R&D TM 40mm FlatSide pumper R&D

Great thread thanks pvisseriii. Cj

Went for a 50 mile run yesterday. After raising the needle to bottom notch, bottom end is stump pulling good. Did a few plug chops at differant speed. All really good except for WOT. Somewhat lean but will have mains in the mail today to change. Idle/pilot circuit is right on. Two turn out and totally responsive to tuning.

Ran it to red line in first, second and Third. That's 105 with my bike and more than enough for me.
Cruizing at 80 is effortless.

I have found Dyno service nearby and if I have some extra scratch, I may venture over there.
Swapping from on setup to another is a piece of cake. For now, I will keep the twin 32 flatside on the shelf but will run the TM40 for I truely have no reason not to.

Starting cold is a 1 kicker. Giving the throttle a couple twists shoot just enough gas to start with no choke at all. Hot starting is also one kick but no touchy touchy of the throttle.

Pilot = 17.5
Air jet = 1.1
Needle = 9DJY04
Needle Jet = 568 Type Y-4
Main = 165 (170, 180 or 190)

see above post

Well I'm back with some jetting results. This is what i started with and how the carb came.
Pilot = 17.5
Air jet = 1.1
Needle = 9DJY04
Needle Jet = 568 Type Y-4
Main = 165
Please remember that all the numbers are relative and the range is great.

I changed the main to a 180, went richer to a Y8 needle jet and richer to a 22.5 on the pilot. This prover to be a little rich in the middle and much too rich on the bottom. I kept the main at 180, reverted the pilot to the 17.5 and split the middle with the needle jet at Y6. This is where life is good. Pulls very strong all the way to 4200 where it get a second wind. Man that feels good.

Here is the plug to show what i conclude at ideal. This remind me of the plugs in my 99 Ducati ss, when I had it, where they were described as clear. These plugs look clear to me. Some highway, some country, and some city driving.

I do not know what the milage is yet for this carb, but it seem good. There is a antique motorcycle ride at the Gilmore Car Museum June 9th in Battle Creek I should get a real good sence of milage then.

I really do not dare to recommend this for it is somewhat early. But I will say this, I am keeping it on and I have fiddle farted with a butt load of carbs.

Can you shut of the petcock til it starves then open it and at the same time give it WOT through a couple gears at Hi RPM to see if the fuel catches back up?

jseng1 said:

Can you shut of the petcock til it starves then open it and at the same time give it WOT through a couple gears at Hi RPM to see if the fuel catches back up?

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I don't see why not. I 'll give it go in the next couple days and report back.

Looks awesome to me now I want one

pvisseriii said:

jseng1 said:

Can you shut of the petcock til it starves then open it and at the same time give it WOT through a couple gears at Hi RPM to see if the fuel catches back up?

Click to expand...

I don't see why not. I 'll give it go in the next couple days and report back.

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I dodged some rain enough to get this done.

Got out on the highway, warmed up and cruising at 70. Turn off the pedcock and about 1/4 mile it started cutting out. I turned it back on, drropped to third and climbed all the way to a ton just a bit under red line without a hitch nor a studder.
I used just the main pedcock leaving the reserve off and had a fairly full tank of fuel.
I am very pleased to say the least. Plugs still showing a clear appearance as before. No more changes for now. Although thinking abut going back up to the Y8 needle jet with the stock 17.5 pilot.
This system is good, real good.

This is a very popular upgrade to a dr650s carb ( my next upgrade to my DR) I also thought of running one on my norton.

Thanks very much for taking the time to post your results...I just got an uninstalled HS40 along with a DR650 I bought...The DR650 runs great with its existing rejetted stock carb so the Mikuni pumper may go on my Norton instead

Again, this does not go without some modifications, frame web cutout and relocation of side cover Dzus connectors. Not a big deal but gut wrenching to some.

Hi Pete,
I was wondering if you are still running the TM40 and liking it? If so, what jetting did you finally end up with? I'm considering putting this carb or the Keihin FCR 39 on my 825cc T140 engined project and just wanted to follow up on your thoughts...thanks, Mark

marksterrtt said:

Hi Pete,
I was wondering if you are still running the TM40 and liking it? If so, what jetting did you finally end up with? I'm considering putting this carb or the Keihin FCR 39 on my 825cc T140 engined project and just wanted to follow up on your thoughts...thanks, Mark

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Yes, I still have it on my bike and I love it.

