Hope the weekend is going good......

2012 103 trying to achieve 10.25 to 1. What's the magic formula? Can it be with thinner head gasket,does it need to be milled? Only way to do it correctly is thru a piston change?

If I use a thinner gasket and mill will bolts line up? Looking to the pros as I don't want problems. And not looking to put in the best piston money can but because it's cool.

Thanks guys.

 

Yep. Pistons.

 

I'd ask that question to whoever you want to mill the heads. If you're doing pistons it would be an opportune time to do a 107 kit.

 

Ya can easily mill a 103 to 10.25. But Pistons would be better. Only real way to know what ya got is to measure.

 

Why 10.25 to 1? A specific cam or something?

 

Yes swapped cam. Thought it might run a little stronger with a cylinder head swap. And it has been suggested to me to run 10.25 while I'm in there.

I just hate swapping out perfectly good pistons if I don't have to.

It's like a good ported head is worth 5/10 whatever? May as well make the most of it and bump compression. But a piston swap too???? #+')(%?#-_)@?- come on!!!!
I

 

Hey, Joe. Been awhile. Hope all is well.

The question posed as to "why 10.25:1" is a good question. I am going to pose a rhetorical question along the same lines. I know you're trying to squeeze more out of your motor, and do it as economically as you can. I get it. However, what is your long term goal with your motor? What do you want this motor to do for you in terms of performance once you feel you've "arrived"?

I think that to answer to and for YOURSELF, where you ultimately want to take this motor is smart. It may save you from having problems down the road, and even money, if you do that before moving forward in looking for a way to increase your compression without increasing your displacement and/or pistons at the same time. If you're absolutely certain that a bump in compression is going to be the "end all" for you, then you can increase compression without increasing displacement or just going with a piston change. But I sense we're pretty similar minded, and after a period of time the increase in compression alone won't be enough.

The only advice I'd give is: think this one through.

Good luck. If you do move forward with a compression bump, post your satisfaction level or shoot me a PM. I'll be interested.

 

Have you talked over your ideas and goals with the guys over at FM? Talk with Bob....he's a very knowledgeable tech, and he'll explore ideas with you on the phone for as long as you need, and make completely sensible suggestions to you without a hard sell. Assuming you haven't already done that, of course.

 

I have a bike with factory milled heads .060" ( 1988 FXRP).

You can;t put metal back, the milled heads caused recurring intake maniford leak problems with teh stock type compliance fitting until I eventually got a solid manifold and had it machined to match the slightly altered angle of the intake (from stock).

Pushrods were also a concern- I couldn't use stock sold rids, I had to use adjustable...which are fine- but I did have one move on me once.

Mike

 

How was the trip grip? I dunno, kinda funny......lol!

Well this is my life. Being satisfied is never easy. Trying to prepare myself to do something bigger. Can I put a cnc head and 2/1 pipe on this 103" And be completed happy with the outcome.

Or do I do all this work, **** a few more bucks down the toilet. Then decide to do a 120"+. If pistons are a must, May as well do the 110" kit switch the cam out and be done.

What is the difference between a 103 and 110, 8 h/p & tq????

Hate miscalculating projects, or coming up short........