Sammo
XS650 Enthusiast
Bike backfires on right side only when I let of the throttle. Can ajusting valves cause this? They are all in.spec.
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deaccelleration backfire?
- Thread starter Sammo
- Start date
Gordon in nc
XS650 Junkie
A leak at the right exhaust header to head??????
Gordon in NC
1975 XS650B Stock Runner
1975 XS650B Pile-O-Parts.....but I'm gathering bits to put it back on the road too.
Sammo
XS650 Enthusiast
Just cleaned the hell out of carbs. So ruling out them. Everything is tight on the head nuts. As well as boots. Bike is running like a.champ. also though on decell the right exshaust putters as I am slowing along with loud backfire. Like firecracker
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Sammo
XS650 Enthusiast
Sprayed carb cleaner at boots, exshaust header no raise in rpms.. I got a timing light coming in mail. Not really sure whats going on here
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Pilot circuit too lean?
Sammo
XS650 Enthusiast
Its just weird cause this backfiring just came out of nowhere. Maybe like 10 miles in.after adjusting intake and.exshaust valves. That must be.the.prob? Bad exshaust valve clearence on right cylinder? Will.this cause backfire.on.letting of throttle
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angus67
Welder's penetrate deeper!!
Whats the condition of your tank? R u running a fuel filter?
Sammo
XS650 Enthusiast
Tank.doesnt have allarming amount of.rust and.yes.filter in place. I believe.im.running.rich in my.right.cylinder plug was.wet and.had.decent carbon ring
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A leak on the exhaust where it fits into the head. +1
or pilot circuit blocked or partially blocked on that side causing lean mixture when you roll the throttle off.
This is if you mean popping or burbling. If you genuinely mean backfiring look for timing or mechanical problems such as worn or improperly adjusted valves.
or pilot circuit blocked or partially blocked on that side causing lean mixture when you roll the throttle off.
This is if you mean popping or burbling. If you genuinely mean backfiring look for timing or mechanical problems such as worn or improperly adjusted valves.
Take Warning15
XS650 Addict
I would also check that the carbs are in synch.
Sammo
XS650 Enthusiast
Bench.synced the carbs. Going to adjust right cylinder valves.and see what happens.
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Could be a collection of unburnt fuel in the exhaust I suppose .?
When you adjusted the valves did you make sure that each cylinder adjusted was on its compression stroke ?
When you adjusted the valves did you make sure that each cylinder adjusted was on its compression stroke ?
Sammo
XS650 Enthusiast
Readjusted the right side.valves. they were a lil to tight I guess. No more.backfiring for now. Rode her for a good.30 min
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There ought to be a "Like" button.
Dave
Dave
Sammo
XS650 Enthusiast
Ya so ive come.to find out my bike will.either backfire or make some minor noise of the valves. Does this call for valve replacement?
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This is just my personal opinion but these are 40 year old bikes. There are some that are noisy and some that aren't. They never sounded like sewing machines when new.
If something is running fine and making a slight noise I leave it but keep and eye on it (or ear). At some point the noise will get worse probably accompanied by the bike NOT running fine anymore or it will be fine.
I've come to this opinion over many years of throwing time and money at problems that either weren't there or didn't need addressing right away.
Some years ago in the UK we went to unleaded petrol. Some older bikes and cars had valves that would eventually burn out unprotected by the new unleaded petrol. Lots of people went out and replaced their valves and valve seats immediately at great cost. Better advice was to wait and when they burned out (and if) to replace them. Run long enough a bike will need a top end job anyway. Why jump the gun?
The ideal valve gap adjustment is one where there is a gap when cold but once the engine warms up the gap goes to zero. There should at this point be no tapping noise (not of the rocker hitting the valve stem). But this is a bit of a theoretical objective.
I've heard of people adjusting the valves when hot to NO gap. I also presume its possible to adjust a running engine to the same objective (no noise in this case).
Most mass produced stuff differs in tolerances. So the valve gaps specification is a "best guess". It's changed several times over the years as Yamaha presumably tried to achieve a balance between customer feedback which said "My engine is noisy" and that which said "My exhaust valve burned out."
Dave
If something is running fine and making a slight noise I leave it but keep and eye on it (or ear). At some point the noise will get worse probably accompanied by the bike NOT running fine anymore or it will be fine.
I've come to this opinion over many years of throwing time and money at problems that either weren't there or didn't need addressing right away.
Some years ago in the UK we went to unleaded petrol. Some older bikes and cars had valves that would eventually burn out unprotected by the new unleaded petrol. Lots of people went out and replaced their valves and valve seats immediately at great cost. Better advice was to wait and when they burned out (and if) to replace them. Run long enough a bike will need a top end job anyway. Why jump the gun?
The ideal valve gap adjustment is one where there is a gap when cold but once the engine warms up the gap goes to zero. There should at this point be no tapping noise (not of the rocker hitting the valve stem). But this is a bit of a theoretical objective.
I've heard of people adjusting the valves when hot to NO gap. I also presume its possible to adjust a running engine to the same objective (no noise in this case).
Most mass produced stuff differs in tolerances. So the valve gaps specification is a "best guess". It's changed several times over the years as Yamaha presumably tried to achieve a balance between customer feedback which said "My engine is noisy" and that which said "My exhaust valve burned out."
Dave
Sammo
XS650 Enthusiast
Ive decided to lap my valves when I end up tearing down.the.engine. I got cam.chain guides to put in, valves.to lap. You think this.could.fix my dilemma with my exshaust valve probs. I.wish my hvac gauges could hook up to my carbs to.check compression lol
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Use a manometer to sync the carbs
Much more accurate. A bench sync is only a starting point.Sammo
XS650 Enthusiast
Totally agree Chris. Recommend one to get for a.fair.price?
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Sammo the first post in this thread.
http://www.xs650.com/forum/showthread.php?t=37&highlight=manometer
There are variations of the same theme. I used a 1 x 4 and have a valve on one side so I can control the fluid. . . kinda. At least it has been a while since some got sucked into the motor. Pilot jets in the tubing help the "pulsing" of the fluid.
Even if you make it fancy fancy I can't see how you could spend more than $10?
http://www.xs650.com/forum/showthread.php?t=37&highlight=manometer
There are variations of the same theme. I used a 1 x 4 and have a valve on one side so I can control the fluid. . . kinda. At least it has been a while since some got sucked into the motor. Pilot jets in the tubing help the "pulsing" of the fluid.
Even if you make it fancy fancy I can't see how you could spend more than $10?
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