Yes, you need a float bowl gasket. Without it, the bowl is sitting a MM or so closer to the floats and jets. That may be enough to stop the floats from dropping enough to let gas in or maybe enough to block fuel flow to the main jet. With pipes and pods, I would try 137.5 or 140 mains. And yes, get brass ones. The large round main is very common and you should be able to find them at a local shop. I have at least 3 in my area that I buy my mains and pilots from - and genuine Mikuni ones to boot.
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I've got 99 problems...and they all involve my XS
- Thread starter poorman9
- Start date
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- carburetors engine tuning
132zed
XS650 Enthusiast
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I registered just so I could get in on this. I HAD to let you know how similar our bike journey is. The only difference is that I am about 2 months ahead of you so let me share what I've learned. That being said, I am no mechanic and I just got into bikes. It was muscle cars before this and only SOME of that knowledge transferred. And the one thing I've learned is that no one can tell you how to fix your car/bike just like no one can tell you how to raise your kids. Advice should be taken with a grain of salt. Hope this helps.
The kick thing, I wouldn't worry about it. Seriously. You have an old bike and old shit happens to old bikes. I've noticed that with mine if I don't complete a full kick it will stick. Next time that happens just make sure its all the way up before you kick again. It can get frustrating after 20 mins of kicking. Just have a beer, a smoke and make sure you are kicking it all the way down and letting it come all the way up. If you have further issues with it please investigate. If not leave it be and work on something more important.
I am glad that the thread moved to your carbs. That's where your problem is. As soon as you said it would run for a few seconds but if you hit the gas it would stop I knew it was your carbs. First off, if that ever happens on just about any carb engine you probably have an air leak. Test it by duct taping the manifold/gasket. I know it sounds strange but it worked for me. It's just a test to let you know that this is AN issue. Not THE issue but AN issue.
I see you are getting good advice about your jets. The last thing I read was spot on. I won't say that you NEED a gasket but I can tell you that I benefited from finding one. I had one without and one with. It makes a difference. Thank you for including pics of your spark plugs. I can't really tell because...well..I can't rub my thumb across the bridge but one looks like it's running fat. The mixture maybe too rich. The other just looks like it got some installation nicks. Id replace them but I am of the mindset that its always worth it to replace cheap parts just incase.
I don't know the bike or carb specs but 3 turns on the fuel screw maybe a bit much. If you haven't already, look it up. It maybe more like 1 and ½ turn. I would try that first. It looks like you have already cleaned and checked the bowl, floats and jets so its time to start stepping down your jets. It's a game you have to play. Step them down and see how it runs. You already have good advice on the main jet, I would also like to say don't start any lower than a 42/45 on your idle jet.
So..this is how I think about things. You have to add up all the problems and the things you have tried. It hardly ran but when it did throttle killed it. You have good compression. You have a full battery (all 12.75 volts). You took the carb off, added starter fluid and it ran like a champ as long as you sprayed. You took the carbs apart and replaced them and now it doesn't run. Yeah..its your carbs. Now once we fix the air leak we have to figure out if its too much gas or too little. Trying to start it with throttle doesn't work (and I assume floods it), fuel screw is out 3 turns and one spark plug looks burnt up. Sounds too rich (jets too fat).
Another thought is you could have intermittent spark. That was A problem I had. The ignition coil was going out on me. That's an easy fix. I don't think that's your problem but if it where you can always cut a spark plug in half, solder on a ground wire, kick it and check the volt meter. Or if you are in the market for new wires anyway, leaving everything connected, splice into the old ones and throw on the meter. I don't recommend the last way.
And that's where I am with my bike. Been messing around with the jets. I have the perfect set up except my idle. Its too lean. The bike runs just fine but if you pull the clutch in it dies. Idle means ¼ throttle on my bike. Still working on it but atleast I can ride it as often as I like. Let me know if this helps or what you try.
