Gmorrone1214
XS650 Addict
Hey guys, just got my bike to start finally. Once it starts it goes to 4k rpms and stays at that with the idle screw all the way out. What could be the problem.
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High RPm
- Thread starter Gmorrone1214
- Start date
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- Tags
- carburetors
DIRTY DOG
XS650 Guru
okkkkkk what is it?? year? what carbs? ignition?exhaust?? stock hardtail .... need more info
Gmorrone1214
XS650 Addict
xs650 1979 with bs38 carbs , stock ignition , exhaust ^^
Also just cleaned out the carbs and replaced the floats and float needle, kick started on 1 kick been sitting 5 years...
DIRTY DOG
XS650 Guru
ok it's sounds like it's running lean what air filters are on it the wrong filters will cause problems,or a vacuum leak around the carbs holders would be a good start
Gmorrone1214
XS650 Addict
got pod filters , not sure the brand , dont have a pic right now sorry, but they are red and kinda pointy shaped. I could check for the vacuum leak around the carb holders tomorrow. its 10:48 atm . WOuld the carbs out of sync like 5TWINS stated?
If synch. is badly out of adjustment due to full disassembly of the carbs, random
tweaking, etc., remove the slides and sight through the venturi at a light source,
adjusting the throttle plates for equal openings; this should be close enough to start the
machine and proceed with adjustment. On early machines the throttle stop ("idle")
screws (see Appendix, item 12) are used to adjust the throttle plates. Later carburetors
use a synchronizing screw, located between the carburetors (see Appendix, item 12).
Turning the screw clockwise opens the throttle plate on the right hand carburetor;
turning counterclockwise closes it.
^^ if this is the case I have the idle screw backed out all the way and it still idles high so would that matter.
Also it states to sync while its running at 1,500 rpms and pull a sparkplug out to sync but the bike wont idle that low so this is also out of the equation.
If synch. is badly out of adjustment due to full disassembly of the carbs, random
tweaking, etc., remove the slides and sight through the venturi at a light source,
adjusting the throttle plates for equal openings; this should be close enough to start the
machine and proceed with adjustment. On early machines the throttle stop ("idle")
screws (see Appendix, item 12) are used to adjust the throttle plates. Later carburetors
use a synchronizing screw, located between the carburetors (see Appendix, item 12).
Turning the screw clockwise opens the throttle plate on the right hand carburetor;
turning counterclockwise closes it.
^^ if this is the case I have the idle screw backed out all the way and it still idles high so would that matter.
Also it states to sync while its running at 1,500 rpms and pull a sparkplug out to sync but the bike wont idle that low so this is also out of the equation.
DIRTY DOG
XS650 Guru
yes 5twins is corect but eye ball it to start with will get it close, what I do may or may not be right but it works for me... I set them both by eye when the left is just closed with the Idle screw set low adj. the right to the same spot or set the idle screw mid way use a drill bit shank to mesure the opening( on the left carb) then adj the right to match then drop the idle screw down. make sure the both move together this may get it close. the do the filters have a rubber lip in side the lip will block of the ports on the back of the carbs.tri with out the filters it may help.
NONclow
Confirmed Laquer Breather
Possible sticking advance unit??
tonyc
XS650 Guru
Check the simplest, less expensive, and less work to do first. Cable adjustment,throttle,sticky advance mechanism.
Posted via Mobile
Posted via Mobile
jd750ace
Front Toward Enemy
The advance unit springs on my 79 were so weak, it didn't "stick", it just could not pull them back in.
The Pamco never sticks!
The Pamco never sticks!
Gmorrone1214
XS650 Addict
Well I resyn the carbs , seems like the butterfly valves were not aligned properly and one was open a little too much. Much better now. I noticed that once and a while when I reved the bike the rpms sometimes stayed high and then slowly came back down.
Also there was white -ish smoke coming out the exhaust. Smelt of Burt....something not sure. What do you think?
Thanks guys.
Also there was white -ish smoke coming out the exhaust. Smelt of Burt....something not sure. What do you think?
Thanks guys.
For carbs read this, www.amckayltd.com/carbguide.pdf
Leo
Leo
Gmorrone1214
XS650 Addict
So i just installed the PAMCO and wired it up. Yesterday it was ideling perfectly. Today I started it to run it, and the idle is going wacky. It just goes up prob at 3-4k rpms and stays there and I have to shut the bike off. Sometimes when I kick it smoke comes out the intake, carbs.
I also have the E advance on the bike, and lubed serviced the advance rod with molly grease.
I also synched the butterfly valves
No leaking around the carb boots.
I start the bike and the rpms shoot up immediately, also backed the idle screw completely out and its still revving high. High as is 3k+
I also have the E advance on the bike, and lubed serviced the advance rod with molly grease.
I also synched the butterfly valves
No leaking around the carb boots.
