1991 Yamaha 540 SRV boggs - Snowmobile Forum: Your #1 Snowmobile Forum

AMSOIL · 01-04-2009, 01:41 PM

Gentlemen,

My son's SRV has a hesitation when staring off, put new piston in mag side, because of a hole almost burnt thru, cleaned carb, idles great and flys when you get past 25-35 mph. At start up it makes a harsh clanking noise,until warmed up almost like the timing is off and is if the spark is firing before TDC because it has backfired a little. Could it be a crank seal or do you think it may be the carb just needs and or timing. Does anyone know how to check the timing and if that's possible? Had track off ground and seems to be fine until its put on the snow or ground and doggs under load, any help would be great. Thanks

soundman23 · 05-17-2009, 11:25 PM

timing on the 540 is timed of the stater side at TDC then move it like 1-2 degree advanced that should take the bog out and then look at the main jet see if it is a 145 or bigger 150 or 155 would be best had the same problem and I don't know if you used wisco pistons but I did and burned a hole right threw after I called them they said that I should have been running BR8ES not BR9ES by running the 9 It got too hot

Dylan9302 · 10-28-2009, 06:17 AM

the br9es shouldnt be hotter than the 8 the lower the number the hotter it gets.

**RJ Gleason** · 10-28-2009, 08:03 AM

The 8 is the hotter plug.

Have you checked for air leaks on that engine?