The kick thing, I wouldn't worry about it. Seriously. You have an old bike and old shit happens to old bikes. I've noticed that with mine if I don't complete a full kick it will stick. Next time that happens just make sure its all the way up before you kick again. It can get frustrating after 20 mins of kicking. Just have a beer, a smoke and make sure you are kicking it all the way down and letting it come all the way up. If you have further issues with it please investigate. If not leave it be and work on something more important.
I am glad that the thread moved to your carbs. That's where your problem is. As soon as you said it would run for a few seconds but if you hit the gas it would stop I knew it was your carbs. First off, if that ever happens on just about any carb engine you probably have an air leak. Test it by duct taping the manifold/gasket. I know it sounds strange but it worked for me. It's just a test to let you know that this is AN issue. Not THE issue but AN issue.
I see you are getting good advice about your jets. The last thing I read was spot on. I won't say that you NEED a gasket but I can tell you that I benefited from finding one. I had one without and one with. It makes a difference. Thank you for including pics of your spark plugs. I can't really tell because...well..I can't rub my thumb across the bridge but one looks like it's running fat. The mixture maybe too rich. The other just looks like it got some installation nicks. Id replace them but I am of the mindset that its always worth it to replace cheap parts just incase.
I don't know the bike or carb specs but 3 turns on the fuel screw maybe a bit much. If you haven't already, look it up. It maybe more like 1 and ½ turn. I would try that first. It looks like you have already cleaned and checked the bowl, floats and jets so its time to start stepping down your jets. It's a game you have to play. Step them down and see how it runs. You already have good advice on the main jet, I would also like to say don't start any lower than a 42/45 on your idle jet.
So..this is how I think about things. You have to add up all the problems and the things you have tried. It hardly ran but when it did throttle killed it. You have good compression. You have a full battery (all 12.75 volts). You took the carb off, added starter fluid and it ran like a champ as long as you sprayed. You took the carbs apart and replaced them and now it doesn't run. Yeah..its your carbs. Now once we fix the air leak we have to figure out if its too much gas or too little. Trying to start it with throttle doesn't work (and I assume floods it), fuel screw is out 3 turns and one spark plug looks burnt up. Sounds too rich (jets too fat).
Another thought is you could have intermittent spark. That was A problem I had. The ignition coil was going out on me. That's an easy fix. I don't think that's your problem but if it where you can always cut a spark plug in half, solder on a ground wire, kick it and check the volt meter. Or if you are in the market for new wires anyway, leaving everything connected, splice into the old ones and throw on the meter. I don't recommend the last way.
And that's where I am with my bike. Been messing around with the jets. I have the perfect set up except my idle. Its too lean. The bike runs just fine but if you pull the clutch in it dies. Idle means ¼ throttle on my bike. Still working on it but atleast I can ride it as often as I like. Let me know if this helps or what you try.
irristeve
Grow old disgracfully
2 things I would be checking 1 vacume pet cock 2 advance mechanism there is a couple of ways it can go together,check that the 2 lines line up & not a 180 out
I may have posted this here but I can't find it . After tossing a hammer and driving the cat , dog , girlfriend , sister , room mate off I finally cooled off and wrote this .
I hear reoccurring themes about our motorcycles I just have to comment on .
I do have to thank our Britt cousins for the early lessons in how to start a motorcycle without getting crippled . It was a BSA 441 Victor with a wee bit more compression than stock . Some will understand Energy transfer ignition , AC lighting , back to back zener diodes and positive earth . If you don't those key words will be an interesting read .
Amal carbs have a tickler . Essentially This allows you to put a bit of raw fuel in the throat of the carb . Just because it may not be quite obvious You can substitute our mixture enrichment knob for the Britt tickler . So here is the drill . With switch off , tickle , establish tdc with the kicker (and or compression release) , hold throttle open an kick , twice , like you mean it . Find tdc again , reload the kick lever , turn the switch on and sell out on the kick lever . I can't stress enough how lame , limp , half hearted attempts at the kicker will fail to start the bike , injure the rider's ankle and pride and generally be a source of humor for weeks to come from your mates .