I start the bike and the rpms shoot up immediately, also backed the idle screw completely out and its still revving high. High as is 3k+
jd750ace
Front Toward Enemy
If you have not vacuum synched the carbs, it ain't synched. The only way it'll run that fast at "idle" is with a big dose of air getting into it. Did you set up the advance with a timing light?
Gmorrone1214
XS650 Addict
Vacuum sync? What and how?
Yeah I have the same guess that there is a air leak somewhere. Yes timing is perfect with light. Sprayed the carb boots and nothing. Thinking throttle shaft seal? Can I tell if this is bad by eye when removed?
Yeah I have the same guess that there is a air leak somewhere. Yes timing is perfect with light. Sprayed the carb boots and nothing. Thinking throttle shaft seal? Can I tell if this is bad by eye when removed?
pamcopete
Ride.Enjoy.Life is Simple
If you have carb boot vacuum barbs with nothing connected to them, the resulting lean mixture can cause high revs.
Gmorrone1214
XS650 Addict
Yeah I have the vacuum barbs , thats what attaches to the percocks correct. I have hoses on them with bolts pluging them.
Gmorrone1214
XS650 Addict
Also Im guessing I should upgrade the pilots and mains. Pilot is #25 and mains are 122.5
Should I go with the 27.5 or 30# pilots and for mains...125 or 127? thanks. Still having the problem with the high rpms. Just opened the carbs and recleaned everything still looked good. Also shot carb clearner around the butterfly valves and nothing happened. Still lost at what this could be.
Also the bike Is only running with the choke on, however I cleaned the pilot circuts and nothing was clogged. Going to try and start again. Any other suggestions to why its only starting with the choke on?
Should I go with the 27.5 or 30# pilots and for mains...125 or 127? thanks. Still having the problem with the high rpms. Just opened the carbs and recleaned everything still looked good. Also shot carb clearner around the butterfly valves and nothing happened. Still lost at what this could be.
Also the bike Is only running with the choke on, however I cleaned the pilot circuts and nothing was clogged. Going to try and start again. Any other suggestions to why its only starting with the choke on?
You say your bike is a '79 but from the jet sizes you've found in your carbs, it would appear you have a '76-'77 carb set. Now, I've said this probably about a million times before but I guess I need to say it again - you must positively I.D. the year of the carb set you're working with in order to properly re-jet it. Re-jetting is based on what was stock in that year carb set, not the year of the bike.
If you actually do have a '76-'77 carb set, it came with very small mains (those 122.5's), the smallest ever put in a 650. They work fine on a stock bike but are quickly out-paced if you have mods. While many of the other carb sets may be fine with just one or two sizes up on the mains, this set usually needs more. My recommendation would be one up on the pilots, needles leaned a step, and 130 or 132.5 mains.
But, before you do any jet buying, we have to I.D. those carbs. If they are '78-'79 carbs then the sizes I just recommended won't work.
What you will want to buy is new air filters. Get UNI UP4200s or UP4200STs (dual layer). You'll never get it tuned right or as well as it could be using cheapo pods.
The motor racing and hanging around 3K could still be a sync issue or it could be the carbs being so lean (still jetted stock with mods). To investigate the sync issue, back the idle speed screw on the left carb out so it's not touching the cable arm, then start adjusting the sync screw between the carbs in and out. I can't tell you which way to turn it as it could be off either way. Try both and see if either starts bringing the revs down. If it does, you've got a sync issue, if not it could be the too lean issue.
If you actually do have a '76-'77 carb set, it came with very small mains (those 122.5's), the smallest ever put in a 650. They work fine on a stock bike but are quickly out-paced if you have mods. While many of the other carb sets may be fine with just one or two sizes up on the mains, this set usually needs more. My recommendation would be one up on the pilots, needles leaned a step, and 130 or 132.5 mains.
But, before you do any jet buying, we have to I.D. those carbs. If they are '78-'79 carbs then the sizes I just recommended won't work.
What you will want to buy is new air filters. Get UNI UP4200s or UP4200STs (dual layer). You'll never get it tuned right or as well as it could be using cheapo pods.
The motor racing and hanging around 3K could still be a sync issue or it could be the carbs being so lean (still jetted stock with mods). To investigate the sync issue, back the idle speed screw on the left carb out so it's not touching the cable arm, then start adjusting the sync screw between the carbs in and out. I can't tell you which way to turn it as it could be off either way. Try both and see if either starts bringing the revs down. If it does, you've got a sync issue, if not it could be the too lean issue.
Gmorrone1214
XS650 Addict
Yeah sorry the bike is a 79 but now that I checked the jet main #s and needle jet is z-8 the bike has 76-77 carb set on it. I will order the parts you listed above I have the crap KnN that has the lip on the inside which blocks the ports.
You stated to adjust the sync screw, do this while the bike is running I am guessing?
I will do this and get back to you. If this does nothing you believe it is just the jetting?
You stated to adjust the sync screw, do this while the bike is running I am guessing?
I will do this and get back to you. If this does nothing you believe it is just the jetting?
