1984 Tundra LT

[Shermanator]

Picked up this old beasty for the grand son and am having a helluva time trying to get it to idle properly! Anything other than idle and it goes like a raped ape, well, sorta. It has a MIC Mikuni carb on it and I've dunged it out as well as I could but can't find any links (even on Mikuni website) as to specs or how to tune this baby. Any ideas on how to "smooth" the idle out??
Sherm

 

[07 Phazer]

If you think the pilot circuit is clean and the carb is working properly, you may have a crank seal leak. That can show up as poor idle.

 

[Shermanator]

And can I assume you can't really check for a crank seal leak? Do you know any links that could get me a schematic of the carb? Although I did clean it as well as possible it was pretty rusted inside. If you adjust the throttle cable from the top of the carb you can get the idle to increase but its still pretty rough.....Sherm

 

[07 Phazer]

You can check the pto side with WD/40. While the machine is running,spray in behind the clutch onto the seal, if its leaking, the idle will smooth out. There isnt a fast easy way to check the mag side, other than a leak down test, but unless you have all the tools, you have to take it into a shop for that. Did you try soaking the carb in a cleaning solution? Sounds like its only missing on one cylinder anyways

 

[Shermanator]

I'll give it a spray and see what happens. There was another cylinder under there somewhere but I guess I'll just have to get by with the one for now! Reminds me of an old Triton air cooled outboard I used to have, used to shake the entire boat apart at idle but had great midrange and top end! Thanks........Sherm

 

[brushwolf]

The mag side seal cal also be checked by shooting a little either or carb cleaner in the hole that the recoil rope comes out of. If it is sucking air , it will suck up the fumes and there will be a change in idle just like on the pto side.

 

[Shermanator]

Right on, thanks! Sherm

 

[IGOTGAS]

I always replace the needle seat on my old sleds....when they go through restoration. Does wonders.

 

[Shermanator]

Thats one of the problems I'm having is finding a schematic of the carb or to find parts. Any links you use? Sherm

 

[dooshredder]

Maybe this will help....

http://www.victorylibrary.com/tech/mikuni-2.htm

 

[stingray719]

In the old days I would take off the pulse line on the crankcase and attach a tube. Then put that piston all the way down in the bore. Then have a smoker blow a mouthful of smoke in tube. Smoke comes out OTHER side or from seals you have an answer.

 

[longtrack156]

In the old days I would take off the pulse line on the crankcase and attach a tube. Then put that piston all the way down in the bore. Then have a smoker blow a mouthful of smoke in tube. Smoke comes out OTHER side or from seals you have an answer.

That sounds like a good idea!