Kid from way back,.... that got Old !
thanks 5Twins you took the words right out'a my mouth ! they are easily damaged by pulling the spark plug cap off the spark plug when it's idling
if that cyliinder is not firing even at higher RPMS when its on the stand then it's 1. either not firing at the plug, or not firing at the right time.
or.2. not getting fuel..... or .3. a bad sparkplug..... 1 in 4 can be Good right out of the box, the rest bad !!!!!! check the plug for fireing after pulling the spark plug leads they may not be firing now.... if not you blew the coil. ( or the handle bar switch is on the OFF position)
it could be that there is water in your gastank and it got into the left carb, they quit working when that happens... you can suck it out by getting it running and slap your hand over the carburator intake for a second if you get it to fire on that cylinder when you do that, its a carb problem !!!!!
.... I am assuming the engine is just worn and its not the valves being too tight which is the reason for the low compression reading.....
as gggGary aluded to...check for Vaccuum air leaks, the left cylinder has the vaccuum port for the petcock on it.... sprey the carb cleaner around all connections of that carb with it idling if it speeds up you found your leak !
the vaccuum petcock can be an unseen source of a vaccuum leak as well not very common but it does happen from what I hear.
these engines run on very low vaccuum compaired to the cars you drive so the carburators have to be excepionally clean to operate correctly
... it took me 5 tries of pulling the carbs to get mine done..... this last tiime i went through them with a fine toothed comb and I still don't know if it'a right or not ! cuz I need another sparkplug !!!!
5 days till sparkplugs gggGary ! LOL !
hope this helped
Bob..............
if that cyliinder is not firing even at higher RPMS when its on the stand then it's 1. either not firing at the plug, or not firing at the right time.
or.2. not getting fuel..... or .3. a bad sparkplug..... 1 in 4 can be Good right out of the box, the rest bad !!!!!! check the plug for fireing after pulling the spark plug leads they may not be firing now.... if not you blew the coil. ( or the handle bar switch is on the OFF position)
it could be that there is water in your gastank and it got into the left carb, they quit working when that happens... you can suck it out by getting it running and slap your hand over the carburator intake for a second if you get it to fire on that cylinder when you do that, its a carb problem !!!!!
.... I am assuming the engine is just worn and its not the valves being too tight which is the reason for the low compression reading.....
as gggGary aluded to...check for Vaccuum air leaks, the left cylinder has the vaccuum port for the petcock on it.... sprey the carb cleaner around all connections of that carb with it idling if it speeds up you found your leak !
the vaccuum petcock can be an unseen source of a vaccuum leak as well not very common but it does happen from what I hear.
these engines run on very low vaccuum compaired to the cars you drive so the carburators have to be excepionally clean to operate correctly
... it took me 5 tries of pulling the carbs to get mine done..... this last tiime i went through them with a fine toothed comb and I still don't know if it'a right or not ! cuz I need another sparkplug !!!!
5 days till sparkplugs gggGary ! LOL !
hope this helped
Bob..............
DanielBlack
XS650 Junkie
It sounds like the bike is pretty new to you. Have you a manual yet? Haynes, Clymer, or preferably factory service? That should be your first step to getting her up to snuff. Next is this forum's tech section. There's guides for bringing home a new bike and that's also where you can find the carb guide Leo linked to. Check out the Buying Guide and General Troubleshooting.
http://www.xs650.com/pages/tech/
Next, the various members' build threads. You'll pick up untold numbers of tips and tricks by reading those. The forum's search feature will help find threads applicable to the issues you may come across.
Re: 5twins' warning. You'll want to get yourself a spare old plug and wire up an alligator clip to it. That way you can clip it to the outside of the motor, grounding it. This will come in handy once it's time to set your mixture screws. You'll be able to safely use the dead cylinder method.
But you have a thorough carb cleaning, shakedown, and proper tuneup to do before you get to the mixture adjustment.
http://www.xs650.com/pages/tech/
Next, the various members' build threads. You'll pick up untold numbers of tips and tricks by reading those. The forum's search feature will help find threads applicable to the issues you may come across.
Re: 5twins' warning. You'll want to get yourself a spare old plug and wire up an alligator clip to it. That way you can clip it to the outside of the motor, grounding it. This will come in handy once it's time to set your mixture screws. You'll be able to safely use the dead cylinder method.
But you have a thorough carb cleaning, shakedown, and proper tuneup to do before you get to the mixture adjustment.
