Carburetor Rebuild

[m38inmaine]

I know there is a place in FL that rebuilds them but it's $315 which I think is too much. Is the "secret" information out there to allow it to run without the choke being partially pulled ?

Thanks
Mark

[rickf]

I only charge 200.00 for a rebuild. I am in NJ. I can tell you the quick and easy way to eliminate the flat spot but this is only going to work if everything else is right with the engine and carburetor. First thing is to do a complete tune up including valve adjustment and be sure the timing is on the mark. Then, when setting the idle mixture on the carb set it just a hair on the rich side at idle and you should have no more flat spot.

[m38inmaine]

Thank you for the information, good to know a source is close by.

[m3a1]

You are mentioning that you're running with the choke partially pulled. I'd be interested to know what symptoms you are experiencing that compells you to do that. There may be another issue here, such as raw air getting in below the carburetor. Are you satisfied that your intake manifold and/or your carb-to-manifold gasket are both leak free? Everything else right, and tight?

I don't want to turn you away from a carb rebuild (which is always a good idea) but no matter what magic Rick can work on your carb, if you have other unresolved issues, you won't be satisfied.

Cheers,
TJ

[rickf]

The flat spot he is talking about is a very common problem with these carbs since they were built to be emissions legal and as such were set to run lean. Adding a little fuel to the primary circuit also adds to the secondary circuit to overcome the problem. But yes, another common problem is intake manifold leaks. Check your intake manifold by spraying carb cleaner around the manifold with the idle up around 1200. Be sure to have the air cleaner hose on or you will get a false positive reading for a vacuum leak.

[m3a1]

I didn't see any mention of a flat spot from him here, and thought maybe you guys were discussing that offline.

[m38inmaine]

I have not even started the engine yet, just getting things ready to start it. I have had 5 other M151's and they all had a dead spot that a slight application of choke fixed. I ended up buying a NOS carburetor that has the adjustable fuel mixture for $185,waiting for it to arrive.

[Mark]

To make it adjustable, remove the plug cover

[rickf]

If it is a true NOS carburetor then it is going to be a 12848 or a 13841. They were the only only ones to have the external adjustments. They were A1 carbs. Those carbs are a bit different from the 13660 that came on the A2 in as much as the jets are different and they do not produce quite as much power. I am only talking a difference of one or two horsepower so no big deal. That was a real good price. There was one carburetor that was sold as a NOS but was a very late contract carb which only has one number on the top of it. These were made in Thailand and are the exact same as the 13660. I have been running one for many years and they run just fine regardless of what some of the uninformed will say. they were built under contract so they had to meet the same specs as the originals. Unfortunately once those contracts ended so did the quality control, as is evidenced by the products coming out of those areas now.

[Surveyor]

as is evidenced by the products coming out of those areas now.

yeah, sidetrack - Don't buy a NOS Thailand rear wire harness as seen on ebay - one wrap of cheap electrical tape with butt connectors at the splits.

[m38inmaine]

Thank you for the info, it is a single number 11681708, I purchased it from a US company in MD, still sealed in the original box and wrapper, looks to be of very high quality.

[rickf]

That is one of the latest manufacture contract carbs. It should work well for you.