Honda GX35 Bogging

[sailorhuete]

The fuel filter is brand new and so is the gas. It was replaced at 200 hours. I think that the valve is sticking. The exhaust port is normal looking with no heavy deposits or carbon clumps. The engine has been mounted with the carb at the rear and the exhaust at the front with the cylinder vertical. The air cleaner is brand new. No oil in it. The filter when saturated with oil from the breather could have decreased the air and fuel flow and increased the oil uptake from the valve cover. The old plug looked fouled. I think that a detonation could have been occurring due to pre ignition, rather than knocking, and because of all of the extra oil instead of the plug looking lean it became deposited and dirty. The portion of the exhaust valve that can be seen with the muffler removed looks ashy and marbled like it was very hot but not glazed, melted hot.

What happens when valves stick? line item # 3
http://www.avweb.com/news/maint/182894-1.html

 

[Otero]

Hmmm? Worn timing belt or cam pulley? sticky valves seem
unlikely to me. If you got 200 hrs. valve clearance could be
an issue. Cold intake should be .08 mm, exhaust .11mm.
You might want to take it to a dealer. The GX35 doesn't
like being run over 7000 rpm for extended periods. Did you
cook it?

P.S. With that many hours it might also need a carb kit,
which is a hassle to install & ya gotta know what your
doing. 2LCSTORE.COM has an O.E.M. Gx35 carb for $29.50
That's the cheapest I seen so far other that Chinese
knockoffs on Ebay. For god's sake don't buy one of them.

 

[sailorhuete]

Thanks for the web reference for a new carb. I was thinking new and bigger jets for the carb i have. I run the engine over 7000rpms every time i ride it because it keeps pulling on the top end and i am going under 30 mph. I have quite frequently had the engine well over 10,000. The intake valve looks brand new and so does the hone on the cylinder. The 35cc will stay around its stock red line with the spark arrester installed. I took it out first thing though. My dealer replaced the belt under warranty at 150 hours. The valves are dealer adjusted to stock. My muffler has vibrated so much you can see daylight from inlet to outlet though it from the baffle breaking into chunks. Every so often I take the can off and shake out all the loose pieces. I think the exhaust is opened up a bit and i need to richen the main. I plan to mount the engine with the exhaust facing downward to make it more difficult for oil to make its way out of the valve cover breather and to keep oil from building up on the air cleaner. This mounting position will keep more oil on the exhaust valve inside the valve cover for cooling and keep the exhaust heat away from the intake and the rest of the engine better. I can also mount a straight pipe that way too. Has anyone mounted a pipe and changed jetting?

 

[Otero]

I can see how the exhaust could be a problem. I know
2 strokes need a certain amount of back pressure. I
wouldn't be surprised if that also applied to a 4. Sounds
like you've just run the daylights outa that little gx35. I stand
in awe that still runs at all. Damn tuff lil' engine, huh. I pretty
much like mine stock. Honda's been building engines a long
time and spent a lot on R&D. I'm inclined to think their engineers
Know what they;re doing. That said, Walbro makes 5 different
carbs for the gx35 depending I guess on what they're used for.
What' best on a bike? Your guess is as good as mine.

 

[csm]

Thank for the tip. Tried running with the fuel cap off and it didn't seem to matter as well as no air filter. So your suggestion is to drive the bike slower? Each thing I mentioned that I tried was completely independent of one another. Try something go for a ride. Didn't work return to stock, try something else, no better...etc etc.

This thing is on the clock. If it doesn't shape up its gonna find itself at the bottom of my recycle bin and be replaced with a Tanaka 40

Did you ever find out what was causing the problem with bogging ? I have same problem, have tried every thing suggested plus , new carb, new coil , replaced fuel lines , fuel filter, still poor performance at 3/4 to WOT . My engine is a Gcast -S3 model (Gx35). My friend has same engine model and bogging proublem was both purchased at same time ,my proublem start after 10 to 12 hours operating and his started after about 60 hours of operation . Any suggestions ?

 

[Otero]

In my case the GX stopped drawing fuel altogether. I guess I botched the carb
rebuild cuz still nothing. the GX is now sitting in a box. I've been running a
Tanaka pf 4000 for nearly 3 years without a problem. I haven't even changed
the plug. If you got your GX from 'small engines warehouse', there's a chance it might
not have been exactly new. I think the problem in your case may be belt wear.
Ive flat given up on 4 cycles & Chinese kits. A quality 2 cycle has fewer parts
to go wrong. Wish I'd figured that about 4 engines ago.

 

[Greg58]

In my case the GX stopped drawing fuel altogether. I guess I botched the carb
rebuild cuz still nothing. the GX is now sitting in a box. I've been running a
Tanaka pf 4000 for nearly 3 years without a problem. I haven't even changed
the plug. If you got your GX from 'small engines warehouse', there's a chance it might
not have been exactly new. I think the problem in your case may be belt wear.
Ive flat given up on 4 cycles & Chinese kits. A quality 2 cycle has fewer parts
to go wrong. Wish I'd figured that about 4 engines ago.

http://pre15.deviantart.net/e0eb/th/pre/i/2006/152/c/b/i__m_a_slow_learner_by_silentnight745.jpg

 

[csm]

Thanks for reply , belts is almost new and can't feel or hear anything that sounds like or see that would indicate belt problem, if I knew what indications a " slipping belt" would produce would help. I was looking at the fuel filter , can't see how very much fuel volume could get thou it . I drilled out the metal part of it and took out the rubber O ring and a tinny round plastic disk that was in the metal filter housing . will try it out this week end and let you know if interested . Both engines purchased with GEBE kit .

 

[Otero]

well. the only other thing I can think of is that before the GX went south
it bogged at throttle until I enlarged the air vent hole?