Finally got the bike started sort of I have to keep on the gas or it just dies out. Cam chain,valves are to spec timing is close so I noticed the left pipe getting real hot quick and changing color. So I pulled the plugs the right was fine but left was black. Just not sure of this issue bs38 carbs uni filters and long exhaust but no baffles this is my first bike so I'm new at this.
-
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.
Help
- Thread starter bsimmons
- Start date
-
- Tags
- carburetors
hobodictator
XS650 Member
have the carbs been cleaned? I would assume the black plug means it was running rich on that cylinder
have you adjusted the valves and timing correctly ?
Apart from possible fuel delivery or ignition issues it sounds like the valve timing might be off or an exhaust valve not seating perhaps?
http://www.650central.com/fsetting_the_valves_on_an_xs650.htm
Apart from possible fuel delivery or ignition issues it sounds like the valve timing might be off or an exhaust valve not seating perhaps?
http://www.650central.com/fsetting_the_valves_on_an_xs650.htm
I take it you adjusted the valves in each cylinder with the cylinder on compression stroke yes ?
ok well tell us a little about your bike !
Is it pre 79 or after ? does it have combined rect and regulator ? does it have a TCi ?
Does it have mechanical or a electronic ignition system ?
What have you already checked by substitution ? coils ? plugs ? plug leads ?
ok well tell us a little about your bike !
Is it pre 79 or after ? does it have combined rect and regulator ? does it have a TCi ?
Does it have mechanical or a electronic ignition system ?
What have you already checked by substitution ? coils ? plugs ? plug leads ?
It's a 79 with all new mikes pma pamco kit electronic ignition I just had to set the cam sprocket over about a tooth it was off and wasn't starting at all so I got that handled so my timing might be a bit off still the coil plugs and wires are all new as well but ill double check to make sure there tight but I'm positive they are. I'm running uni filters on carbs and my pipes run all the way back on my frame but no baffles.
Been reading on the tech section for 2 days now and only thing that's making Sence it the pilot screw might need cleaned mind you I've had them apart 3 times already cleaning.
Plug wise I have b8es plugs might be wrong but I was gonna switch those today to another size. But when I took them out the left plug was black and the pipe had changed color quick. But the right side was good. Thanks
Been reading on the tech section for 2 days now and only thing that's making Sence it the pilot screw might need cleaned mind you I've had them apart 3 times already cleaning.
Plug wise I have b8es plugs might be wrong but I was gonna switch those today to another size. But when I took them out the left plug was black and the pipe had changed color quick. But the right side was good. Thanks
hobodictator
XS650 Member
i had a very similar problem. Had to run the enrichener (choke) to keep it running. Ended up blackening the plug on one side becaue it wasnt clogged. Cleaned the carbs twice. Turns out i didn't clean them well enough the first time because on the second i found gunk in the pilot circuit that I missed. How did you clean them?
hobodictator
XS650 Member
plugs are an issue as well, too cold. throw some bp7es's in there and see how much it helps. You also really want to blow compressed air through after the carb cleaner and wires as well.What jets and mix screw settings do you have ?
hobodictator
XS650 Member
jets will have the sizes stamped on top of them.
http://www.amckayltd.com/carbguide.pdf - This is the bible for these carbs. It will tell you all you need to know. Just off of memory, you want the mix screws 2.25 turns out.stock jets should be 135 main and 27.5 pilot. With your filters and exhaust i would reccomend rejetting as per the carb guide. Grab those new plugs and doublecheck everything in your carb. It'll at least run with stock jetting and then go from there
http://www.amckayltd.com/carbguide.pdf - This is the bible for these carbs. It will tell you all you need to know. Just off of memory, you want the mix screws 2.25 turns out.stock jets should be 135 main and 27.5 pilot. With your filters and exhaust i would reccomend rejetting as per the carb guide. Grab those new plugs and doublecheck everything in your carb. It'll at least run with stock jetting and then go from there
Plugs either run cooler or hotter depending on the required burn characteristics you need. If you have valve/timing/fuel/ignition problems, changing plugs isn't going to help
at best it might disguise the symptoms of the faultThe reason I asked about your valve settings is because if the exhaust valve wasn't seating properly in the hot cylinder that would cause the exhaust and header to run very hot on that cylinder. A burnt exhaust valve can make the exhaust glow cherry red ! ask me how I know
is the other cylinder firing normally and the exhaust getting normal temperature ?
You have a good strong spark to both plugs yes ?
and both cylinders are receiving fuel yes?
Is the sooty plug wet with fuel after running ? or is it just dry sooty ? is there any blue smoke from either exhaust when running ?
We can see nothing so you need to be our eyes and ears. Pictures and video would be mighty helpful for diagnosis
hobodictator
XS650 Member
he's had another thread checking most of the valve and timing issues, his cam chain was of a tooth. from a brief glance over there http://www.xs650.com/forum/showthread.php?t=29705 that's where i assumed he got the valves and timing set. so not it would either be spark and/or fuel right? just offering what little info i know 
ahh I see....thanks for the link
Its difficult to keep track when folk post several threads on a related problem. Much information gets missed and there is some duplication
Its difficult to keep track when folk post several threads on a related problem. Much information gets missed and there is some duplication
There about 2 different issues one was getting it started witch got solved now is trying to get to idle and run I just figured I'd post what the issue is in the right area. Sorry just trying to get my situation figured out
hey no worries !
its a common assumption but actually the two issues are likely to be very related issues but if in doubt you could always include a link to the other thread so that any relevant information posted in that thread can be seen by anyone trying to help in this thread
Things like bike model year, new parts, upgrades , tests already done etc.
edited to remove unwarranted comment. Apologies
You say the timing and valve settings are ok but judging by the mess you made of the cam timing in the other thread I don't think you can be so certain.
For your engine to start and run you need 3x things fuel and air, compression and a spark at the right time its that simple !
If your plugs are dry and it only starts with starter fluid then your carbs are not supplying fuel ! find out why.
If the engine is only running on one cylinder as you describe then either you are not getting fuel and air to the dead cylinder or no compression (possibly due to valve not correctly set ) or you are getting no spark or a spark at the wrong time (timing out).
Last edited:
