runs rough and almost dies just above idle?

[Jawknee21]

Ok so im giving you guys very little to work with but i should be able to do more later in the week. I haven't done a compression test or anything but i will when i get the tool.

When im slowing down (downshifting and engine braking) it almost wants to die. It seems when it is just above idle (going up or down) and i get off the throttle, it stumbles for a second. it doesn't actually die and it never has but it may be just because i wont let it. i rev it back up until i get completely stopped. Could one cylinder be going away for a second? Im thinking jetting. i havent done anything to make it richer and it is finally getting cold. Its usually around 90s in the summer and it seemed to be running good. but now its been 60 or below (yes, i complain about that weather haha). Someone said i should rejet for ideal performance with 10 degrees of change. I just rechecked timing and synced my carbs. Today i tried to kick it and it wouldnt start even with the choke pulled all the way out. I had to turn the throttle about half way or more to get it to run. Im expecting too much out of this old bike arent i? Should i put it away for the winter (2 months? hahaha)...

 

[xjwmx]

I suspected your idle is set too low, and when you said you have to twist the throttle to start it, it reinforced the theory. I have mine set to idle around 1300 or so. It's definitely not a loping harley style idle.

 

[Jawknee21]

i did mess with the idle while it was off. ill try turning it up.
On another note, Theres a guy out by me that works at the harley shop who used to work for yamaha when these were new. He set my idle so low before. i thought it was going to die. I usually set my idle to about 1400 but since its been cold its not the same. What could make my tach be so unresponsive? I have to rev it way up for the tach to catch up and actually move. It eventually moves but it isnt sensitive at all...

 

[xjwmx]

On mine the needle shaft on the tach face got some crud on it from somewhere and it was unresponsive. It eventually fixed itself. There's just magnetic influence in it, not a direct geared connection.

 

[Jawknee21]

i turned up the idle and it still runs like crap. everything electrical is new. damn carbs! anyone with any experience with using different needles in bs34s? is it necessary?

 

[littlebill31]

If it's doing this at idle, then it's the pilot circuit or floats. The jet needle/needle jet is mostly 1/4 to 3/4 throttle. How are your mix screws set?

 

[CDNTX650]

needles has nothing to do with this problem.. This sounds idle jet or passage related....as in they are dirty.

 

[littlebill31]

needles has nothing to do with this problem.. This sounds idle jet or passage related....as in they are dirty.

1+ on the dirty.

 

[Jawknee21]

its just above idle. the mix screws are on the top of the carb right? Im not sure i cant get to the left side one with the carbs on. i have bs34s and they were uncovered when i got the bike. Im going to spend more time with the carb guide tonight. i will probably go get the bucket of carb cleaner and work on taking apart my carbs tomorrow. Im going to be taking my baffles out so ill probably need to jet up. i have 142.5s in it now but it was already jetted for pod filters and stock exhaust. It just seems like it doesnt want to go fast...
what do you guys have for jets? what else should i expect to order from mikes?

 

[CDNTX650]

start from stock jetting and see....here, with out elevation, pods and stock exhaust i run 135mj up from 132.5 with stock needles and stock pilots.

you cant buy jets and go on any ones reccomendations.

ride, plug chop, and see where you have flat spots or bogging.

142.5 is high for just pods....

 

[Jawknee21]

the guy i bought it from jetted it in the winter. i ran it with the baffles out and it still ran bad. Ill clean everything out tomorrow and start fresh. gonna have to wait for jets though. thanks for the help. i love this bike but i hate it too...

 

[CDNTX650]

what color are your plugs? i guarantee black,.

 

[Jawknee21]

Yep. With a little tan on one side. Better black than white isn't it?

Posted via Mobile

 

[CDNTX650]

yeh, your rich. bad both ways. rich dumpes to much fuel in and washes the oil from the cylinder walls causing wear. and carbons the shit out of the motor.

 

[littlebill31]

BS34's must, repeat, must have those mix screws set properly using the "dead cylinder" method. Usually 2 1/2 - 3 turns out from bottom will get it going ok, but every bike is different.