37 ULH Carb/Throttle Mismatch?

[warkshop]

My 1937 ULH Bobber was built from bits, by someone else. It does have the correct M51 Linkert, had Kevin Lobasso redo it for me, great guy, great job done. The bike has a set of risers and a one piece handlebar setup that i've been told was a HD factory accessory in the late 40s, early 50s. My trouble is no matter what i try if the throttle is set to close the butterfly for a decent idle this will only allow maybe 2/3 open throttle setting. I would like wide open when needed! It is as if the trottle on the handlebar does not have enough travel to do it's job. Do i have an incorrect (sure looks like original HD) throttle (45?) or is mine so badly worn it can not do it's job. I am perplexed! Help!
bob wark in Ohio

[Rubone]

Bob,
A picture would do wonders for being able to help you. If the bars are indeed H-D (the only risers and one piece handlebar they offered were rubber mount using Hydra-Glide risers and '49 type bars), they should work All the throttle sleeves are the same for all models. The lever on the carb is also the same on BT SV and 45, so they are not model specific. There is minimal play in a stock throttle. Does yours have all the proper rollers in place? Is the outer cable properly attached within the bars and to the frame of the machine? There are too many scenarios to guess at without clear pictures of your issues.
Robbie

[warkshop]

Bob,
A picture would do wonders for being able to help you. If the bars are indeed H-D (the only risers and one piece handlebar they offered were rubber mount using Hydra-Glide risers and '49 type bars), they should work All the throttle sleeves are the same for all models. The lever on the carb is also the same on BT SV and 45, so they are not model specific. There is minimal play in a stock throttle. Does yours have all the proper rollers in place? Is the outer cable properly attached within the bars and to the frame of the machine? There are too many scenarios to guess at without clear pictures of your issues.
Robbie

Robbie,
I will take some images. I just spoke to Paul Friebus (American Cycle Fab.) and he has suggested some things to check out/possibly adjust on the throttle spiral, related bits. My outer cable is held down with what appears a factory clamp on the front head. I believe the throttle arm is correctly timed on the carb throttle shaft. I am hoping/thinking the issue is within the throttle assembly on the handlebar. Images later today,,,thank you!
bob wark, Ohio

[D.A.Bagin]

I ran into a similar problem when installing new inners on my 58. I was chasing it for days. I felt like a real idiot when I found the problem. The inner cable was left uncut after pushing it thru the slider and locking it down it was hitting the internal of the grip when turning the grip. Make sure you trim the inner back on the grip end after installing it. Hellooooo....

[warkshop]

37carb linkage.JPG
Thanks D.A.,,,i did that little learning experience last year and that is not the issue this time. Note in the image i only have about 7/8inch of inner showing at idle setting, my shop manual says that should 1 to 1 1/2 inch,,i have extra stainless 'inner' so i'll make a longer one. I strongly suspect my issue lies within the throttle assembly. Time to dismantle and hopefully learn!

[warkshop]

P.S.,,,,Robbie (or anyone else) can you tell me if my location for the throttle cable clamp bracket on the head and cable routing as shown is correct,and ,,or not? Thanks, bob wark

[warkshop]

DSC03424.JPGDSC04516.JPG
Thought you might like to see what the old axe looks like, i dearly love it! An image of the handlebars to see if they are what we think they are, i also have a chrome cover for the top, it is off so i could put on a route-sheet holder for a road run. See also the widgets from inside the handlebar,,i see mention of a roller in my manual but i don't have one. This setup has been functioning for 3 years,,,but not optimally. I find the outer cable will move about a 1/2inch toward and away from the handlebar end,,,,i don't see any way to lock down the cable on the bars,,,???

[warkshop]

DSC04515.JPG
this one didn't load last time,,,?

[Robert Luland]

Bob, their is one more thing that nobody mentioned. Twist grip end play. After market spirals suck. Unfortunately you have to have the grip off to check this. This is the travel the twist grip goes before it hits the handlebar end plug. If your spirals are worn badly it may require the use of custom made thrust washers to prevent the excess travel. The spirals should not have any play back and fort to have full cable throw. Hope this helps, Bob L

[warkshop]

Thank you Robert L.,,,,I am getting more of idea of just exactly how this mechanism works,,,still wondering why my throttle has no roller pin just a lug on the barrel. My manual shows a roller,,? In the end i hope to fully understand this rather complex assembly. bobwark

[Rubone]

What "manual" are you looking at Bob? The -53 part number throttle used from '54 up is totally different. So is the '48 and earlier one. You need the '49 type throttle information to make sense of it.

[warkshop]

Thanks Robbie,
I had no idea, just my luck to have one year only handlebars and throttle. Now i know what info to seek. Thanks!!! It is a cool set of bar and risers and they help make the bike fit me very well so i'll stick with this setup. I'll report as i work thru this.
bobwark

[Steve Slocombe]

Yes those are good tips to check if the spirals are more than a few thousandths shorter than the bars. And you may be missing the 3320-10 roller on top of the plunger pin, which would give plenty of slop in the throttle spirals. I've also made some 3321-31A roller blocks if you have worn slots in the bars. These are 7/16" x 1/2" so you can file out the 3/8" slot to fit if it is worn. Finally I reckon the correct carb for a 1937 ULH would be an M51L with the 1 1/8" venturi.

[Robert Luland]

What "manual" are you looking at Bob? The -53 part number throttle used from '54 up is totally different. So is the '48 and earlier one. You need the '49 type throttle information to make sense of it.

Rob, the picture of the bars above my post wasn't up when I posted. Bob

[Rubone]

Rob, the picture of the bars above my post wasn't up when I posted. Bob

Bob Luland,
Two different Bobs on this thread, I was responding to the OP about his post.
Bobwark,
Those are not one year only, just that '49 was the first year that type was used and if your manual does not show that type it is tough to understand them. They have an internal spiral affair. But the total amount of travel is still compatible with Sidevalve throttle arms for full travel . So it is a matter of finding where you are losing the movement.
As noted before, the spool on the end of the outer cable must be locked solidly in the bars by the set screw, and the outer cable must be flush with the throttle side of the spool.
Also note that at full travel of the throttle arm on the carb when it hits the stop it is beyond full throttle and is actually slightly closing again. The throttle cable must be set on the idle side of travel, not the full open side. Not sure how you are approaching this.