Mikuni Tm 40 carb

Just traded my original carb against a Mikuni Tm 40pumper carb
I will get it in 2 weeks.Do any one of you have one, and are you happy with it?

Welcome to the Tm40 club
Badcooky and myself on this board have the carb. i'm still trying to dial it in.
So far the main jet is right, thats about it. pulls hard and stays that way on the main jet.

They are a bitch to tune, but i hope eventually it gets tuned right.
I might even give up and give it to a pro

Welcome fella.
I've got a TM40 on mine and i like it.
They are hard to find setup though.

Doesn't BWB have a jetting guide for a TM40? I know he does for the stocker, and I'm pretty sure he has one for a TM as well. Check Borynack's site; he has a lot of good jetting info on it.

The chart is all the way at the very bottom...
http://borynack.com/XR650R/HorsePowerMods.htm

Thumpmeister wrote:Doesn't BWB have a jetting guide for a TM40? I know he does for the stocker, and I'm pretty sure he has one for a TM as well. Check Borynack's site; he has a lot of good jetting info on it.

The chart is all the way at the very bottom...
http://borynack.com/XR650R/HorsePowerMods.htm

Can´t find this file...can some post or send it?

babuja wrote:
Can´t find this file...can some post or send it?

Just received my TM40...need some help to find a jetting starting point.

This is the set up that I used for my carb when I got it on a standard never corked XR sea level to 1500 feet. Found it on the ADV site somewhere but it was some time ago.
It may not be 100percent but it is good enough that I have never bothered making any changes.
I bought my carb second hand but new as the original owner had not been able to set it up. and even though it was a XR kit the jets were miles out. Apparently these carbs are a common harley mod and most TMs are set up for them. It is important to change the pilot air jet as well as the others.
Good luck

Pilot air jet BS30/97-1.2

Pilot Jet VM28/486-25

Main Jet N100.604-140

Needle Jet 784-13002-Y4

Foggit, just lost a long post
'Ere we go again....

Start wit the basics (open sidepanel, clean filter, some exhaust mod, fresh plug, valves set perfect):

Pilot 25 (27.5 is too big, 22.5 is too small)
Airjet 1.2 (1.1 is too small)
The above sets the screw around 1.5 turns hence is perfect.
Main 140, and unless you've got major mods done this is the size which will supply fine for WO.

This setup idles well and is fine for wide-open, the inbetween bits the needle-jet & jet-needle take care of.
There's several types (characteristics) for them but popular one's are the 9DJY1 needle & Y4 needle-jet (that long thing, and do NOT overtighten it, I did that for you already ).
Clip in 3rd position but note, and play with, "half" positions, that little washer under or on top of the clip.

Can't remember the accel-pump jet-size , around 50 I think but it is a small size, and it will be fine (unless you have a huuge size, say 70 or bigger). Aim the squirt so it hits the needle, preferably on the rhs when looking from the intake side.
During tuning take the command-rod OUT ie test without pump.
Once happy with all put it in, and set it so that the slide is already moving before the pump starts squirting (ie some delay).
Also, stop injecting around halfway the slide's stroke, no use & waste of petrol. Both begin and end are adjustable, find where this is.

This carb delivers everywhere in the powerband, and the engine reacts super! Lifting the front is instant, plenty linear power and best of all (!!!) the bike uses considerably less fuel than with the std carb - you will like this I'm sure And yes, it does this whilst the engine runs lots better everywhere.
This simple & straightforward carb is in my opinion the best there is, and even those running the (obsolete!) Edelbrock will not look back once installed & dialed in.
Have fun!

Hi guys,

tnks for your help.

Not sure yet what setup is installed on TM 40 but have this parts:

Pilot: 1J 27.5 (i believe)
Airjet: no idea
Main 137,5;140, 145, 147,5
Needle: no idea

Where can I in UK get my hands on some parts (buy in internet)?

What's the diference between 9DJY1 needle & Y4 needle?

