Carb bypass/idle mixture circuit

[laxman]

Hi,

 

My bike been running perfect for a long time until #4 cyl suddenly became a bit rough. A check of the exhaust temps confirmed the weak cylinder (not hot compared to other cyls). Problem seems to be from the idle mixture circuit, which was not responding to any adjustment.

 

Avoiding to pull down the carbs, I sprayed carb cleaner on both the pilot jet and idle mixture orifice hoping to get lucky. It improved and the cylinder started firing again. Just to be sure, I used colortune and confirmed the correct mixture was there. Unfortunately that was good for about 15 miles only and the problem came back .

 

Note that the basics checked out : compression, ignition, fuel, vac leaks.

 

Would appreciate any input on this. Thanks.

[Gearhead]

Junk in your carbs causing a repeat of the blockage. Try draining the bowls, spray carb cleaner up the drains and let it drain back out. Spray out the pilot screw hole again. Run a strong Seafoam mix thru it. If that doesn't get it, you're probably stuck removing the carbs.

 

Jeremy

[laxman]

Thanks for the tip Jeremy. Bike is back to normal. Wish we had Sea-foam over here. Took 2 cans of 3M carb cleaner to clear that junk out.