BGF Hongdu/Solex

Well, the tank wasn't rusty in mine. It definitely was run. It had light vertical scratch in the cylinder. But it looks in excellent condition. I may be a tad heavy on the oil in the mix. When I say it is low on power it can't propel the bike.
 
Yeah, that is low power.

Mine took off and ran first try. I found that the tires need to be pretty firm though. With 55 PSI it runs great. With 40 psi, it's a slug.
 
Alright, well mine starts pretty decently but I just can't get it to rev out like it should. I drilled the exhaust which did, nothing. Ideas?
 
Alright, I've tried both knock-off and original carb, old and new exhaust, removing the head gasket to bump compression... different spark plug, and there just seems to be no way to liven up the lump. Pretty much a zero on power but its easy to start and it idles very well. Has anyone had timing/CDI issues with these?
 
Well it doesn't ever really "rev out", it just sorta putts along and goes faster slowly.

It takes a long time to get up to speed when it's cold too. I mean it takes like a half mile to accelerate all the way up.

Is your throttle wide open like it should be? That's the default on these motors. Moving the throttle lever closes the throttle.
 
Alright, let me add a tidbit of information. This is WITHOUT asserting a load. The engine is in the fully off the wheel. I realize that the carb is fully open as its natural position.
 
I don't expect it to be fast. I'm not new to the 'speed' of a solex. But I do wish it could actually propel itself. :/
 
ace158 said:
I don't expect it to be fast. I'm not new to the 'speed' of a solex. But I do wish it could actually propel itself. :/
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I bought two of these kits, and they both ran like crap until I soldered and drilled the jets smaller.
And they ran even better after shaving about .040 off the heads. Seems that the hongdu's have much lower compression ratio than the originals.

Also what helped a lot was to do a good crosshatch hone, to make the rings seat easily. The factory finish of the bore has hardly any hone marks at all.

All these mods have been covered way back in this thread.
once you get one to wind up and run smoothly, you'll love it.

Both mine have been happy from the first start running on Pennzoil air cooled oil at 50/1 .
 
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If you feel its a timing issue, you might pull the flywheel to check it. The ignition has fixed timing, but on a long shot I suppose the flywheel could have been installed wrong. It has a cast in key which is fairly small and delicate, and I suppose easily crushed if it misses the keyway. I have always felt the timing was way conservative on these engines hence the lowspeed tractability. I have been meaning to remove a key from an extra flywheel I have and advance the timing some just to see. Also check the compression release for seating/leakage. You can lap it in with valve compound. It appears to be just a screw of some sort, kina crude.
 
Interesting about the jet. I guess mine was good as the plug shows a perfect tan color.

I can see why a too big jet would be lethal though, the pump just fills up the tube, the excess returns to the tank and the gas just runs out the jet.

Yeah, try that first.
 
Further back Wayne gives the correct jet size. Out of three carbs I had three different jets. Mine were not marked, you need to find the size with jet drills first then go from there. Strangely the Solex carb I have likes a bigger jet than the HDs, is possibly a bigger carb throat I have never measured it. If you constanly 4 stroke then the jet is a good place to start. You need to have the bike under operating load though.
 
Here is a link to the vid posted further back. This was after getting the engine to run cleanly. Its all Hongdu at this point. The vid is fairly boring(was holding the camera, so it aint great filiming) just showing the engines running and decent power for what it is. Was bucking a 15mph head wind in the slow direction hauled pretty good downwind. Also shows how one will idle at the very end of the vid. Also there was no pedaling, I made it pull from stop and up the few hills on its own.http://youtu.be/cc5n_FORkAs
 
A few pics of the bike which is now finished to my liking. Not a fan of whitewalls so replaced them, painted the engine covers and fuel tank with gloss black engine enamal, and added a bullet tail light, which is not wired yet. Am waiting on some more vintage style cotton wiring for the job. I think its a nice vintage style build to compliment the Solex type engine.
 

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These two are a matched pair! You were pretty smart getting a pink trimmed bike for the ladies, never occurred to me might entice em to ride. Guess I am a block head like my wife says!
 
cannonball2 said:
These two are a matched pair! You were pretty smart getting a pink trimmed bike for the ladies, never occurred to me might entice em to ride. Guess I am a block head like my wife says!
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Nah, I bought off ebay and the pic was fuzzy and I thought the rims were red like yours.
I'm a kinda big ol burly guy , but I didn't feel out of place cruising around in the french Qtr with it LOL

Ya can't beat these little engines for their smooth, reliable and non stress inducing performance.
 
Yeah I started off with swapping the carb with my original Solex carb thinking that was the best option. The jets are very very close I think... I shall double check.
 
Well I emailed the guy @ toys4boys about the missing headlight , and he said that I could drop by and pick one up.
And I am still up in the air about what type of bike to install this on, trying to keep a eye out for a nice used bike.
 
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