I remember seeing an article about a company that could replace the stock needles on the Series III twin's carbs with needles that have the venturi's on them. Does anyone else remember seeing this post/article and where can I find the article (or company)? Has anyone had their carbs reworked by this company? Other thoughts?

:D

Xtreme Performance 303-654-0867 is one you can call.

I heard the mod was mentioned in snowest magazine but didn't see it.

I basically replaces your (unhooded) needle jet with one that has a hood that extends into the carb bore (venturi). The latest 800 carbs (rev)have this and you might just recalibrate to their specs as a baseline. If your dealer had performed the nj height recall he should have the tool to press the nj in and out?

IMHO the TMX mikunis that doo put on were fricken 4 stroke carbs! generally a 2 stroke doesn't have enough "signal" at the nj to pull fuel up. The only TMX's I have seen without hooded NJ were on 4 stroke bikes. This basically caused doo a lot of calibration problems like lean midrange (excessive timing also added to this) and/or poor fuel milage. It forced the use of (too) big mainjets to try and cover the NJ in ability to pull fuel. If you do the mod you will be WAY down on your main sizes. Let me also add that any airbox mods or carb boring will make the "problem" worse, so leave the box intact with the un hooded jets.

IMHO the TMX mikunis that doo put on were fricken 4 stroke carbs! generally a 2 stroke doesn't have enough "signal" at the nj to pull fuel up. The only TMX's I have seen without hooded NJ were on 4 stroke bikes. This basically caused doo a lot of calibration problems like lean midrange (excessive timing also added to this) and/or poor fuel milage. It forced the use of (too) big mainjets to try and cover the NJ in ability to pull fuel. If you do the mod you will be WAY down on your main sizes. Let me also add that any airbox mods or carb boring will make the "problem" worse, so leave the box intact with the un hooded jets.

Good one hillpounder. I agree 110% with this statement. Someone had there head somewhere besides where it should have been. Then again, maybe the engineers hands were just tied.

I have my carbs off, torn completely down, and laying conspicuously all over my desk right now. I am in the process of picking the needle jet that I want to use right now. I am going to make a step tool (since that's what I do) to bore needle jet hole to fit whatever jet I choose to try. Cyberdyne is one of the company's that have decided that they have the solution. What they have done works from what I have heard, but they are installing another needle jet that is pressed in and not replaceable. In my opinion that is a half-fix. Sure it works better, no... say it works great on a stock sled. For lots of guys, it is the solution. But, what about the guys that are going to continue performance tuning their sleds. What if the need arises for a different needle jet? Do you send it back to the folks that did the first replacement. You got it. How nice for them. Built in repeat business.

What is needed is a needle jet that is replaceable by the consumer. I can see the wheels turning out there right now. Well...I don't care who does it, it just needs to be done.

But...the needle jet is not the only area that can be improved on these carbs. There is no real idle circuit. Sure, there's a fuel bleed hole. Who they trying to kid? That is no way to try to control the idle, let alone trying to get a decent launch off the line. The fuel you are getting at idle on these machines equipped with #junkmikTM40's is raw! It is not a homogeneous mixture. How many of you need to flick the choke to get your rig to idle? No idle circuit!

First we're going to see how much the new needle jet works. If it's not the improvement I seek, then we're moving on to machining the idle circuit into this set of carbs scattered all over my desk.

Guess I oughta get my engine together first, eh? :p

:withstupid: not that he is, but i'd listen to him if i were you. :D

Thanks...I think. :) :D :p

idooski, Working on my bike last night I noticed the type54 magnesium bing carbs have a very interesting way of providing idle air for emulsion. Looks like it might be an ez mod that would work on the tm's? It's sooo simple! not sure how it would work though?

Got pics?? Or a web site where I could get a look? I would very much like to see them.

Dunkmaster...By the way the article about that carb alteration can be found at SnoWest.

idooski, It'll take a couple pics, where can I send them?

durkee@toolgrinder.com

Thanks man! I'll let you know if I decide to try what I see. Just picked up a set of TM40's to experiment with.

I had a friend of mine drill out the nj .004 i believe and put in the jn from an 03 600 h.o. on my 01 800 and it seems to work really well so far on a moded motor. P.S dont quote me on the .004

i agree with all that was said on the tm-40's that are on the ski-doos,they suck ,there is no real idle circuit on them at least on polaris you can change the pilot jet in the air inlet side to get a decent idle

I took and reamed the needle tube .004 bigger using a #? reamer. Can't remember the size, I'd have to look it up. But anyways I also used the 942 needle on the second notch and my midrange temps would hold steady at 1150 deg. Even when held steady for a while. About 6500-7000. My mains are at 410's with the RKT head and it's still too rich on top.. Sled runs 115 when rung out with heelclickers. I very happy with the performance now.

My sled is a 01 800 with RK Tech head on a stock engine with .8mm gasket. I can't run anything under 480s with stock pilots, and 942s in the middle clip. Temps run 1230 or so.

God forbid I should mention something like this but has anyone considered using the flat slide carbs from an Arctic Cat ZR 800? I'm not sure they would fit but it was something that just occurred to me. I haven't read any complaints from cat riders about the sled not being able to idle or having mid range lean conditions. Here is a picture of the exploded view from an 02 ZR 900 I got off the web and the part references are below.

Ref# Part Info
N/S 1670-294
TM40-93 (Complete Carburetor)
1 Not a service part.
Body, Mixing - Right
1 Not a service part.
Body, Mixing - Left
2 6505-591
Screw Assembly
3 6506-142
Cap, Top
4 6506-034
Gasket
5 6506-137
Cap, Starter Plunger
6 6506-138
Spring, Starter Plunger
7 6506-139
Starter Plunger
8 6506-209
Gasket
9 6506-239
Funnel Assembly
10 6505-980
Screw
11 6506-120
Valve, Throttle CA 3.0
12 6506-304
Jet Needle 9DFH9-59-4
13 6505-552
Washer, E-Clip
14 6505-628
E-Clip
15 6506-055
Plate, Jet Needle Retaining
16 6506-054
Screw, Retaining Plate
17 6506-047
Lever Assembly - Left
17 6506-043
Lever Assembly - Right
18 6506-053
Bushing, Clip
19 6506-040
Clip
20 6506-039
Plate
21 6506-052
Washer
22 6506-051
E-Ring
23 6506-145
Screw, Fuel Mixture 1.5
24 6506-076
Cap, Fuel Mixture Screw
25 6506-079
Spring, Fuel Mixture Screw
26 6506-078
Washer, Fuel Mixture Screw
27 6506-080
Washer, Rubber
28 6506-265
Starter Jet 130
29 6505-278
Pilot Jet 45
30 6506-217
Spring
31 6505-146
Main Jet 430**
32 6506-144
Float Assembly 1.8
33 6506-100
O-Ring
34 6506-037
Screw, Float Arm
35 6506-270
Chamber, Float - Assembly - Right
35 6506-036
Chamber, Float - Assembly - Left
36 6506-038
Gasket, Float Chamber
37 6506-072
Screw
38 6506-032
Plug, Drain
39 6505-185
O-Ring, Drain Plug
40 6506-202
O-Ring
41 6506-218
Washer
42 6506-220
Screw, Air

Dunkmaster, I was told that they would interchange. I believe you have to use the rack system from the Doo and they would bolt right up. Unfortunately, I think it is the challenge to fix what we have rather than buying $400+ (new) carbs