August 20, 201511 yr Hi all. 280 gassa 2011 clunk noise with a quick hand full of throttle, spoke to a few people at the trials and the overall was the bike is running lean / engine clunk...The fuel screw is 3.5 turns out, the bike idles sweet & runs very well. Could anyone point me in the right direction- Main jet / pilot jet correct setting or factory settings, or how to get rid of the light clunk... Thanks Deano.
August 20, 201511 yr Standard if think is 118 main, 36 pilot. Sounds more a low end knock, so maybe try your mixture screw out a half or full turn (dellorto mixture screws control fuel). And maybe check your needle clip. I think running a 38 pilot is relatively common Its gonna run richer in the summer, so id maybe give the carb a good clean before playing with jets. A drop of water in the floatbowl can block the pilot somewhat and make them run weak. Edited August 20, 201511 yr by faussy
August 20, 201511 yr Author Hi Faussy, just had the carb off for a good clean two trials ago, forgot to check the jet numbers... . I was with you until you mentioned the needle clip.
August 21, 201511 yr The needle has a circlip and notches to raise or lower it to lean it out or richen it
August 21, 201511 yr " with a quick hand full of throttle"? What are you doing? Sitting there wacking it off? Do you ride that way? Lean throttle chop ping(knock) may be caused because you just shut off the fuel to a revving motor! The pilot(low speed) jet is the one that helps here, providing you are using good fuel of proper octane. 36/38 or possibly even 40 is not out of the question. Finding the sweet spot while maintaining good running is the key, and you will likely have to come way off the 3.5 turn thing and down into the 2-3 turn range with the larger jet installed.
August 21, 201511 yr " with a quick hand full of throttle"? What are you doing? Sitting there wacking it off? Do you ride that way? Lean throttle chop ping(knock) may be caused because you just shut off the fuel to a revving motor! The pilot(low speed) jet is the one that helps here, providing you are using good fuel of proper octane. 36/38 or possibly even 40 is not out of the question. Finding the sweet spot while maintaining good running is the key, and you will likely have to come way off the 3.5 turn thing and down into the 2-3 turn range with the larger jet installed. Agree with all of this.
August 21, 201511 yr Author OK, Lost my back brake on the last two sections of the last trial. bled it got it back and there is a very slight, mind very slight weep out of the gap in the reservoir cap. Brake is very good and I did get a few air bubbles out, could this just be over-fill ? OH, stripping car tomorrow so will let you all know the both jet sizes. Thanks Deano.
August 21, 201511 yr Have you not just overfilled it ? Or over tightened one side rather than the other ?
August 21, 201511 yr Author Evenly with the screws / not heavy handed, hope I've just over filled it. will find out at the next trial .
August 22, 201511 yr Author Hi Guys Deano here, Main jet = 120 Pilot jet = 35 Just moved the needle up onto its last notch...OH by the way found out why I have no back brake hose has cracked right at the banjo going into the reservoir.. looks like I need a new complete hose, any ideas where to go for this thanks Deano.
August 22, 201511 yr I would put in a 38 pilot. So is the clip in the top notch or bottom notch. Ideally the clip should be in the middle range, so you have some adjustment if conditions change.
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