Engine bogs under load

[arkives1]

Hi Jim,
Daaahhhh! I'm ashamed to say that I didn't think of that. I'll check that this morning and I sure hope that's the problem.

My friend will do a compression test for me when he gets back in town, he's on an early vacation. I may just get my own kit and get it done.

How could I fail to do a fuel flow check, that would be tooo easy though hahaha
Thanks again Jim. Woody

 

[Bobbyoutback]

Hi Woody ,
I do feel for you on this problem as I coped the same on a resent rebuild from one frame to another .
Tried everything to rid the bog & then found a way to fix the problem !!

I warmed it up and then rode around with different choke levels untill at about 27% on choke it runs great with no more bog
I know I've got a small air leak that I can't find but so what for now .

Good Luck
Bobby.

 

[arkives1]

Hi Bobby,
This morning I went out, and as James suggested, checked the fuel flow from the tank, it was fine but engine still was goofy. I took the newer carb off, put the one I had removed back on the engine, let it run on full choke for awhile then at about a quarter choke, like yours. The darn thing runs fine now, after a half a mile or so of mid speed running I pushed the choke all the way off, it ran like it's supposed to. I have no idea what the problem was.
It's odd that I changed carbs because of the problem, then went back to the original and it ran fine.Possibly I had an air leak and all the switching finally stopped it? Probably the next time I run it I'll have the same problem back again. I swear these engines are just like women, they require constant attention and pampering to keep them happy. Thanks for the help and the sympathy!
Woody

 

[Bobbyoutback]

Pleased you got it going OK at last Woody .

Every china engine I have or helped install has its own personality just like a woman as you said , its almost like the mood of the Chinaman who assembled it was transfered to that individual motor .

I needed to mark the best choke position for reference so as not to stuff around until it got real hot , then almost no choke was OK .

Cheers
Bobby.

 

[arkives1]

engine bogs down under load

That's why we call them china girls I guess. I think we will all agree that the chinese quality control is not the greatest. But at the price of these engines, we can't expect much either. I have one engine that will start easily in cold weather and two more that refuse to go if it's below freezing outside. But then, I refuse to ride below 50 degrees anyway. All three engines from the same vendor, all the same models too. Go figure!
Woody

 

[AussieSteve]

Woody, it looks like it's time to put some thought into better sealing of your carb/inlet joint.
It's well worth the effort of getting an alloy inlet and filing an 'O' ring groove - no more of these problems.

 

[arkives1]

Steve,
I removed the air filter yesterday and ran it for about 5 minutes until it would idle with no choke, then rode it full bore for about a half a block and back. Power was as it should be. Put the air filter back on and restarted the engine and again took the short ride full bore, again power to spare, no bogging at all. Today I'll try it again and if I find it bogs again it will sure indicate an intake leak. Im thinking that once the engine is heated up things expand enough to block the leak then allow it to open again when it cools down.
I don't know if piston rings can be leaking part of the time and work well others due to temperature changes. Heat would cause the piston and rings to expand a bit. I don't know if cylinder walls would expand inward as well as outward with heat.
I'll let you know the results of todays test. Thanks for all the help!
Woody

 

[Vclean]

Thanks