Carb help

[NicoNP]

Well first off I want to thank you'all for the previous help on getting my ‘47 WL going. Yup after several months and much grinding of teeth it finally lit off in a cloud of smoke (sorry neighbor about the oil cloud I sent your way) needless to say I was grinnin' through all that smoke. Thanks for all the helpful suggestions and dare I say . . . Marvel Mystery Oil. Yes I said it, nothing was working until I adding some of that mystery oil and, blammo . . .

Currently I (think I) have carb problems and hope you’ll have some suggestions for this Linkert carb running on an original un-restored '47 WL. Once started the bike idles fine but the throttle response is horrible. It’s like an on/off switch. Turn the throttle, a little, a little more, a little more and finally caroooom, oh crap, she’s gonna blow . . . back the throttle off and (eventually) gets it back to idle. Also I think it is why it is still hard starting . . . I think some kind of carb (fuel delivery) problem.

Yes I rode it like this, pretty exciting!

When I first got it started I had the low speed way to high and brought the idle down using the low speed needle.

So . . . could the float be tweeked, I had problems from the start with the float. Initially the float needle (what the float pivots on) was frozen and the float wouldn’t swing up and down. So after cleaning etc. I finally got it to swing and tested the float with the bowl un-attached from the carb body. Simply plugged the bottom of the bowl opening and filled her with gas. Low and behold it floated . . . but still wondering if I can trust it - would this cause terrible throttle response?
What else can I look for, there’s only hi and low speed needles, so I am probably missing something.
Thx all

[Sargehere]

Your float may be set too low, so the float bowl doesn't fill, holding a supply of gasoline for the carburetor to vacuum-up when you open the throttle. The float lever pivot should be loose as all get out. The float can just flop around, up-and-down. You have to go by the diagram in the Service Manual (I assume you have a 45 "Service Manual" handy by this stage. If you don't, just let me know. and PM me your mailing address).

You set the float with the bowl off the carburetor. Turn the bowl assembly upside-down, and the edge of the float should fall, closing the needle valve, 1/4" above the rim of the bowl (that's upside-down "above," actually 1/4" below the rim in service.
Be very patient with the float. Don't gorilla bend it, still attached. With it all together, check it.

If it has to be moved, take it apart to bend the float lever and test fit it back together again. You can blow into where the gas line enters the float valve, and make sure it's closing. Make sure the final position of the float (btw, what kind of float are you using?)

If it's an old-time ring of cork, maybe coated with shellac, or any yellow or white piece of plastic, or a soldered brass thing ("too heavy"), discard it, and get a modern float, made for today's caustic camel piss that passes for gasoline! Get the modern substitute for cork. Get a float from this guy, for instance, for about $40:

Liberty Motorcycle Specialties,
118 N. Washington Street
Lacon, Illinois, USA 61540
Phone: 309-246-3509
Email: Liberty@npoint.net

That's Cotten, he's an old curmudgeon, but his lathe-cut Linkert floats are first class. So check if the float level's too low. Then your needle settings. Screw what you have all the way in, and make a note of where they were and turn them back to where they were report to us back here. Good luck!

[c.o.]

Also, did you do a manifold "leak" test? If it's sucking air, you'll never get it to run right. Or if you do get it reasonable, you risk early wear on the top end.

[QUOTE=Sargehere;119021]
That's Cotten, he's an old curmudgeon, but his lathe-cut Linkert floats are first class. QUOTE]

I grinned at that one Sarge. He might be a curmudgeon but I can't say enough good about the man. He's part of the reason that my bikes run as good as they do. I'll also second the comment on his floats. I've not had to worry about a boat anchor in the bowl yet!

[Tom Lovejoy]

All good advice, I have wasted alot of time trying to adjust a carb or two. If you have any intake leaks your just wasting your time, like Cory said you will never git it right. Make sure about that, either of those problems - leak or float, will really mess ya up. Congrats on getting your 45 up and running, right on.

[Sargehere]

... If you have any intake leaks your just wasting your time, like Cory said you will never git it right. Make sure about that, either of those problems - leak or float, will really mess ya up...

And speaking of which, you can remove your 45's intake manifold (two large nuts) and under them are brass rings. You can "service" those faces to do everything to insure an air-tight seal between the faces of the cylinder intakes, which are supposed to be FLAT, not uneven or nicked, and the very ends of the manifold that butt against the cylinders.

You may "freshen" the brass rings, perhaps by cleaning and then annealing them with a moderate amount of heat, as by a torch, and then glass-beading them, and "polishing" their flat faces in a circular motion on a piece of fine sandpaper or emery cloth, flat, held flat on a solid, flat surface, like a steel plate or a piece of glass on your bench-top. You can also polish the ends of the intake manifold "flat."

A modern alternative to the brass entirely would be for you to buy a pair of "PEEK" seals, which are replacements for the brass rings made of modern material, when you buy the new bowl float. Hope this helps!

