Converting KT100 to Tilly alcohol carb?

B

Brettm57

Member
I'm thinking about converting a KT100 to run on alcohol, and I'd like to switch to a Tillotson HL carb when I do. Has anyone else done this, and if so what model Tilly did you use?
 
I've done up a lot of these over the years:

KT-HLadaptor.jpg


Pretty simple with a drill press, and if you are good with laying out a pattern,
but I made a jig to drill the holes.
I bored them for the 1"-ish throttle bore carbs like an HL360, but also made them fit the larger HL380.

But don't expect much of a gain without running higher compression.
 
I have used a tilly HL360. on gas though. same manifold as GoFast's picture. worked great. probably used his picture back then as it was not long ago.(thank you)
 
Make sure it's the 360A , it's has the .945 venturi. the 360B an C have a .875 . The 360A is a gas carb so an alky conversion with alky stacks are needed. The 380 would be better yet it flows 20 cfm more than a stock WB3A, but would need some drill pattern changes on both the alky or gas version when used on a KT. It will pick it up a little, but get you a stock untouched head, cut the relief down to near 0, end up with about .035 deck height ( whatever head gasket it takes). With the small pocket of an uncut head , no relief and about .035 deck height you'll have about a 9.5 cc volume at TDC, that will make it feel like a whole different engine. Of course porting will complement the build.
 
Thanks for all the tips! Keep 'em coming! What about ignition timing? Should I advance that for better performance on alcohol?
 
The stock Timing's fairly steep at 28 degrees, .136 BTDC initially and then backs up at some point to 24 degrees, I'd leave it there if you bump the compression up a bunch.
 
You can make up for weak ignition by running a tighter plug gap, and one of the more modern fine wire electrode plugs.
One of my flat track bikes liked .016" gap. Anything more, and it would drop spark at high rpm.
 
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