Looking for feedback on Pro-X 330 bolt on top end

[hostilerob]

I have a bolt on 330 top end that has the piston and sleeve skirts cut short so the cases don't need machining. Since the piston skirt is shorter, will it have less life expectancy as in should the piston be replaced more often than a full skirt piston since it loses some stability from the shorter skirt?

[barnett468]

Well that's most xlnt, lol.

Can you post photos for our amusement?

How much did they remove from the piston?

Has it been run before?

How much piston to cyl clearance is there,?

Since you already have it you could run it if you don't mind taking a chance that it will grenade but i would likely throw the pidton on the trash at the very least.

[El Camexican]

Has it been run before? That would be something if it has. Curious to know if the remaining skirt on the exhaust side is still covering the port at TDC.



Ultra High Performance 330cc top end and piston = $600

Hacking them up to avoid boring the cases = Priceless!

[shortline10]

I service a ESR 330 motor regularly with a regular skirt and it goes threw a piston every 50 hours . I can’t imagine a short skirt lasting very long .

[hostilerob]

Well that's most xlnt, lol.

Can you post photos for our amusement?

How much did they remove from the piston?

Has it been run before?

How much piston to cyl clearance is there,?

Since you already have it you could run it if you don't mind taking a chance that it will grenade but i would likely throw the pidton on the trash at the very least.

I bought from BDT in 2014. Raced it a few times. Runs amazing. Clearance was done by BDT. I have not had any issues. I am simply asking for guys with experience with the bolt on kit to see if they require more frequent rebuild than full skirt top ends.

[deathman53]

I had one, I used it for awhile. I found it ran hot, but it was the intake boot that had a slight crack that caused it. I didn't like it, I put a stock ported/polished back on and later 295(what most call a 310)pv.....much much better. Only thing with the short skirt is that you only can overbore it 2 times(not even a true 330). It doesn't require more frequent top end rebuilds, I suspect something else is wrong if you need a new piston at 50 hours.

[Gabriel]

I don't know anything about these engine but am curious what is making the piston life so short?

[shortline10]

The ESR motor I built is used for drag racing and has the high compression head , life expentinsy on the piston is 50 hours . I’m sure we could push it a few more hours but we don’t .
Regular top end service on any modern racing 2 stroke is every 60 hours .




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I had one, I used it for awhile. I found it ran hot, but it was the intake boot that had a slight crack that caused it. I didn't like it, I put a stock ported/polished back on and later 295(what most call a 310)pv.....much much better. Only thing with the short skirt is that you only can overbore it 2 times(not even a true 330). It doesn't require more frequent top end rebuilds, I suspect something else is wrong if you need a new piston at 50 hours.