Will a 38 Mikuni Roundslide work on Scrambler400? Will it work any better than the stock 34? The motor has a big bore 421cc, Delta Force reeds, ports just cleaned up not ported. ( Will be one day.)A friend has one I can have. should I try it?

 

JWC,

The 38 roundslide will work, but it won't have the throttle response of the flatslide. I wouldn't even begin to know where to start with the jetting.

The whole idea behind the flatslide is to smooth out the airflow as the air is running through the carb. You might want to try a U.F.O. (Ultimate Flow Optimiizer) on it. I have one on the Trailblazer and it works great. The U.F.O. will smooth out the airflow through the carb and will make it act like a flatslide. The throttle response is improved greatly.

 

Thanks Mike

Iam going to monkey with a litte. Iam planing on buying a 39 PWK Keihin. Has anyone compaired the PWK and the TMX?

 

Be careful about the 38 roundslides. They are probably from a sled which has a pressurized fuel system (fuel pump). The carb is set up different and would require some work to change over to run properly on a gravity fed system like the atv's have. I've tried it . . . doesn't work.

Anymore today, it seems the the 39 PWk's are the way to go, but I've not really seen a flow test or comparison of throttle response between the two.

Many have complained in the past about the 38 TMX's being tough to tune on the 400L motor, but I have personally not seen that. Also, I've heard about the 38's running lean in mid-range, but we've not had that problem with them on two atv's for 4 years now, I guess that's another "old mechanic's story" which seems to surface occasinally from those who don't want to sell them.

http://www.GoDigital-Design.com/SchultzMotorsports

 

i have ran the 38 mikuni with the ufo setup. it worked great. you do have to make a few changes because it wont let enough fuel in at top end if you dont. the tmx and 39pwk. had both liked the tmx had great throttle response but did have a lean mid range on my exhaust temp gauge, run 39 now it seems ok but runs rich onlow end and dont respond like the tmx. if you want the jetting and changes for the 38 roundslide just email me.