Request for 102 Carb Rebuild Information

[Al Peffley]

I am in the process of rebuilding a used Yamato 102 carb that has been sitting off of a motor for a long time. Can some of you give me some advice as to which gaskets are the most important to replace, and what settings work best for the air bleed screw adjustments? Are there any alternate fuel jet changes available that are legal for APBA/AOF racing?

I have the Yamato 102 Manual from Ric Montoya and also have extracted a parts list of gaskets from Ric's website.

Al Peffley

[mike ross]

Al the only gasket I am aware of is the one on the top of the float bowl. Make sure that one is good. High speed adjustment is best set with a water pump and a test wheel. You can start at 31 clicks. I believe this is about 1 turn and a 1/4. air screw is also best set when on a test wheel. Try 1 turn and that will be close. When you take a part the high speed needle. make sure it is aligned in the center of the whole and not touching the side. Also make sure you replace all the o rings so the carb dosn't drip. Thats all I know. Mike

[Al Peffley]

Carb No. 2 Rebuild...

Thanks Mike, for the thoughtful feedback. I have a second carb that was "rebuilt" a few years ago by a local factory rep mechanic. It does not work in the higher rpms range like it should at any of the Y102 manual's carb spec settings. I have run this carb at rediculous float settings to try to make it work, but it is still disfunctional (it has no mid-range punch.) This second carb is also feeding air bubbles back into the fuel line. I always use a quality fuel filter, make sure I have no cuts in the line, and check the float bowl for fuel system debris. It's such a simple gravity feed system, but the air bubbles generation has me stumped...

I will tear the second carb apart again to check the high speed needle alignment. The Y102 manual I have does not really tell one how to totally rebuild a 102 carb. There are a lot more gaskets in the carb than the float bowl gasket, but I will change it again (if it was really changed before) when I tear it down and replace the o-rings (along with a few other gaskets.)

regards,
Al

[mike ross]

Al dubble check the filter in the tank. Sometimes the solder that holds there screen in place flakes of and plugs up thew hole inside the screen. Last year in the C finals we had a small beery fall from the tree we pitted under and plug the hole. We took our screens out of the tank. Make sure to put new points in the motor every year. And re do your spark plug caps. Mike

[Fast Jack]

Make sure the "choke " is seated properly, this can cause a high speed problem, The mixture wanders.

[Al Peffley]

Thanks Again

Thanks for the added tips to fix my fuel feed system problem. Neither fuel tank I have has a stock Yamato screen left in it (only the cage). I have a spare fuel shutoff valve now that I will swap out to see if that helps solve my fuel in-line "bubbles" problem.

Maybe I should let the carb parts set in trays of purple Super Clean before I re-assemble them.

Al

[Al Peffley]

More Carb Info Please

Hello Again,

I did a web-search through the APBA Tech Manual today and found a reference to a Mikuni model BV36 carburetor for the 102/302 engines. Does anyone out there have an owners manual or repair/rebuild instruction sheet from Mikuni for this carb?

The APBA Stock Outboard Inspection Manual for Yamato-102C & 302F Specs (Class C, dated 3/01/06, page 16) also states that a racer/owner can replace the original carb in accordance with this statement under "General": "The latest replacement Carburetor has been approved for use on the 102 and 302." Does anyone know what model number the latest "replacement" carb is and how much one costs?

Al Peffley