Squish

[KB]

Mr Duval, we need to talk about this "squish" thing. I am going to be doing a top end on my KTM 250exc soon and need some more info on this.

I understand the concept of different thickness base gaskets to give you the correct amount of squish. I'm sort of unclear on how to actually measure the "squish", and if not knowing what the previous owner was using for a gasket (in the case that they rebuilt it b4 I got it) where to go when ordering a new gasket set.

Help Mr E Duval.

KB

[Paul_E_D]

At your service... If you want to come out to my place some saturday or sunday, we can do the top end and then break it in out back. Once you have done one, all will make sense. Also, you get a baseline, and future topends don't require much measuring/tweaking.

it's hard to visualize until you do it... The bike will be SWEET after it's done...

Mr Duval, we need to talk about this "squish" thing. I am going to be doing a top end on my KTM 250exc soon and need some more info on this.

I understand the concept of different thickness base gaskets to give you the correct amount of squish. I'm sort of unclear on how to actually measure the "squish", and if not knowing what the previous owner was using for a gasket (in the case that they rebuilt it b4 I got it) where to go when ordering a new gasket set.

Help Mr E Duval.

KB

[KB]

At your service... If you want to come out to my place some saturday or sunday, we can do the top end and then break it in out back. Once you have done one, all will make sense. Also, you get a baseline, and future topends don't require much measuring/tweaking.

it's hard to visualize until you do it... The bike will be SWEET after it's done...

Ok so do I just get a piston rings and gasket set? Do I need to buy more than one base gasket? Should I take it apart have the cylinder measured to ensure it's in spec?

Thanks Paul I will take you up on that offer for sure. She runs ok now but I'm unsure if the previous owner ever opened it up, and would rather freshen it up then have to buy a new cylinder.

KB

[Paul_E_D]

Gaskets are cheap. i would get a few. Thick, med, and a couple thin ones. There is a KTM dealer 3 miles from my house though, so if you need one you don't have you could get it (sat 10-3)
The cylinder is likely fine. They last a long time. We can measure it though. A replate is all that's ever really needed and that's cheap.
One thing you should definitely do is disassemble the powervalve and clean it really well. There are some common wear parts there, so I'd read up on it, and just by that stuff so you have it if you need it.

Otherwise, just get the piston/ring/gasket set. Check if it comes with circlips and small end bearing or not. You need those.

All told it might cost 200 bucks, but it's well worth it in both performance and reliability.