Back to the mighty TM 40

[baz]

I had to remove my single mikuni TM 40 a while ago because it was never a first kick starter with this carb fitted and my knee was on its last legs so to speak!
I only have a few kicks in me
So I went back to twin 32mm mk1s, my Norton would always start first or second kick with these once tickled
And once dialed in properly they were brilliant
In the meantime I bought a modified Alton starter from Yves
This has been a brilliant addition to the bike
Eventually the the twin amals have started to wear out so I had the choice of fitting anodised slides to them and carrying on or re fit the TM now I don't need to kick it anymore,so that's what I did
The reward is a light action throttle better bottom end
Much better mid range
And top end the same as twin amals
The TM 40 is a much different animal to the VM mikuni although the biggest VM I tried was a 36mm
These are my findings from going from twin amals to the single TM on the same day for testing not days or weeks between riding
And yes my amals were very well set up in my opinion and the only issue was the occasional rise in revs at idle
I realize the single verses dual carb debate will rumble on forever but there it is
I'd love to try the high end dual setups offered by cnw one day if money allows

 

[Time Warp]

I put one on my DR650SE back in 2009 and they make a noticeable improvement (over the stock BST) but are far from cheap costing more than two new Premiers , did the pump not making starting a little easier (with a few twists of the throttle)

The TM42 might be even better but perhaps any real restriction if there might be the inlet manifold itself.

 

[baz]

I put one on my DR650SE back in 2009 and they make a noticeable improvement (over the stock BST) but are far from cheap costing more than two new Premiers , did the pump not making starting a little easier (with a few twists of the throttle)

The TM42 might be even better but perhaps any real restriction if there might be the inlet manifold itself.

I used to give it full choke and two pumps on the throttle
Sometimes it's start
But if I did it again it'd flood
If I only used the choke (enrichener jet) it would not start
I tried all sorts , kicking over with ignition off etc etc
With the starter motor it's a different ball game
Just pull the choke and hit the button
I made my own manifold , I could easily open it up to 42mm
Cheers

 

[Time Warp]

That would be the key (big carburetor and decent manifold)
Any time a single carburettor is mentioned on FarceBook there seems to be a stampede of Amal stickered walking frames.

 

[bsaboss]

I've always thought this would be a great conversion. Could I ask what jets, needles etc you used in your setup?

 

[baz]

I've always thought this would be a great conversion. Could I ask what jets, needles etc you used in your setup?

Sorry I can't remember
I bought the carb from fleabay it came from a big Harley twin
It'd already done 70,000 miles
I do remember changing the main jet and the needle jet for a larger one but that's all I can remember
Cheers

 

[cliffa]

I used to give it full choke and two pumps on the throttle
Sometimes it's start
But if I did it again it'd flood
If I only used the choke (enrichener jet) it would not start
I tried all sorts , kicking over with ignition off etc etc
With the starter motor it's a different ball game
Just pull the choke and hit the button
I made my own manifold , I could easily open it up to 42mm
Cheers

baz, any chance of sharing some pics of your setup (especially the manifold) ?

Cheers,

cliffa.

 

[Fast Eddie]

+1 Cliffa...

Baz, available manifolds for the normal single carb set ups have been blamed by some folk (inc Comnoz) for much of the performance loss that is normally experienced with a single carb.

So, pics of your manifold would be most interesting sir...

 

[baz]

baz, any chance of sharing some pics of your setup (especially the manifold) ?

Cheers,

cliffa.

Yep I'll do that

 

[baz]

Here you go

 

[Bernhard]

Here you go

Don't wsh to knock your setup, but there appears to be only 2 studs holding the manifold onto the head, is that correct?

 

[EstuaryBoy]

Donwish to knock your setup, but there appears to be only 2 studs holding the manifold onto the head, is that correct?

Even the Phoenix SU set up only uses two studs for a far larger carb....

 

[baz]

Donwish to knock your setup, but there appears to be only 2 studs holding the manifold onto the head, is that correct?

Yep two studs is all it needs

 

[jaydee75]

Yep two studs is all it needs

I like it. Did you have to notch the frame at all?
Jaydee

 

[baz]

I like it. Did you have to notch the frame at all?
Jaydee

You do have to notch the gusset on the frame yes
But on my bike the gusset was already completely removed by the previous owner

 

[EstuaryBoy]

You do have to notch the gusset on the frame yes
But on my bike the gusset was already completely removed by the previous owner

Ann Summer's customer?

 

[baz]

Ann Summer's customer?

It could well have been mate
I bought the bike in Dagenham!!

 

[cliffa]

Thanks for the pics baz, it looks very professional. What 's it made of, steel? Any chance of a pic or two of the whole setup? (excluding your gusset of course)

 

[baz]

Thanks for the pics baz, it looks very professional. What 's it made of, steel? Any chance of a pic or two of the whole setup? (excluding your gusset of course)

Ha ha it's not professional at all I'm afraid
Just two mild steel elbows welded together
I just thought I'd try it to see if it'd work,I was just a bit taken back with the results
I painted it silver so as not to shock people too much ,plus it stops people telling me that steel is not the right material to use etc etc

 

[Derek Wilson]

I am a total newby to the single carb world on a Commando - I have always run twin Amal's. But the bike I am restoring currently requires some carb work and I am open to exploring options.

Just curious on the sizing - why 40 mm? Why not 38 or 42?

Principle reason I ask is it seems (where I am), 38mm are substantially less expensive.