Linkert M36-A

[Mr.Big]

Cotten!

I was reading Shop Dope 303 where it talks about the retrofit of an M36 to an M36A. It states that the conversion could not be done by supplying the dealers with a kit and it must be returned to the factory for them to do.

So, what was done? In Palmer's the only difference appears to be installing a number 18 fixed jet. Everything else appears to be the same.

[Cotten]

Mr. Big!

One has never crossed my benches.

The M45A had a raised lip around the HS needle seat,

M45ASEAT.jpg

and a unique side vent:

M45ACAST.jpg

....Cotten

[Mr.Big]

It looks like they put in a smaller seat for the HS needle so it now performs like a trimmer on an M74B with the addition of the fixed jet. That would explain the need for it to be returned to the factory, correct?

[Cotten]

That's the best guess, Mr. Big!

[Hauula Pan]

Sorry, Don't know a thing about the M36 but its nice to see Mr. Cotton back !!!

[Panacea]

Mr. Big, is that the five dollar conversion they speak of in the rigid manual?

[Mr.Big]

Mr. Big, is that the five dollar conversion they speak of in the rigid manual?

Yup. Everything back then was either 5 dollars or 50 cents........

[Mr.Big]

Following up on this M36 to M36A conversion, it looks like the full meal deal included the following.....

Install smaller HS seat to convert it to a trimmer
Add number 18 fixed jet
Patch air correction hole in side of carb and drill larger hole (why not just drill the original hole bigger??)
Change nozzle from a #1258-40 (4 air bleed holes) to a #1258-50A (11 air bleed holes)

And last, but not least, according to Palmer's the venturi went from a #1265-40 1-1/8" venturi to an "unlisted" part that was also 1-1/8" but the depth of the groove for the air correction went from 1/6" to 1/8". Not sure how that was done because the thickness there is only 1/8" so........??

Anyhoo, I also noticed that Mr. Wilderness offers a kit to upgrade "any" 1-1/2" Linkert to M74B specs by installing the 74's venturi, nozzle and number 18 fixed jet with no carb changes. Wouldn't it be appropriate in the case of the M36 or M45 to modify the air correction hole (as the picture above for the original conversion) for this to work properly?

[Cotten]

Well, Mr. Big,

Linkerts are very, very forgiving.
That's why ebay has an endless supply of so-called "rebuilds".

Drilling an un-converted M36 or M45 would severely depreciate its market value, as "field conversions" are an AMCA fault, whether they run "better", or not.
M74Bs are the most common Linkert on the planet; Why not just shelve the heirloom and get one, if desired?

The only restricted nozzle vents ("air correction hole") were the M35TP, M36, and apparently the M45. Why L&L decided to put a smaller vent on a raised boss is anybody's guess. (The M35T had no boss, but a medium-sized hole on the opposite side.)

Why did they go to the large venturi in 1940, and then return to 1 1/8"? (The nozzle went through a similar back-step).

We may never know.
But I would bet that vacuum leaks confused a lot of R&D theory!

....Cotten

[Mr.Big]

Right, I was speaking to the Mr. Wilderness kit to install M74B guts in "any" 1-1/2" Linkert and the carbs you mentioned may not be good candidates for that upgrade without modifying the "nozzle vent".

Heck, I just like tryin' to figger out what the engineers were thinkin' in their fat little heads. In Shop Dope 303 they state that the M36A will work super duper on both a 61 and a 74. The M45A will also work on both but works best on a 74.

How do they know that? What kind of testing did they do to arrive at that conclusion??

[RUBONE]

Heck, I just like tryin' to figger out what the engineers were thinkin' in their fat little heads. In Shop Dope 303 they state that the M36A will work super duper on both a 61 and a 74. The M45A will also work on both but works best on a 74.

How do they know that? What kind of testing did they do to arrive at that conclusion??

They base it on venturi size. An M36-A comes with 1-1/8, an M45-A comes with 1-5/16ths. Little works well on big. big not so well on little....

[Cotten]

Heck, I just like tryin' to figger out what the engineers were thinkin' in their fat little heads. In Shop Dope 303 they state that the M36A will work super duper on both a 61 and a 74. The M45A will also work on both but works best on a 74.

How do they know that? What kind of testing did they do to arrive at that conclusion??

Mr. Big!

"Testing" was what the test riders reported, or maybe public feedback.

As I mentioned previously, 1 5/16" venturies were introduced in 1940, on both 61" and 74" models, but subsequent years went back to 1 1/8"

Apparently they were still being cautious, as the large venturi can, and will work great on a 61", I assure you.

But USA roads were just beginning to improve in 1950!

...Cotten

[old.wrench]

But USA roads were just beginning to improve in 1950!

...Cotten

That is a good point, and maybe an important factor which is often left out of consideration. I think a lot of us tend to think of the performance of these old bikes in terms of "highway performance". Back when many of these older bikes were built and ridden, there really weren't any highways, at least not the modern interstate highways that we take for granted now. When I was a pup, the closest we had to a interstate highway was the old Route 21 (now known as I-77) which was a patchwork of roads connecting small and large towns that included intersections and traffic lights. Riding a bike back in those days included a lot of stop-and-go and low speed riding, and I would imagine the focus on low end performance dictated the smaller venturis and milder cam grinds. It seems like many of the threads you see posted are concerned with tuning and gearing for cruising at 75 mph. Time trudges on .

Geo.

[Cotten]

Geo!

The same perspective applies to tension on the footclutch.

A good friend and associate pulled up at D-port on his wonderfull Knuck.
I asked why the pedal was in the air. His reply was basically because he was told to...
Reminding him that it robbed all feel for the clutch, he then left with a GRRUUUNNCCHHH,HH,hh..... sound.

Sound familiar to any of you?

....Cotten

[john HD]

i remember a conversation i had with a long time dealer many years ago, he told me most of the bikes he sold in wisconsin in the late 40's and early 50's were outfitted with side cars because of the condition of the roads.

john