Anybody got info on this setup?

[250Renvy]

The guy says it's a 91 CR250 cylinder on a 89 bottom end with a yz250 piston.

Will this just bolt up and any special concerns.

Do you think the pipe would mount properly because of the powervalve location?

http://i7.ebayimg.com/07/i/000/81/b2/33af_1.JPG

It's more expensive than a stock cylinder but way cheaper than an aftermarket Powervalve cylinder.

[matt250r21]

FTZ Racing dose this mod. I know they sell a special exhaust flange to mount TRX pipes to the CR cylinder. The CR power valves are pluged off and do not work on the TRX bottom end. I think the only advantage over a TRX cylinder is the Niksile sleeve and more recent port specs. I have scene YZ pistons in TRX cylinders with 2mm spacer plates before, Sparks and Duncan. The advantage is larger bore sizes over TRX pistons.

[Rich250RRacer]

Originally posted by matt250r21
FTZ Racing dose this mod. I know they sell a special exhaust flange to mount TRX pipes to the CR cylinder. The CR power valves are pluged off and do not work on the TRX bottom end. I think the only advantage over a TRX cylinder is the Niksile sleeve and more recent port specs. I have scene YZ pistons in TRX cylinders with 2mm spacer plates before, Sparks and Duncan. The advantage is larger bore sizes over TRX pistons.

He right, there's no drive mechanism for the power valve. I think it's more of a top-end type motor. I might still have one of those cylinders laying around, I'll have to look.

[C-LEIGH RACING]

FTZ builds a lot of mini Sprint car engines useing those cylinders set up on alky fuel & the CR250R cylinder with the nikisal bore was a cooler running (temp wise) set up than the TRX cylinders. Few other addvantages as well, the straight in plug hole in the head made for easier machining. The head was thicker & would hold more coolant as well as the cylinder itself. Different port layout.
The Sprint cars are alot heavier than a bike or atv & build more heat in the engine when trying to make big power, so in turn is the reason for the cooling deal.

Some of the car classes have to maintain a 250cc (66.00mm) size engine & was a way to make it a little harder for those car guys to get the cylinder up to a big bore because of the plated cylinder.
A sleeve bore cylinder all you have to do is have a piston & somebody to bore it, the plated cylinder take a bit more time to complete the job with boring the cylinder & re-plating.
Neil

[jkkj]

I have a paul turner maximum overdrive version. It has a yz piston, and a base plate. Mine did just bolt up and as these guys have stated the powervalve just blocked off and does not function. I picked it up cheap and like it.