PapeCAT

I don't know anyone who has a 4200 spring in

Ilikebikes

Specialzed demo 8, 888RC2X, roco, hope M6's, etc... pretty sweet ride.

I would also like to know what bill has to say. The 3200 was such a great bang for the buck, I wonder if the 4200 will help anymore...

JAyers

Heres my experience with the 4200rpm spring. Ive had one in my truck, the throttle is really really touchy. It was hard to get used to especially in town. In my truck I found that the pump had to be maxed out for it to work, cuz if it wasnt it liked to cut out a 2500rpm. Its ok i guess but the people Ive talked to said that no matter what you do the VE, it can only fuel so far. If your seeing that kind of rpm you also need to upgrade you plunger return springs in the pump. A floating plunger is bad.

bgilbert

I had a trimmed to stock gov spring length 3800 rpm (374) gov spring. The 3800 and 4200 springs are longer than stock or the 366 spring. They will bottom out or hit the inside of the pump. I ran the 374 spring untrimmed, then trimmed to stock length and seat of the pants I gained much more with it trimmed. I then dynoed it and it defueled at 2800rpm. Put the 3200 spring in and it defueled at 3000rpm. When I say defueled, I mean where the straight line on the dynosheet starts to fall. It still had 'some' power left beyond those numbers.

Take a look at 'the man's' dyno sheets, KTA. He makes all his 'big' power before 3200rpm. Sure he ran them out to 4000rpm, but it didn't make much power out there. He also uses the 366 spring, well last I asked.

I still would like to find a spring setup to fuel to 4000. Keep up the R&D guys.