drr 50 squish and base gasket / port timing questions

[jplltz50]

Got a drr 50 with steel cylinder,i put a replacement piston in that hits the head, I made sure the head was centered over the piston so I'm sure its just a variation in dome height .........now my plan is to make it up with a thicker base gasket. My questions are

1. How much will this alter port timing. Just as an example say I had to use a base gasket that's .050 and the gasket I had been running our bike with was .010 would there be a noticeable difference in power, rpm range etc

2. What is the ideal squish clearances.

[EthansDad]

what cylinder did you start with then switch to? I'm assuming the new one is the air cooled, yes?

I think the safe zone is .030 if memory serves me, might want to search to forum on "squish" and confirm that, I know there has been some talk in the past. on ours 50cs, I've seen it go as low as .017, but again that was based on our porting and matching up port timings. the more squish, the less compression - that will also effect peak power.

to your question - yes, it will effect things, how much you'll have to find out. it might not be that bad if you are on a non-ported stock setup.

I think I still have some national ported DRR 50cc air cooled cylinders and heads lying around if you are interested, just pm me.

-EA

[jplltz50]

The quad is water cooled, the cylinder in question has been on it since we bought it new, I just took it apart a day or so ago to replace piston and rings after putting it back together the piston hits the head. I either have a piston dome shape variation or a thinner base gasket or combo of the two I am just curious is adding a thicker base gasket to get proper squish gonna be felt in the seat

[EthansDad]

I gotcha now. I think I had this happen this year. Does your old drr piston have a pitted head and the new one have a polished head? The new style polished piston is a bit taller I think, although I am told it's not.

Put in a thicker base gasket. Remember, if the piston is a bit taller, and you go up in base gasket, your squish might stay the same. Once you put the new top end together with bigger gasket, do a proper squish test and see where you're at. If you over shoot a bit, you likely won't feel it. Might be a little lower on compression and less responsive to race gas. Can aim for .025 is pretty aggressive on a non- blueprinted motor.

[Logan #34's Dad]

It sounds like your piston's are different. If I'd have to guess, the pin location on the pistons itself are in a different locations. If you have a digital caliber and measure the pin location to the top of the piston - probably different.