If you can't find or don't know how to find TDC with the kick lever have someone that does know show you . If you are the one teaching this have your student first do it by hand (with switch off of course ) and then with the foot . Be patient I've had to show this to a few that needed "several" sessions .
Vibration . So you re-phased guys can take a nap here . In something of an order I'll start with engine to chassis mounting . Leave any of the engine mounting bolts loose and not only will the shake get worse it will eventually destroy the rear mount whether it's tight or not . I don't use any locking agent on any of the mounting bolts preferring to regularly re-torque and inspect .
Pipes , mufflers , inner pipe and brackets . The stock header pipes are double wall . If the inner pipe separates at the connection to the muffler that whole 26" some length is unsupported and dancing to harmonics within . You would be surprised at the result if you ever correctly diagnose and fix this one . I just drill the outer in a couple places just ahead of the muffler joint and plug weld them . Make sure the pipe is snugged up at the head and all mounting points .
The next two will require a bit of advanced or remedial reading depending on your experience .
Valve adjust . Yes a sloppy valve adjust will introduce harmonics into the system as sure as an out of balance crankshaft . I've said it over and over again . There is one correct way to adjust valves and that is with a degree wheel and a dial indicator . The short version is when .001" of valve lash can result in a difference in as much as 5 degrees at valve opening you are sure to introduce "noise" at the crankshaft . Ignition timing . All you electronic ignition types can join the twist crank folk in a nap now . Set the set of points fixed to the plate at .014-.015 " an place a dwell meter on them . It doesn't matter what the number of cylinders is set to or what the dwell reading is as long as it's a consistent reading . Move over to the other side and make the dwell the same . Now set timing for both and check dwell again . Repeat as necessary until both have the same dwell and fall on the same spot at or near the full advance mark viewed with a timing light . Worn point pivot , mechanical advance parts and near fouled plugs can contribute to timing inaccuracies but what I described is for the most part related to vibration .
Finally , now that the mechanical and electrical is squared away tackle the carbs . . First sync then mixture . Repeat as necessary .
Look these thoughts and procedures won't eliminate vibration in the XS650 but they will reduce it .
The above starting procedure works with a near 12:1 alcoholic 750 and an ARD with just a little bit of gasoline dribbled on the filters . I have it timed on the edge of stupidity or ability to cold start without injury , fixed at 42 degrees BTDC .
I've gone on long enough here to give some food for thought . I've got some thoughts on engine operation and ignition timing for later consumption but this is enough for now .
~kop
P.S. Hot lead to the points was grounded through the tail light (don't ask) and the four hole washer in the petcock had disintegrated and had partially blocked the fuel line . Also didn't help that the rotor had partially broken the key and had slid 6-10 degrees forward ....
I hear reoccurring themes about our motorcycles I just have to comment on .
I do have to thank our Britt cousins for the early lessons in how to start a motorcycle without getting crippled . It was a BSA 441 Victor with a wee bit more compression than stock . Some will understand Energy transfer ignition , AC lighting , back to back zener diodes and positive earth . If you don't those key words will be an interesting read .
Amal carbs have a tickler . Essentially This allows you to put a bit of raw fuel in the throat of the carb . Just because it may not be quite obvious You can substitute our mixture enrichment knob for the Britt tickler . So here is the drill . With switch off , tickle , establish tdc with the kicker (and or compression release) , hold throttle open an kick , twice , like you mean it . Find tdc again , reload the kick lever , turn the switch on and sell out on the kick lever . I can't stress enough how lame , limp , half hearted attempts at the kicker will fail to start the bike , injure the rider's ankle and pride and generally be a source of humor for weeks to come from your mates .
If you can't find or don't know how to find TDC with the kick lever have someone that does know show you . If you are the one teaching this have your student first do it by hand (with switch off of course ) and then with the foot . Be patient I've had to show this to a few that needed "several" sessions .
