help needed: someone to please tune my motor

[rstiemert]

Hello everyone, I'm right next to Aurora, illinois and have a HuaSheng 142f four stroke, that has about 12 hours on it, that's giving me hell. I was wondering if anyone is on here close to me on here, or anyone has a recommendation of where I can find someone to tune my bike properly, or if I can send my motor to someone at my rough altitude tune.

The carb (stock on 142f) is in desperate need of being tuned properly and most likely, something else. I just put a bunch of new parts on it. After watching countless videos, reading lots of articles/posts, and then monkeying with it for countless hours, I still can't get it going right. although, I've never been able to tune a carb or motor before. I'm about ready to pull what's left of my hair out.

I'm getting major hip surgery done next month, so it's not the easiest to get around, or do much of anything. Let alone do something that I've never done before.

Can anyone please help me? I'd gladly pay someone whatever you think is fair as I'm trying my best to avoid buying an entire new motor, tranny, and everything else I'd need for the 79cc predator upgrade.

 

[darwin]

What new parts are added? Is this an in frame mount or rear mount? Trying to see what fuel system/tank type feed your using. Does it start then die, runs but sputters, idles but sputters when idle increases, won't run at all/start? Let us know some details to narrow it down.

 

[rstiemert]

Thank you so much for the reply!

I added a straight pipe, an air filter from sick bike parts that has the crankcase vent tube going to the air filter, just like the stock one has, a new clutch with new springs, a hub adapter with a 44 tooth sprocket, I got a genuine dellorto SHA 15.15 carburetor, a NT carburetor with a velocity stack, and a new stock carburetor, with the stock #70 jet (I'm pretty sure that's the stock size that comes with it). I also had a valve lash done to Hondas specifications, as well as fit multiple different spark plugs. To which, I have NGK's iridium CR5HIX in it right now.

I just got it back from a guy that I hired to fix/tune everything, whom put the new stock carburetor on after he couldn't get it running at all with the NT, even with the multiple jets I got. He promised he could get it running perfectly, but it's definitely not. It cuts out at WOT. Which, is the exact opposite of what happened prior to me bringing my bike to him, as it would only run at wide open throttle.

I'm not exactly sure what's going on, or how to properly dial this thing in, and it's driving me insane.

 

[HeadSmess]

my experience of the 142 f was that...if you even contemplate removing that little plastic cap come idle jet...buy a new carb and leave it alone.
the o-rings shred out when you remove it then block all the little orifices up. end result.

i even made an adaptor and stuck a known good mikuni carb on there...and it still spluttered! never got it to run right...until i bought a new carb.

theres no way to rejet the carb. fixed. untuneable.

it was either the new carb or being left outside in the rain for 6 months that scared it into behaving itself. still not exactly sure.

and do NOT run them on premium! thats what killed mine in the end.
hi octane fuel leaving carbon deposits in the cylinder, enough to stop the exhaust valve opening, and from there...impossible to regrind the valve seats.

just run the cheap nasty stuff .

but...did you consider checking the coil mounting and gap between the flywheel? doesnt matter what carb or fancy plug you throw at it. if the gaps too big it ill never run properly.

the huasheng is cheap enough to just get a collection of them going. not worth fixing or contemplating "tuning".

changing an air filter is not tuning. but, you paid for it, so i guess it must be.

 

[rstiemert]

Hmm. This is the 2nd new stock carb I've put on it. This is brand new and I'm having these problems. I ran premium in it for a couple tanks but not enough to run everything as everything was fine internally. There's 3 screws on the stock carb for adjusting. Most of the times, drilling out the brass plug they put in is necessary though. I've read about a ton of people doing that and after they adjusted it, it fixed their problems, but its early hard on my body (nearly impossible right now) to monkey with anything like that.

I'm really bummed man. This thing ran fine for a long time but jpie it doesn't. I might just go pick up a Honda gx100 and throw that on there. I want something bulletproof that I'm not going to have these problems that comes with buying cheap china junk. The only problem is that I have no clue who makes a good clutch or a transmission for those. Do you? Here's a few pictures I took today of her and a video if it'll let me load it.

 

[rstiemert]

Nope, the videos are way too big.

 

[rstiemert]

This way is better lol

 

[rstiemert]

my experience of the 142 f was that...if you even contemplate removing that little plastic cap come idle jet...buy a new carb and leave it alone.
the o-rings shred out when you remove it then block all the little orifices up. end result.

i even made an adaptor and stuck a known good mikuni carb on there...and it still spluttered! never got it to run right...until i bought a new carb.

theres no way to rejet the carb. fixed. untuneable.

it was either the new carb or being left outside in the rain for 6 months that scared it into behaving itself. still not exactly sure.

and do NOT run them on premium! thats what killed mine in the end.
hi octane fuel leaving carbon deposits in the cylinder, enough to stop the exhaust valve opening, and from there...impossible to regrind the valve seats.

just run the cheap nasty stuff .

but...did you consider checking the coil mounting and gap between the flywheel? doesnt matter what carb or fancy plug you throw at it. if the gaps too big it ill never run properly.

the huasheng is cheap enough to just get a collection of them going. not worth fixing or contemplating "tuning".

changing an air filter is not tuning. but, you paid for it, so i guess it must be.

I'm not exactly sure what coil and gap you're talking about. Could you perhaps send me a picture showing it? I'll definitely check that out.

 

[HeadSmess]

take off the cowling. get to the flywheel. the ignition coil is bolted to the sideof the cylinder. you want a sheet of paper between the coil and magnets on the flywheel. even less if possible. more is bad. undo the screws, let it sit where it wants (on a strip of paper) then retighten the screws.

yeah, i never figured out why mine spluttered and coughed. it was weird that a perfectly fine pitbike carb did it as well. only went away after leaving the thing to rot in the rain and sticking a new carb on. i may have changed the coil at the same time. cant recall. cloudy memories...

yet i have one that came from a cheap inverter generator that will fire up and run perfectly whenever i get in the mood to start it. but its a weird variant of the 142f. most of the time they are fine... the odd one just has issues. no idea why.

its probably possible to re-grind the valves if they havent had the carbon build up that i got. they just arent easy to get to, being all the way down in that cylinder. too small to take suction caps on them (twiddle sticks....) but on other engines ive had some luck with some rubber tubing rammed over the valve stem and a drill in a hand drill, just (extremely!) fiddly. pretty easy engines to tear apart as long as you can get the flywheel off. make sure you keep the conrod bearing cap around the right way if you are tempted to dig into one that far. ie, put the bolts back in as soon as you get it off the crankpin.

the screws should only be the idle air screw, under the brass cap, and the idle speed. i havent seen any of the carbs with an adjustable main jet yet.

i was pretty bummed when the original carb decided to pack it in.... i had a 20km ride home with an engine that wouldnt let me use more than 1/4 throttle, even with the choke held half on.

 

[rstiemert]

Ok. I'll give that a look. the kid I took it to, to get fixed, messed it up even more. Now it's way worse off. I'm strongly thinking of just getting a Honda gxh50 and putting it in there. I should be able to use everything I already have on there already. Which is all in great shape. I'm tired of messing with this thing. Do you have any experience with the gxh50? Would it work for the swap?