1980 xs 650 warm up ignition problem

[uksparky]

Hi all...ever since i put my engine back in after rings/ tensioner job i have this ignition problem...all stock...starting cold with choke ok, idle ok revs ok. Taking out on road the engine will cut out for a second through the throttle range, it will do this about four times while under a load. Once engine is hot its perfect...past work new stator 14.3 volts charging...good spark..carbs rebuilt new boots, no vacuum leaks..wiring connectors all clean...Its almost like turning the ignition off and on...lights and guages all ok nothing goes off. I checked inside headlamp wiring all ok...like i said when the engine is hot it runs perfect.. I was thinking TCI ignition box... California XS

 

[Its been a long time]

Reading the symptoms, if it seems the ignition is randomly switching off then on, that's most likely what's happening.

If you haven't already, I'd start by overhauling the kill and ignition switches. I found inside my kill switch the springs were corroded and broken. Bought new ones off eBay. My ignition switch wasn't so bad. Then see if that cures the issue. If not, then a methodical check of every ignition wire and crimped joint is next on the agenda.

 

[gggGary]

Bs34 have notoriously lean pilot needle jet settings. The "simple fix" for more or less stock bikes is the needle shim washer ( Only one washer)

 

[uksparky]

I decided to pull the carbs, i did notice in the garage just of idle around 1400 rpm stumble not smooth, past that rpm it was ok...there was some crap in the pilot jets but not blocked, so sprayed good with carb cleaner, clear now floats still 27mm...fit carbs in morning..
The needle jet is fixed on the 80 model
If that dont fix it ..back to the ignition

 

[gggGary]

See above and search bs34 shim washer.
Also check the oriface in the float bowl. Someone please post the pic. ;^)

 

[Jim]

Shine the light in the red arrow hole and it should be visible in the yellow arrow hole.
Flush with the solvent of choice, along with copious amounts of shop air.

 

[uksparky]

Thanks Jim/Gary they did have blockage ...carb cleaner sorted it... the bowl vent...thats one thing i overlooked

 

[uksparky]

See above and search bs34 shim washer.
Also check the oriface in the float bowl. Someone please post the pic. ;^)

I read the shim washer is about 20 thou thick....can i get one at local hardware rather than Mikesxs

 

[gggGary]

Yup iirc just a 3mm stainless washer about = to half a clip notch works great with stock air filter, exhaust

 

[Jim]

If you can't find any, PM me your address and I'll send you some.

 

[uksparky]

The needle jet has pegs on plastic washer how can you put a shim washer in there

 

[Jim]

Maybe they're not 3mm after all?

 

[GLJ]

I think you need to slide the plastic thing off, put washer on needle then slide plastic thing back.
It seems to me that's what I had to do on a pair of BS34s that I rebuilt. Then again I could be wrong.

 

[uksparky]

Still got the warm up stumble...it feels like when trying to run with no choke....heated up engine no problem...so stock needles.. ...1980 Cali emmisions suck

 

[uksparky]

I think you need to slide the plastic thing off, put washer on needle then slide plastic thing back.
It seems to me that's what I had to do on a pair of BS34s that I rebuilt. Then again I could be wrong

 

[gggGary]

Yes have a cup of hot water handy, dip the needle with plastic in, the pill will then slip off the needle, the washer must go between the pill and the E-clip.
Only ONE washer per needle.

 

[gggGary]

PS the needles measure 2.9mm a 3mm washer works fine

 

[gggGary]

If you insert more than one washer the spring binds and the needle is no longer free floating, this is a very bad thing.
PS the pin needs to fit into the hole in the slide when reassembling.

 

[gggGary]

The spring, pin and that little raised bump are designed to stop the needle from rattling in the needle jet bore, causing excessive wear of both needle and jet.

 

[gggGary]

Sorry I was away from my 'puter full of stored pics earlier.