M53 non bombshell carb

[ryan]

Hello,
I am just wondering if a non bombshell site M53 Linkert, with a 1.5" throat will work OK on a Fl or El Knucklehead motor? I have not gotten a set of jugs nor heads yet, but am thinking of just going with a set of aftermarket heads.
I just want the bike to run descent, not looking for numbers matching.

Thanks

[Rubone]

You would be better off trading it for a BT carb. The low speed circuit is different and isn't set up for enrichment when choking or starting. It would work, but may be a bit frustrating.

[T. Cotten]

Ryan!

An M-53 will only work with its proper 'bombsight' venturi, and if all things are in order. (Most original venturies have shrank..)
The later M-53 A1 was a conventional venturi design, and much more practical to service.

Just about any Linkert of the proper nominal size for its manifold can be made to work on just about any American V-twin, if all things are in order.

....Cotten

[ryan]

Ryan!

An M-53 will only work with its proper 'bombsight' venturi, and if all things are in order. (Most original venturies have shrank..)
The later M-53 A1 was a conventional venturi design, and much more practical to service.

Just about any Linkert of the proper nominal size for its manifold can be made to work on just about any American V-twin, if all things are in order.

....Cotten

Cotten,
My M53 does not have the bombsight venturi, but it also does not have M53A1 stamped on it as well, just M53. I am getting confused now? Also it is not painted black, just has 1 1/2" throat on the side.

Thanks for the replies

[Rubone]

Ryan,
Don't get confused. The M53 was superseded by the M53A-1. Neither was ever used on a Big Twin and both were based on the earlier Competition carbs, MR3 and MR4 types.
All Big Twin (and most small twin also) have a provision to lift the low speed needle when choked for more fuel flow. The M53 and M53A-1 do not. They can be used, but as I said, they are not optimum for ease of use.

[ryan]

Ryan,
Don't get confused. The M53 was superseded by the M53A-1. Neither was ever used on a Big Twin and both were based on the earlier Competition carbs, MR3 and MR4 types.
All Big Twin (and most small twin also) have a provision to lift the low speed needle when choked for more fuel flow. The M53 and M53A-1 do not. They can be used, but as I said, they are not optimum for ease of use.

Robbie,
I am confused to as why my M53 does not have a bombsite, but it also does not have M53A1 stamped on it, that is my confusion. So not all M53s have bombsights then?

Kind of stinks it is not for a big twin, because it looks brand new with no visible wear in it what so ever.

Thanks again!

[ryan]

So, what do I really have if my Linkert carburetor only has the stamp M53 without the bombsight venturi?

[duffeycycles]

you have the wrong venturi

[Rubone]

Someone likely changed the venturi to match the updated specs on M53A-1 type carbs. The bombsite venturi was not of any advantage and quickly dropped for street use. The carb will function fine with the non bombsite venturi.

[T. Cotten]

Well, Ryan,

One must presume that the bombsight has been removed, and a conventional venturi installed.

Linkerts are very forgiving!

.....Cotten

[ryan]

So should I try the carb or just try to trade it off? Do you have any interest Cotten? It does not even have any wear marks in the throat from the butterflies nor pits in the venturi.

[T. Cotten]

Ryan!

I have no interest, as I do not wheel'n'deal, but only offer services, and only to established accounts at this time.

If you can get all things in order, it will probably run.

"Pits in the venturi" are inconsequential.
Daylight around it is an issue, normally; Your main nozzle is captured by the body casting rather than the venturi, so I would only be conjuring any guess at all.

As far as trading it off, somebody certainly wants it more than you, but please be gentle with anyone into Ks. They are in their own purgatory.

....Cotten

[Rubone]

The hipsters like them because they mistakenly think the bombsite is a magic performance trick, regretfully they will pass yours by since it is missing even though it would likely work better. I have two sitting on my shelf along with an NOS M53A-1 and the original on my KHK. I am using one on my WLDR since I don't have an MR3 for it and it will work fine. The TROG guys would be interested as it is a definite performance item for a 45. Put it out there for trade, it will go...

[ryan]

Ryan!

I have no interest, as I do not wheel'n'deal, but only offer services, and only to established accounts at this time.

If you can get all things in order, it will probably run.

"Pits in the venturi" are inconsequential.
Daylight around it is an issue, normally; Your main nozzle is captured by the body casting rather than the venturi, so I would only be conjuring any guess at all.

As far as trading it off, somebody certainly wants it more than you, but please be gentle with anyone into Ks. They are in their own purgatory.

....Cotten

Cotten,
Thank you for your valued information! I was only asking you option on what to do with it, not in trading with ya. I need to go back to the guys shop and dig around some more. I had to get out of there because I was having a very rough day with my leg pain, of all days to have a rough day. I also got a complete mouse trap assy. along with some other needed goodies while I was there like an original set of leather knuckle bags, without dead leather, but do need some new straps. I do have some good old leather, that matches the patina of the bags, to replace the straps.

Robbie,
Thank you for all your valued information as well! I have no clue when it comes to Linkert carbs. I did watch a video on a guy repairing the bodies, mainly the throats, by soldering the butterfly wear marks. I think his name is Tatro. I also looked up TROG because I was not familiar with the term, they do look like they have a lot of fun.

Last question, what style Linkert should I be looking for for a nice running knuckle engine? Again, I am not looking for numbers matching because I have to buy new heads and jugs and I am not even sure where I should buy them as far as make and quality? This project is next in line and all I have is the 1938 knucklehead motor with 54 jugs and heads, a rebuilt tranny and wheels. I just want a running knucklehead bike and do not care if it is a mixed year knucklehead bike. Way to costly to bring it back to original.

[T. Cotten]

Golly Ryan,

I guess you want to trade it for a common M-35.
An M-75 would be "sweet", and more suited to modern highway speeds, but you can always install the larger venturi and nozzle into an M-35.
M74-Bs are most common, of course.

Although most Linkerts are forgiving enough for duty after a basic-go through (including a float that will withstand modern fuels), a thorough re-conditioning is far more involved, of course. I am not a fan of soldering the borewear, however, as it just gums up the hone.

...Cotten