Waking up your H1 and KH500

[Deleted]

Late models had the transfer ports blocked to slow em down. I got some info on Fixing the
ports from our friends down south....


Just draw a line even with the base gasket surface and cut. round to the stock look when cut.
-JA-MOO


I did it this way, and it worked. Before I cut it with the dremel, I drilled holes at the edges for a nice, rounded look.
-Lane

This is somewhat higher (2-3mm?) than the stock '69-73 cutout. If you choose to go this deep you may want to leave a larger than stock radius on the intake side to support the lower cylinder sleeve IMHO.
-Looney Cylinders

There is plenty of sleeve left, but to each his own.....


Thanks to JA-MOO, Lane and Looney for their tuning tips
Biker Don

[tripletriplenut]

now match the pistons windows to the cylinder windows and you will get the full effect

[Deleted]

I'm just learning this tuning stuff. So the pistons need to be chewed away to? not mentioned on the US site, they changed the pistons to match the de-tuned porting on all
detuned H1's or just late KH's? Believe me I will never attempt any more than changing out a crank or replacing pistons and rings. Grinding away at cylinders/pistons isn't for me and I never
really race so all out performance isn't a concern. I like noise and reliability above performance

[Rick]

Hey Don, I did a LOT of mods to my S2 race bike, I'll show you how or do it for you if you're squeemish....you'll have an explosive powerband from 6000-?? rpm's... ;D ;D


I had JA do a set of reeds for the 350..best bang for the buck and you have a very driveable bike when done...


Rick

[tripletriplenut]

just widen the piston window to match the cylinder window width otherwise it will still be restricted

[Deleted]

Makes sense, i will take you up on that offer Rick. I have a dozen spare cylinders and a bunch
of pistons. I'll pop up sometime and you can show me and "the boy" on some old stuff and maybe I'll get the nerve up. My 72, would it need them opened? Someone told me they were
the last year of the "real fast" engines. I've always been a leave it the way the Factory Built
it guy. I seen many a snowmobile engine fried cause amatures start messin around. The
engineers design pipes, which still are a form of an expansion chamber to work with the porting
and carb set-ups, timing, compression etc...My current ride's engine is also a 72, I don't think
biker Don really needs to go any quicker. It was really my first tuning to a pipe experience
and I think it's real close to being spot on, a tad rich. I was thinking I may drop a size or 2 on the main and go up a touch on pilot but I rode near 4000 miles and still not fouled a plug so I never bothered, I got sick and tired of 3 carbs off, 3 on, 3 carbs off, 3 on, 3 carbs off, 3 on,
3 carbs off, 3 on, etc....