4 stroke engine stalling out

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Mr Hydroseed

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I have a 4 stroke engine kit I bought off of ebay. It worked pretty well for the first couple of rides. I loved it, I had to just modify it right away of course. So I bought a Sick Bikes shift kit for it and liked it for the most part. I did get stranded out on my first ride though because the chain wrapped around the crank sprocket. There is a lot of moving parts than can potentially malfunction here. I also ordered the high flow air filter to squeeze out a little more power. Before the bike reached a peak high speed of 38.2 MPH, but with the new set up I could only get up to 35ish. The problem was when the bike got really warmed up it would run to lean, to the point of the bike only going 32 MPH. So I read up on jetting and happened to have a .028" drill bit so I drilled out the jet. That was pretty much the last time I really rode my bike. It ran kind of rough, from idle and I couldn't tune it with the low jet screw. So I probably went a little too big with the jet? This is what happens, I can do a 200ft lap in my yard, I would make about 1 lap but then it would stall out and die. It will start right up and will do maybe a ½ lap then die. Maybe its got something blocking the jet? Maybe its not getting fuel? After it dies I close the pet cock to see if it will still run the same? It doesn't start as well and sometimes it won't go 2 ft and sometimes it will go 100ft. I open the bowl and a good amount of fuel comes out? Ok so I'm going open it up and clean it out. I did see one speck of something. I repeat this procedure several times. I happen to have another identical motor kit, so I put in the stock size jet assuming I will be running like I did before but at least running. It ran a little better but still conks out after I back off the throttle then put it back on. I'm like screw this, I'm putting on the brand new carb and the stock jet! Along with an inline filter. I'm like cool its running great, I'm on my 4th lap and then BLAH! It sputters into a stall. WHY!!! I've tried countless runs each time trying to adjust the low idle jet from 1-4turns each with ¼ turn increments.
Whats the deal here people! I'm usually pretty good at getting small engines to run well, what am I missing? I filled the tank completely full but, but. did notice some of the black paint softening up where there was some overspray on the first ¼" of the inside of the tank. I did not see any debris inside the inline filter and fuel was getting inside the bowl everytime. PLEASE HELP! I really want to ride this bike again.
 
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what engine, what carb?

checked your exhaust valve clearance? ;)
 
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engine

Like I said, I tried running it with every combination from 1-4 turns in 1/4 turn increments. My starting point was 1.75 turns. Well i don't know exactly what kind of engine it is, I'm guessing its a Huasheng? The manual says its a 142F engine. its the same engine that comes on 97% of the 4 stroke kits out there. Some one help me, I wanna ride, I wanna ride, I wanna ride!
 
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Do a serious clean on the carburetor. Check float needle to make sure it is opening & closing correctly. Check float to make sure it doesn't have a leak [replaced one about 3 years ago].

If you opened the main jet too much, you can simply solder it closed and re-drill to a smaller size.

I normally put Gummout carburetor cleaner in about every 4th tank of gas to keep the jets clean, as they are so small and plug up very easily.

Have fun,
 
Clean a new carb?

I tried a brand new carburetor with zero seconds of use on it, so I don't think I would have to clean that too much. The float works as it should since its brand new. The motor runs the same with the "old" carb (if you call under 10 hrs old)
I may have drilled the jet too much but I also tried the stock jet as well.

I used Sea Foam in my fuel, I'm barely on my second tank of gas.

I won't have fun until this runs right :eek:

But thanks anyways for trying to help.
 
Hi Hydroseed,

I know those motor inside and out, and will do my best to help you back to "having fun".


I will share my thoughts on locating the problem, and hope it is helpful. Your problem appearers to be difficult to trouble shoot because the problem appeared after you modified the carburetor. And the mystery continues when the problem remains even after the carburetor was returned to normal and even replaced with another.

Maybe it is related to carburetor problems, and maybe not.
My first guideline for trouble shooting is KISS [keep it simple stupid], and always makes problem solving easier for me.

Here are few things I would consider...................

If both carburetor act the same it is unlikely a carburetor problem [but not impossible].

If the problem appeared after the carburetor was removed and re-installed, might there be a bad seal between the carburetor & motor [gasket, cracked plastic manifold, bolts not torqued, etc].

We have sold hundreds of the HS motors in our kits, and they are amazing and basically trouble free. Our warranties in 3 plus years on the carburetor are limited to one float, and one exchange [only needed cleaned].

New gas tanks should ALWAYS be flushed out prior to use, as the most common problem is caused by the new tank. Often paint chips near the cap will enter the gas and somehow get past the filter [if used], and find its way to the tiny jets. I normally fill the fuel line with cleaner several times if I think the jets are obstructed, and often it solves the problem.

If the motor has been operated in a no or minimum load condition, internal damage may occur. No load would be operating on a stand with wheel off the ground, and minimun load would be shift kits, and "wild" gearing. Look at valve train for bent pushrods, cracked or bent rocker arms, bent valves, and lifter clearance.

Make sure key is intack on flywheel.

Never trust a spark plug on a single cylinder motor. Plugs can fire outside the motor and misfire when installed, and if ever foulded should be replaced. Always suspect the plug, and replacement is the only way to be sure. I can't count the times a spark plug has let me down. I think the replacement for the HS motor is an Autolite 4194.

A few last comments..............
The HS and Honda motors will quickly and smoothly exceed 10,000 RPMs without a load, and is hard to tell it is running so high. Just like any motor, if run past the red line too often or too long it might decide to re-condition certain internal parts. I would strongly suggest you invest in a tachometer when using a shift kit.

Both motors use a fiber camshaft and hasn't been a problem, but if all else fails , it should be checked to make sure it hasn't jumped time.


Hope some of my comments leads to getting you back on the road and "having fun".

Keep us posted, as I am sure you will find the problem.

Have fun,




If the plug has ever been fouled, may spark outside of motor, but not when installed. Never trust a spark plug on a single cylinder motor!!! Sub with new plug.

Make sure plug wire is firmly screwed into the coil [can lose spark if loose].

Almost all carburetor issues
 
THANK YOU! That's how you reply back!

Now that was the great reply I was looking for!:bowdown: Much appreciated, even though it hasn't helped me yet. One important thing I noticed with the new carb or old and with the stock jet or enlarged is that it seems to stall when ever I throw down the hammer. Even if its just a little hammer. So from a stand still, 33% of the time when i give it throttle it bogs down and stalls and 33% of the time it hesitates but then gets power and 34% it will run fine but the whole process starts as soon as I back off throttle and try to go again. Wow that was confusing. AND please, of course I'm trying to dial in the low idle jet (usually between 1.5-2.5 turns) I also unplugged the kill switch harness just in case it was faulting somehow. This is driving me crazy!!!:eek:
 
Those carbs can be finicky.
Did you take the plastic low speed jet out?
It is under and captured by the black idle screw
and it is removed by prying it straight up after
the idle screw is removed.

Be careful as it has a small O ring on it.
Blow those passages out with compressed air.

Just leave the mixture screw at 2 to 2 1/2 turns out.
 
Yea what he said...............maybe an air leak?
 
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