Big bore SRX

[Nathan]

If you get a 600 srx bored out to 660, would you need a radiator due to the extra strain?

[SteveL]

erm...radiator? do you mean an oil cooler? I would always recommend an oil cooler, easy to install, use one from an XT. but as the engine is aircooled, there is no liquid for a 'radiator' to cool. 660 cc is a bit big for a std 600cc srx (can be done, not sure about the relaibility in the long term, usually they are opened up for racing) you should get 620cc out of the original liner, then its a question of boring out the barrel and a new (bigger) liner, starts to get expensive. talk to Roger at Denver Motorcycles Norfolk, he's done several, can give you a price, and tell you where the problems are

[themoudie]

Sally when bought was 634cc, biggest oversize on a standard liner. Next size up requires machining of the barrel casting to accept larger diameter liner specific to larger piston.

The 634 piston if not warmed through and of the Wiseco variety having little skirt, consequently wears quickly on the fore and aft skirt faces. Sally ran with 8thou wear, with max tolerance being 3thou. Lots of slap when cold and still there until hot.

I went back the way and bought a Wiseco liner and piston of 598cc standard bore and had the liner fitted and honed by a reputable engineer. Ensure ring end gaps are to spec, use plenty of oil when assembling, take the motor for a run on first starting, don't sit with it ticking over or blipping the throttle. Up through the gears, when warmed through revving to 4000. Turning freely, no lugging. They may thump, but not like a Pussy!

Drop the oil and filter as soon as you get back, then new filter and oil. When cool torque everything up and run for 500miles, spinning the motor to 4000. Change oil again. Increase revs and change oil and filter after another 1000 miles. Will take another 1000 miles to really free off. Sally now sits at 4500 in top at 75 - 85mph and returns 60mpg at these speeds.

Unless you are seriously racing, can't see the need for the 'big' piston.

Cheers, Bill

[Steve H]

Unless you are seriously racing, can't see the need for the 'big' piston.

Stronger mid-range

[Nathan]

Should have asked what mods would I need, thx for going into more detail.

I wasnt thinking for my SRX, its just im slowly getting to the point where i might start a project, and i would consider taking that extra step of having the engine done.

not sure which engine to use atm, but purely for some aspecs of the idea it will need to be a single, (or at least one cylinderhead , like the yam XS650.)