JE FORGED PISTON 442CC BIGBORE KIT?

[magg]

From further correspondence with Mike Norman, the bushed piston pin idea, to overcome the pin diameter difference between a VFR rod and FZR piston, he also considers is a practical solution.

The risk of offset sleeves in the OEM cylinders is not a problem because to achieve 60mm bore, the cylinder has to bored to 64mm and a new sleeve fitted. A 64mm bore will remove all the OEM sleeve.

This will leave approx 3mm of the aluminium cylinder casting. Although thin when compared to the OEM aluminium thickness, this the same as used by Mike in his race engines. He is also only using aluminium sleeves of approx 3.5mm whereas I propose to use 2mm wall iron sleeves. For a road engine, Mike thinks the iron sleeve and thin aluminium cylinders will be satisfactory.

[Variablevalves suck]

Ive used the Fzr 6 pistons in the GSXR4, the TTS 59mm kits use the very same piston rings.
Problem you will have is if the 1mm smallend caps are not a PERFECT fit you can have problems with the circlips coming out, i know because race Lambrettas have been using this method for 20 years and its a known fault.

[magg]

Using circlips to locate the piston pins was to be my 2nd choice, had planned to use buttons as 1st choice, provided I can info to convince me that they are along term solution. Buttons appear to be popular in race piston applications which means long term wear performance is not an issue, road bike mileage may be another matter.

[JC120]

Working on the assumption that a ready to go 490cc kit is not an option and IMO 443cc is too small for the trouble, I am planning to get 483cc by running FZR600 pistons, a Mike Norman suggestion. Max oversize OEM FZR piston is 60.0mm and Wiseco make a 60.5mm version, giving 475cc and 483cc respectively.

The FZR piston appears to have very similar in design to the NC30 piston, particularly pin to deck height and may have the advantage a shorter shirt. Mike Norman's recommendation of the FZR piston is based on the good ring pack and low weight. Only problem is that the pin size is 16mm not 14mm as per NC30. Solution to this might be capped 1mm wall thickness bushes fitted to the end of the NC30 piston pins. Cylinders will need to be re-sleeved.

Will acquire an FZR600 piston to confirm dimensions and go from there. Would anyone have access to a top case to measure the wall thickness of NC30 cylinders. My major problem here in Oz is access to NC30 parts, engine in particular, can only buy a complete engine for a lot of money, and I am not keen to disassemble my running NC30.

Just out of curiosity, did you ever find a FZR600 piston and the other measurements you where looking for?

It would be great if we could figure this out.

[magg]

Have shelved the idea because I could not access to the bits to make actual measurements.

Used NC30 engine parts in Oz are effectively non-existent and a used engine costs $500. Not willing to disassemble my running NC30. Same problem with FZR600 pistons, would have had to get used ones for USA just to make measurements. A lot of trouble and expense for what if project.

Needs someone with access to a NC30 cylinder block and piston, a FZR600 piston and sleeve dimensions and a machine shop willing to endorse the idea. Last think you need is an expensive big bore engine that blows head gaskets and drinks oil because the cylinder wall thickness is too thin.

New FZR600 pistons and sleeves from USA cost $800 delivered to Oz and then machining the cylinders would cost $400 more.

[vfrman]

For those prices it would be better to get GForce to set up a motor for you.

[CRM]

Magg, have you spoke to anyone in the UK regarding these ? reason i ask is because the big bore route over here has been tried and tested and all this data is out there. saves reinventing the wheel so to speak.

[Drunkn Munky]

Yep im sure the race boys are getting 80+ from +1 pistons now, im sure sure ABR can give more detail on his go faster secrets

[magg]

55mm +1 and 80+ hp race engines do not usually make good road engines. Available big bore kits are still quite expensive for just 4 piston and ring sets and the increase in capacity hardly seams worth the effort.

After a lot of research I have decided to save the money and spend it on fuel to ride as often as possible on reliable as designed by Honda NC30.

[JC120]

Have shelved the idea because I could not access to the bits to make actual measurements.

Used NC30 engine parts in Oz are effectively non-existent and a used engine costs $500. Not willing to disassemble my running NC30. Same problem with FZR600 pistons, would have had to get used ones for USA just to make measurements. A lot of trouble and expense for what if project.

Needs someone with access to a NC30 cylinder block and piston, a FZR600 piston and sleeve dimensions and a machine shop willing to endorse the idea. Last think you need is an expensive big bore engine that blows head gaskets and drinks oil because the cylinder wall thickness is too thin.

New FZR600 pistons and sleeves from USA cost $800 delivered to Oz and then machining the cylinders would cost $400 more.

I can get block measurements when my engine goes in to get worked on in 3 or 4 months and I have some +1 NC30/35 race pistons or the OEM NC35 pistons when they get swapped out.
Being that I'm in Los Angeles, it shouldn't be too hard to find some FZR600 pistons to measure either. If I just keep my eye's open for one, I'm sure something will pop up.

Hopefully I can give my road bike some more grunt one of these days.