SlowMaintenance
'76 XS650 Chopper
Having a similar issue myself, I'll be watching this thread closely. Best of luck to you!
yeah it is. i put it together from bits and pieces over the last year. got the clymer manual. im gona clean carb and check up on my pilot circut. i really dont think its ignition related.
Thanks man. Im gona give all this a shot after i get out of work tonight. I really wana lean tward it being a carb issue bassed off of the fact that it fires up with some throttle. As far as my spark it actually looked real strong and consistant when i checked it. But then again im new to the wonderfull world of combustion so i really dont know how it's soposed to look
Bob Kelly III
Ranch Kid from way back,.... that got Old !
my bike is running and idling on both cylinders now.... but the right cylinder is trying to drop out sometimes....
and it is a major knock-down drag out fight to get that beast started !!!!!!
I had the carbs out and made sure all the pilot and choke passages were not plugged too....
if I put the choke on first thing , like you should have to to get it started it will go Vroom and then die and never hit again !
carb cleaner is the only way after that..... and for the life of me I do not know what's up
after I had it going and warmed up the right cylinder started fireing so I adjusted the air screws a bit.... wound up pulling the tank back off and setting the air screws at 3 1/4 turns out from their seat.... I did not do the "dead cylinder test" I was going to but decided to try to adjust them just by listening to it run at idle and you can get it purdy darn close that way too it seams...as long as both cylinders are fireing and one doesn't stop fireing !
anyway ..... time to replace sparkplugs and give it another go and do the "Dead cylinder test on it" and see if that changes anything
but I seriously doubt that will help the starting !
I'm going to do a search here on Starting ishues!
later all !
Bob.........
and it is a major knock-down drag out fight to get that beast started !!!!!!
I had the carbs out and made sure all the pilot and choke passages were not plugged too....
if I put the choke on first thing , like you should have to to get it started it will go Vroom and then die and never hit again !
carb cleaner is the only way after that..... and for the life of me I do not know what's up
after I had it going and warmed up the right cylinder started fireing so I adjusted the air screws a bit.... wound up pulling the tank back off and setting the air screws at 3 1/4 turns out from their seat.... I did not do the "dead cylinder test" I was going to but decided to try to adjust them just by listening to it run at idle and you can get it purdy darn close that way too it seams...as long as both cylinders are fireing and one doesn't stop fireing !
anyway ..... time to replace sparkplugs and give it another go and do the "Dead cylinder test on it" and see if that changes anything
but I seriously doubt that will help the starting !
I'm going to do a search here on Starting ishues!
later all !
Bob.........
DanielBlack
XS650 Junkie
I'd think it's possible, but start at the beginning. Clean those carbs. Follow the carb guide. Check all parts and specs. Set cam chain tension, valve lash, timing, mixture, then sync. Skipping the first steps will just make you frustrated and it's all general maintenance anyway.
Bob Kelly III
Ranch Kid from way back,.... that got Old !
First and formost I alwayse replace sparkplugs because they are the first thing to go and give you trouble.... spark plugs can break down under compression some times that's why it's best to just replace them and see if it runs any better....
I assumed you already did this but that was stupid of me Sorry....
go buy 5 or 6 spark plugs and replace both of the plugs in the bike and try it..... chances are it'll run fine for a while and one of the plugs will crap out on you but that's ok because you bot a few extras !
.....
I have searched this site from top to bottom and found nothing on Hard starting ...any one got a link for me ? Please !
.....
Bob.........
I assumed you already did this but that was stupid of me Sorry....
go buy 5 or 6 spark plugs and replace both of the plugs in the bike and try it..... chances are it'll run fine for a while and one of the plugs will crap out on you but that's ok because you bot a few extras !
.....
I have searched this site from top to bottom and found nothing on Hard starting ...any one got a link for me ? Please !
.....
Bob.........
Twitchknaf
XS650 Member
New myself to the xs650 but I went through the same issues, dead left cylinder then hard starts
Carbs where not cleaned properly was my left cylinder issue after triple checking valves and cam chain
As for your hard start I would look into timing my advance plate was destroyed putting my timing way out of whack, and make sure your vacuum ports are plugged or hooked up correctly if so equipped, massive air leak low float height fuel not flowing from the petcock
After doing all the above my 78 fires on the first kick
Carbs where not cleaned properly was my left cylinder issue after triple checking valves and cam chain
As for your hard start I would look into timing my advance plate was destroyed putting my timing way out of whack, and make sure your vacuum ports are plugged or hooked up correctly if so equipped, massive air leak low float height fuel not flowing from the petcock
After doing all the above my 78 fires on the first kick