Here is a link to allens performance who have great service in the UK.
The link is to an exploded drawing of the TM carb.
You will see the links to the Jet lists on the LH side.

http://www.allensperformance.co.uk/exp-tm.html

babuja wrote:
Airjet: no idea

What's the diference between 9DJY1 needle & Y4 needle?

I take it you've got the carb?
The airjet sits screwed in the bellmouth - unscrew & read what you have!

And, the Y4 is a jet (albeit a large one), a needle-jet - this is the central mixture tube, the biggest part of all mentioned.
The 9DJY1 needle (officially jet-needle) goes/slides into the Y4, and mounts in the slide.

BuRP wrote:

babuja wrote:
Airjet: no idea
What's the diference between 9DJY1 needle & Y4 needle?

I take it you've got the carb?
The airjet sits screwed in the bellmouth - unscrew & read what you have!

Can´t do that now, unless I ask some doctor for a screw drive

Just need to travel back home with all items to avoid trying to proper jet and need some part 8000km away

BuRP, what's parts do you think I should put my hand-on?

Motor: stock
Exhaust: Pro-Circuit complete exhaust
Inlet: Xronly Side Panel cutout

Altitude: Sea level < 1000feet
Temperature: 75-95ºF
Humidity: 70-80% [Angola]

Hew wrote:

Pilot air jet BS30/97-1.2

Pilot Jet VM28/486-25

Main Jet N100.604-140

Needle Jet 784-13002-Y4

Ups, missed this data ...tnks Hew

If you going to buy from XRsOnly then I'd buy some airfilters, either TwinAir or UNI.
When busy anyway I'd buy some oilfilters also, no idea how easy you get them in Luanda.
Some spark plugs maybe? I mean, you're going to pay for shipping anyway, so I just added some stuff I wanted anyway.

The jets I'd get (and mostly have, same mods as you: PC4, open side, foam filter):
Pilot 25 - you need it, you've got a 27.5
Airjet 1.2 - maybe you already have it?
(Main140 you already have)
9DJY1 needle - maybe you already have it?
Y4 needle jet - maybe you already have it?
You can get all this from Sudco (US).

Please note though, this TM40 carb works with different cables! You have these? If so good, but are they long enough? If not you will want to measure the length you need, to compensate for risers and/or high bars you may have.
I had my 3"-longer cables made by Pro-Motion I think. They make any cable at any length, contact them if you need some.

What else to buy? Hey bru, you know you'll need a large tank, no idea if you've got one. If not get the large IMS or Acerbis or Safari, no idea what flavour you prefer - try www.justgastanks.com?


PSst, you dad already?

BuRP wrote:If you going to buy from XRsOnly then I'd buy some airfilters, either TwinAir or UNI.
When busy anyway I'd buy some oilfilters also, no idea how easy you get them in Luanda.

Already solved that, have about 10 airfilter+10 oilfiter

Just buy from US when I can't find those parts in Europe...usually try first in UK, ebay or some online store. I send everything to PT and then pick it up.

BuRP wrote:Some spark plugs maybe? I mean, you're going to pay for shipping anyway, so I just added some stuff I wanted anyway.

Just bought some new spark plug (the BKR7 E11). Some one told me that for low octane gas the cold spark was better than hotter BKR8E. That's correct i hope?!


The jets I'd get (and mostly have, same mods as you: PC4, open side, foam filter):

Pilot 25 - you need it, you've got a 27.5 - Check
Airjet 1.2 - maybe you already have it? - Waiting for confirmation
(Main140 you already have)
9DJY1 needle - maybe you already have it? Check
Y4 needle jet - maybe you already have it? Check
You can get all this from Sudco (US).

BuRP wrote:
Please note though, this TM40 carb works with different cables! You have these? If so good, but are they long enough? If not you will want to measure the length you need, to compensate for risers and/or high bars you may have.
I had my 3"-longer cables made by Pro-Motion I think. They make any cable at any length, contact them if you need some.

Check

BuRP wrote:
What else to buy? Hey bru, you know you'll need a large tank, no idea if you've got one. If not get the large IMS or Acerbis or Safari, no idea what flavour you prefer - try www.justgastanks.com?

