BGF Hongdu/Solex

[HarveyO]

Hi,

First time on this thread. I have found it very useful and encouraging. I am restoring a 1974 Velosolex, using the Hongdu engine. I live in Canada so it is easy to get the engine. Everthing is working fine, but I couldn't believe the original design of the muffler joint. I cut out a chunk of the exhaust pipe and use a length of silicone heater hose. That burned out pretty fast, probably because I removed so much of the exhaust pipe and exposed the hose to the direct exhaust. So I cut out even more of the pipe, attached the exhaust pipe to the front wheel axle and used a flexible stainless steel pipe to replace the section I cut out. Because the flexible section is quite long, it flexes nicely.

 

[cannonball2]

Nice mod with the flex pipe. I am restoring a 73. I have finished the engine, it consists of Hongdu engine cases clutch and electrics with all new Velosolex rod/cylinder/piston/ head and a NOS carb. Mine was originally orange also, but was rattle caned black. Am stripping paint now, what a pain! Maybe one day it will all come together.

 

[HarveyO]

I know what you mean about the paint. We have a U-blast place in town (a dollar a minute) but I wasted money on sandblasting before stripping - the black paint came off like it wasn't there but the yellow paint just stuck like powder coat. I had to go back to paint stripper. Just poured a gallon of stripper in a big container and threw the parts in. Left it over night and steel wooled and pressure washed the next day. THEN sandblasted the rust.

 

[ace158]

HarveyO/RusticoRay, You have a velosolex you have mounted the H-Solex motor on. Did you find any nuances with replacing the original motor with the Hongdu?

 

[muddybike]

Thinking of picking one up went down to toys4boys and took a look at them.
How fast is the tire wear on them , seems every pic I see of them has a fairly chewed tire.

 

[HarveyO]

I am still on my first tank of gas with the Hongdu, but the original Velosolex does not show any unusual tire wear -I would guess that they are the original 1974 tires (a few small cracks in the sidewalls and they are Michelins.) The roller on the original French engine is grittier that the Hongdu, which actually might reduce tire wear if the problem is slippage. If you get to see the engine before you buy it, take a good look at the roller to see if it is continuous - no gaps in the coating, etc. I bought two engines, the first roller was good but I had to repair a gap in the second roller with JB weld. I also added some tiny pieces of ceramic for grit while I was at it (smashed a teacup to bits for my grit). Also make sure you tighten the flywheel nut (not just the outer nut but the main nut under the outer protective disc).

 

[HarveyO]

Ace158,

The Hongdu is an exact fit for the VeloSolex. As I indicated in an earlier post, I was not satisfied with the design of the VeloSolex exhaust system, so I modified that. But that is optional. Also, the engine lifting mechanism is just a simple vertical lever on the Hongdu. The 1974 VeloSolex 4600 uses a more complicated horizontal lever. In some ways, I prefer the vertical lever on the Hongdu because I can easily reach it when riding. However I had to fabricate a catch for this lever. The nice chrome one provided with the kit didn't work for me but I was able to use some of the parts from the kit to make my own. See the picture.

 

[ace158]

It appears in pictures that the casting for where the lever/fulcrum for the 4600 is can still be found on the Hongdu. Am I wrong?

Yay for page 56.

 

[cannonball2]

You are correct, am intending on using that lift on my restoration.

 

[HarveyO]

I agree with Cannonball2. It certainly looks feasible to use the VeloSolex engine lifter, and I believe it would make the lifting easier, but at first glance, it looks like you would have to modify or cut away part of the Hongdu plastic housing for the headlight. Since I only have one original lifter for two bikes, I will try it on the next one.

 

[ace158]

This is encouraging to hear. Now I sit and wait...

 

[muddybike]

Well I went and picked one up from toy4boys, the box was in good shape, and it had the same dense packing material I have seen in other pic's, but must have been a good day for the packing boy, they did i really good job. No bent nothing , except some minor dings in the tank.

