tommygun32

I've got a new and modded Jammin JPX 21. Ordered a shim for it from Amain but they shipped it with no cardboard protector. So the shim has been slightly bent and tweaked. I'll be running 25% Byron's gen 2 through it. I also need to get an exhaust gasket for it, so my questions:

a) Should i shim it
b) Is it OK to use the shim if its a bit tweaked
c) Any idea which silicone exhaust gasket I need to get (I've only had OS engines before and they came with gaskets)? I can see that there's no groove on the exhaust port of the Jammin like there is on the OS, so those gaskets aren't interchangeable.

As always, thanks for sharing your knowledge and experience.

**Addition: Just took the cooling head off the JPX 21 and realized unlike the OS engines, there is a seperate glow plug seat that isn't attached to the cooling head. How do i remove that to add the shim?

xjqkz

to my understanding, shims go through some compression force other than that they are just spacers to keep things apart and moving. If you can get the shim bent backward to as close to its original shape as you possibly can, then it shouldn't make that much of a difference. Worst case - it will cost you a bearing or two should they cease.

jikkuria

the head button(plug seat) should just pop right out, and the shims should be there on the part that goes into the block.

rageworks

You will need the exhaust seal made for the
Picco/Jammin engines. It is Ofna part #51915.

SManMTB

It is perfectly fine to use the shim.

What a bent shim has to do with broken bearings and exhaust adapter gaskets beats me.
[8D]

tommygun32

Thanks guys.

tommygun32

Is this it? No lip against the engine block or anything?

j_blaze

once you tighten the head down any "tweak" to the shim will dissapear. more shims = less power, lower mileage, longer life. less shims = more power, better mileage, shorter life.