cr250 piston in R?

[muddymess]

I was given a new piston for a motor that was being built and I noticed it was cr250 piston. I've never heard of anyone running a cr piston before. The motor is an 86 with a hot rod crank and connecting rod. He said it was a longer stroke and it uses a spacer plate but I havnt been able to find any info on the numbers that are stamped into it yet to find out how long it is. Would this be why he had a cr piston or did he just give me the wrong piston.

[addictedtomud]

84-85 CR 250 pistons are the same as 86 TRX250r. As far as the stroke, he must have put an 87-89 style crank in it (sometimes called a "long rod"). When you run an 86 piston with that crank, you have to use the spacer plate under the cylinder to accomodate the longer stroke. Sounds ok to me...anyone else agree / disagree??

[muddymess]

I'm thinking that's what the rod is also. the spacer plate is .18" which if i remember correctly is the size used for the 87+ rod and 86 piston setup. The numbers on the side of the rod is ck 109 b but i haven't found anything with those numbers.

i looked up the piston and it has to be wrong. it came up as a 86-96 cr250 piston for a 67.5 bore. The bore on the cylinder is 68.072.

[C-LEIGH RACING]

That CR piston you have, is it a flat top piston or crown top ??.

If it is a flat top, sometime builders will use that piston to build what is called a flat top 265.
The piston size you listed & the cylinder bore size surely not going to match up & you'll need another piston to get the engine going.
Is it a number 614MO6750 Wiseco piston.
Neil

[muddymess]

yes thats the part number

[C-LEIGH RACING]

I think in the Wiseco catolog, it has that 614MO piston listed for the CR250R & the 85/86 ATC250R & TRX250R.
Neil

[89250rhonda]

j run a 84 cr 250 piston and long rod, works grate for me, lots of compreshion.

[86 Quad R]

Originally posted by 89250rhonda
j run a 84 cr 250 piston and long rod, works grate for me, lots of compreshion.

yuppers en i like em on the short rods aswell. :D