Now to find the bike to put it on.

One odd thing it said solex 4800 made in china on the side of the box, when I went down a few days ago to check them out they showed me a solex with a headlight , this one does not have one , is that what makes a 4800 different?

 

[HarveyO]

Muddybike,

The headlight is built into the black plastic engine cover. This cover has "4800" embossed on it (or at least mine does). Assuming you have that part, and it is like both of mine were, you will have to run a wire from the light socket to a ground to make the light work. I attached the wire to the bolt that holds the whole engine cover in place and also protrudes right through the roller housing to act as a sort of scraper for the roller. If you don't have the light, hopefully you can get one from the store (from somebody else's box, probably)

 

[ace158]

Well I got mine today. The box was pristine but it's too bad that the magneto cover was cracked and the tank dented. The flywheel nut was loose and I checked the rings and the gaps actually were spaced 'okay'. Just taking my time with it making sure everything is tight...

 

[ace158]

On another note, the bore is the same diameter as my original.

 

[cannonball2]

The bores on mine were not the same as the original by a small margin. All my engines are buttoned up now so I am pulling this from memory, but as I recall the Hongdu piston/bore is slightly larger? Any way I couldnt use a Hongdu piston in a Solex jug, but the entire assemblies interchange. This is noted further back in the thread somewhere. Check your fuel tanks for rust. I had a beautifully clean one and a rusty one. I etched em both and sealed them. As with all Chinese engine kits its a crap shoot, some good some aint. These are worth making em right though.

 

[Mike B]

Yeah, these were done on a whole different quality level than the happy time engines are.

Maybe that's why they are hard to get?

Just a beautiful nostalgic piece of work from another time when people were not in such a big hurry.

 

[ace158]

Well I have my Solex together, and it runs... but (I know har har) it is low on power... is this common in the break in period?

 

[cannonball2]

They do benefit from running in and generally the power does increase somewhat. If it makes around 20mph on the flats thats about it. As has been addressed in the thread the Hongdu compression seems to have been lowered, by head depth and the crazy stacking of multiple base and head gaskets. WayneZ cut his head down to raise compression and when I got an original head sure enough it was just about the same as Waynes reworked head dimensionally. The originals run only one base and head gasket. My original engine, now a hybrid Hongdu bottom end/Solex top end makes excellent power and climbs average hills well(for what it is). Another charcterisric is they tend to hunt around for a few minutes(requiring playing with the choke usually) 4 stroking and such until they warm up thoroughly. At which point if all is right they settle down to a nice even 2 stroke purr. I found they dont like the oil mix called for by the Chinese. I ran one tank @ 32:1 and went to 50:1 after that. If you run the 16 or 20:1(I forget which is specified) thay arent very happy, smoke a lot and dont make great power. If it runs consistantly, and doesnt have problems, continue on with it until it broken in. Then you will have a base line of performance to compare against if you begin to use some of the mods in the thread. Hang in there with it. There are faster and more powerful MBs, but these thing are just plain unique, and mine never fails to make me smile easing down the road.

 

[Mike B]

Mine didn't need any break in, it was well worn when I got it. Cylinder very smooth with fine verticle scratches, stink of decades old gas in the well rusted tank.

There is no way this motor was new as advertised. Only the controls, the hardware and the muffler were new.

But, I have no complaints other than false advertising. It starts easy, runs great and putt putts down the road w/o complaint. I have never used anything other than 50:1 mix.

I like it for its slowness and smoothness. I have no desire to improve its performance as it runs perfectly right now. I don't think I'll ever buy another, but I'm glad I have this one. Mine had the "high rise" low compression head, but only one head gasket which looked brand new. I think this was a reworked old engine. And it has a grindstone friction wheel as opposed to the toothed steel ones.

Like I said, I don't care, it runs great.

And if it's Chinese and it runs great, that is as good as you can hope for -