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#1 |
Join Date: Nov 2019
Posts: 353
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Carb Alternative for RXB150 or other YX engined pit bikes
I have been messing with setting up the Mikuni 26mm carb that was supplied with my bike. It is a pain in the butt that you have to take the carb off to adjust the pilot fuel screw. I tried a small 90 degree screwdriver ratchet from Harbor Freight, but couldn't get the blade engaged.
There is some confusion on my part because this carb is sometimes called a VM26, but a real VM26 is actually a 30mm carb that I am considering using on my TT250. They are completely different. https://www.scooterpartscatalog.com/...or-114-20.html) https://www.denniskirk.com/mikuni/26...prd/165142.sku However, there is a true VM carb, that has better access for adjustment and easier to find parts. This is the flange mount VM22. https://jetsrus.com/photos/photo_mik...dimensions.JPG https://www.denniskirk.com/mikuni/22...prd/165139.sku However, it has a 49mm on center mounting flange rather than the 48 mm for my stock 26mm carb. Has anyone used this true VM22 on the YX or similar engine? Is a different manifold needed for changing to 49mm or for clearance issues?
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CSC TT250 Orion RXB 150XL |
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#2 |
Join Date: May 2006
Location: Yuma, Arizona
Posts: 9,035
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Contact Pete at Kronik Racing. He is the Vader 125 guru, but prior to dealing with Vaders, he was dealing with pitbikes and racing them.
www.kronikracing.com
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"They say that life's a carousel, spinning fast you got to ride it well..." TGB Delivery Scooter 150 TMEC 200 Enduro--carcass is sadly rotting in the backyard |
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#3 |
Join Date: Nov 2019
Posts: 353
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A good source for carbs and parts
I have been doing more searching.
I found TboltUSA.com. Others probably already know of them. They have lots of parts and tech information. They sell SSR and other pit bikes. This is what I will likely do: a true VM24 carb with a spigot manifold adaptor. https://tboltusa.com/store/tbparts-m...rb-p-1369.html https://tboltusa.com/store/26mm-carb...oot-p-599.html This way I get the good jet access in the bottom of the bowl and pilot screw adjuster where it is accessible. Also, I am getting the VM26 (which is actually 30mm) for my TT250, so I will be able to use the same jets and become very proficient at tuning.
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CSC TT250 Orion RXB 150XL |
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#4 | |
Join Date: Nov 2019
Posts: 353
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Sent Kronik an e-mail
Quote:
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CSC TT250 Orion RXB 150XL |
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#5 | |
Join Date: Nov 2019
Posts: 353
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Size?
Quote:
Is the VM26 too big? It is really a 30mm...the same as I plan to put on my TT250. If I read the Mikuni convention right the VM24 will actually be a 26mm, which is what I have now. Also, the VM24 is a bit smaller...matching more closely to what I have. The fit is pretty close, especially at the top near the fuel petcock. But, I guess I could relocate the petcock. I am OK with the performance as it is. I just don't like the carb. https://jetsrus.com/photos/photo_mik...dimensions.JPG Is your Pirahna 150 a stock YX engine? If so, how did you set up the jets (main & Pilot) and needle position? I am in Denver, 5280ft, so your settings may not apply, but I would have a starting point. Thanks a bunch!
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CSC TT250 Orion RXB 150XL |
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#6 | |
Join Date: Nov 2019
Posts: 353
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Cool man!
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I will go for the VM26 with adaptor. This is great because once I change out my TT250 to VM26 I will have only one type of carb to mess with. Right now it has a KOSO PWK (Keihin knockoff) 30mm flat slide on it that I think is too much for a stock CG250 engine. But, it runs good, so I can wait on this change out. The carb at Dennis Kirk is $84, but that doesn't include the $14.50 worth of main jets that Tbolt gives you for $110. Only a $11.50 difference. So, I'll buy from Tbolt as I like their site and they have a lot of parts and good info.
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CSC TT250 Orion RXB 150XL |
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#7 |
Join Date: Aug 2009
Posts: 522
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Just an FYI, the Genuine Mikuni spigot mount carbs are measured at the ID of the flange intake (Letter A in the jetsRus photo in the original post). They are straight bore carbs, meaning the measurement at the spigot opening is the same as the measurement where the carb throat and venturi meet (at the throttle slide). A VM26-606 is a 26mm opening, you'll find that a Genuine VM24 will measure 24mm ID.
The various flange-mount Mikuni-clone carbs that come standard on a lot of Chinese pitbikes will measure to be quite smaller than the intake opening, and usually have a rounded rectangular bore size at the throttle slide. |
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#8 | |
Join Date: Nov 2019
Posts: 353
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Thanks...
Quote:
I have had folks on the CR Dual-Sport blog tell me the VM26 is a 30mm. I think your information is more document oriented, so likely correct. So, I think at 26mm this should work with the RXB150. I am also considering it for my CSC TT250. Right now I have a KOSO 30mm flat-slide on it, which gives good performance, but at the cost of fuel mileage. I am only getting 60mpg and would like to approach 70mpg. This is a commuter bike, so mileage trumps power.
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#9 |
Join Date: Aug 2019
Location: Indiana
Posts: 176
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Did you go with the tbolt vm26 setup for your rxb 150 I'm looking at doing a diffrent carb setup on mine as I'm having a lot of issues getting my stock carb dialed in and would like a carb I can get parts for eaisier.
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Current Bikes 2019 Lifan Xpect 2016 Harley Davidson Roadster |
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#10 |
Join Date: Aug 2019
Location: Indiana
Posts: 176
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Double post
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Current Bikes 2019 Lifan Xpect 2016 Harley Davidson Roadster |
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#11 |
Join Date: Aug 2019
Location: Indiana
Posts: 176
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#12 | |
Join Date: Aug 2019
Location: Indiana
Posts: 176
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Quote:
Thanks I went ahead and orderd the kit. After buying the carb separate and the boot spacers and gaskets. it was only about a $20 difference. And they did not have the carb in stock by its self either only had the kits left. Hopefully this gets my rxb runnig right finally.
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