Check

BuRP wrote:PSst, you dad already?

Nope, still waiting little guy...Angolan doctor mess up and give a incorrect birth date, 2 weeks wrong. Let's see what happens this week.

tnks

babuja wrote:
Airjet 1.2 - maybe you already have it? - Waiting for confirmation

Check, it's a 1.2 AJ

Ooh, wait, cold & warm sparkplugs...... has zero to do with the gas-quality.
Mind, in theory - and only there* - it does, as the combustion chamber's volume (hence compression ratio hence the detonation-sensitivity) depends for a small part on the 'open volume' the sparkplug represents.
A 'cold' plug has a shorter nose (less open volume) than a 'warm' plug (more), so in theory a colder plug will effect a higher compression - and consequently, for a low fuel quality (octane rating) a warmer plug would be better (the the CR is less hence more tolerant against detonation) hence the advice given is wrong..... however never-ever put a warmer plug in an engine than what the manufacturer prescribes!
I'd stick to the prescribed plug B, after all the Baja's as warm as Africa is. Maybe 1 degree colder but that's it, not more (colder plugs foul hence fail earlier).

Looks like your carb is "plug & play" as it is!

Tell il dottore he's a coillone, but at least you'll have 2 more weeks sleep


* disclaimer: for very small displacement engines is does make a diff, like a 50cc racing 2stroke, but on our big bugger forget it.

I forget/forgot:
- some copper-paste/anti-seize compound (used anywhere you do not use Locktite).
- Locktite Blue (nutlocker) and Red (studlocker) to prevent bolts rattling loose.
- waterproof grease (normal grease is not, so I use only waterproof stuff these days), and you may have to search for it.
I always use some copaslip on the sparkplug, better heat-transfer then too.

BuRP wrote:Ooh, wait, cold & warm sparkplugs...... has zero to do with the gas-quality.
Mind, in theory - and only there* - it does, as the combustion chamber's volume (hence compression ratio hence the detonation-sensitivity) depends for a small part on the 'open volume' the sparkplug represents.
A 'cold' plug has a shorter nose (less open volume) than a 'warm' plug (more), so in theory a colder plug will effect a higher compression - and consequently, for a low fuel quality (octane rating) a warmer plug would be better (the the CR is less hence more tolerant against detonation) hence the advice given is wrong..... however never-ever put a warmer plug in an engine than what the manufacturer prescribes!
I'd stick to the prescribed plug B, after all the Baja's as warm as Africa is. Maybe 1 degree colder but that's it, not more (colder plugs foul hence fail earlier).

oowoo, okapa.

BuRP wrote:Looks like your carb is "plug & play" as it is!

I believe this babes are a litle temperamental, aren't they?...

BuRP wrote: Tell il dottore he's a coillone, but at least you'll have 2 more weeks sleep

I already did ...at this moment i'm in hospital and tomorrow who knows

BuRP wrote:I forget/forgot:
- some copper-paste/anti-seize compound (used anywhere you do not use Locktite).
- Locktite Blue (nutlocker) and Red (studlocker) to prevent bolts rattling loose.
- waterproof grease (normal grease is not, so I use only waterproof stuff these days), and you may have to search for it.
I always use some copaslip on the sparkplug, better heat-transfer then too.

Tnks BuRP...Already have that

Some update...carb installed and rocking...need to teste it for fine tunning.
Filter installed...




Need to proper hold it...

honda actually list the bkr8e-11 as a colder plug to use for more low speed running

I like how you solved the choke problem , mine solution looks far worse , i need to make some kind of bracket for it , cable ties and safety wire at this moment  

Mad Frosty wrote:I like how you solved the choke problem , mine solution looks far worse , i need to make some kind of bracket for it  , cable ties and safety wire at this moment  

Pass me the bucket I'm going to be sick.... 

Mad Frosty wrote:... mine solution looks far worse 

Really?!  

But if i was you , i would not ask for pictures seriously