330 pro cross cr 250r

[Action69]

So yesterday I was doing my daily FB market place surfing and I came across a complete 2000 cr250r motor,electronics,carb,radiators,fmf full exhaust and some other random parts.Needless to say I scooped it up asap being the whole lot was $800.😬😬😬😬.Today upon closer inspection of the pictures I bought it off of I noticed a pro cross head and a cylinder without a power valve.I called pro cross for some info on it and it winds up being a 330 BB cylinder that doesn’t require case boring.Im pretty stoked to say the least,after talking to them about the cylinder he said they don’t make them anymore because they weren’t popular with MX guys being it starts to really build power around 2500 rpm,has anyone ever seen one of these or know anything about it?thanks for ant input.

[Action69]

Some more pictures

[croat1]

Very cool find

Joe

[Jerry Hall]

Yes I am very familiar with the CR330 CP cylinder.  I did a lot of development on that CP cylinder on a 1996 CR 250 lower end around 1996 or 1997.  I had a customer that funded the development on an engine package for outlaw shifter kart application.  We went though a hand full of cylinders, heads and built a lot of test pipes.  The ports and the casting are the same on the TRX 330 cylinder except where the exhaust pipe connects to the exhaust port.  The exhaust pipe plugged in to a socket in the cylinder on the CR 330 version where the TRX 330 had the bolt on flange that the TRX 250R cylinder used. 

We were getting power at the counter shaft in the mid to high 60s on gas and low 70s on alcohol on the OEM CR250 cylinder  The customer wanted more power, so we spent a couple more months developing the 330 top end.  The stock 330 cylinder made mid 40s with the 250 pipes that were on the market at that time. The box stock 1996 CR 250 also made mid 40s with same groups of 250 pipes

We developed the 330 package on gas until we knew we had reached the thermal limit of the thin piston tops when they started to sag at power levels in the high 60s.  We put it on alcohol and continued to develop the engine package.  We reached the thermal limits of the piston top on alcohol when the power level reached the mid 70s. 

In summary:

The customer spent over 20,000.00 to develop the 330cc top end that only made 3 more hp than we could get out of 250cc from the Honda CR 250 OEM cylinder.

[Action69]

Thank you very much for your in-depth input,I’m sure once I get into it I’ll have some more questions for you.I couldn’t find much info on this beside what I was told on the phone today..thank you Jerry hall..

[The norm]

Very cool find!

[Hawaiiysr]

Wow thats a lot of history