BGF Hongdu/Solex

After 3 years of being dead reliable mine suddenly wouldn't run right. I thought it would be something simple that I could fix. Well, I couldn't, and then I couldn't keep it running. I don't think I have given up on it quite yet but I am frustrated with it and as of right now it refuses to start even though it has fuel, spark and compression.

I noticed these kits are no longer so easy to come by as they were a few years ago which is rather unfortunate.
 
cannonball2 said:
Finished the build on the H-Solex. Was a perfect match for the Macargi 24. Once I tweeked the hardware a bit it was a 30min. bolt on. Its a really cool bike, very smooth and runs great. Its a leisurely ride, top speed around 20. It is also very quiet. I really like it. I have three other bikes with top speeds from 30- 50mph, so figured this one rounds out the collection. This little thing is just plain fun to ease around on!
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I am going with your idea where do I get these clamps from.... That's clean without junk piled on, how fast can my 25cc take me at stock build? Bolens Bl110, btw my wife may still be getting me a moped so moped to work and show bike for around the town.
 
I realize this thread is dead but it's the only one I've ever posted in and I wanted to give an update that anyone with one of these should find interesting. As per my last post my engine had not been running. Whenever I had time and inclination I'd attempt to fix it but was never successful. The last thing I suspected was a bad base gasket since I could see bubbles coming from there when trying to start it. But the nuts were tight and the gasket looked OK after pulling the barrel. So the engine sat for awhile.

Then I picked up a bike I really wanted to use it on, so I was inspired to put it all back together and try again to get it running. After getting it buttoned up (and using new base and head gaskets just for good measure) I turned it over by hand, it all looked good so I attempted to bench start it with a drill. After turning over several dozen times (and still not starting) the engine seized. I knew I'd have to tear it back down to figure out what happened. The pictures show my reward.

I'm at a real loss. When I worked on the top end everything still looked new. I know there was nothing in the crankcase to cause the washer to break like it did. Is the metal on these so subpar it would just come off like that? Maybe it got brittle from running hot?

I'm not sure it is worth trying to fix at this point. I'd have to figure out how to dislodge the part of the washer stuck between the crank and the case, and the side cover has a couple nice gouges. Not to mention I still don't know why it won't start.

I'm interested in hearing from anyone who has one of these and whether or not they are still running. I want to power the bike I got but I'm evaluating my other options now.
 

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It banged it up pretty well but it still looks like it could be saved with judicious use of a good sealer/gasket maker.

Since it ran for 3yrs you might have a worn crank seal. If it is leaking the cylinder wont charge as the mixture escapes at the seal. A quick check for crankcase loss is a squirt of fuel in to the carb. If it doesn't run then. Shoot a squirt into the cylinder directly(spark plug) if it runs then its more than likely a leak in the case area( gaskets or seals). This is assuming compression and properly timed spark.

The Solex parts interchange for the most part if not individually in assemblies. I rebuilt the engine for my 1974 Velosolex project using NOS Hungarian parts. The removed used stuff was still pretty good so I built an engine using a Hongdu bottom end with the rest Solex. Was a good runner.

I think I still have a box of engine parts. Let me know if you need something and I will dig through the attic.
 
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Colony Five said:
I realize this thread is dead but it's the only one I've ever posted in and I wanted to give an update that anyone with one of these should find interesting. As per my last post my engine had not been running. Whenever I had time and inclination I'd attempt to fix it but was never successful. The last thing I suspected was a bad base gasket since I could see bubbles coming from there when trying to start it. But the nuts were tight and the gasket looked OK after pulling the barrel. So the engine sat for awhile.

Then I picked up a bike I really wanted to use it on, so I was inspired to put it all back together and try again to get it running. After getting it buttoned up (and using new base and head gaskets just for good measure) I turned it over by hand, it all looked good so I attempted to bench start it with a drill. After turning over several dozen times (and still not starting) the engine seized. I knew I'd have to tear it back down to figure out what happened. The pictures show my reward.

I'm at a real loss. When I worked on the top end everything still looked new. I know there was nothing in the crankcase to cause the washer to break like it did. Is the metal on these so subpar it would just come off like that? Maybe it got brittle from running hot?

I'm not sure it is worth trying to fix at this point. I'd have to figure out how to dislodge the part of the washer stuck between the crank and the case, and the side cover has a couple nice gouges. Not to mention I still don't know why it won't start.

I'm interested in hearing from anyone who has one of these and whether or not they are still running. I want to power the bike I got but I'm evaluating my other options now.
Click to expand...


Need new base gasket and head gasket never exeed 9ft lbs of torque, on head/base gaskets use a gasket sealer that comes in a small packet at autozone for water pumps for the base only. Also never drill start and make sure you lube the piston, ring, and wrist pin + needle bearing with some 2 stroke oil don't use premixed gas as it may be too thin for break in.
 
cannonball2 said:
It banged it up pretty well but it still looks like it could be saved with judicious use of a good sealer/gasket maker.

Since it ran for 3yrs you might have a worn crank seal. If it is leaking the cylinder wont charge as the mixture escapes at the seal. A quick check for crankcase loss is a squirt of fuel in to the carb. If it doesn't run then. Shoot a squirt into the cylinder directly(spark plug) if it runs then its more than likely a leak in the case area( gaskets or seals). This is assuming compression and properly timed spark.