I reverted to the Amals cause the new Premiers came out and felt they deserved a try. I finally got a set of 32's. They were good and I really have no complaints on their performance and I recommend them. However, they just did not have the low end pull, the midrange responce and the higher end thrash the tm40 does.

Let me stop here and say that this setup is proprietry to my bike (cam, pipe etc.) and i make no claims that is for every bike, although I believe many could benefit.

Here is my final settings.
Pilot = 17.5
Air jet = 1.1
Needle = 9DJY04
Needle Jet = 568 Type Y-8
Main = 160

I had a bad studder at 4500 under wide open throttle. It drove me nuts for a while thinking it was all sorts of things. I was running all the way to a 190 main jet and it seemed like it was starving and needed a bigger one. Going on a hunch, I had a 170 and although it did not cure it, it didn't make it worse. I ordered up a 165, 160, and a 155. I popped in the 165 and it got better. Went to the 160 and BAM. I true winner.

I hope you have read the whole thread particularly the part about removing some of the webbing where the main harness goes through. Some members are really put off by this but as i always say, "It's my bike, I do what i want".

There is another member who has a tm40 and asked me for info regarding the install. Seems his frame webbing is either missing or something like that. I have not heard from him lately but it pretty cold around here and working on such stuff just needs to wait.

My goal has been to get the most out of what i have and that all other aspect of the bike are in top notch condition to safely take advantage of it. This is of course within reason and keeping the bike looking as it should, stock. I hope to get it on the Dyno in spring to see what I can see. I have no base line or comparison but I will know where I stand.

Anyhow, feel free to PM me if you want more details.

Pete V ,Thanks for the post and update, have your new Premiers here with me in India, (got to me via Canada)have fabfricated a couple of bolt up flanges ready for manifolds extensions when I get back to New Zealand and will use these carbs for R&D on the race bike. Pity I cant use a 40mm pumper on the race bike, doesn't make class if i do!!!
Regards Mike

Thanks for the info on the carb, I need to get one of the TM's in my hand so that I can see if it fits, the linkage assy. is on the left as is my monoshock, may be close. I have trial fit the FCR with no problem as it's linkage is on the right side. I also have a Keihin CV 40mm pumper off of a Harley big twin that I thought would be fun to play with, with the Dynojet or other aftermarket jetting kits it might make a real nice street carb especially considering the potential sea level to 8K+ altitudes all in a days ride from here. The Harley CV is short vertically as compared to other similar bore CV's and the only one I know of with an accelerator pump, also may be available in 44mm if I remember correctly.

Pete, thanks for the contact & I will pm you with any further questions but for now I'm good and if and when I get this thing together I will post as to the function of my single big carb choice...Mark

Hi Pete

Can you post the carb reference for me? Hopefully I can find one this side of the pond.

Thanks Chris

Chris said:

Hi Pete

Can you post the carb reference for me? Hopefully I can find one this side of the pond.

Thanks Chris

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The carbs proper name is the Mikuni TM40-6 also know as the HS40. Google away, Chris.

This is where I got mine and the price has not changed from when I got it.
http://www.ebay.com/itm/Mikuni-TM-40mm- ... 9757964%26

Hi Pete

That is a good price. I will look up the filter & manifolds you have spoken of as well as the jets. I have family going to Florida in Feb so may ask for a present to be brought back

Thanks

all the best Chris

Chris said:

Hi Pete

That is a good price. I will look up the filter & manifolds you have spoken of as well as the jets. I have family going to Florida in Feb so may ask for a present to be brought back

Thanks

all the best Chris

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Have them get you the 36 to 40mm Manifold and the Flange-to-spigot adapter from RockyPoint Cycle. I also googled "Mikuni Push-pull kit KRS-001" and got this push pull kit.
http://www.rockypointcycle.com/p-norton ... -2535.html
http://www.rockypointcycle.com/p-norton ... -2565.html

More fine tuning.

I have gone richer on the pilot and needle, and leaner on the main.

Here is my final settings.
Pilot = 22.5
Air jet = 1.1
Needle = 9DJY02 (these are out of sequence from lean to rich they go 01, 03, 04, 02)
Needle Jet = 568 Type Y-8
Main = 155