38mm fs Mikuni on '85 250r

[xr132]

I've got a 38mm fs mikuni on the way and i thought before it got here i'd order some jets....Could someone tell me the estimated main and pilot jet size i would need for a stock, except no air box lid '85 250R at 1,400 ft above sea, and about 40° F. And any other tips on a flat slide mikuni.

Thanks very much!
Tyler

[dcreel]

Is it a new carb or was it used on something else? Find out what the jet sizes are on the carb you are getting and order some larger and smaller ones.

Here is a link for the cheapest Mikuni jets I have found for the TM 38 carb.

http://www.rockymountainatvmc.com/productDetail.do?&navType=type&webTypeId=454&navTitle=Intake%2FFuel&webCatId=16&prodFamilyId=24377

The Mikuni TM flat slide carb is an awesome carb, I won't use anything else for a 250 2 stroke. They are easy to work on and work great once you get the jetting tuned in.

[nd4speed]

I had a heck of a time finding this info for my 250 Tecate / KX

I got a bike with a 38mm TM that looked new.

I am using whatever pilot was in it and a 280 main for summer.

Here's the thing, I found a thread that I have a link to at my girlfriend's house and I 'll try to remember to post it.

The thread says the new carb comes with a needle jet that is too lean and mine is like that. It have the clip one up from the lowest position and it still scares me that it is too lean. When I took the carb apart to jet it, the clip was in the lowest position.

[STROK'IN-2SMOKE]

Nice carb for sure yo, fast fast fast when tuned correct.
I've never put this bigO MIK on a stock bike, and honestly I don't think it would run right with the more fuel and no mods. CORRECT ME if I'm wrong.
Either way let us know how she runs.

[tecate 250rr]

I've got a 38mm fs mikuni on the way and i thought before it got here i'd order some jets....Could someone tell me the estimated main and pilot jet size i would need for a stock, except no air box lid '85 250R at 1,400 ft above sea, and about 40° F. And any other tips on a flat slide mikuni.

Thanks very much!
Tyler

Do you know if it is a TMX or TMS carb? Sudco's book says that the TMX 38-18 and TMX38-27 come stock with a 370 main jet and a VM22/210 20 pilot jet and a 6EJ12-55 jet
needle. That is stock. Clip is on 3rd clip (middle). Do you know which one you have? It should say on the front top righthand side face the slide.

[dcreel]

Now you got me confused.. What is a TMS carb? I know there is a TM and a TMX.. I'd like to try out a TMX carb. The TMX carbs have TMX embossed into the slide area of the carb.

[tecate 250rr]

I found this site awile back has some good info.
http://www.exriders.com/vbb/showthread.php?threadid=373992

[tecate 250rr]

Now you got me confused.. What is a TMS carb? I know there is a TM and a TMX.. I'd like to try out a TMX carb. The TMX carbs have TMX embossed into the slide area of the carb.

From my research I have found that there are 2models of TMX the older model has just TM on the side the newer models have TMX on the side the newer models are supposed to be better. But I can't remember how.
This is from the Sudco Book "An evolution of the popular TMX model,The MIkuni TMS38 carburetoroffers vastly improved mid-range and top end performancewith percise jetability. Design changes include a TMS flatslide throttlewith no cutawa. Instead the slide has a speacially designed internal chamberwith two metering orfices. there is no screw in pilotjet, and the piloy fuelis now meteredby the jet needle. Tuning is quikerand more simplified with less components."

[tecate 250rr]

Mikuni TM carbs front body screws to the main body. TMX carbs are one piece. Ther are two Model sizes of TMX 35 and 38. The TMX38 being more prevelent.

[dcreel]

hmmm.. Sudco only lists a TM or a TMX on their website. But there are parts for sale on Ebay for a TMS Mikuni carb. Maybe the TMS was a carb released between the 2.

http://www.sudco.com/Carburetor01.html

But when you click on the TMX part it shows TMS/TMX

http://www.sudco.com/CatalogJPG/113.jpg

It does note that the TMS isn't in production anymore. Learn something new every day.

[tecate 250rr]

Thatt's the way is sounds like to me . I have never seen or used a TMS before. I have the older version of the TMX38

[dcreel]

Thatt's the way is sounds like to me . I have never seen or used a TMS before. I have the older version of the TMX38

I've got a Klemm Research TM38 that was bored to 41mm and love it. How do you like your TMX38? I have a TM38 for this new build, wonder if a TMX38 would be the way to go?

[tecate 250rr]

I gotta say that it's the best carb I have ever used. Very simple and basic yet clean and accurate performance. The sudco link you posted does only show the TM and TMX but if you click on the mikuni PDF pages at top of list and scroll down to the TMX section you'll see the parts and what not for the TMS. The book I have is a 4th edition,so now I gotta get the 5Th edition That book has helped me alot.

[tecate 250rr]

Dang! Where did you get that Klemm Carb from?

[dcreel]

Dang! Where did you get that Klemm Carb from?

