ypvs big bore kit

[ivymike]

does anyone know if the 400cc big bore kit is still available. or if it ever was, as I remember someone mentioning it to my brother some time ago. I know you can get the 485 kits but they dont just bolt on,. plus other mods needed.
rebuliding a spare engine, and thought it bee a good idea, as it is going in my rgv 250

[cinder]

wiesco do a 68mm piston originally for the banshee.ive got the part number if you need it.that will take it to about 400.

[tsa]

You can get an Athena kit, cheetah or a cub kit these are all available in 421cc or stroke your 350 to 385cc ish.

[ivymike]

been looking at the kits but they dont have the power valves. by stroking the engine, would this be done by longer rods and a base plate?

[midlifecrisisrd]

Sept 18, 2011 16:28:52 GMT 1 ivymike said:

been looking at the kits but they dont have the power valves. by stroking the engine, would this be done by longer rods and a base plate?

In the middle of doing this at the moment. Using a TSS balanced crank with +4mm stroke and 5 mm longer rods. Think the longer rod reduced side thrust on the piston. You can use a barrel spacer to take up the extra rod length and stroke but I'm going down the route of using wiseco 795 forged pistons that have a 5mm pin offset so takes up the 5mm rod and head is being recut to allow the piston to go 2mm further and getting ports altered to suit. Larger bore clearances needed for the forged pistons.

Also got kenny making a set of stroker SS pipes to suit.

Should make a very grunty motor putting out over 70 BHP at rear wheel.

Steve

[ivymike]

thanks for info. already got one engine with a mick abby fast road tune and pipes with zeeltronic ignition that puts out approx 72 bhp @ rw. thats in my rd. I know by adding extra exhaust boost ports and m aking new poweervalves on tuned barrels to suit you can get 80 to 85 on stock bore size, just want that bit more for my rgv . it is a track day tool now, just want to make it an ultimate track tool without the fuss of trying to fined an rg500 engine. how much biggger does the bore clearances have to be for the forged pistons?

[midlifecrisisrd]

Sept 18, 2011 19:18:56 GMT 1 ivymike said:

thanks for info. already got one engine with a mick abby fast road tune and pipes with zeeltronic ignition that puts out approx 72 bhp @ rw. thats in my rd. I know by adding extra exhaust boost ports and m aking new poweervalves on tuned barrels to suit you can get 80 to 85 on stock bore size, just want that bit more for my rgv . it is a track day tool now, just want to make it an ultimate track tool without the fuss of trying to fined an rg500 engine. how much biggger does the bore clearances have to be for the forged pistons?

Think it's only an extra 0.015mm but don't quote me. Mick will be doing the porting work and got some re worked powervalves for it. Peak power is a 9900rpm so not a screamer either. The "abbey" pipes will work on it but told the stroker pipes add 7 bhp from 5k to 10k

Steve

[ivymike]

thanks for info. gonna go through a few options next week. mick oinly lives up the road from me. unless your going whole hog with extra exhaust boost ports, the standard powervalves are fine. mick will re profile them to the shape of the exhaust port.