Trying to get an old friend started

#1
Afternoon Gentleman, it has been at least three years since I have ridden my 1969-ish Alexander Reynolds. It has a predator engine with the governor removed, new connecting rod springs aluminum fly wheel, Mikuni carburetor. last time I was on it there were no issues. Figured I try to get it started. Install new spark plug, new fuel line with fuel filter, new gas. sprayed the carburetor with carburetor cleaner. The tube at the bottom of the carburetor bowl was leaking gas excessively........ :/ stuck at 6/32 screw in it and gave it a yank ..... OK a lot of yanks. nothing. Was looking for some direction recommendations. Thanks in advance
 

Lizardking

Well-Known Member
#2
Disassemble the carburetor and give it a good cleaning. Jets get clogged up from the aging gas as it sits unused. Replace any needed gaskets and slap it on. YouTube for video
 
#5
Usually just dopping the bowl gets it going. Just clean the bowl and spray up in the jet. You will be able to tell right away if its clean or if it has some crud in it. after 3 years im sure it has some but its probably not totally gunked up
 
#8
Does it run when you spray some starting fluid?
I had some time yesterday, disassembled the carburetor without a kit and cleaned it with some carburetor cleaner. It would fire up when I would throttle up. Bowl gasket looked a little questionable. We need to be thoroughly cleaned and tuned again I think
 

Lizardking

Well-Known Member
#10
I don't have much experience with the makuni yet but on the original carb that comes with the predator there is a small black jet that controls the idle and needs to be cleaned with a thin wire to unclog the tiny hole. Did you clean any small holes with a thin wire. Bread tie wire size or thinner is what I've used. My Coleman 196cc would idle terrible when I first bought it. Cleaned the carb and now starts and idles great.
 
#11
I did what you recommended. It won’t idle. Have to mess with some fine-tuning. The bowl was definitely dirty. Thanks
That is the symptom of a clogged pilot jet. It has a tiny orifice that becomes plugged over time with lack of use and the engine will only run on the main jet, which has a much larger hole. Remove the pilot jet and clean out the orifice and passage. I poke at it with a sewing needle. Here is a diagram of a basic Mikuni carburetor.

 
#12
That is the symptom of a clogged pilot jet. It has a tiny orifice that becomes plugged over time with lack of use and the engine will only run on the main jet, which has a much larger hole. Remove the pilot jet and clean out the orifice and passage. I poke at it with a sewing needle. Here is a diagram of a basic Mikuni carburetor.

This is very helpful!!! Thank you
 
#13
That is the symptom of a clogged pilot jet. It has a tiny orifice that becomes plugged over time with lack of use and the engine will only run on the main jet, which has a much larger hole. Remove the pilot jet and clean out the orifice and passage. I poke at it with a sewing needle. Here is a diagram of a basic Mikuni carburetor.

Where did you get this exploded view from?
 
#14
Where did you get this exploded view from?
Parts lists and diagrams for Japanese motorcycles are easily available for free online. Here's a link to the site that I prefer. The diagram that I posted yesterday is for a 1975 Yamaha DT125B. I picked that one because it has a Flintstones-simple Mikuni carb that I guessed is similar to the one you are working on.

Parts Locator
 
#15
Parts lists and diagrams for Japanese motorcycles are easily available for free online. Here's a link to the site that I prefer. The diagram that I posted yesterday is for a 1975 Yamaha DT125B. I picked that one because it has a Flintstones-simple Mikuni carb that I guessed is similar to the one you are working on.

Parts Locator
Yes it’s the one , very helpful
 
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