Fuel economy for KHK?

[Coolbreeze]

How many mpg should I be getting with my '56 KHK when driven at 60+ mph over a long distance?
Seems like I got ~25mpg the last trip I took. This looks a bit low. My Chief gets 35 mpg. Is it possible that the float is set wrong and that it is dumping gas into the engine?

[T. Cotten]

George!

If your float is of proper buoyancy, then there is only one float setting: 1/4 inch.

If performance seems unimpaired, but far too much fuel is being used, it would suggest that it has been enrichened to accomodate extra air from a vacuum leak.
I suggest bubble-testing your intake manifold assembly, as discussed at http://virtualindian.org/11techleaktest.html for certainty.

A #9 rubber stopper works as well as a testplate, although it requires three hands.
A stopper is the only way the individual nipples into each cylinderhead can be tested separately.

Good luck,

....Cotten

[Coolbreeze]

Mike S., a member of Vintage Iron Riders, rides a beautifully re-engineered KH with KR performance pieces. The last time he checked, he got 48.2 mpg. Of course, his bike has a CV carb; so, that probably makes a big difference.

[T. Cotten]

George!

The difference is the landmark innovation of a horizontal throttle over a vertical.
L&L introduced this with the DC series, marking the end of classical "tube" carburetors, and the beginning of modern.
(Ignoring AMALs, and Marvels on Fours of course.)

A vertical disc or aperture favors one cylinder of a V-twin over the other.
A horizontal disc can only split the flow evenly. Significant efficiency is gained, no doubt.

So comparing classic carbs to modern is apples and oranges at that point.
(Just as comparing a classic Linkert to a true antique Schebler HX wouldn't be a match.)

It would be interesting to see what a DC hooked up would do!

....Cotten

[John A]

I get about 50miles per US gall on my 56 KHK riding quite hard. It has the stock Linkert M-53 A1. I have factory references for the float height on this model to be 3/16" and that's what I'm on.

[T. Cotten]

That's quite impressive, JohnA!

Can we assume it has a modern float?

....Cotten

[John A]

Yes, Ducky float. One thing I should have said which would make some difference is that I think it has stock KH cylinders. KHK ports I believe are dimensionally different as well as polished. I don't have anything for comparison, but as the ports are rough cast I guess they must be KH.

It feel good though. Recently took it to North Weald Airfield (an old WW2 fighter station) for a bike sprint. I'm not an experienced sprinter but my best time was 16.2 and 76mph into a 14mph headwind. Had a lot of fun. Photo attached - hope it comes out the right size (haven't got the hang oif this yet!).scan0002.jpg

[Coolbreeze]

Great photo -- I saved it on my computer.