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Thread: Mikuni carb

  1. #1

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    Mikuni carb

    I am looking at my mikuni carb running rich and contemplating the next move. 1985 D50 power ram 2.6l. Did a compression test yesterday and had 145, 127, 145, 145. Squirted a little oil down 2 checked again and bang 175psi so I have a ring issue. This truck has been sitting for who knows how long so plan on driving as is. I have another 2.6 on another truck and the plan now is a rebuild of that and then into this truck. Rebuilding over the winter. At that time I'd probably go with the consensus on here and put in a weber carb.
    My question now is does anyone still use a mikuni carb? Anyone rebuilt one to any degree of success? I have two extras and see kits and float kits are not to expensive so am thinking of trying a rebuild. I read all the changeover to Webers posts and the success posters are having, and wonder are there no Mikuni satisfied users out there? Thanks.

  2. #2

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    Once you put on the Weber and see all the junk hoses and what goes with it you can clean up from under the hood you will see the point of not keeping the old style of carb.

  3. #3

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    There are 2 main problems with the Mikuni carb - their CFM restriction and the anti pollution mechanisms. The Mikuni is a complicated carb to perform a full rebuild on if you are stripping it down to every last 'O' ring and seal. I have found that most rebuild kits need to be custom trimmed by hand as the main gaskets don't fit properly and overhang into the main venturis and internal vacuum galleries. The Mikuni also suffers from water choke mechanism failures which are really difficult to replace (the wax pellet housing corrode out + the inner seals fail if they are overheated/run without coolant and generally fail from age). Their primary function is low to mid range torque but on highway driving strangle the engine and are well, terrible for any kind of performance due to the pollution gear on them (this isn't just the carb but the exhaust gas recirculation into the intake as well) You can delete some of the EGR junk on the stock carb which will improve engine efficiency but you're still stuck with the biggest stumbling block of the Mikuni's CFM rate. The Weber 32/36 does a great job of fuel delivery as it can keep ahead of the demand for CFM that the 4 cylinder engines need across the rpm range (it will trade a small loss of low rpm torque for the improvement of power from about 1500 rpm onwards). They're easy to pull down and rebuild, the kits are cheap, the electric chokes eliminate coolant hoses and the problem with the wax pellet choke on the factory carb, and the 2.0 - 2.6 engines respond very well to these carbs with both power and fuel economy when they're tuned properly.

  4. #4

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    Quote Originally Posted by geezer101 View Post
    There are 2 main problems with the Mikuni carb - their CFM restriction and the anti pollution mechanisms. The Mikuni is a complicated carb to perform a full rebuild on if you are stripping it down to every last 'O' ring and seal. I have found that most rebuild kits need to be custom trimmed by hand as the main gaskets don't fit properly and overhang into the main venturis and internal vacuum galleries. The Mikuni also suffers from water choke mechanism failures which are really difficult to replace (the wax pellet housing corrode out + the inner seals fail if they are overheated/run without coolant and generally fail from age). Their primary function is low to mid range torque but on highway driving strangle the engine and are well, terrible for any kind of performance due to the pollution gear on them (this isn't just the carb but the exhaust gas recirculation into the intake as well) You can delete some of the EGR junk on the stock carb which will improve engine efficiency but you're still stuck with the biggest stumbling block of the Mikuni's CFM rate. The Weber 32/36 does a great job of fuel delivery as it can keep ahead of the demand for CFM that the 4 cylinder engines need across the rpm range (it will trade a small loss of low rpm torque for the improvement of power from about 1500 rpm onwards). They're easy to pull down and rebuild, the kits are cheap, the electric chokes eliminate coolant hoses and the problem with the wax pellet choke on the factory carb, and the 2.0 - 2.6 engines respond very well to these carbs with both power and fuel economy when they're tuned properly.


    Thank you Geezer for the explanation. I appreciate the time you took in your response. I guess I knew the Weber was the way to go. I have another engine to get rebuilt and when I do I'll top er off with a nice new weber 32/36 electric choke carb.

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