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Carburetor Help
- DLongRT1/360
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Carburetor Help was created by DLongRT1/360
Need help from the carburetor experts. Removed my Mikuni carburetor from my recently purchased 1972 RT2 Yamaha 360 enduro for a cleaning, inspection and to check the floats and float level. I noticed the number on the carburetor was 275-E1. Am I correct that this is the wrong carburetor for the RT2 and for a DT1 or DT2 250? This 275-E1 carb has a #220 main jet, #30 pilot Jet and a #3.3 valve seat. The service manual for the RT2 carb calls for a #230 main jet, #45 pilot jet.
Float levels, air screw settings, and jets are different. Do I need to find a 308 E2 carb?
Appreciate any opinions and recommendations.
Float levels, air screw settings, and jets are different. Do I need to find a 308 E2 carb?
Appreciate any opinions and recommendations.
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- Swoop56
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Replied by Swoop56 on topic Carburetor Help
Your carb is for a 70 RT1 .Technically if you changed all the parts over to RT 2/3 specs , it would work fine ,
but it might be actually cheaper to get a proper RT 2 or 3 carb complete .
but it might be actually cheaper to get a proper RT 2 or 3 carb complete .
03 Feb 2025 19:53
#2
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- RT325
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Replied by RT325 on topic Carburetor Help
My first thoughts are--do you have a problem you're looking to cure or has it been running good for a long time.
I tend to think "if it aint broke then don't fix it".
But then again i always seem to be fixing things so that theory doesn't work for me.
Also, important to replace the miniature Oring on the 'jet setter' screwed into the needle jet because if it doesn't seal you'll be chassing rich main jet symptoms as it leaks past there & bypasses the main jet or at least adds to what the jet passes.
I tend to think "if it aint broke then don't fix it".
But then again i always seem to be fixing things so that theory doesn't work for me.
Also, important to replace the miniature Oring on the 'jet setter' screwed into the needle jet because if it doesn't seal you'll be chassing rich main jet symptoms as it leaks past there & bypasses the main jet or at least adds to what the jet passes.
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- DLongRT1/360
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Replied by DLongRT1/360 on topic Carburetor Help
Thanks to you both. If I went with another pump would a 308 E2 be correct? Also, if I used the pump I have what parts could stay? Do I keep the throttle and air screws, throttle valve and needle, float arm etc. Replace jets per RT2 then use all RT2 settings?
RT325 I recently ordered that needle jet setter O ring from Partzilla. Bike is not running at this time.
RT325 I recently ordered that needle jet setter O ring from Partzilla. Bike is not running at this time.
04 Feb 2025 00:34
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- RT325
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Replied by RT325 on topic Carburetor Help
Sorry to be a pain. But you say 'not running at this time', which has me intrigued. Has it been running recently but stopped, never to go again. Or similar. Ignore me if ya like haha no problem. I just like digging till I find what caused it not to run. Can post pics via "imgur". We love pics. Thanks.
04 Feb 2025 02:04
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- Swoop56
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Replied by Swoop56 on topic Carburetor Help
There were significant changes to the carb specs from RT1 to RT2&3 , due to the adoption of the Reed Valve induction .
The Throttle Slide , Needle , Needle Jet , Pilot Jet and Main Jet were all altered .
Due to the number of parts required , and availability of some , a replacement carb might well be a more economic option .
And yes , a 308 E2 carb will do the job .
The Throttle Slide , Needle , Needle Jet , Pilot Jet and Main Jet were all altered .
Due to the number of parts required , and availability of some , a replacement carb might well be a more economic option .
And yes , a 308 E2 carb will do the job .
The following user(s) Liked this Post: RT325
04 Feb 2025 11:41
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- DLongRT1/360
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Replied by DLongRT1/360 on topic Carburetor Help
So SWOOP56 if I changed out the Throttle Slide, Needle, Needle Jet, Pilot Jet and Main Jet I could ride with this Carb? I have cleaned this one up so nice and pretty. I guess I can see what's out there also for the correct carb.
RT325, I purchased the bike in December and test drove it and it ran fine. Took it home and a few weeks later started it up and took a brief ride but could not get it started again and noticed the carb leaking gas.
