Rebirth of and old 1948 VAP.4

Discussion in 'Photos & Bicycle Builds' started by Poupoudoum, Dec 20, 2012.

  1. Poupoudoum

    Poupoudoum New Member


    I wanted to share my build of a real old school motored bike!

    I'm currently rebuilding an antique VAP.4 from 1948! 64 years old engine, 40 years older than me :eek: !


    This kind of engine was common after WorldWar2 in France, it was the cheapest way to go to work without pedaling or walking.
    VAP was one for the 50+ builders of the time, but one of the biggest, and one of the oldest! The VAP4 started in 1948 (I have the #662) and have been one of the best selling engine. It was used in an improved version in mopeds and the VeloVap concurenced the VeloSolex a short while after.

    But enough history, what about this particular engine!
    It's a 48cc, 2 stroke, 40mm bore / 38mm stroke, 1.2 HP engine, with a manual clutch (made of cork i belive!) and a chain final drive.
    The engine is mounted on the rear wheel with a custom nut, so it hangs on the side of the bike.

    Here is an old ad:

    Mine was missing the tank, the chain and sprocket, the special clutch handle.
    I brought an old bike of the 50's to mount it on, and I had a fantastic new project for the winter!

    For the fuel tank, I found a bike with a "Mosquito" tank (another engine kit from the 50's). To make the sprocket I used an old Crankset, and adapted it on the brake drum.

    Here it is after a bit of work :



    After a complete engine cleanup, a lot of spare parts, and a lot of evening work, it runs and drives!

    It does about 40km/h at full throttle, it has no power at low RPM, a slippy clutch, and a faulty carburetor, but its is great and I'm really happy with it!


    I ordered another carburetor to fix the major issue: it is too lean, and I can't find a bigger jet... So I will change the whole carburetor...
    If it doesn't fix the problem, I will probably build an adjustable jet...

    A bit of explanation on my motivations to build this bike, and the problems I'm facing!

    I've got about 6 other motored bikes at home, all great, but this one will rise above all others: it will be street legal!
    Here in France, despite the great history of mopeds and other motorized bikes as the VeloSolex you might have heard about, there is no way to be street legal on a bike/motorbike/car/whatsoever you build or modify yourself. The law is stupid, and more frustrating, even if you stick to the law, there is now way of being inspected to have papers... So all my bikes are just used on small roads, hopping I will not meet the police, and won't have an accident.

    But the VAP4 was a registered bicycle engine! So I can have papers for it, an insurance, and I will be able to use it to go to work! My dream for years now!
    More important, it is a custom built bike, not a "standard" moped (witch you can't legally modify...) and it will still be legal!

    The problems I'm facing are quite complex!
    First the papers, even if it is legal, archives from 1948 have burnt in the past, and having papers is a bit more complex than my expectations... I'm working hard on this point!

    Second problem, insurance! When I tell them I'm only 24 years old, and I'm riding a 1948 bike, they just don't want to see me... But once I will have papers, it will be easier!

    And third problem: stupid people! I don't know why but here, custom built stuff is not always seen as a good stuff. So I'm facing people telling me I don't understand anything, that putting a new speedo is a nonsense, that drilling a hole in an old bike is a crime, and that I may just go back to chainsaw engines... This is not a big problem in first place, because I just don't listen to stupid people, but if I ever got an accident, I will have to be credible with the policemen and the insurance experts on my 1948 bike...

    I will make a full video in English showing you how this engine is built and how it works and drives!


  2. tom-fishing

    tom-fishing Member

    Nice job on your machine restoration, looks very good. :likelots:
  3. Ludwig II

    Ludwig II Member

    I'm going to have to put my bike through the Single Vehicle Approval test here, but there is a sequence of events that you go through and end up with a legal bike.

    There are Originality Police here for old bikes, but a lot of people ignore them as they want to be able to use them, not fix them.

    Have you thought about a chainsaw carb for the Vap? I have read about the Gurtners from Mobylettes and Raleigh here, and they need replacing with something modern.

