Brand new GXH50, bogging problem...

[Max-M]

Update: The bogging problem with my Honda GXH50 engine has resurfaced. I took the long way home from work yesterday (lots of hills, and riding a little faster than usual on the flats). About four miles from home, after the bogging started, I gave the carb nearly full choke, and I was able to ride fairly normally to get home, although with reduced power. It was a rather cool day, with very low humidity. My gas was new.

Since this bogging problem seems to start only after I've been riding for quite a few miles, I can only guess that it's related to overheating. But I've got a fresh crankcase of 10-30 Castrol GTX. The engine doesn't yet have 300 miles on it.

I'm puzzled. Any ideas?

 

[Max-M]

After further research about the possibility of overheating:

I read this in a June 2011 thread on this forum:

Too much oil will cause the oil to foam up because it is being hit by other parts of the rotating assembly. Once it foams up it loses some of its ability to draw heat out of the engine. This is very bad especially on an air cooled engine. You are better off just disconnecting the low oil sensor and just keep a close eye on the oil level. I had this explained to me by a small engine expert. I never would have believed that more oil could be bad but it is very bad for these engines. Go figure...

If having an oil level that's a bit too high is causing my engine's oil to foam, and therefore causing the oil to be less effective, and causing the engine to overheat: could this overheating effect the carburetor's functioning? (As I mentioned before, my engine runs great for many miles on each ride before the bogging problem starts. And since I can limp home if I turn on the choke, I'm assuming that this situation is related to the carb.)

Anyway, I'm going to lower my oil level a bit, and see what happens. Then I'll eventually disconnect my Honda GXH50's low-oil cutoff feature, with Irish John's great instruction sheet as my guide (PDF attached). I don't know if the low-oil cutoff sensor could be related to my bogging situation, but it's really unnecessary for me as I really keep my eye on my oil, and I'd like to eliminate that gadget as a future source of engine trouble.

Again, any thoughts will be greatly appreciated.

 

[darwin]

OP I would clean your idle jet out, if the oil is overfilled best symptom would be your air breather being soaked with oil. Check the oil with the motor level and standing straight up. Thatsdax has a good video on you tube for cleaning the idle jet out.......also next time it bugs out on you try running it with the cap half way on and see if that fixes it, if so cap isn't venting properly.

 

[Max-M]

Thanks, Darwin. I've ruled out the overfilled, foaming oil idea. Loosening the gas cap is also something that I've tried. But cleaning the idle jet on the Honda, I haven't. I've cleaned the idle jet plenty of times on Huashengs, though...nice easy procedure.

Last night, I drained the not-so-new gas out of the bike's tank into my 5-gallon can, and then dumped my bike gas into my car. I then bought a few gallons of fresh gas...at a busy, high-volume gas station on the other side of my town. I'm going to see how the Honda runs with the fresh gas, and then clean the idle jet if the bogging persists.

 

[Max-M]

Well, the fresh 89 octane gas made no difference. And even though the idle is fine, I pulled out the idle jet/slow jet and cleaned it. But I've still got serious bogging, unless I run at nearly full choke. So obviously the engine's not getting enough gas flow, right?

To recap my situation:

- factory-new Honda GXH50 with only 150+/- miles on it
- fresh 89 octane gas
- gas flows freely from tank, through filter, to carb
- new sintered bronze inline fuel filter
- clean idle jet
- engine starts on one pull and idles nicely

But, after letting the engine warm up a bit, twisting the throttle results in complete bogging of the engine. I can ride with decreased power if I give the engine full choke. And sometimes, I can start up the bike and ride for 10 miles before the bogging starts. That's confusing to me; I think the problem has gone away, and then eight miles from home, the bike starts bucking and bogging!

As you can see in the closeup photo of the Honda carb at the beginning of this thread, the adjustment range of the air/fuel screw is only about a quarter of a turn.

When I first installed the engine, it ran just fine. But after putting about 120 miles or so on it, this bogging started.

I'd hate to think that the factory-set valves would be causing this already.

This is really getting annoying!

 

[Quenton Guenther]

Be sure to check the pilot jet as it is the biggest issue with fuel flow. If partially plugged it can respond to heat and cause your problem. The jet is located below the mechanical idle setting screw. Remove idle adjustment screw and lift [gently pry] the jet from the carburetor. It is very difficult to clean and most often cleaner and air don't get the job done. Use a strand from a "frayed" cable to force the obstruction from the jet. Never use a drill bit as it can easily open the jet size too large.

Are you using the Honda or HS carburetor?

Have fun,

 

[Max-M]

Quenton: I'm using the stock Honda carb. I pulled out its pilot jet and cleaned it yesterday.

I noticed that it doesn't look the same as the Huasheng's pilot jet, once you pull it out. On the Honda jet, there's no visible brass at the end of it. On the Huasheng carb's pilot jet, the brass, with the tiny jet-hole, is right at the end of the black plastic part that gets pushed into the opening on the carb. The jet-hole is apparently recessed on the Honda's pilot jet assembly, so I decided to just blow it out with my mouth. It was obvious that I had air flowing through the tiny hole. I'm going to try again with a pair of dental loupes with an LED light attached (a tool of my wife's trade). Hopefully I can see the hole, and get a strand of wire through it.

But the bike ran well today. No bogging on a long ride. But it's been unpredictable when the bogging has come back in the recent past, so I'm just cautiously optimistic.

Until I read your reply to my post, I didn't realize that the pilot/idle/slow jet is the biggest issue with fuel flow. I thought it was just of concern for the carb's idle.

Thanks Quenton, and I'll keep you posted on my progress.

 

[Quenton Guenther]

After reading some of your earlier post on this issue, I noticed you might still be using the oil sensor. If so, I would unplug it, as most of our customers reported intermittent ignition problems with it connected. We were also informed it often triggered when leaning into a corner. As far as I know, neither the Honda or HS motors have any problems with oil usage, therefore the sensor can be safely disconnected. Just check the oil often.

If you don't solve the problem, we will gladly loan you a Honda carburetor to try if needed. Of course you will have to pay all shipping costs concerned.

keep us posted.


Have fun,

 

[Max-M]

Thanks for that Honda carb offer, Quenton. I'll keep that in mind.

I did disconnect the oil sensor a couple of days ago.

This morning, I had a nice, fairly trouble-free ride to work. At one point, after a long nearly full-throttle stretch, I started to slightly feel the bucking/bogging coming on. So I backed off the throttle a bit for 20 seconds or so, and then resumed the WOT activity without trouble. It seemed as if the float bowl was emptying before it could replenish the fuel. My fuel flow from the tank, through the inline filter up to the carb inlet is a good strong gush; no fuel restriction up to the carb. Could it be that I'm emptying out the bowl faster than it can replenish?!

 

[Big Red]

I HATE the carbs on those things. they clog every time ya sneeze, Are ya using an inline filter. ya GOTTA use a fuel filter with those touchy carbs. Give it a real good cleaning Just dont sneeze on it or it'll clog up again. yer high speed jet is clogged.