86 Marathon go fast help needed.

[67HotRod]

Hey guys. I just picked up my first cart, an 86 gasser. The engine is shot, so it will be getting the full upper and bottom end job. I'm planning on milling the head to get over the stock 6:1 compression. I'm needing some help on a few things. How high will these things go on pump gas without detonating? Surely I can get by with 8:1?? Also, how do I go about porting this thing? I've done everything from diesel pulling tractors to 2,500 HP alcohol drag motors, but have never been in a 2 stroker.
I know it's never going to be a hot rod, but while I'm in it I want to get as much as I can. Hoping to pull 4 people up hills with 22" tires.

Thanks!


Sent from my own phone, not an obama-phone!

[Vavoomskill]

I milled mine to where it had .055 piston to head clearance and it turned out just over 9 to 1 You sound like you know porting .. so just radius everything and raise the intake ports a bit 1mm ish .. widen the ex port a bit.. bigger carb like a 24mm, if you take it all the way apart you can port the crank case to match the cylinder transfer ports too! brush up the intake,,, Boyesen reeds model #650 work good too.... Ex system from a 88 is much better.. hard to find though and costly too

Post some pix!!

[67HotRod]

I read your post with great interest regarding milling the head. Missed the part where you said it ended up at 9:1.
I'm a certified dummy on reeds. What is different about that one, and what will it do? Thanks for the porting ideas.

Will definitely post pics. At least that'll give you guys something entertaining to look at!! :)

[Vavoomskill]

The fiber reads are just better, the flex faster seal better and are just the way to go.. you cant buy stock ones,, not that I've found anyways. the old ones get weak and should be replaced. If that break the tend to trash the motor!!

The 9 ta 1 is just what I ended up with.. I didn't post it in the other thread. it's about 140 psi from the 110 it had stock.

[67HotRod]

Boyesen says the 650 is only for 89 and later. Did it match up for size and thickness on your's?

Thanks

[Vavoomskill]

I have them in my 83. .. Hummm some times they just don't go back in years and the company doesn't care to do the research. The reed cages are the same ... I'm quite sure.... maybe some one else will chime in here. The bolt pattern for the gasket might be a tad different but that's all...

[Dmontgomery]

Any updates? I keep reading but cant find anything on the #650 boyeson reeds working on a 88.