CB350 Sly... Now with 2 finger braking!!!
- Thread starter overdraft
- Start date
overdraft
Coast to Coast
Re: CB350 Sly... it was fun while it lasted
ok, changed the oil, reset the tappets (only one needed adjustment, none were tight) checked the timing and got it to start (barely) but it only runs at half to full throttle. anything under 5 grand and it's on it's way to a stall unless you blip the throttle like crazy. if you don't catch it in time it runs slower and slower and then kinda pops out of the carbs and stalls.
so... could it be carbs? i mean if brand new Mikuni VM30's will go to almost total failure after what, 10-20 hours of operation? then they're pretty shitty carbs...
could it be the cam chain slipping a tooth? i don't even know if this is possible, but it might explain the almost instant change from sweet running to piece of shit. the check/fix on this requires engine removal so i don't want to go down this road if it's not possible/likely...
any input appreciated!
ok, changed the oil, reset the tappets (only one needed adjustment, none were tight) checked the timing and got it to start (barely) but it only runs at half to full throttle. anything under 5 grand and it's on it's way to a stall unless you blip the throttle like crazy. if you don't catch it in time it runs slower and slower and then kinda pops out of the carbs and stalls.
so... could it be carbs? i mean if brand new Mikuni VM30's will go to almost total failure after what, 10-20 hours of operation? then they're pretty shitty carbs...
could it be the cam chain slipping a tooth? i don't even know if this is possible, but it might explain the almost instant change from sweet running to piece of shit. the check/fix on this requires engine removal so i don't want to go down this road if it's not possible/likely...
any input appreciated!
axeugene27
Over 1,000 Posts
Re: CB350 Sly... it was fun while it lasted
Your coils might be shot. Mine have given me nothing but shit. One coil fires only once the thing gets up to speed. Does it seem like only one cylinder is firing once it starts to bog? even if you have spark it may be the case. Just a thought as that is what i am going through.
Your coils might be shot. Mine have given me nothing but shit. One coil fires only once the thing gets up to speed. Does it seem like only one cylinder is firing once it starts to bog? even if you have spark it may be the case. Just a thought as that is what i am going through.
overdraft
Coast to Coast
Re: CB350 Sly... it was fun while it lasted
ya, coils are brand new... but it's definitely one side (right) that's the problem... choke to start it even though it's hotter than hell, then keep the revs up and it's ok... try to let it down to idle and it starts backfiring through the pipe and the right carb... if you don't catch it in time it dies and white smoke pours out of the right carb... I'm sure that means something but I just don't know what...
ya, coils are brand new... but it's definitely one side (right) that's the problem... choke to start it even though it's hotter than hell, then keep the revs up and it's ok... try to let it down to idle and it starts backfiring through the pipe and the right carb... if you don't catch it in time it dies and white smoke pours out of the right carb... I'm sure that means something but I just don't know what...
axeugene27
Over 1,000 Posts
Re: CB350 Sly... smoke out of the carb?
Yeah my coils are new too. Don't rule that out till you have tested that cylinder with the other coil.
Yeah my coils are new too. Don't rule that out till you have tested that cylinder with the other coil.
overdraft
Coast to Coast
Re: CB350 Sly... smoke out of the carb?
ok, swapped the carbs... the problem stayed on the right side.... swapped the coils... the problem stayed on the right side... so what are we left with? right cylinder backfires through the pipe and carb at medium low speed, doesn't run at all at idle, but does run at mid or larger throttle opening without issue...
arghhhhhhh!!!!
ok, swapped the carbs... the problem stayed on the right side.... swapped the coils... the problem stayed on the right side... so what are we left with? right cylinder backfires through the pipe and carb at medium low speed, doesn't run at all at idle, but does run at mid or larger throttle opening without issue...
arghhhhhhh!!!!
HerrDeacon
Over 1,000 Posts
Re: CB350 Sly... smoke out of the carb?
Is the timing correct for the right side? Points look good? Also, wondering if the points (especially right side) is shorting out against the points cover. Its a known problem. Take it off and see if it makes a difference. Do you have the throttle cable properly sync'd to open both carbs the same at the same time?
Also, hows the compression in both cylinders?
overdraft said:
Is the timing correct for the right side? Points look good? Also, wondering if the points (especially right side) is shorting out against the points cover. Its a known problem. Take it off and see if it makes a difference. Do you have the throttle cable properly sync'd to open both carbs the same at the same time?
Also, hows the compression in both cylinders?
Maritime
Over 10,000 Posts
Re: CB350 Sly... smoke out of the carb?
Very well could be points, they can just slip and go from running awesome to running like shit in seconds. Also the grounding out on the plate can be an issue if one of the fiber washers breaks or the clamp screw loosens on a wire and it twists to make contact with the backplate etc. you can have all kinds of shitty running issues. Sometimes a thicker gasket is needed to move the cover away if the gasket is worn and they arc. Check them and you very well could find your problem. I went to my local metric fastner supplier and swapped all the screws in my points system from the crappy phillips heads to hex in ss and have had a much better time having my plates and points stay put and in time. Worth the 15.00 I spent and I bought a double set so if any get even a bit stripped or worn when I do the timing I throw them away and replace. Good luck you should be able to find the issue.
Very well could be points, they can just slip and go from running awesome to running like shit in seconds. Also the grounding out on the plate can be an issue if one of the fiber washers breaks or the clamp screw loosens on a wire and it twists to make contact with the backplate etc. you can have all kinds of shitty running issues. Sometimes a thicker gasket is needed to move the cover away if the gasket is worn and they arc. Check them and you very well could find your problem. I went to my local metric fastner supplier and swapped all the screws in my points system from the crappy phillips heads to hex in ss and have had a much better time having my plates and points stay put and in time. Worth the 15.00 I spent and I bought a double set so if any get even a bit stripped or worn when I do the timing I throw them away and replace. Good luck you should be able to find the issue.
overdraft
Coast to Coast
Re: CB350 Sly... smoke out of the carb?