Vibration . So you re-phased guys can take a nap here . In something of an order I'll start with engine to chassis mounting . Leave any of the engine mounting bolts loose and not only will the shake get worse it will eventually destroy the rear mount whether it's tight or not . I don't use any locking agent on any of the mounting bolts preferring to regularly re-torque and inspect .
Pipes , mufflers , inner pipe and brackets . The stock header pipes are double wall . If the inner pipe separates at the connection to the muffler that whole 26" some length is unsupported and dancing to harmonics within . You would be surprised at the result if you ever correctly diagnose and fix this one . I just drill the outer in a couple places just ahead of the muffler joint and plug weld them . Make sure the pipe is snugged up at the head and all mounting points .
The next two will require a bit of advanced or remedial reading depending on your experience .
Valve adjust . Yes a sloppy valve adjust will introduce harmonics into the system as sure as an out of balance crankshaft . I've said it over and over again . There is one correct way to adjust valves and that is with a degree wheel and a dial indicator . The short version is when .001" of valve lash can result in a difference in as much as 5 degrees at valve opening you are sure to introduce "noise" at the crankshaft . Ignition timing . All you electronic ignition types can join the twist crank folk in a nap now . Set the set of points fixed to the plate at .014-.015 " an place a dwell meter on them . It doesn't matter what the number of cylinders is set to or what the dwell reading is as long as it's a consistent reading . Move over to the other side and make the dwell the same . Now set timing for both and check dwell again . Repeat as necessary until both have the same dwell and fall on the same spot at or near the full advance mark viewed with a timing light . Worn point pivot , mechanical advance parts and near fouled plugs can contribute to timing inaccuracies but what I described is for the most part related to vibration .
Finally , now that the mechanical and electrical is squared away tackle the carbs . . First sync then mixture . Repeat as necessary .
Look these thoughts and procedures won't eliminate vibration in the XS650 but they will reduce it .
The above starting procedure works with a near 12:1 alcoholic 750 and an ARD with just a little bit of gasoline dribbled on the filters . I have it timed on the edge of stupidity or ability to cold start without injury , fixed at 42 degrees BTDC .
I've gone on long enough here to give some food for thought . I've got some thoughts on engine operation and ignition timing for later consumption but this is enough for now .
~kop
P.S. Hot lead to the points was grounded through the tail light (don't ask) and the four hole washer in the petcock had disintegrated and had partially blocked the fuel line . Also didn't help that the rotor had partially broken the key and had slid 6-10 degrees forward ....
Last edited:
poorman9
XS650 Addict
Thanks a lot for the great post, I'm soaking my carbs right now in a chem-dip soak (took all the plastics off first, don't worry). After that I'll reassemble and start working through your idea's.
I'll keep everybody posted.
poorman9
XS650 Addict
After soaking my carbs, I made some float bowl gaskets out of 1mm, gas resistant gasket material, took a while with an exacto knife and got them to line up pretty good. Now both side have (temporary) gaskets.
Reassembled the carbs, after crawling around on the floor looking for the stupid choke rod ball bearing that I almost lost, bolted it back together, kicked it a few times and is started up and ran for a few seconds, which is what it used to do, a few days ago. So that was a good step, at least it's trying to run again.
I got out the duct tape and wrapped the manifolds up real tight, kicked it, did pretty much the same thing, ran for 2 or 3 seconds, then died. If I give it any gas, it dies. I was feeling around down there for air leaks or whatever else, while I have my buddy kick it, and I'm feeling a bunch of air shooting out of this -
The book calls it a breather plate, so maybe that's what it's supposed to do? Obviously mines broken, does this matter? What should this hole attach to? Looks like just a bunch of hose in the book.
After kicking it more, no I can't even get it to try to start. I got out the starter fluid and it'll run with that being sprayed in still, but only with the choke on. Starter fluid + no choke = nothing.
