#3 cylinder fires....eventually

[Guest]

Hi all. I'm getting close. I finally found the problem with my high idle on my '81 GS850G; it was a bent throttle butterfly valve on the #3 carb. Fixed it with a good one from Ebay.

So now that it idles normally, another problem has cropped up. The #3 cylinder takes at least 2-3 minutes to start firing. In the interim, it pops and backfires. Once it starts to fire, the bike smooths out pretty nicely and pulls pretty strong. I know just enough about these carbs now to suspect a clogged (or partially clogged) pilot jet. Any other suggestions?

[chuck hahn]

Im thinking they need vacuum syned now..Steve just did those carbs and unless something migrated past the in tank filter of the petcock or a little rubber sluffed off the main fuel feed line a clogged jet isnt the problem. If they arent synced with gauges then what happens is the offending cylinders butterfly doesnt open at the same gap as the rest are at...thus it takes longer for that cylinder to catch...and stop popping.

[ukjules]

Is #3 cylinder sparking ?

[Guest]

Is #3 cylinder sparking ?

Yes. It does run after 3-4 minutes, and it couldn't do that if it didn't have spark.

[TxGSrider]

Is the valve lash pretty close (especially on #3)?

[Guest]

I checked the valves before I started this adventure; all were within spec except for one, and we replaced the shim to bring in spec.