Quote:
Originally Posted by Racer x
I mean jet size. I have spent hundreds of hours on the dyno with this engine. If you aren't pulling enough fuel through the carbs you don't make the power. You should have an A/F ratio about 13 maybe 12.5 to 1 . With 108 to 111 jets that is just about 30 hp. When I got 34 hp on my most powerful motor. 13.5 to 1 shaved block. Race gas and the ignition timing hitting 44 deg I was using 117 jets with stock carbs. I now use 129 jets in my cr special carbs and am about at 33 hp and the AF is some place around 13.
We will see but I would start at the 108 and watch it close. That's all.
|
I ordered 112, 115, 118 and 120 jets. I will put in the 112 and test from there. Better to be too rich in my opinion. With race gas, the extra oxygen in the fuel requires more total fuel.
One thing that must be considered is that the larger bore size on your CR carbs will automatically take larger jets to get the same amount of fuel. I learned this when working on my CRF250X and turning it into a CRF250R. The R had a larger carb for top end and used larger jets. I tried to mimic the stock R jetting and was coming out EXTREMELY rich. Smaller jets gave me the correct A/F.