My TM34 jetting efforts got continued in another thread, but here's where I'm at now:

Mikuni TM34
Muzzy full system with quiet core and spark arrestor
KDX snorkle, no backfire screen, K&N filter
de-smogged, external crankcase breather
#140 MJ
#37.5 PJ
needle clip set to 4th position down from top
fuel screw for best idle (probably around 1 - 1/2 turns out)

It's running pretty darn good, but I still have a flat spot around 1/8th throttle, but I have a Q-0 needle jet and an assortment of air jets to play with
(I think I'll need the Q-0 when I remove the airbox lid again)

My next couple of trials will include:

- stepping down the pilot air jet (hoping this might correct the flat spot at 1/8th throttle)
- removing the airbox lid again and trying the Q-0 jet, I'll probably have several subtrials involving different needle positions or upping the P.J.

After that, I have a 331cc kit on the shelf to install. I'll immediately up the MJ to 142.5 and then going through the fine tuning process again. Hopefully with what I have learned so far, I'll zero in pretty quickly.

 

http://video.google.com/videoplay?do...35096766547755

Dan, when you get to the 331, you may find that the 142.5 is a little large. I jetted up and down the scale with my 331 and Bill Blue TM 34 setup. The bike lost about 1.5 hp with the 142.5 over the 140 main jet. I am at 1200' asl. I had the airbox lid on with the snorkel removed, Muzzy exhaust. Of course each bike is different. I also ran the needle second or third clip from the top. Shortening the accelerator pump rod .150 also helped with the tip in lean condition. Actually, it went away completely with that mod.

My only concern with the TM 34 on the big bore was that at high RPM, (above 8000), power began to drop from the 28.3 max hp. I'm working on a fix for that now, but I don't have a final report yet. I still need a little more jet work and a final dyno run. I'll post that once it's done. I can tell you though that the bike should be well over that illusive 30 HP barrier even now. Honestly, this is turning into the best overall bike I have ever had when I consider diversity in all arenas. I should mention that I've had over 60 to compare it to.

I think that if you have a 331 kit on the shelf, it might be a good idea to cut to the chase and get'er done. Whether you cam the bike or not is up to you. It'll make great power either way. It would be a good idea to clean up the ports and releave the combuston chamber area around the valves a bit. If you're not doing cams, the TM 34 should let you have all there is.

The video is with the TM 34 before I got the last 2500 rpm to come on line. The on-off throttle is not the bike cutting out, it's me trying to manage variable traction on that danged gravel.

Bill Dragoo
Norman, Oklahoma
331 Squidflipper

 

Finally got some time to install the 331cc kit, I've got it back together up to the head cover - I'll take a look at the valve clearances before topping it off.

I'm am a bit concerned about the jetting though, especially since Kustom Kraft has a strong warning about it being too lean during break in. I might bump the jets for good measure and then back them off if necessary.

I'm curious about the pump rod shortening mod, I've seen shortening it by 0.150" and 0.125" - Any one else have some results on this mod?

Also got a T-handle air/fuel screw (from Bill Blue) to add that'll make setting the idle mixture easier.

Should have it fired up this evening!

 

Hey, Dan. On my first dyno run with the big bore and TM 34, I had a slight lean spike at tip in throttle. Shortening the pump rod .150 cleaned that up nicely. That should leave your pump rod right at 2.7" If I remember correctly. Check me on this, but I'm almost certain that's correct. You can also use a piece of welding rod to make a replacement rod and keep your stock one...although I'm not sure why anyone would want to. It seems to work better when it's shorter.

I used a 140 MJ and again, it's vague here, but a 40 pilot sounds right. Needle on second clip from the top. At that time I had the airbox lid on with the snorkel removed.

Bill Dragoo
Norman, Oklahoma
1200' ASL

 

I may have said this already on another thread, but here goes.

I'm running the HMF pipe with a Yoshimura, glass wrapped quiet tip, KDX snorkle, stock filter and screen, TM34, short A/P rod. The jetting is fine with one exception.
I'm at 137.5 MJ, needle full rich (bottom notch), stock 37.5 pilot, airscrew about 1 & 3/4 turns. The exception is surging at high load, constant state throttle, such as cruising at 70 mph in high gear.
I'm dropping in the 140 MJ to see if that finishes the tuning. I might try the next richer needle, don't know the # of it, to see if I could get back to the middle notch arrangement.

 

Goatknob/Bake/Bill/Dan,

Could one or all of you tell me where you are getting the jets and needles? I sent Bill Blue money for a carb last week. I have a new cylinder for a 300, I live at 5300 feet, so I may have to make some changes to the setup as it comes from Bill.

I sent an email to DynoJet, oddly enough, they can't tell me if they have a kit. They can't cross-reference a Mikuni TM33, all their kits are listed by bike make and model.

 

I buy my jets from the local dealer. Take an old pilot and main jet in for comparison. Sometimes you can sweet talk them into letting you swap out jets you haven't installed yet. That saves a few bucks.

One thing I noticed and my dyno tuner commented on was that these little bikes really liked fuel. When we tried to jet it according to the dyno manual, it was way too lean. This is born out in the way the bike ran with the airbox lid off. If it's worse, it's too lean.

Bill Dragoo
Norman, Oklahoma
331

 

I got my jets from here:

http://www.cyclewareables.com/

 

Your local Suzuki dealer will have the main & pilot jets.

 

This is an old thread but good repository for TM33 jetting data.

I've been working on my jetting for couple weekends now.
I'm using LM-2 A/F meter to measure the A/F ratio and do a test ride (with meter on) after each change. Taking notes after each test run about throttle response, feel about how the engine pulls and A/F readings at idle, 1/4, 1/2, 3/4 and WOT is the key. I write down notes into my garage notebook before even taking the helmet off.

I'm almost at optimum point now, it's very clear from here what I want to do next.

Stock 250 engine, FMF Q4 muffler.
Stock airbox and snorkel. (The airbox configuration makes HUGE difference on the WOT jetting, almost none below 1/2 throttle)
Sea level, temp 70F.

Idle jet#35, screw set to A/F=13.5 - 14 when engine is fully hot.
Still using the stock TM33 needle jet, P-8, needle in middle position.
MJ = 117.5 (WOT A/F = ~ 13.0)

AP rod cut down to 68mm (stock is ~72mm) and AP nozzle adjusted so that spray hits the needle. These are important to do!

Another critical point!
The 1/4 - 1/2 throttle jetting is lean with the P-8 jet needle, A/F 14.5 - 15.5 at steady cruise.
This will get fixed with richer needle jet, Q-0 (Sudco p/n 003-701)

WOT A/F was rich at 12.0 - 12.5 with MJ #120, will change it to #115 for a trip to Colorado, then #117.5 when I come back to home again.

The carb is a generic TM33, not the bored out "TM34" from BB.

--
Mikko