I don't have access to any other jets to try. Apparently nowhere in Portland sells them.
iristeve could you explain this to me -
Reassembled the carbs, after crawling around on the floor looking for the stupid choke rod ball bearing that I almost lost, bolted it back together, kicked it a few times and is started up and ran for a few seconds, which is what it used to do, a few days ago. So that was a good step, at least it's trying to run again.
I got out the duct tape and wrapped the manifolds up real tight, kicked it, did pretty much the same thing, ran for 2 or 3 seconds, then died. If I give it any gas, it dies. I was feeling around down there for air leaks or whatever else, while I have my buddy kick it, and I'm feeling a bunch of air shooting out of this -
The book calls it a breather plate, so maybe that's what it's supposed to do? Obviously mines broken, does this matter? What should this hole attach to? Looks like just a bunch of hose in the book.
After kicking it more, no I can't even get it to try to start. I got out the starter fluid and it'll run with that being sprayed in still, but only with the choke on. Starter fluid + no choke = nothing.
I don't have access to any other jets to try. Apparently nowhere in Portland sells them.
iristeve could you explain this to me -
You don't have an advance assembly, they were only installed on points models. Yes, your breather housing is broken. A rubber hose attached there and fed oil vapors into the airbox. You can probably run like that but it will most likely make an oily mess on top of your carbs. You might be able to repair it by finding a threaded hose barb to bolt in there.
It definitely sounds like you have fuel flow problems, as in you're not getting enough. Are the bowls filling with gas? If so, maybe it's those funky plastic mains. On your carbs, the pilots pull fuel from the side, from the needle jet area - which is fed by the main. If the main's not flowing properly, it would throw everything off.
It definitely sounds like you have fuel flow problems, as in you're not getting enough. Are the bowls filling with gas? If so, maybe it's those funky plastic mains. On your carbs, the pilots pull fuel from the side, from the needle jet area - which is fed by the main. If the main's not flowing properly, it would throw everything off.
poorman9
XS650 Addict
Yeah, bowls are always full when I check by loosening off the drain screw.
I'll hopefully be getting some new jets tomorrow.
If that doesn't work, anybody wanna buy a motorcycle?
You say you cleaned your carbs but did you remove and clean the needle jets? Many overlook these and they are usually in need of cleaning. On your carbs, they will effect how both the main and pilot jets flow.
poorman9
XS650 Addict
It's been a while, but anybody still subscribed to this thread, I've posted the next of my 99 problems here -
http://www.xs650.com/forum/showthread.php?p=99691#post99691
I was working through those carb issues and decided to just buy a new (old) set of carbs from my bike junk yard. I'm in there so often the guy just loaned them to me for troubleshooting. I cleaned them up and pu them on, kick it and....well read the thread linked about.
http://www.xs650.com/forum/showthread.php?p=99691#post99691
I was working through those carb issues and decided to just buy a new (old) set of carbs from my bike junk yard. I'm in there so often the guy just loaned them to me for troubleshooting. I cleaned them up and pu them on, kick it and....well read the thread linked about.
poorman9
XS650 Addict
So much for my 99 problems, I've got the bike running!!!
Everybody that's helped out, I want to personally thank you. I've posted pictures and video here - http://www.xs650.com/forum/showthread.php?t=10291
BTW, I think what might have been causing a lot of my problems here was a stuck exhaust valve. I ended up tearing my top end back apart, and found one of the valve bent and stuck open just enough to kiss the cylinder. New valves, lap job, back together now no more deing, no more kick backs and more importantly it runs.
Everybody that's helped out, I want to personally thank you. I've posted pictures and video here - http://www.xs650.com/forum/showthread.php?t=10291
BTW, I think what might have been causing a lot of my problems here was a stuck exhaust valve. I ended up tearing my top end back apart, and found one of the valve bent and stuck open just enough to kiss the cylinder. New valves, lap job, back together now no more deing, no more kick backs and more importantly it runs.
