1939 Linkert M51 Throttle lever

[dukekleman]

I'm looking for advice, options and/or opinions on the throttle lever travel on a 1939 HD UL with a M51 Carburetor.

The throttle lever will not travel from from Idle position to 100% open throttle. It will travel from idle to approximately 7/8 throttle opening.

IMG_20260804_141422174.jpg
I believe I've checked and measured everything to be correct?

My thoughts are that I need to change the geometry of this particular throttle lever...I'm thinking about bending it to move the two pivot points (center lines) closer to one another.

Has anyone encountered this before?
Does anyone have any advice to share?
Has anyone bent an arm before?
If so, can you please share your method used to do so successfully?

Thank you,

Duke Kleman

[T. Cotten]

[QUOTE=dukekleman;n350985]I'm looking for advice, options and/or opinions on the throttle lever travel on a 1939 HD UL with a M51 Carburetor.

The throttle lever will not travel from from Idle position to 100% open throttle. It will travel from idle to approximately 7/8 throttle opening.

I believe I've checked and measured everything to be correct?

My thoughts are that I need to change the geometry of this particular throttle lever...I'm thinking about bending it to move the two pivot points (center lines) closer to one another.

Has anyone encountered this before?

Not really, Duke,

Does anyone have any advice to share?
Has anyone bent an arm before?

Only to un-bend them, Duke!
(Chill them; do not heat.)

If so, can you please share your method used to do so successfully?

Please open the installed throttledisc fully, to where it is parallel to the bore;
Then place the lever upon the shaft (with friction spring) such that its stop is against the tower upon the body, before tightening the pinch screw.

The disc should be able to close fully, only to then be adjusted slightly open by the idle adjustment screw.

Let us know if it doesn't...

....Cotten

[dukekleman]

Thank you Cotten.

I use a machinist square to set the throttle disc at WOT as you explained and then tighten the screen when at 90 degrees.

I'm measuring cable travel of 0.875"
The required lever travel currently is 1.200"
My thought was to achieve another 0.325" by changing its ratio...
I'm not 100% sure it's possible?
Perhaps I'm overlooking something yet?

Thank you,
Duke Kleman

[T. Cotten]

Thank you Cotten.

I use a machinist square to set the throttle disc at WOT as you explained and then tighten the screen when at 90 degrees.

I'm measuring cable travel of 0.875"
The required lever travel currently is 1.200"
My thought was to achieve another 0.325" by changing its ratio...
I'm not 100% sure it's possible?
Perhaps I'm overlooking something yet?

Thank you,
Duke Kleman

I wouldn't punish the lever, Duke,

If there is a 'cable' or spiral control issue!

The carb has its own stops, but the 'cable' throw must exceed it both ways to work.

....Cotten

[dukekleman]

I agree Cotten!
I haven't gone after the throttle lever yet because I really don't want too...
This motorcycle was fully restored 500 miles ago by someone else.
Everything I've checked in the throttle system seems to check out, but like I keep thinking, what am I missing???

Thank you,
Duke Kleman

[Rubone]

I start at WOT against the stop and work backwards. I've never seen an OEM spiral that did not supply enough travel. I would look upstream beyond the lever.