Cyclone mikuni carb

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JDMIKE8100
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Location: Maryhill,Ontario,Canada

Cyclone mikuni carb

Post by JDMIKE8100 »

Found 3 34VM mikuni carbs to replace the original carb. The original has 34124 stamped on it and the others have 3493,34A309 and no number.
Are they the same carbs. Still have a fuel delivery problem. Got spark,compression and a rebuilt fuel pump.Fuel is getting to the carb. want to use one of the different carbs with jetting from the original.
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400brian
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Re: Cyclone mikuni carb

Post by 400brian »

Please explain your fuel delivery issue. In my experience with these 40+ year old carbs, the biggest problems are the needle / seat, and the enrichener seat / plunger.

'09 Vintage Challenge Survivor, and I wasn't late for supper!
'10, '11, '12, '13,'14,'15,'16,'17, '18, 19, 20, 21, 22 Vintage Challenge Survivor !
72 400 restored, Father bought new in '71
73 X8 restored
'74 340 green machine
'74 X8 9 time VC finisher
'78 Spitfire in progress
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JDMIKE8100
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Re: Cyclone mikuni carb

Post by JDMIKE8100 »

There was a mouse nest in the airbox so I am suspect of damage
Cleaned carb and carb kit and fuel pump kit
Dumping some fuel at exhaust joint
Compression is 145 per side and good spark
Sled has 417 original miles
will growl with a thimble of fuel down the cylinder
Guessing the sled has not run since the 80s
Is 77 440 Cyclone
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400brian
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Re: Cyclone mikuni carb

Post by 400brian »

Do you suspect that it was ran with the nest in place?

If you have spark and compression, it should run on spray into the carb throat. Your compression sounds great, so I wonder if it is firing the plugs under compression.

'09 Vintage Challenge Survivor, and I wasn't late for supper!
'10, '11, '12, '13,'14,'15,'16,'17, '18, 19, 20, 21, 22 Vintage Challenge Survivor !
72 400 restored, Father bought new in '71
73 X8 restored
'74 340 green machine
'74 X8 9 time VC finisher
'78 Spitfire in progress
2 '75 340S 1 running, one on deck
'78 LF 440 future CC clone
'73 Skiroule RTX 440, 500 mi.
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JDMIKE8100
Posts: 133
Joined: Wed Jun 09, 2010 9:48 pm
Location: Maryhill,Ontario,Canada

Re: Cyclone mikuni carb

Post by JDMIKE8100 »

I dont think it was it was parked in a trailer for a short time said the previous owner
I think thats where maybe some damage happened
Going to have to recheck some things and try again
The darn thing should run
I have 3 34 carbs no idea what they are from can I swap parts off the original or are they different by models and years
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jep_800
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Re: Cyclone mikuni carb

Post by jep_800 »

To my knowledge, all VM34's are similar... there's just small changes depending on model that manufacturer's put on their sleds. Some had a straight brass plug in the bowl, while others had the moisture collection tube on the bottom. Some had different ports to attach testers to... it just depends. But, they all should function similarly, and you should be able to plug and play all the internal parts.

I had to clean the carb on my Cyclone 3 times before I got all the gunk out and it would run under it's own power. If you're getting fuel out of your exhaust, I agree with Brian that you may not be getting the spark or explosion in one of the Cylinders so it's not burning the fuel. Is one plug considerably fouled compared to the other, or do they look the same?
1975 John Deere 800
1975 JDX8 (VC Finisher 2019)
1976 440 Cyclone (VC Finisher 2022)
1974 El Tigre 440 (Sold)
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JDMIKE8100
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Location: Maryhill,Ontario,Canada

Re: Cyclone mikuni carb

Post by JDMIKE8100 »

Going to spend a half day on it and recheck
Thought I had good spark The plugs look the same
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