Got it running...now I need some ideas

[tech3sandcars]

Got the motor running, actually runs pretty good. The response off idle is very good but....it never seems to settle back to the same idle each time. If I rev it up it drops down to about 2500 and then creeps back to my 1200 rpm idle i want.....sometimes, other times it goes to 1700rpm for a while. This motor is a V-twin 2 cylinder in a rhino type UTV. It has extensive motor work including 11:1 compression, lots of port work, and really wild cams that don't make power till 7000rpm (this is normal for a CVT belt system). The side effect of the real wild cams is crappy vacuum at idle, it idles at about 80-85 kpa. I did make a little plenum to connect the 2 cylinders together and then to my MAP sensor. I have done no tuning yet except to play with the required fuel to see where the idle likes to be. Is this the type of situation where I should be going down the Alpha N path instead of the speed density? or maybe a blend?? Just some initial ideas anyone? I will play some more this weekend and post my msq and some datalog files.

Anyway you slice it...its already better than my crappy carbs I had that everybody on the UTV forums swore were the best.....whatever!!!

[Matt Cramer]

Are you using an IAC valve?

Also, if you could post a data log of this and your MSQ, I'll have a look at them.

[tech3sandcars]

No IAC just Fidle, will post files late this weekend, thanks.

[gboezio]

Use Alpha-N blend and if you are not running forced induction you could even use pure alpha-N, it's not possible to tune a twin with a big cam using speed density, the idle bins, light load, medium load are the same, making the fuel erratic.
My bike has a stock 245 ° cams @ 1mm and is a mess, I do blend it before the turbo spools up.