What is it with Jetting - 2004 EC300

[bigkatuna]

I have a stock EC300 with a LTR jetting kit, I am using a #7 slide, 178 main, 45 slow, clip in 2nd position. Some days the bike runs good, some days the bike seems like it will not clear out until mid to WOT. The idle is all over the place, sometimes too fast, other times it will not idle- all this with out adjusting anything. Is this typical of Gasgas bikes? Seems like the cooler the weather, the better the bike runs. Also, I am at about 400+ sea level. I would appreciate any suggestions.
Thanks.

[Eric K]

First, I would suggest going down on the pilot. Try a 42. You may need a 40 for real hot weather.

If that does not give you what you are looking for and you don't want to hassle with jetting, send your carb to RB Designs for his carb mod.

[jeffd]

Ron at RB-Designs has a carb mod and a carb fix. The fix is to replace the worn nozzle. This is the orifice that the needle fits into.

Ron guesses that the excessive wear that some bikes see in this area is due to the use of the boyeson rad valve and it's associated short carb insulator (the rubber piece is short and doesn't isolate the vibrations from the reed valve and motor from the carb itself).

If your bike has a bit of time on it - a worn nozzle might be contributing to your problems. If you send your carb to Ron you can have him replace the nozzle along with his other mods... (by the way, he is the only one who can replace the nozzle for you as Keihin doesn't sell this as a replacement part - he makes them up himself).

jeff

[GMP]

FYI, the '06+ bikes with the VForce have the same length manifold, same rubber coupler. The manifold looks like a copy of the RAD valve with the cage milled off, so the same theory would apply hear as well.

[juzzasmith]

I've had similar issues with an 05 EC300 currently running at around 800ft and 70F, although I haven't had problems with the idle.

I was running the LT needle, 178 main and 45 pilot with a #7 slide and had the same issues of sometimes running ok, sometimes not.

I agree with Eric K that a 42 pilot might help, it made a difference to my bike.

After an awful lot of jetting work and experimentation, I've settled on an N1EG needle (leaner than the LT needle) on the 2nd clip, 175 main and 42 pilot at 2 and 1/2 turns out. This set up ain't absolutely perfect, but it's the best I've had my bike running to date.

Lots of people have suggested trying a #8 slide to clean things up but I haven't tryed it myself.

[Treesmacker]

I did the RB head mod and that seemed to help my jetting with temp. changes.

[jefgil123]

Keep in mind the gas we're getting these days is from all
different refinerys and varies in oxigination content from
summer to winter.
Half "race gas" from Sunoco or others mixed with hi-test
from Shell or Mobile will help deal with the inconsistency
and makes my bike run crisper.