piston size on a 330

[bansheeboyo]

my piston went boom on saturday so im in need of a bore out ,if i have a new 78.5mm piston what size should the bore be ??
cheers scott

[woodsracer144]

IIt would need a 78.5 mm. And the first bore is 78 mm

[C-LEIGH RACING]

You sure its a 330 cylinder, because the normal 330 piston sizes start at 76.00mm STD bore & go to 77.50mm for the last bore.
It is possible though to bore in a 78.00mm size piston in a 330 jug, but the sleeve at the top between the bore & inner o ring groove is getting mighty thin & could chip off.
I've had that happen before, the sleeve chip off & it happened early on during break in.
If you have a new 78.50mm piston kit & if measure it, it would measure out 78.45mm in size

A 350 jug, the STD piston for it starts at 77.50mm & can go to a 79.00mm.

ESR has pistons now, that go up to 82.00mm in size for like their 420 cylinder kits.
Those new ESR pistons, are machined different from the old Pro-X design. Machined to prevent the port linking issues we were having with the old Pro-x design.
Neil

[bansheeboyo]

well when it was sold to me i was told it was a 350 ,got it off ebay ,full engine shipped over .i then went to get a new piston for it as i blew it a few days later ,phoned the R guru over her in the uk how said it wasnt a 350 but a 330 on its first over bore .
So it could very well be a 350 i took the digital calipers to the top of the bore and it reads 77.71 ,i then took the calipers to the liner or atleast what i belive to be the liner ,wich read 1.26mm,this was the darker coloured material next to lighter colour metal next to the oring would this be right ?? cheers scott

[bansheeboyo]

i see no point in outting in a 78.5 mm bore if i can get away wit a 78.
are you meaning the wossner pistons or wiseco
i see on there website the wossner is 40 grams heavyer than the wiseco .
Are heavyer pistons better ??
cheers scott

[C-LEIGH RACING]

Ok, the 77.71mm measurement at the top of the jug, to me that indicating it is a 330cc cylinder on the last bore size.

The 1.26mm measurement your getting at the top, between the bore & the inside wall of the o ring groove, that sounds just about the right thickness that the iron sleeve should be if it was a 330 cylinder. All this is if I'm understanding you correctly.

The new pistons that ESR has, are made by Wiseco. It might be that a Wossnor piston would be easier for you to get than a Wiseco, since they are made in Germany.
I see your in Scotland.
Neil

[bansheeboyo]

i have counted up the cost of gettin the cylinde resleved ,and have decided to buy a new 1 instead going for a 350 this time .
which porter would you recomend ??
also is the esr cylinders the one to go for or is there a better make ??
i see there is a guy on ebay "250rtrikes" offering them for 859.99 HAND PORTED FOR CLEAN UP TO CASTING...NOT "AS CAST" PORTING SOLD BY ESR
i tryed contacting him thru ebay but he has blocked messages on ebay dose anyone know of a email address for him so i can find out more about what he is offering

[bansheeboyo]

http://cgi.ebay.com/ebaymotors/HONDA-TRX-250R-R-TRX250R-ESR-ENGINE-350-CYLINDER-KIT-_W0QQcmdZViewItemQQhashZitem3f09f45e98QQitemZ27074 9949592QQptZMotorsQ5fATVQ5fPartsQ5fAccessories

[C-LEIGH RACING]

"250rtrikes" & BDT Motorsports are the same.
Neil

[cdrookie]

i'd get an as cast cylinder and send it to c-leigh. his price, quality of work, and turn around time are tough to beat.

[Fear250r]

Originally posted by cdrookie
i'd get an as cast cylinder and send it to c-leigh. his price, quality of work, and turn around time are tough to beat.


x2. Neil's a good guy to deal with.

[dtek01]

Yea, I am curious on the piston weight as well. Is the heavier Wossner going to make a noticable difference?

I was told by LA Sleeve the Wiseco skirts will no last nearly as long.