Kawasaki KH400 conversion for a 150

[Scooterslag]

Just looking at webbo's book and reading up about this conversion. Did anyone run one of these back in the day? any good/ was it worth the hassle? I think the pistons are still available, all be it as a taiwanese copy. Cheers Paul

[dickie]

Sorry for asking a question instead of answering yours, but what's the point other than a better quality piston. They're both 57mm aren't they? Why not do a suzuki ts185 based conversion taking it to 185?

[Scooterslag]

Sorry for asking a question instead of answering yours, but what's the point other than a better quality piston. They're both 57mm aren't they? Why not do a suzuki ts185 based conversion taking it to 185?

Well this is it, why did people do this conversion other than maybe for group class in racing? looking at the work involved than yes- the 185 conversion makes more sense but still curious to hear what this kit was like. Paul

[Storkfoot]

I know my GP ( frame and bodywork, not the engine) was raced by Ian Frankland, Taffspeed in Group 3 (I doubt this group has existed for several years) as a 150. I recall chatting to him about it. I am fairly certain Taffspeed’s used a KH400 piston and had very large porting. I came to the conclusion, probably prompted by Ian, that it would be unrideable on anything other than a racetrack.

[gp200ts1]

I did a conversion on my vega using a kh400 piston and port timings supplied by the Frankland brothers, it was a flyer using a 6mm packer, 30mm dellorto and a chiselspeed expansion.

[Knowledge]

I rode in group 3 in the mid-80’s using this conversion. I think John Howe did the Porting and the transfers were so big I had to repair the (inadvertent) holes into the studs using Devcon.

The engine didn’t do much at low revs (no surprise there) but things got very hectic at the top of the revs.

One disadvantage of this conversion was that at 57mm, the piston was already on its second oversize, so when you blew it up, you would have few places to go if the bore was wrecked.

If you fancied a play, I have a piston that you can play with FOC.

[dscscotty]

KH400 57mm and KH500 60mm for short stroke engines were widely used as stated in group 3 race engines, kh400 pistons also had 15mm gudgeon pins, required the cylinder to be top n tailed and head re-profiled, lots of work really but at the time good quality pistons were not available unlike today, there was no performance gains it was just they could cope with higher revving/highly tuned engines.

[Scooterslag]

Thanks for all the replies, interesting stuff. Paul

[Vega125s]

My Vegas still running with the KH piston as a 140! Until the casa 135 kit is ready!