BGF Hongdu/Solex

GoldenMotor.com

wayne z

Active Member
Dec 5, 2010
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Yes that little groove at the bottom is what I saw.Do you think a solex coil will work. Gonna bring it up to BGF but I don't expect much help there.

Gonna just check the timing key and run it some more
 

cannonball2

Well-Known Member
Oct 28, 2010
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Colonial Coast USA.
Good luck with BGF! I feel that the current model the Black n Roll is the same engine so the parts should be exact. Major components are $$$ though. I dont know about the original Solex coils, might work and should be easy to find. Go back and look at the clutch pic I posted it clearly shows the coils.
 

wayne z

Active Member
Dec 5, 2010
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OK, I drove ii around for about an hour, and it does run better. It will slowly take off under it's own power now and will hit about 15 mph now on level road, and it will chug it's way up slight hills.

I hope it gets better after a few tankfulls like the chinagirls do.
I like it a lot, so quiet and smooth, and a great old school look
 

wayne z

Active Member
Dec 5, 2010
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Forgot to mention that I drilled the 5.5mm hole in the muffler. There was weld bead restricting the outlet tube of the muffler so I drilled that out too.
I modified the sparkplug by removing enough of the tang to expose about half of the center electrode. You can do this to a Ducati and see the difference on the dyno. Doubt that it helped this thing though.
 

cannonball2

Well-Known Member
Oct 28, 2010
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Great, just needs running in probably. Mine has enough power to climb all but the really steep hill with no assistance. It just loads up and chugs up most about 10-12 mph. Its top speed on the flats right now is 19+. Probably all it will ever do. I read on the Velo USA spec page that it makes a whopping .8hp, but it does it at 2200 rpm, so its a torque motor, not speed. From what I understand it was developed to be limited to 20mph by design, if you got any more you were really lucky!
 

cannonball2

Well-Known Member
Oct 28, 2010
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I noticed an immediate difference in the extended tip plug, from what I read on the Velo "tuning pages"(ha ha), it raises the compression a noticible amount, besides running cleaner.
 

Colony Five

New Member
Feb 14, 2011
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that's good wayne...there's certainly not much power to spare with these, but at least if you do have to pedal up a hill or something it's easy with the motor helping. i am waiting to see how mine handles 30+ lbs of cargo when i take it to get supplies. that is going to be the real test.

I noticed an immediate difference in the extended tip plug, from what I read on the Velo "tuning pages"(ha ha), it raises the compression a noticible amount, besides running cleaner.
yeah, i was reading those pages. it's kind of funny because most of the mods listed all say either not recommended or won't really help on a solex. only a few of them are all that feasible. if someone is looking for speed and power then a solex is not exactly the place to start.

the spark plug recommendation is a hotter projected nose plug and while the hotter plug should foul less, it says a colder plug is better for long high rpm trips and heavy loads...which is exactly how i intend to use mine. riding long stretches of road at WOT with few stops and lots of cargo. perhaps instead i will try a colder projected nose plug, or one in the same heat range as stock.
 

wayne z

Active Member
Dec 5, 2010
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So, where can I find those "Velo tuning pages" I found some u-tube clips of Velo demonstrations and races, and they ran WAY better than mine.

Still haven't ruled out that mine may have some issue that is keeping it from what is normal performance for these engines.

One guy demonstrated start and take-off with helmet cam . He started and was wound out to about 3- 4000 rpm in about 100 feet. Mine won't make that rpm even with the motor lifted.

If mine doesn't gain some power after some more runnung, I'm gonna be experimenting with performance mods.
 

cannonball2

Well-Known Member
Oct 28, 2010
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Hey Wayne, the mods are funny in that most listed are not really recommended, go figure. I still havent got a handle on linking sites, but this will get you there Goggle Velosolex S3800 Carburator click on the link that has BrianSolex as the address, that gets you to the carb mod page, you can navigate to all the mods form there, great reading. Still before I built a full house race engine(LOL) I would see whats up stock wise with yours. Seems the rest are running pretty well, there must be a hidden issue you havent found yet. One thing for sure 2 strokes respond well to an increase in timing. The stock setting is supposed to be around 23degrees I think a bump to 26-28 would wake it up(the engines in general). Would require shaving the key out of the flywheel, lapping the flywheel a bit then determining the timing, probably no more that a key width. Have to get out the degree wheel. I may do this to #2. The original Solex flywheel was keyless I believe and the timing was set with it(as well as point gap). Probably need some input from people famailar with the older Solex.
 

cannonball2

Well-Known Member
Oct 28, 2010
3,682
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Colonial Coast USA.
I read somewhere that the porting on the Hongdu might be different. Still mine basically runs 20mph and will pull away from idle unassisted on the flat. Supposedly the basket case Solex I bought to restore(havent got it yet) has a parts engine with cyl, piston, head, that I will compare. But I still think youve got a hidden problem holding you back.
 

deacon

minor bike philosopher
Jan 15, 2008
8,114
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north carolina
I was at the thrift store today looking for a cruiser for my new motor on the way. I didn't see anything I wanted but they did have a trike there. It was in nice shape and only $30 bucks. I have no room in the shop for one now, I have an ebike and trailer the bumblebee bike and a another motor on the way. I was wondering how this engine you guys are playing with would work on the heavier trike. It's one of those Schwinn things I think
 

camlifter

Active Member
May 4, 2009
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acme labs marion ohio
got the motor mocked up, didn't use the clamps from the kit, my fork is the 40's solid steal flat one so i drilled and taped it and mounted right to that.
check your gas tanks as mine is full of rusty scale.
 

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cannonball2

Well-Known Member
Oct 28, 2010
3,682
223
63
Colonial Coast USA.
I was at the thrift store today looking for a cruiser for my new motor on the way. I didn't see anything I wanted but they did have a trike there. It was in nice shape and only $30 bucks. I have no room in the shop for one now, I have an ebike and trailer the bumblebee bike and a another motor on the way. I was wondering how this engine you guys are playing with would work on the heavier trike. It's one of those Schwinn things I think
Probably be underpowered especially considering the hills you encounter.
 

Colony Five

New Member
Feb 14, 2011
63
0
0
Southwest
I was at the thrift store today looking for a cruiser for my new motor on the way. I didn't see anything I wanted but they did have a trike there. It was in nice shape and only $30 bucks. I have no room in the shop for one now, I have an ebike and trailer the bumblebee bike and a another motor on the way. I was wondering how this engine you guys are playing with would work on the heavier trike. It's one of those Schwinn things I think
it should work...they had the solex triporteur. that's what i like about these. you can put one on darn near anything. one of these days i want to have a longtail bike powered with one.
 

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