BGF Hongdu/Solex

Was tearing down the project Velosolex motor today and was comparing Hongdu to Solex parts. There are many differences as have been noted in the past. The latest find is the crankcase compression(stuffing) is higher in the Solex. The crankcase end cover on the Hd has more area lowering the ratio. Ordered a bunch of new parts today from Velocruz. Intend to make a composite engine using a Solex cylinder, piston, rings and rod on the Hd lower end assembly, running a Solex original carb. I like the CDI on the Hd and so far the electrics seem fine. I believe this combo will make better power, hope so anyway.
 
Do you know if the Solex crankcase cover will fit the HD?

Is there any possibility that you could determine the volume of each motor's crankcase for us by filling them with liquid and measuring what pours out?

Love to know the cc's of either's cylinder head too.

I may try to stuff my HD cover or crankcase to match the Solex.

Thanks, Wayne
 
Hey Wayne, the covers physically interchange, but the crank pin on the Hd sticks out further and hits the Solex cover. When I get the new parts for the build I will see if the pin can be shortened, appears to have a excess of thread that could be trimmed, but I dont have the rod bushing now to determine that. Also cc ing them is not possible now as the cranks are out of the cases. Its a sure thing the Solex side cover has less volume though. Guess I could measure the volume of the side covers if you want.
 
just seen similar engines on alibaba.com i think it was. look at jiangdu woodpecker gasoline engine factory. Probably the same engine. seems to a lot of them about..shft.
 
Hey, if any of you watch the show " The amazing Race" next sundays episode has the players riding around on some solex powered bikes.
 
well then how many of the specs on the briansolex page are even applicable to these? the compression ratio is definitely different. wayne tested low compression (compared to a velosolex) on his, but that might be within spec on a hongdu...if i ever dig up my compression gauge i will test mine for comparison purposes, but i'd really like to have the hondgu specific data.

and if the ignition goes out on a hongdu what will fit it as a replacement?
 
Im thinking there may be 2 versions. The parts on the Velosolex USA site(aka Steves moped) look like the original Solex design. The parts in our engines look like a detuned version maybe Who knows, Ive yet to get my parts order from Steves, or Velocruz to compare with the Hd. The best way to handle an ignition failure is a replacement for a BnR. Mines got miles and miles on it and its running great. I dont think the electrics are problematic. My light coil is in full time operation with no problem so far. The few China girls I fooled with barfed their ignitions pretty short order. I think we are OK with these.
 
Was just on the Grubee website checking on parts. Entered the 2 stroke section and the Hongdu is listed. Has some great pics of it and an installation. Says not available in the US due to EPA non cert. I guess the BnR/Velosolex is certified?
 
i havent been on in a wile been busy with other stuff

heres my solex copy engine on my 1951 columbia
5667275942_773710c389.jpg


it runs great but no power coming out of lighting coil seeing how rays lights work on his i might just ditch the whole lighting coil and just run the lights off a small 12 volt gel cell
 
Looks great! Has a really vintage look with the blue air filter cover and the white tank and fan cover. I have my light wired direct so it runs constantly. Have had no problems with the system. May be easier to go battery than to get another coil though.
 
the engine/light cover doesnt fit right so im gonna make a new one and put a different light on it

im not gonna ride it at night too much so this little 12 volt 1.5 ah battery should work fine plus the lights will be really bright
 
Nice bike Jay, I am looking forward to building mine.

I hope my coil works, I was planning to add a small red light for a tail light too.

Was there any rust in the gas tank? I have POR-15 on hand - :)
 
OK, I pulled the head off my freshly ringed, weak running motor today to check the squish band of the head.
Specs convert to .059 inches.

My head squish band measured .100". So I chucked it in the lathe and cut off .040"

Great improvement in power, it runs as good as my good engine on the Micargi build. All that 4 cycling gone now.

Check your heads if it runs real weak, or if you have it off for any reason.
 
Mine came today.

Unusual hardware set, doesn't look like anything I've seen here or at Grubee. No hook either. Otherwise it looks pretty good. Except the gas tank which is rusted bad and smells like it still has gas in it from WW II. The paint on the outside was all blistered and I scratched through and sure enough, rust. They just painted over the rust.

Amazing.

I don't think the tank is worth saving, I'll just have to remote it.

The muffler looks like it was made yesterday. I zapped myself touching the plug wire and turning the crank, so that works. The drive roller is not toothed steel, it looks like a grinding wheel.

Yeah, this will be fun.

Oh yeah, nobody has Micargi Osakas in the step through frames either.

The show up on the net and they show up as stock and you order and they e-mail you back as no stock. Fix your websites please.

Idiots.

Any gas tank ideas?
 
The originals are around used if you search. You have nothing to loose with the old one, clean it with acid and slosh it. The Moped Recyclers in Ohio I believe, just got a Solex disassmebled in a box in nice shape. I bought the engine less covers and tank. He will sell the tank. email him @ [email protected].
 
I bought the tank from Kevin. Good guy, he even through in the hook for me. Thanks much, I appreciate it.

It's a plastic genuine Solex tank. Plastic, what a concept, doesn't rust.

Nothing to lose eh? Not even if all that rust plugs up the fuel pump? Like I said it's rusted inside and out. Not just a little rust like the HT tank, but decades of really deep flaky serious rust. So I spend a couple hours with the naval jelly and the gravel only to find it leaks like a sieve? Nah, ain't got time. Not that I wouldn't try to save it if I thought it had a chance...but when I scratched through the paint blisters on the outside and found serious rust, that means there's a good chance that it's rusted through.

Going to put it on my wife's mountain bike. It has a step though frame and it's free.

Need to pick up another 26x2 tire though and I should be good to go.
 
Hey Mike, Is your engine an original Solex or is it the China clone?

You've got a stone fricton wheel and decades old gas residue.
Sounds like maybe it could be an original?
 
I dunno. The motor looks good. Cranks over by hand, not a lot of compression, but the compression release works. The tilt handle went through the box, so maybe my hook is somewhere between here and Canada. The flywheel cover hits the flywheel lightly in 2 spotsthe middle cover says 4800 on it and doesn't fit well. The top cover has "Start" and start in another language with an arrow for the choke lever which is actually an enricher I guess.

Another thing I noticed, I guess these things are wide open throttle default and the "gas" lever slows them down?

I dunno, this is my first "Solex". Bought it because I always thought they were cool.

There was no decal on the tank and the hose they put on for the tank breather is no good. I'll post some pics when I get home today. Was going to last night, but I was too busy going over it and finding out all this stuff.

I still think they are cool. Funky looking, but cool and nostalgic. I do have a proper air filter though with the little backing ring on it. The spark plug also looks decades old.

Maybe I hit the jackpot eh?
 
Jackpot for sure if it's an original, they run a lot better than the clones. Which vendor did you get your kit from?
 
You must log in or register to reply here.
Back
Top