Linkert M74B

[duffeycycles]

Going back to the first page of this thread, Jerry Wieland said that he didn't have good results trying to run an M74B on Knuck's. I had problems with my '49 Pan with low compression pistons & M74B. I changed the jet from 19 to 17 to get the high speed needle in an operable range.

[T. Cotten]

Going back to the first page of this thread, Jerry Wieland said that he didn't have good results trying to run an M74B on Knuck's. I had problems with my '49 Pan with low compression pistons & M74B. I changed the jet from 19 to 17 to get the high speed needle in an operable range.

Everybody's results differ, Duffey!

I built a '39 EL (already had an added 4th gear) for an associate with an M74B, and it always jumped like a scalded dog.

Then a new owner wanted a 'correct' M35, and with all other conditions the same,.. it de-tuned it.

Would never have noticed if it was only ridden on gravel.

....Cotten

[dukekleman]

Going back to the first page of this thread, Jerry Wieland said that he didn't have good results trying to run an M74B on Knuck's. I had problems with my '49 Pan with low compression pistons & M74B. I changed the jet from 19 to 17 to get the high speed needle in an operable range.

Duffeycycles,

I have always found the #19 to be out of range as you stated.

Based on the condition of the engine, #18 and smaller have been required to put the adjustable needles taper into a more useable range.
Well built tolerance engines commonly require the #17 just as you mentioned.

Sharing my observations and experiences,

Duke Kleman

[duffeycycles]

Thanx Duke& Cotton, Both of your experience is greatly appreciated

[T. Cotten]

Going back to the first page of this thread, Jerry Wieland said that he didn't have good results trying to run an M74B on Knuck's. I had problems with my '49 Pan with low compression pistons & M74B. I changed the jet from 19 to 17 to get the high speed needle in an operable range.

We better define 'operable range', Duffey!

Let us review the manual:

74B trimmer.jpg
That means the needle can be set just about anywhere, with the OEM fixed jet.

Please beware the early 74s (no B) with the smaller jet, had an even more restrictive HS needle:

M74POINT.jpg

The later B series used larger jets and larger needles, presumably so there would be more than ample fuel, yet the needle could completely shut it off when necessary: Like when racing up Pike's Peak.

In actual practice, I sent them out (with spec'd jets) at three-quarters of a turn, and suggested the customers just left them there.

Until they rode in the mountains.

...Cotten
PS:

Fixed jets have always been an idiot switch.

Beware modern ethanol fuels have a reduced volumetric efficiency, compared to 1950 fuels. It takes more now.

If I must error, and error I did, I was happiest to do it to the rich side of things.