[c.o.]

Another good one Sarge! PEEK rules!

[Ohio-Rider]

Turn the throttle, a little, a little more, a little more and finally caroooom, oh crap, she’s gonna blow . . . back the throttle off and (eventually) gets it back to idle. Also I think it is why it is still hard starting . . . I think some kind of carb (fuel delivery) problem.
Thx all

Mine did this when the set screw that holds the handlebar grip to the bar got loose and caused to much slop in the control.

[Rollo]

One more thing to check on the float issue is the play between the top of the needle and the fingers on the float lever. Too much or too little and your needle isn't letting gas into the float bowl properly. I think it is .003 but better check the manual as I'm quoting big twin carb specs. I went through a lot of trail and error and finally stopped and made sure all my tolerances were correct and voila they all run fine now. Good Luck!

Tom (Rollo) Hardy
AMCA # 12766

[T. Cotten]

Thanks for your endorsements Folks,
But let me comment:

There is only one float setting.
If you must vary from spec, something's wrong with the float.

Manifold testing is reviewed at http://virtualindian.org/11techleaktest.html
Please rinse thoroughly.

PEEK is a noble material, but must fit tight: A light press fit.
Its remarkable re-useability is compromised if distorted from over-compression, or imprinted by blemishes from worn manifold spigots.
PEEK manifold seals will not alleviate leaks between nipples and the cylinderhead.

....Cotten

[Steve Slocombe]

Dear Nico, original carbs often suffer from partially blocked idle passages, which makes it hard to get a smooth tickover and easy changeover between the fast and low speed settings. Nearly all earlier Linkerts have number 55 and 70 drill size holes in the rear body, with a 0.009" slot between them. These can be cleaned out with the matching tiny drills, used by hand, and a piece of shim material. The set screws at the back and top of the idle passages can then be removed and a number 42 drill used, again by hand, to remove the crud of ages. This should help.

[NicoNP]

Great input, dang I haven’t thought of air leaks. Was such a common problem with my Harleys of the 70’s, 80’s and so on, I’d forgotten. Will check during my next chance in the garage.
Also will check the throttle Ohio Rider Steve mentioned . . . good one.

Yes I have owners/service manuals, and Palmers, “How too . . . “ book (lucked out on that one, came with a ‘41 I fell into once).

Hey Sarge loved the pics from the Flathead Owners Group.

I’m running some type of plastic float. I believe the float “floats” ok but had a problem getting the .003 correct. I just wasn’t able to get it flush anywhere, it seemed tweaked on an angle . . . i.e. float measurement near the “front” of the bike was different that the measurement near the “rear” of the bike (float bowl). I played with it for hours, it seemed to stick and could not see where it was hanging up, I got it to float reasonably and said screw it, let just see if this thing will start, which it eventually did.
Ok guys, it’s back to the drawing board . . . i mean float, see if I can get it right. Will check for leaks and other suggs made.

As usual great input and thanks.
Nick

[duffeycycles]

The last '45 that came to my shop the points started to ground out as the RPMs came up. That makes them run like crap and die if you rev far enough, but this guy was riding it and couldn't figure it out . He kept blaming the carb that I had rebuilt . He put a round head screw in to hold the points and caused clearance problems above idle.I filed the top off his screw and it ran.

[T. Cotten]

Dear Nico, original carbs often suffer from partially blocked idle passages, which makes it hard to get a smooth tickover and easy changeover between the fast and low speed settings. Nearly all earlier Linkerts have number 55 and 70 drill size holes in the rear body, with a 0.009" slot between them. These can be cleaned out with the matching tiny drills, used by hand, and a piece of shim material. The set screws at the back and top of the idle passages can then be removed and a number 42 drill used, again by hand, to remove the crud of ages. This should help.

Steve!

Don't look now, but the general public hasn't as steady a hand as thee.

I have an immaculate DLX113 on the bench that has been gouged.
If that is not tragic, nothing is.
Even modern import service manuals stress that a drill bit will change the flow characteristic of a fixed jet, and the idle bleeds of DLX Scheblers and Linkerts are more delicate.

Keep the goddam drillbits out of them Folks,
A safety pin is safe and effective.

....Cotten

[c.o.]

Keep the goddam drillbits out of them Folks,
A safety pin is safe and effective.

....Cotten

I knew that was coming... (I'll spare you the silly smiley face) It seems to me I can recall a discussion that referenced early Linkert carb tool kits including drill bits and they weren't such a good idea for most folks.

[Steve Slocombe]

Dear Tom, much of my reply was summarised from early Harley Shop Dopes. These advise use of the drills by hand, but also remind us not to bottom them out and damage the seat at the end of the idle passage. Dealer Accessory catalogs from the 1930s show the cleaning drills mounted in handles as part of a kit, presumably for sale to the careful bike owner.