Just a note. Back in January I started a post in regard to an oil pump for this bike as it was removed and runs on pre-mix. I posted pics of my bike and an oil pump right off my computer photo album on the post with success but did not work when I attempted this time to post photos of my carb. Wonder why it worked then and not now. anyway, thank you both.
Just thought I would ask who sells original Mikuni parts?
RT325, I purchased the bike in December and test drove it and it ran fine. Took it home and a few weeks later started it up and took a brief ride but could not get it started again and noticed the carb leaking gas.
Just a note. Back in January I started a post in regard to an oil pump for this bike as it was removed and runs on pre-mix. I posted pics of my bike and an oil pump right off my computer photo album on the post with success but did not work when I attempted this time to post photos of my carb. Wonder why it worked then and not now. anyway, thank you both.
Just thought I would ask who sells original Mikuni parts?
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- Swoop56
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Replied by Swoop56 on topic Carburetor Help
My RT2 parts book shows the following parts for the carb .
Main Jet # 220
Needle Jet P-0 ( 275-14140-40 )
Needle 6DH3-3 ( 308-14116-03 )
Slide Cutaway 3.0 ( 275-14112-30 )
Pilot jet # 45 ( 193-14142-45 )
Needle / seat 3.3 ( 239-14190-33 )
Setter O ring ( 214-14147-00 )
OK . So those are the jets and such that should be in your carb .
I have included the original part numbers , some of which , like the needle and seat / float valve ,
likely have been superceded . The carb slide is likely available on Ebay , as is likely the Needle too .
The Needle jet however is a rare beast , and no longer available through Mikuni stockists .
The other jets could be ordered through a Yamaha dealer , or Mikuni agent like Niche Cycle ,
or Jets R Us .
I included the Needle & Seat because if your carb is leaking , then either your seat is damaged
or has some rust or dirt in it , or your float level is incorrect .
The setter O ring is critical , for clean running , so replacing it as a matter of course isn't silly .
Do some research on prices and availability of these parts , to determine what your best course of action might be .
The hardest bit to locate will be the Needle jet . I happen to have a couple of NOS ones in stock .
PM me for a price if you think you might swing that way .
Main Jet # 220
Needle Jet P-0 ( 275-14140-40 )
Needle 6DH3-3 ( 308-14116-03 )
Slide Cutaway 3.0 ( 275-14112-30 )
Pilot jet # 45 ( 193-14142-45 )
Needle / seat 3.3 ( 239-14190-33 )
Setter O ring ( 214-14147-00 )
OK . So those are the jets and such that should be in your carb .
I have included the original part numbers , some of which , like the needle and seat / float valve ,
likely have been superceded . The carb slide is likely available on Ebay , as is likely the Needle too .
The Needle jet however is a rare beast , and no longer available through Mikuni stockists .
The other jets could be ordered through a Yamaha dealer , or Mikuni agent like Niche Cycle ,
or Jets R Us .
I included the Needle & Seat because if your carb is leaking , then either your seat is damaged
or has some rust or dirt in it , or your float level is incorrect .
The setter O ring is critical , for clean running , so replacing it as a matter of course isn't silly .
Do some research on prices and availability of these parts , to determine what your best course of action might be .
The hardest bit to locate will be the Needle jet . I happen to have a couple of NOS ones in stock .
PM me for a price if you think you might swing that way .
05 Feb 2025 05:36
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- automan
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Replied by automan on topic Carburetor Help
and 2.5 float valve!
3.3 will leak easier
3.3 will leak easier
05 Feb 2025 05:50
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- MarkT
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Replied by MarkT on topic Carburetor Help
First step is to completely disassemble and identify and list ALL the parts in your carb. You might be fine.
Yamaha also had jetting revisions so don't get too caught up in a specific jet size until you have a complete list of everything in the carb,,, the jets work as a "system" as well as individually.
Yamaha also had jetting revisions so don't get too caught up in a specific jet size until you have a complete list of everything in the carb,,, the jets work as a "system" as well as individually.
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
The following user(s) Liked this Post: Swoop56, Ht1kid
05 Feb 2025 09:02
#10
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