Got bike going, now engine issues - 33cc 2 stroke Keyang KY171

C

cmanns

New Member
Let me start off by saying since I got this motor it was a ***** to get going. Once I did it ran great, eventually noticed the exhaust wasn't too tight and a gasket was completely missing the bottom half thus the exhaust residue on the block.

Now I made my own gaskets and what not, rode it yesterday chain kept throwing so I didn't go far, but enough to let the plug show it's nice color, and get the engine warm. She likes to die occasionally when warm, not sure if it's due to the lines vibrating though I loosened them a little more.

Also yesterday the exhaust came loose, which also caused a difficult start situation. I've checked the exhaust earlier wasn't loose but I'll see once it's cold.

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So today with chain not flinging off, I rode a few miles letting the engine idle and turn it off every 20min or so. Started great, ran pretty good. I played with the A/F screw, during idle turning it 3 or so turns clickwise while ilding and i could hear it bogging and die. Turned it a turn back, rode. would bog under more then half throttle. Now I've turned it counter clockwise all the way till it was nearly going to come out, and it still doesn't run right. This is after playing with plug gap, though I've put it back to where it was before roughly. It's prob about .20, I tried to get it around .25~ manually but when I got it spaced and went to start, was a pain and wouldn't run. Closed the gap alil more and it ran, bad.

Engines a Keyang KY 171 32.9CC

Running Echo 50:1 semi blend premix, 50:1 is for 1 gallon, I put the entire bottle pretty much except the last drops in about .4 or .6gal, I forget. So it's either 25~32:1 roughly. The engine doesn't smoke much.

Also I noticed when it doesn't want to run, jiggling the choke up and down and it spikes back up with the throttle, try to leave choke up too long and it dies. If you do that for a bit and then keep the idle up, and eventually put choke up and go, it'll idle but occasionally dies.

Sorry if thats confusing as ****, I tried to point out the details of how this engine was running and what does what. If it was let me know what needs more explanation.

Also I got it with a ghetto gas tank, bike water bottle. Bottle was like 3/4ths full and 2 miles roughly ate it till empty, maybe it's too rich?


Edit: After chatting I feel the plug may be damaged, but the carb is alil wet, not much though. Also the motor has ran like a rabid ape choke not on, high load. It wasn't till i dicked with it that it messed up. I have seen lil black things in the fuel lines occasionally though, so maybe I need to rebuild the carb and revise my fuel setup.

http://www.ereplacementparts.com/walbro-wyk991-carburetor-parts-c-139716_142763_142479.html

Any idea of other names of the above, maybe a local store might have it. Otherwise I'll have to wait to order online :(
 
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young grease monkey said:
I would try taking the carb apart and cleaning it, maybe there's some junk in the jets and passages.
Click to expand...

If pushing the bulb primer puts air in the return line when I push it hard maybe the gaskets and bulb in the carb are slightly leaking?

There is ALWAYS a bubble in the return line, you can clear them out, start it, poof a bubble.

I rode it today with the A/F screw reset to stock and slowly played with it but not the plug. It seems the engine dying yesterday before I played with the A/F was not the lines shaking and getting bubbles but might be due to warmth.

The warmer the engine is, the quicker it bogs down and dies. When it does bog you gotta flutter the throttle till it idles again. If you turn it off and wait 5-10 minutes, you can jam pretty fast for 5 or so and then it dies again.

What I think it is by playing with the A/F screw is it it becomes lean and rich due to the carb being dirty, so it's hot, and then dumps too much fuel or something.
 
Maybe you have old winter mix gas? It's more volatile so it turns to gas faster at higher temps and could be your problem, but I'm guessing you got new-ish gas. Just take it apart and see if any gaskets are damaged and check for air leaks. You could have an air leak, spray an aerosol on all carb connections with engine running and if rpm changes then there's your problem. Careful not to get it near the air filter as that will give you a false reading. Try wd 40 or starting fluid. Take apart that carb if no air leak.
 
Will carb cleaner show a leak? I rode again today, same path pretty much. I made it there with little issues. I put the A/F to stock as they said. It did die once it got warm, was hard to run it warm, tried to play with A/F settings with no luck.

Plug looked like this http://www.dansmc.com/spark_plugs/24.html

it also seemed the a/f screw was much more then 2 turns back (Stock setting is all the way in, 2 turns back counter clockwise) I had to turn it back maybe 1 turn initially but I went slow.