The Solex parts interchange for the most part if not individually in assemblies. I rebuilt the engine for my 1974 Velosolex project using NOS Hungarian parts. The removed used stuff was still pretty good so I built an engine using a Hongdu bottom end with the rest Solex. Was a good runner.

I think I still have a box of engine parts. Let me know if you need something and I will dig through the attic.
Click to expand...

Thanks Cannonball. This is one of those times when I'm going to have to think about what to do next for awhile. I'm not even sure I can free the crank. Maybe if I dismantle the rest of the engine, but I need to get the flywheel puller first for that.

As for troubleshooting the non running condition, I never got a chance to try anything before it seized, but before taking down the top end I did try fuel into the carb and plug hole with no joy. I was thinking maybe the compression was just low enough not to start and the new gaskets would help but it didn't seem like it was going to fire.

You mentioned properly timed spark...ours have a cdi don't they? All the literature I have on Solex engine is for points ignitions. I thought I had read somewhere that as long as the flywheel was on correctly the timing would be right for a cdi. If I'm wrong about that, maybe that is my problem.
 
cannonball2 said:
It banged it up pretty well but it still looks like it could be saved with judicious use of a good sealer/gasket maker.

Since it ran for 3yrs you might have a worn crank seal. If it is leaking the cylinder wont charge as the mixture escapes at the seal. A quick check for crankcase loss is a squirt of fuel in to the carb. If it doesn't run then. Shoot a squirt into the cylinder directly(spark plug) if it runs then its more than likely a leak in the case area( gaskets or seals). This is assuming compression and properly timed spark.

The Solex parts interchange for the most part if not individually in assemblies. I rebuilt the engine for my 1974 Velosolex project using NOS Hungarian parts. The removed used stuff was still pretty good so I built an engine using a Hongdu bottom end with the rest Solex. Was a good runner.

I think I still have a box of engine parts. Let me know if you need something and I will dig through the attic.
Click to expand...



Cough* not my knowledge "tip toes away slowly."

I'm more along the lines of lawnmower, go kart, moped, and scooter engines most of my skills formed off the back line of auto mechanics although they shouldn't be mixed in any shape form or fashion.
 
Colony Five said:
Thanks Cannonball. This is one of those times when I'm going to have to think about what to do next for awhile. I'm not even sure I can free the crank. Maybe if I dismantle the rest of the engine, but I need to get the flywheel puller first for that.

As for troubleshooting the non running condition, I never got a chance to try anything before it seized, but before taking down the top end I did try fuel into the carb and plug hole with no joy. I was thinking maybe the compression was just low enough not to start and the new gaskets would help but it didn't seem like it was going to fire.

You mentioned properly timed spark...ours have a cdi don't they? All the literature I have on Solex engine is for points ignitions. I thought I had read somewhere that as long as the flywheel was on correctly the timing would be right for a cdi. If I'm wrong about that, maybe that is my problem.
Click to expand...


If she's still sized squirt some pb blaster in her and work it back and forth gently til it frees up if your lucky and rings where installed correct when you look inside your exhaust port your rings won't be sitting on top of your piston which means you didn't jump the ring lands. Once you see those rings above the piston kiss the sleeve goodbye.v.duh.
Jumping ring lands is caused by improper gap as well for run on while the engines off accompanied by excessive un combustible splooge.
 
TheSignGuy said:
If she's still sized squirt some pb blaster in her and work it back and forth gently til it frees up if your lucky and rings where installed correct when you look inside your exhaust port your rings won't be sitting on top of your piston which means you didn't jump the ring lands. Once you see those rings above the piston kiss the sleeve goodbye.v.duh.
Jumping ring lands is caused by improper gap as well for run on while the engines off accompanied by excessive un combustible splooge.
Click to expand...

The top end is fine. And I set the ring gap myself when I put it back on so I know that was right. It isn't seized due to a running condition, it is because the edge of the con rod washer simply chipped off for no apparent reason while attempting to start it. I imagine the same thing would have happened just turning it by hand, though I probably could have kept it from getting up under the crank. I know if I get too brutal with it more stuff is going to break. The metal on these clones is flimsy. Can't speak for a genuine Solex since I've never had one but I'd hope it would be better! The aluminum parts on mine are the worst-i can never get the air filter cover off the housing without having more of it chip off. Even the top of the carb that goes into the air filter housing has a big chip in it, not sure when that happened. It just seems to crumble away with time.
 
Yep the castings are lacking on some of the clones. Others are pretty decent. I believe these were made by many different "factories"(some I have seen online look like backyards).
The clone is CDI. If the key/key way is ok timing considered timed. I have in the past seen bad ignition modules that made spark but at the wrong time even when the flywheel was correctly timed.

If you want to get up and running search used Velosolex engines. They were plentiful a few years back. The external clone parts(gas tank, shrouds etc fit). If you get a decent engine(most were stripped long blocks) its just a matter of swapping the clone stuff over. The plastic parts and the gas tanks were worth more than the engines so most were stripped. The three I bought were salvagable from neglect from sitting. These things run forever with care.
 
These things have probably been 'refurbished' using parts leftover from French
IndoChina in the early '50s. You can still buy a real solex engine, but they ain't
Cheap. Have to do a search for 'em, I've forgotten the actual site, think it
might be in Belgium.
 
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