Thanks for the input everyone! I'll swap the boots and check the compression...
Timing is going to be a different matter... I have a Pamco pointless system (and all stainless hex head fasteners! Good call Maritime!) and a visual inspection didn't show anything awry... no burns on the circuit board, nothing loose, but i guess the plate COULD have slipped... just don't get why it would only affect one side! Maybe Pamco Pete will chime in...
Thanks for the input everyone! I'll swap the boots and check the compression...
Timing is going to be a different matter... I have a Pamco pointless system (and all stainless hex head fasteners! Good call Maritime!) and a visual inspection didn't show anything awry... no burns on the circuit board, nothing loose, but i guess the plate COULD have slipped... just don't get why it would only affect one side! Maybe Pamco Pete will chime in...
Re: CB350 Sly... smoke out of the carb?
Intake boot perhaps. They bow when tightened, so it's worth removing and checking against a straightedge. Possibly a tight/sticky intake valve or one that's not seating perfectly. Check compression and do a leak down test.
Intake boot perhaps. They bow when tightened, so it's worth removing and checking against a straightedge. Possibly a tight/sticky intake valve or one that's not seating perfectly. Check compression and do a leak down test.
overdraft
Coast to Coast
Re: CB350 Sly... smoke out of the carb?
ugh. boots are fine.
don't know much about compression... it's kick only. first kick goes to like 60, second 90, third 120, fourth 150 and that seems to be it, stays around 150. and both sides seem pretty much the same which doesn't help me with the fact that the problem is only on the right side.
gonna be parted out soon at this rate.
ugh. boots are fine.
don't know much about compression... it's kick only. first kick goes to like 60, second 90, third 120, fourth 150 and that seems to be it, stays around 150. and both sides seem pretty much the same which doesn't help me with the fact that the problem is only on the right side.
gonna be parted out soon at this rate.
overdraft
Coast to Coast
Re: CB350 POS... with video to prove it
ok, sorry for the crappy phone video, but here it is in all it's annoying splendor...
idles (barely) on the left cylinder... backfires/misfires on the right without bringing anything to the party... you'll see me pull the plug wire off at low revs and it actually improves the operation as it just runs on the left cylinder...
THEN I rev it up and give it some throttle and you'll see that when I connect the plug the bike revs up more because the right cylinder is now working... I fucking hate this bike.
http://www.youtube.com/watch?v=50f9twv8tlE&feature=youtube_gdata_player
ok, sorry for the crappy phone video, but here it is in all it's annoying splendor...
idles (barely) on the left cylinder... backfires/misfires on the right without bringing anything to the party... you'll see me pull the plug wire off at low revs and it actually improves the operation as it just runs on the left cylinder...
THEN I rev it up and give it some throttle and you'll see that when I connect the plug the bike revs up more because the right cylinder is now working... I fucking hate this bike.
http://www.youtube.com/watch?v=50f9twv8tlE&feature=youtube_gdata_player
axeugene27
Over 1,000 Posts
Re: CB350 POS... with video to prove it
Id reinstall the points ignition and set it up and see if you still have issue. Sorry to hear about the problems man but you got to keep it in perspective you just got the thing together you are gonna have some issues to iron out plus even though it looks new it's 40 yrs old give the old girl a break she is trying to knock the dust off.... good luck bud.
Id reinstall the points ignition and set it up and see if you still have issue. Sorry to hear about the problems man but you got to keep it in perspective you just got the thing together you are gonna have some issues to iron out plus even though it looks new it's 40 yrs old give the old girl a break she is trying to knock the dust off.... good luck bud.
rockcitycafe
I make things.
Re: CB350 POS... with video to prove it
what's that godawful tapping noise?
that and it could very well be a fuel issue, check the idle circuit on the right carb, and check them for sync, on any 350 I do, I drill 2 6mm threaded holes into the intake passages so I can use a vacuum gauge, you may want to do that too. I had a bike that ran like that and it actually turned out that the right side carb fuel line was somewhat blocked, so it wouldn't fire at lower rpms, only at higher where there was enough vacuum to suck fuel from the bottom of the bowl
what's that godawful tapping noise?
that and it could very well be a fuel issue, check the idle circuit on the right carb, and check them for sync, on any 350 I do, I drill 2 6mm threaded holes into the intake passages so I can use a vacuum gauge, you may want to do that too. I had a bike that ran like that and it actually turned out that the right side carb fuel line was somewhat blocked, so it wouldn't fire at lower rpms, only at higher where there was enough vacuum to suck fuel from the bottom of the bowl
overdraft
Coast to Coast
Re: CB350 POS... with video to prove it
that said, thanks for the words of support.
I'm not inclined to scrap the pointless ignition on a maybe... if someone was saying 'oh, that's definitely a points issue' then I'd be more likely to chuck the electronic system and rewire everything...
ya, I'd buy that and be patient if it hadn't immediately worked and worked well... you have to remember the frustration comes not from the fact that it doesn't work, but from the fact that it worked flawlessly for a month and a half and THEN mysteriously fucked up...axeugene27 said:
that said, thanks for the words of support.
I'm not inclined to scrap the pointless ignition on a maybe... if someone was saying 'oh, that's definitely a points issue' then I'd be more likely to chuck the electronic system and rewire everything...
