I will be getting this new 250R tommorow and I would like to check the compression and the dome size.
Do I have to get a special compression checking gauge or can I use one from a automobile?? And how many times do I kick it over to check?
Checking for dome size, what do I do there? Is the size on the dome on the outside or inside??

 

sorry about delay..GOSH DARN computers! yes, a car type is fine,screw-in is the way to go,tight seal.hold throttle wfo and kick fast until gauge doesnt go any higher.usually about 4-5 kicks is fine.to check rings dump about 2-3 tablespoons of oil in hole and check again,if its the same...your golden!im out[img]i/expressions/face-icon-small-happy.gif[/img]

 

Ok I checked my compression and it read 160. I did it 3 different times and it read the same. The motor is not a sparks motor, which I thought it was, but there is no engraving of sparks on it. Just a D G on the left side, with a Duncan power head.

Well I took off the head to see what size the dome is, but I could not see any stamp numbers on it. The piston had these numbers on it.
I96H6
1.25 mm
526P5
CD with an arrow pointing to the exhuast.

What do these numbers represent, and what size motor do I have?? WHich leads to, can I run pump gas of 87 octane??

 

at 160psi you should be fine with 87. Im running 175 on 87 or 92 mixed 40:1 with R50.

 

At 160 PSI 87 is fine.

Can't help with the piston numbers.

HA2 what is your compression?

 

stock mike. i want to run i believe a 17cc dome this season.

 

If yours is stock your wasting money on race gas. Will run the same if not better on just 92. *shrug*

 

i mixed half and half when i did it. i originally thought that i was hearing it detonating and knew i was running pretty rich.

We should do a night run in Sept after SSSS. im sure my bike will still be put together then.

 

The 526P5 represents a Wiseco piston at .050" overbore. This also tells me you have an '86 motor, at least the piston part number is for an '86 motor. Standard bore size for an '86 is 66MM and you are at 67.25mm, or basically in the middle of your "bore allottment" for this motor. The 1.25 you mention is simply 66MM + 1.25MM = 67.25MM

 

Cool, thanks for the info.

It has a 86 bottom, and 86 piston with a 89 cylinder and a spacer plate I believe.

I will run the 87 thanks people.