motor help

[Fast_quad_03]

Ive got my suspension set up perfect for my riding. But now i just want a real motor. Right now i have a dune port, pd cool head with 21cc domes, t5 pipes, 30 okos with pods, vf3 reeds, adj timing plate and hd clutch kit.

 

i want to build a 7mm 421 serval. is it going to be too much to trail ride? All ill need is the crank and top end right?

[#1JUANstunna]

i want to build a 7mm 421 serval. is it going to be too much to trail ride? All ill need is the crank and top end right?

 

A 421 serval is a 4mil not a 7mil. I think a 7mil is like 443ish

[Surfrjag]

How is a dune ported motor not enough for trail riding?

[Jereme6655]

i just built a 421 serval for my friend this year.  It all depends what kind of trails your riding.  On tight trails.....personally there is no way I would want to ride his bike for very long.  Even though its still a serval......your powerband comes on SO hard and so down low, that if your trails are real tight things, you may get in trouble.

 

Don't get me wrong his bike is fun as hell.....and easy in mildly tight areas...but he's been riding for over 18years now and he's had the front end come up a few times already that he wasn't expecting and almost lay him off the back.

 

So my comment would be to just get a 421 Serval (which is a 4mil) and have just the castings cleaned up (if nothing else) or get it ported....save your money from a 7mil.

[Fast_quad_03]

the trails are big enough you could drive your truck down them with room to spare. most of the trails are logging roads, gas lines, power lines etc. there are some tight trails but not very many. im usually in 3rd to 5th gear when on the trails. but we mess around a lot on the atv roads near by when im 6th wide open all the time. i want a real top end motor like a cheetah cub, but i still need bottom end for on the trails.

 

also, how much could i get out of a ported top end and a welded stock stroke crank with the best bearings there are (cant remember what theyre called)

[Jereme6655]

if you wanting low to mid power.....you want a serval.  If you want a top end high hp motor for drag racing, your gonna want something like a cub or a dm.  You can have both....its doesn't totally work........its more a one or other type thing.

[Fast_quad_03]

I know i want a serval. What does a longer crank stroke do for performance?