So after I saw the plug so lean and what not, I thought well, if it looked great before but alil dark from oil, maybe the mixture of oils too high for such a high quality synthetic. My fuel looks black, it's echo 50:1 1gal mix, so now I put it more near 40-45:1 which the company suggests for synthetic blends, 32:1 for crap premix.

I havn't checked plug yet but the engine already ran less far, I also sprayed the carb with carb cleaner and sprayed up into the inlet.

It's fresh gas, 89, and then I added same amount of 91, so prob 90 octane now. There's not much oil smoke now, and it was running pretty good, was getting fast where I don't want to go quicker, though didn't have much acceleration. It's def not running right, the engine has more hp the higher you go, it should atleast go a tiny bit faster. On heavy scooters they said it goes 20-25 and I have it geared alil higher even.

Will it pretty much ruin the existing carb gaskets if I take it apart? I don't know where to get a repair kit local, but I guess thats tomorrows next step.
 
The gaskets are rubber so they will not be damaged. What type of carb is it? Is it a bowl or diaphragm? I would guess bowl if it came from a scooter. Carb cleaner is for the inside of the carb, nothing on the outside would cause performance issues like this. Take it apart and use thin wire to poke any gunk out of the jets, they are brass screws with a hole in the middle that controls how much fuel goes in the engine. Try taking it to Santa cruize scoot works, they build great bikes and will be able to help you.
 
Walbro WYK-99-1 or WYK991

What doesn't make sense to me though is it runs, choke off almsot 30 sec to a min after starting. You go and jam, goes quick. Then poof wants to die. I richened it to keep it alive so much till it was 4 stroking, then backed off just a hair, went to jam, was going great, was doing 50% throttle or so then WOT for awhile. Then pewf nothing for 20 minutes. So all day today it was less then 75F. I can't say for sure if it's overheating or not, I mean it's not too hot to touch with gloves, bare hands 5 mins or so after its flaming hot and you can touch most parts prob runs around 130-200 deg on the block. Well this alst ride when it died, it tinked like a hot car exhaust shields for 2 seconds and was touchable after 5 mins.

I'm def going to pull the carb apart tomorrow. I'd hit up a shop but I'm completely out of cash and keep borrowing to just keep this going. Really wish I got a new motor instead of used, next it'll be the magneto LOL
 
Make sure all the nuts n bolts on the engine are tight. Head or crankcase could be leaking, and then it worsens when the metal heats up and expands. Until you take apart the carb and give me some new info, I have no idea what is wrong. Could be an ignition problem, order one you could use a spare even if it's not the problem this time. Get everything for the ignition if it's not too expensive. Take apart that carb and clean the jets, blast all metal parts with carb cleaner, reassemble and make sure it has a good seal to the manifold. Check for leaks. Can someone else chime in? I'm out of ideas. Good luck cman
 
Is carb cleaner ok to test for manifold leaks

I took the carb apart, looked bad but not bad bad, like maybe sat a yr. Some junk in the screen, the flapping diaphram (Theres like 2) one sealed on the primer bulbs other side seemed alil worn, the other that I could remove was awful. I'll be rebuilding the carb soon.

I tweaked settings more today, also inside the intake manifold looked fine. Has great compression with the intake off even :|

After I redid the carb started after a few pulls, as always I had to turn the high speed mixture to get it to idle/run right.

I did notice though I am setting the main jet screw 1/2 turn too far out I believe.

"There is also a main jet adjustment screw dead center on the top of the carburetor. This is most always set at 1 full turn out. If this is not adjusted correctly, your scooter may not run, or run very poorly. Once again, turn screw all the way in (clockwise) and then out (counter-clockwise) 360 degrees (1 full turn)." regardless the carb works then jitters, then works. So it must be dirty.

Thanks for opinions
 
Got new plug, half rebuilt the carb with new gaskets. Works fantastic.

When I have a compressed air source I'm going to re-go through, and then replace the o-rings, but other then that it seemed to be missing 1 pumper diaphragm gasket, and the main diaphragm seemed to be sort of worn, no holes but it started up even better, and the plug actually has some color to it now!

thanks guys. I'll post again if it poses issues but I really think i twas missing a part, the rebuilt kit covered about 20 different carbs of my type, so it appeares 2 gaskets and 1 pumper diaphragm membrane I didn't need, and there was one nearly identical to the gasket that went on the membrane that I pulled out (Only 2 though) so I assumed the 3rd was the one missing- so I sandwhiched the membrane between the two gaskets which matched both sides.
 
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