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Discussion Starter #1
Can anyone tell me where to start for jetting a vm28-418 for my 02 tw200? I've searched and couldn't come up with anything. I want to order everything one one shot. And before I order are there any other direct replacement carbs for the tk to consider? Or is the vm-28 the best option? Below is the one I will be ordering.

http://www.amazon.com/Mikuni-Series-Slide-Carburetor-VM28-418/dp/B000GZO5EG
 

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Sebastian (MacBig) is the only one that I am aware of that is using the VM28, and his bike is not a stock TW200.

He has posted that it is not a easy carb to get properly tuned.

Perhaps he will soon post about it.

An alternative carb is one of the Chinese copies of of the Mikuni VM24/26, listed on eBay as a BW200 carb.

The carb will work (I have tried one on my TW). However, you will need to modify the carb screw-on top, where the throttle cable connects.

Or better yet, make a custom throttle cable, so you don't need to mod the carb top.

Either way you will need a different cable, and perhaps a different throttle control. The stock throttle cables are in a push-pull configuration, and the VM28 is a single pull cable, which has a different lug on the carb end.

The Chinese carb is also shorter from front to back so the air box boot is too short. Another forum member has solved the problem using duct tape.

If you bike is a pre-2001, you will also need a separate start/kill switch.

Jb
 

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Have you searched archives here, specifically those of PalmStateCrawler and MR.Bracket? They have both been down the road of all that is involved with the care and feeding of the Mikuni VM28-418 in a TW application and have reported here in depth. Somewhere in those depths I seem to recall baseline jetting numbers. I seem to recall a bit of modifications were required and the resulting performance was never good enough to sweep the world by storm.
To bad as I drooled over idea of crisper throttle response of the pumper carb option but Mr.Bracket couldn't get sufficient performance out of that one either it to make a conversion kit for TWs.
You could start here, although I think PalmSrateCrawler sold his bike and moved on.Jets for mikuni tm28-1 and vm28 for sale
 

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Have you searched archives here, specifically those of PalmStateCrawler and MR.Bracket? They have both been down the road of all that is involved with the care and feeding of the Mikuni VM28-418 in a TW application and have reported here in depth. Somewhere in those depths I seem to recall baseline jetting numbers. I seem to recall a bit of modifications were required and the resulting performance was never good enough to sweep the world by storm.
To bad as I drooled over idea of crisper throttle response of the pumper carb option but Mr.Bracket couldn't get sufficient performance out of that one either it to make a conversion kit for TWs.
You could start here, although I think PalmSrateCrawler sold his bike and moved on.Jets for mikuni tm28-1 and vm28 for sale
Fred, didn't Mr. Bracket and Palm State Crawler use the TM, a pumper carb?

The VM is not a pumper carb.

Jb
 

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Well, there may be a bit of confusion on my part.

I checked the Mikuni catalog, and the VM carbs are all listed as "round slide" carbs. All except for the VM28-418 which is listed along with the "flat side" TM carbs....?

...waiting for MacBig or Mr. Bracket to clarify.

jb
 

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Escuse me, I was referring to the TM28-1 not the VM28-418 ,as the Mikuni pumper that Mr.Bracket and PalmState Crawler also experimented with unsuccessfully; discussions for both conversions were part of the referenced postings by both authors if I recall correctly. Either way neither Mikuni was deemed a perfect upgrade for everyday use.
 

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Escuse me, I was referring to the TM28-1 not the VM28-418 ,as the Mikuni pumper that Mr.Bracket and PalmState Crawler also experimented with unsuccessfully; discussions for both conversions were part of the referenced postings by both authors if I recall correctly. Either way neither Mikuni was deemed a perfect upgrade for everyday use.
Fred, you are getting old and forgetful. How could you recall so poorly!?


Oh dear. I have been bad again....... Who will you have punish me this time Fred?:D

I will be waiting patiently with a glass of wine and some lotion:tongue9:



Tom
 

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Escuse me, I was referring to the TM28-1 not the VM28-418 ,as the Mikuni pumper that Mr.Bracket and PalmState Crawler also experimented with unsuccessfully; discussions for both conversions were part of the referenced postings by both authors if I recall correctly. Either way neither Mikuni was deemed a perfect upgrade for everyday use.
Here's the carb Mr. B used:

http://tw200forum.com/forum/performance-customization/5418-mrbracket-s-tw200-build-5.html#post56577

Apparently, the VM28 is part of the TM series of the Mikuni flat slide carbs...really confusing to me.

The link provided by the JD87 shows the carb listed as both a TM and a VM.

IMO.., a better choice for for a stock TW200 would be the Mikuni VM24 or VM26 round slide carb.

Those are the ones that the Chinese clones are copied from, and we know the Chinese carb will work, with modifications to the throttle and cable, and the boot to the air box.

jb
 

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I got really confused with various posts referring to two different carbs and designations, sorry. But to quote MrBracket in his build post #390
"Yes, it's a Mikuni TM28 (aka:VM28-418) It is a 28mm Flat slide carb that is very similar to the ones found on 1980-1990's Suzuki RM80's"
Yet PalmStateCrawler's classified add seems to depict and refer to two different carburetors. Odd. Jets for mikuni tm28-1 and vm28 for sale
I'll back out now and let Original Posters clarify things, was just trying to help.
If indeed Jd's carb is the same as MrBrackets as depicted in posts around #390 he might find the jetting answers he seeks starting around post #340.
Remember carb says "Not For Aircraft" so be careful how high you get that hot rodded TW flying after she's all jetted up.
:D

P.S. BIGFOOT could be contacted via his Amazon.com sales site for details
 

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I got really confused with various posts referring to two different carbs and designations, sorry. But to quote MrBracket in his build post #390
"Yes, it's a Mikuni TM28 (aka:VM28-418) It is a 28mm Flat slide carb that is very similar to the ones found on 1980-1990's Suzuki RM80's"
Yet PalmStateCrawler's classified add seems to depict and refer to two different carburetors. Odd. Jets for mikuni tm28-1 and vm28 for sale
I'll back out now....
Fred, you can't back out now...it's just getting interesting.

