HELP ! Honda GX35 won't run at full throttle

Porkchop

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My Honda GX35, not quite 2 years old and has less than 10 hours running time on it will not run at full throttle. It starts fine and idles as it should. Will run at idle all day long, but when I give it full throttle, it just dies, just as if I had pressed the kill switch. Plug looks good, air filter is clean. Anyone got any bright ideas or know anything about these engines. I bought this engine new from Tewarehouse. It came with no instructions or owners manual, and I admit I have not researched it on line yet. First thing that went through my mind was high speed adjustment, but there seems to be no adjustment screws on the carb. But as I said, I have not done any research yet. This just happened this afternoon. Any and all help will be greatly appreciated. Thanks !
 
Had that on a 25. Needed a new diaphragm in the carb. Whole new carb was just 10 bucks more, so I went with that.
 
First thing I would think of is the carb, perhaps the jet is blocked or fuel has gummed it up and it is getting to much air versus fuel at WOT?
 
Same problem. I got my motor under warranty and it was in the shop 3 times. One time they replaced CARB then they said they do not know what is causing the problem but they will not fix it because it is not designed for the bike (so I decided not to deal with idiots anymore). Honda service is the worst I could ever imagine. Called supprot guy today and he hang up on me when I told him I'm recording it. Will not buy anything from Hopnda ever again! but in the meantime before I trush my (still on warranty motor) I was wondering if anybody has solved the dying motor issue ?
 
It's the carb if the fuel lines are good to go and the cap is venting properly. New carb is $10 on fleabay. It's the alcohol in the gas that messes them up is my theory.
 
It's the alcohol in the gas that messes them up is my theory.

I agree. Either soak the old one (minus any seals/rubber parts/gaskets) in good carb cleaner and blow out all the passages good, or if buying a new carb cheap on eBay is the path of least resistance, take it. Your engine is almost certainly fine otherwise.

And once you've got it running good, run ethanol free fuel if you can get it. And if you can't, be sure to drain the tank and the carb anytime you let it sit for any time, like over a winter. Old oxygenated fuel will absorb moisture and rot your carb if it sits in there.
 
Here is reply from HONDA I got:



On 6/17/2019 5:59 AM, PE CR wrote:

Here is what was sent to you on June 5th and the 9th


Hello Arthur,
We have inspected the engine for you and we see a few things that are causing the issue, due to the condition of the scoured piston and cyl we do not see a need to actually run the engine.
Due to the metal particles in the engine oil it has been operated at some point low on oil, the extra fuel tank in the video with the modified fuel cap with a hose allows for a longer running time so the oil may not have been checked as often as it should.
1- The compression is low on this engine at 80 psi, the spec is 138 on a new engine.
2- The cyl. and piston are scoured causing the low compression and poor running, a bore scope was used to look into the cyl.
3- We added oil but never started the engine but it is very dark with metal particles mixed in the oil caused by the scoured piston and cyl.
4- The air filter is dry, this air filter should have oil or a product called Motul on the filter.
5- Holes drilled into the air filter cover allowing air to bypass the filter.
6- Non approved application for this engine.
If you would like we can completely disassemble the engine and send you more photos but at that point the engine could not be reassembled.
Please let us know what you would like us to do with the engine.
Thank You
ref:_00Do0JBy0._5001Jk5aso:ref
 
here is one more Email from HONDA

============================================


Hello Arthur,
What we have told you is that this application is not approved by Honda.
What we have explained to you this type of application will always have problems since this engine was not designed to be used on a bicycle.
Just because you can mount an engine on anything does not guarantee it will work properly, if you check with the company that sold you the kit you will find out it is not a approved application because it does not work properly because the application is as bad as it can get.
Once again back in January I offered for you to send in the engine and we would inspect it, you will need to drain all the oil and gas out of the engine and pay for the shipping to us then we will inspect it and return it to you.
Until the engine is inspected nothing can be determined at all, the engine would be returned to you at no charge.
Honda has provided you with good customer service but unfortunately you do not like the answers you receive for the application of this engine.
Your other Honda products worked properly because they were designed to work for the proper application.

Honda Power Equipment
4900 Marconi Dr.
Alpharetta Ga. 30005
Attn CR
ref:_00Do0JBy0._5001Jk5aso:ref
 
I'm skeptical on their diagnosis since the getgo they're gonna deny any claim over it's application that we use them for. But I'd assume it's correct and not rebuild that motor, pucker up and believe what they say. I'd just replace it with a hs 38cc 4 stroke, real honda 35 or a honda 35 clone. Get your old one back for parts if it's free. I'd buy the HS 38cc to replace it if it was my choice. Any time you store a motor for months at a time empty the fuel tank out and run the fuel out of the lines by running the motor till it dies. Suck all that fuel out even just pulling on the rope a few times to use the suction to help. Sounds to me like you need to check and change your oil more often. 1 QT will last you 2 years.
 
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Using in high grass full throttle it pulls oil to the top of the piston and shuts it off, making the first pulls hard to restart. Also oil on the plug keeping the spark low for a few pulls. When I do get running again runs fine just not in high grass. Some how the first generation made do this, they pull oil to top of the piston at full throttle in high grass ??
 
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