jrs_dodge_diesel

Update, it's running good now. No throttle hesitation now. It starts and idles fine. 1.5 turns out on the air screw didn't work, the engine would simply sputter and die. Right now the air screw (#2) is about 1/4 turn out.

I wonder if the cold temperatures are affecting it. It's been 25-45° lately. Don't know if the mixture is/was a problem, it runs like when we first bought it.

Thank you to everyone in helping get this 48cc beast running well again.

That is the prime reason I am putting this on the road (not the highway ).

Raspy

JR,

If it ran good "before" then it should be fine after all the passages are cleaned. Or close enough to fine tune it.

On the Mikunis I've worked on, you should set the float to level or parralel with the top of the carb when held upside down. This sets the fuel level in the bowl. Don't force the float to this position or you might crack it or damage the seat.

Once its running reasonably well go for a wide open test and make sure it runs smooth, meaning it two cycles, pulls well, and doesn't smoke excessively. Check the plug for a dry brown look. The full throttle mixture is set by the main jet. Its on the bottom and the needle rides in it. Next, the needle can be adjusted by moving the clip. Lowering the needle leans the mixture in the mid range, approx. 1/4 to 3/4 throttle. Again, mostly two cycle under light load. Then the idle screw for the idle mixure. It will be 4 or 8 cycling but will be dependable and slightly lean when cold. Turn it in till the engine slows or gets a bit rough, then back a bit. This setting will be affected by engine temp.

If it has a dead spot somewhere in the range, the passages are dirty. A can of Berryman B-12 Chemtool at about ten times the recommended dose and sitting overnight can really help. And, of course, fresh gas.

Next time you park it for a while turn off the gas and run it dry. The gas is so bad these days that even a couple of months seems like it can be a problem.

John

jrs_dodge_diesel

Another update. I let it sit for 2 days (I had duty yesterday). I rolled it out of the garage and kick started it. It started on the first kick. Had a rough idle for a few seconds (it's 45º out), and then it smoothed out and idled fine. Light smoke out of the tailpipe (it's a 2 stroke). It responds well to any throttle setting. I ran it up to normal temperature and then shut it down. I pulled the plug and it was dry and brown/light brown. Seems that everything is running like it should.

Thank you to everyone for helping me get this carb tuned. I really appreciate it.

jrs_dodge_diesel

Update :

It started to run progressively worse. To the point that it did not want to idle.

Then I realized that the gas that was in it was at least 8 months old, and I had forgot to put stabilizer in it. So I drained the tank and filled it with fresh 89 octane. It did not want to start after that, it would sputter and die (if it sputtered at all). Ended up having to push it home .

So tonight, with the advice in the stale gas thread, I decided to tear down the carb completely, and clean the heck out of it. Cleaned out every passage with carb cleaner , pipe cleaners, and some compressed air. I then reassembled it and rolled it outside to test it. 1.5 turns out on the air screw and it fired up, had to adjust the idle screw too. After running it, I fine tuned the air screw setting. It's now about 2 turns out. Runs like a champ now.

Thank you to everyone who helped to get this engine going again.

Raspy

What a pain. Good work getting it going again.

If you have that problem again (bad gas and barely firing), try a blast of either. On gas engines only, NOT DIESELS, you can give it all you want and often get it running enough to get the new gas through the carb. Then it will clear up and run good without a teardown. I have a little 49 cc engine on a bicycle that got fouled up like that and I just ran it on either till it cleared up.

Yes, I do keep either around. But it NEVER gets near my Cummins!


John