It was on my Klemm KX250 motor.. ;-) When I bought the bike back in 87, Harry Klemm showed me how to repack the silencer.

http://i176.photobucket.com/albums/w182/dcreel/Tecate/100_1712.jpg
http://i176.photobucket.com/albums/w182/dcreel/Tecate/100_1711.jpg
http://i176.photobucket.com/albums/w182/dcreel/Tecate/100_1713.jpg

[tecate 250rr]

Those ports are hogged the f@#k out! That carb looks nice too. What do you want for the cylinder? HaHa!

[xr132]

http://cgi.ebay.com/ebaymotors/MIKUNI-FLAT-SLIDE-CARBURETOR-38mm-_W0QQcmdZViewItemQQhashZitem35ad0cd36fQQitemZ23053 6565615QQptZMotorcyclesQ5fPartsQ5fAccessories

It's the exact same as this one(used)

[dcreel]

http://cgi.ebay.com/ebaymotors/MIKUNI-FLAT-SLIDE-CARBURETOR-38mm-_W0QQcmdZViewItemQQhashZitem35ad0cd36fQQitemZ23053 6565615QQptZMotorcyclesQ5fPartsQ5fAccessories

It's the exact same as this one(used)


That would be a Mikuni TM carb. I have 3 of those.

[xr132]

That would be a Mikuni TM carb. I have 3 of those.
They're a good carb aren't they? Do you have yours on anything?

[tundrawillie]

I've got a Mikuni Flat slide that came on a 250R I recently purchased. The seller claimed he ran it as an alky carb. The markings I find are T34 with 02E below that. That is on a square raised area. Below that, on a circular raised area is T6 and 6 1 below that(quite a bit of space between the 6 and the 1. I presume this is a 34mm carb. It looks to be an older model. Vertical choke on the side with a knurled screw (idle?). It look to need rebuilding. The rubber gasket material where the flat side screws to the main body is rotted and almost resembles some sort of liquid gasket material, not sure.

Is this carb worth fooling with? I like it, other than the fact that it seems to be a 34 in size. I'm going with a 310 or larger kit, although not sure which brand. They all look the same and porting is what really makes the difference.

I talk with Allen Knowles (CT Racing) fairly regular and he talks big about his 350 PV engine. My engines bottom end is pristine with a brand new left inner case. All powder coated to resemble brushed aluminum. Plus, Allen told me he'll build a custom expansion chamber for the kit of my choice. Where can one find the required kit to rebuild this carb?

If someone is interested in it, I'll make a good price on it. Anything in question, I sell LOL.

[dcreel]

They're a good carb aren't they? Do you have yours on anything?

I use them on both of my 250's as well as the Tecate I just traded out. I tried and tried to jet a Keihin PJ carb, and just gave up on it. I run a 41mm TM on my Klemm Tecate.

If you wish to rebuild your TM carb tundrawillie, Sudco has all the parts to rebuild it. If it was a 38mm I might pick it up off of you. The only real way to tell would be to measure it.

[xr132]

Well i got the carb today...something fishy about it though(pic attatched) just behind the choke something's been ground out, what the heck? The bottom hole is threaded for another screw to hold the back to the base, the hole farthest out goes somewhere and the one beside it is dead, the square on beside that goes straight into the carb just behind the slide. Any idears? Anyway it's got a 300 main, will that be a bit lean?(trike's basically stock)
Thanks again!
Tyler

[beets442]

Not to deture you from what you are doing, to run a larger carb it helps to port it so it can handle the extra fuel. Is there anything wrong with the stock carb?

[xr132]

I plan on porting and pipe next season, ad yes there is something wrong with the old carb is a keihin roundslide LOL the needle and seat leaks and it's jetted wrong for my reeds.

[tundrawillie]

I completely disassembled my Mikuni and cleaned every single part with carb cleaner and naval jelly. Looks good now. I'll have to get out my calipers and measure to verify the carb size. It's a nice carb, although I don't know what bike'trike this carb came on as OEM part. I'm going with a much bigger carb, so if someone might beinterested in this one, let me know. I have a cable for it, as well. Make me a low ball offer and it's yours LOL.

[beets442]

I like Mikuni myself too on a 2stroke, to me they are easier to fine adjust. Port and pipe will help on your power delivery....let us know how it goes.. Good luck Beets

[jeffatc250r]

Only downfall with running it on a 250r is the fuel inlet spigot is on the wrong side. I had one on mine before and it worked well other than the long looped fuel libe going to it. Also hope your rubber boots arent hard as a rock.
If you have trouble getting the rubbers over the carb, hang them over a wood stove or heat up with a heat gun until pliable enough.
Another issue i had was the thumb pull is stiff, so i cut a little off the slide spring until it felt right.

[factoryX]

xr132, is that carb chipped? looks like someone dropped it.

[xr132]

xr132, is that carb chipped? looks like someone dropped it.

Ya, somebody ground a piece out for some reason??? Does anyone know where the holes are suposed to join??? I thought if i knew i could just bend a piece of pipe to connect them and then JB weld around it....