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CT2 Carb Problem

  • Bikenut71
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CT2 Carb Problem was created by Bikenut71

The flange ears on the carburetor of my CT2 do not lay flat as they should, so when I snug them down to the cylinder, the carb body distorts just enough to make the slide stick open. I tried resurfacing the flange with limited success. With the bolts tightened anything beyond barely snug, (I'm talking maybe half a turn past finger tight), the slide sticks. I'm worried about two things as it sits now: the throttle sticking open or a manifold air leak.

Since they no longer make the flange mount Mikuni, at least I can't find one, is there an adapter that would allow me to mount a spigot type replacement? Or does anybody have a VM24sh carb lying around they could part with? 

Any advice or experience with this problem would be appreciated. Thanks
04 May 2021 12:24 #1

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Replied by Mothersbaugh on topic CT2 Carb Problem

Does the carb have the right size O-ring on the mouth of the carb? Maybe a PO stuffed an oversize one on there, and it would not compress like the standard Yamaha ring does? Might a correct O-ring atke care of some of that?
I had a similar problem with a carb from a CL-175 Honda. I was able to sand the front of the carb down a few thousandths with some 600 wet-or-dry and continue down through about 1500 and got it to seal up well.
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04 May 2021 12:40 #2

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Replied by Bikenut71 on topic CT2 Carb Problem

I thought of that, too but its a new OEM o-ring. I even tried removing the o-ring and placing a gasket there instead thinking the carb face may lie flatter but had the same result. I just now ran the bike to warm it up then sprayed starting fluid around the intake with no increase in revs, so things are sealed up even with the bolts not very tight. But I know its not right and still worry about the slide sticking on me. 
04 May 2021 13:01 #3

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Replied by MarkT on topic CT2 Carb Problem

What number is stamped on the upper edge of the mounting flange?  I might have a carb body you could swap to.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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04 May 2021 21:04 #4

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Replied by RT325 on topic CT2 Carb Problem

Do they have a thin insulator block between carb & manifold. If so, is it a bit out of shape or more squashed on the outer edges. Can you do away with it & bolt it up solid. Could you get away with whizzing a bit of the slide, or spin it & take a whisker overall which you'd get away with a little extra clearance in desperation. Mind you--anodized slide i guess so not sure how that idea would work. Get an early RD250-350 rubber manifold & an RD28mm carb--it'll love it. Would need the left carb to get the choke & blank off the choke feed to the right side..
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05 May 2021 01:09 #5

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Replied by Bikenut71 on topic CT2 Carb Problem

The number is 314  E1. Thanks
05 May 2021 10:49 #6

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Replied by Bikenut71 on topic CT2 Carb Problem

It does have an insulator block but because of the length, or should I say shortness, of the intake boot, it needs to be there. I bought a new block thinking the same as you, but no difference. The RD 250/350 carb is an interesting idea. I'll have to look into that if nothing else works. 
05 May 2021 13:21 #7

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Replied by Pete-RT1 on topic CT2 Carb Problem

I had a similar problem with my RT1, here's the thread for what it's worth.
www.yamaha-enduros.com/index.php/forums/...curvy-flange?start=0
Yamaha RT-1
Yamaha CT1-B
Yamaha CT1-C
Honda XR250
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05 May 2021 13:41 #8

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Replied by Bikenut71 on topic CT2 Carb Problem

That's great information. Thank you!
05 May 2021 15:53 #9

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Replied by RT325 on topic CT2 Carb Problem

YZ80 carb would be good in the RD type manifold. i used to use an old one on something of mine. might've been my RX125 with a 175 top end come to think. Side pull choke & had a 190 main jet originally on the yz which don't think i changed. Only a thought!!.


www.amazon.com/Carburetor-YAMAHA-YZ80-20...RCYCLE/dp/B00APOOWIW
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05 May 2021 16:27 #10

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