I think the confusion is caused by Mikuni classifying the VM28-418 as a TM carb. All the other VM carbs are round slides, whereas the VM28 is a flat side one. They should have just called it a TM28-418 and eliminate the VM designation.

...
Remember carb says "Not For Aircraft" so be careful how high you get that hot rodded TW flying....
Fred, is that flying high "elevation" or "altitude"? ;)

jb
 

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Good question jb, when I take a jump on the TW I don't seem to get much altitude irregardless of my elevation nor attitude.:(
Certainly PalmStateCrawler's pics show parts for different carbs and in his early posts he said was looking for a foreign sourced TM28. Could the nomenclature confusion be due to different designation in foreign markets?
I gave up paying attention months ago when I found I could not get a simple plug and play properly jetted pumper carb conversion. My bike is bastardized enough without further modifying the throttle, start button and kill switchology.
 

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.....
Certainly PalmStateCrawler's pics show parts for different carbs and in his early posts he said was looking for a foreign sourced TM28. Could the nomenclature confusion be due to different designation in foreign markets?
I gave up paying attention months ago when I found I could not get a simple plug and play properly jetted pumper carb conversion......
Fred, I think you are on to something. I vaguely remember a discussion of obtaining a "foreign" sourced (non-USA) TM/VM28 pumper carb...at twice the price.

After looking at the parts diagram of the TM carbs in the US Mikuni catalog, they don't appear to have accelerator pumps. I believe there are two different carbs. I don't have the time to go searching for the details right now.

MacBig or Mr. B/Pro Cycle should be able to clarify.

I've spent so much time rebuilding/repairing the Teikei carbs that I really don't need an alternative. The TK works fine for me.

However, my curiosity keeps me thinking there is an inexpensive, bolt-on option possible. I believe I have it figured out, but will have to wait until I return to NC in the spring to try it out.

jb

EDIT:

Here's PSC's post about the Mikunni TM28-1 pumper carb:

http://tw200forum.com/forum/performance-customization/6593-searching-mikuni-tm28-1-pumper-carb-overseas.html

http://tw200forum.com/forum/performance-customization/6188-aftermarket-exhaust-carb-options.html
 

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Thanks JB, you solved the dilemma. Think we have confused JD yet?
 

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Discussion Starter #15
You guys have defiantly confused me! What I'm looking for is a replacement carb that fits in the original airboots without modifying the boots. I don't care about changing the cable and control. It doesn't have to be a flat slide. Heck round slide would be just as good. Is there a mikuni round slide that fits in factory location?
 

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JD87,

I am not certain, but from a table of Mikuni specs, it looks like the VM26-606 would be a pretty close fit.

There are 4 versions of the VM26. The 606 looks to be the closest fit...with the largest stock jets.

This is the carb that the Chinese clones are patterned after (there are some differences).

I have a VM26 on order, and have another carb to try on the TW, but won't be able be sure which works until I return to NC.

In my cluttered mind, I believe the Chinese clone ( all the clones are not exactly the same), with a custom cable, and spacer for the airbox boot will be a viable solution for a total under $100.

jb
 

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You guys have defiantly confused me! What I'm looking for is a replacement carb that fits in the original airboots without modifying the boots.......?
To answer your question, the only carb we know that fits with the stock rubber boot to the airbox is the TM/VM28 as used by PSC and MacBig. Mr. Bracket had to fabricate an aluminum spacer for the end of his carb.

However, it should be mentioned that the rubber boot for the pre-2001 TW is a different length than the 2001 and newer.

And to add to the confusion, the rubber boots have been known to shrink considerably over time. So if the rubber boot on your TW is old and hardened, it is likely not to be the same size as a new boot.

jb
 

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Discussion Starter #18
So to clear things up the vm28-418 will run good if jetted properly? My tk has been giving me headaches and its got to go!
 

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So to clear things up the vm28-418 will run good if jetted properly? My tk has been giving me headaches and its got to go!
If you can get it tuned properly...

MacBig, a TW parts vendor with lots of TW expertise, has said it is difficult to tune.

Palm State Crawler tried dozens of combinations of jets with some success, but never got it fully to his liking.

Mister Bracket put in an oxygen sensor in his header pipe to measure the air/fuel ratio. I don't believe he was fully satisfied. The last I read he returned his TW to its stock configuration.... He has now purchased a pile of high performance parts, and when installed, his carb settings won't apply to a stock TW.

The only one who has said it worked great was Bigfoot, the reviewer on Amazon, and we don't know the details of his carb settings or if his bike is a stock TW.

Also the TM28 is a very tall carb, and unless you get it mounted just right it, the top of the carb or throttle cable may hit the frame.

IMO, there is not a perfect bolt-on ready carb solution without any modification of some sort.

Most of the people who have had serious carburetor problems, have ended up purchasing a new stock Teikei carb.

The Chinese clones of the Mikuni BW200 do work with modications to the throttle cable/throttle, rubber boot, and start/kill switch, if you have a pre-2001 TW.

**** I'm writing most of this from memory, which isn't all that great. If there are any Forum members that have other suggestions or corrections, please feel free to speak up.

jb
 

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JB, your memory is pretty good. Your post pretty much sums it up.
 
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