Q: I’ve just acquired an old Suzuki RM250 two-stroke, which is an air-cooled model. I only paid a 4k for the thing and I’m not even sure what I’m going to do with it, and I think it’s from the late eighties.
Besides that I’m sure it’ll be fun to ride and I’ll probably hurt myself. But the reason I’m writing is that a guy told me to fit three to four base gaskets under the barrel to improve performance. So, quite simply, is this true because it’s easy to do on these old engines, and will it affect reliability? Just wondering….
A: This has been done for years on many two-stroke engines, and all it does is to raise the transfer ports and exhaust port by a few millimeters, depending on how ‘high’ you lift the barrel.
What this tends to do is increase top end power, sometimes? But the trade off is it makes the engine more ‘peaky’ at the top end and therefore you’ll get a loss of bottom end power. It will also lower the compression ratio and squish band, which isn’t a good thing either.
So it all depends on the type of riding. Personally I’d leave it alone because Suzuki knows what they’re doing better than the ‘guy’ in the pub. Shouldn’t affect reliability though, if you fancy fiddling around.