    What other bikes do you have, and what engines? Just asking, you know, just asking......
  4. Scootmeister

    Scootmeister Member

    Hi Poupoudoum(French for what?). Good job restoring an old post war horse. I read your account of what you cannot do in France and it should resonate with those of us in the US who value the ability to create/innovate. What kind of mileage do you expect to get with this engine?
  5. Poupoudoum

    Poupoudoum New Member


    Yes I'm French.

    The 1948 advertisement says the mileage is about 1.8L/100km (130MPG) but after 70Km I already consumed 1.5L so I think it will be around 2.2 - 2.5L/100Km (94MPG). I've seen better mileage but for a 64 years old engine, it's not that bad.

    I've just quickly read the Single Vehicle Approval test documentation on the UK government website, it's just wonderful to see that this kind of test exists. I hope your bike will be approved!
    Maybe I can register my bikes in UK, but it may be a bit expensive if I need an address for registration.

    I've found another carb that was noted as compatible with my engine, but it was not that compatible in fact!
    Here is how it ended:
    The engine works way better now.
    I also had clutch slipping issues, I drained the oil from the gears case, and the problem has disappeared, I'm going to change my oil to a less fluid one to solve the problem.

    My other bikes are mainly chainsaw bikes and mini choppers. But as I mentioned, I can't really use them...
    Here are some of them:
    52cc chainsaw, Spindle drive with a belt transfering power from the chainsaw clutch to the spindle. It's very reliable, and I've done about 3000km with it.

    A little moped engine and a bike I use to go downtown (it can be folded in my car's trunk)

    An electric bike powered by a 70Ah 12v car battery and a Citro├źn 2cv starter engine.

    Fully homemade mini chopper, With a 80cc 1962 chainsaw

    Homemade Bobber, 5HP briggs, Springer forks and a lot of little details.

    Here is a little retrospective of what me and my friends did:
    Last edited by a moderator: Dec 18, 2015
  6. Ludwig II

    Ludwig II Member

    Last edited: Dec 25, 2012
  7. Ludwig II

    Ludwig II Member

    You should come over at the start of March for the Swanage Blues Festival. St Malo/Cherbourg to Poole, and then one local bus ride.
  8. Ludwig II

    Ludwig II Member

    While I think, you should be able to find a classic or vintage bike specialist to reline your clutch. There is also the question of what oil you are using if it is a wet clutch. It needs to be a motorcycle oil, as car oils contain additives now that make wet clutches slip.
  9. Poupoudoum

    Poupoudoum New Member

    Yes I am CicloTRON (with a "i", the cyclotron is a particule accelerator ;-) )

    St Malo is about 8 hours of road from Bordeaux ;-) it's a bit far, but if I ever go that north, I'll contact you.

    I think my oil was not adapted, it was 15W40 turbo diesel (I took what I had).
  10. Ludwig II

    Ludwig II Member

    It might be your oil, then, that is the clutch slip problem.

    I looked at routes from you to the south coast of Britain, Bordeaux/Southampton would take forever. You could fly into Bournemouth though, and it would only be 2 local bus rides to the festival town.

    I'll have to see if anybody wants to pay the fare for a slide guitar player in Bordeaux, I can bring back a Vap as luggage :grin5:
  11. Poupoudoum

    Poupoudoum New Member


    I've got my "Grey card" (Title or Registration document in US/UK) for my VAP!
    It's been a bit hard to prove that this bike is legal... but I finally succeded! For the first time im my life, I'm part street legal (I've got no insurance for the moment... It's a bit hard too...)

    I've added new stuff on the bike since my first post:
    2 generators for lights
    A rear light and a registration plate holder.
    The original chain tentioner
    And other little but useful stuff...

    Here are some pictures taken this afternoon:




  12. Ludwig II

    Ludwig II Member

    It's beautiful, tres belle, mine will look like an absolute shed in comparison.
  13. Ludwig II

    Ludwig II Member

    You forgot the number plate!


  14. Poupoudoum

    Poupoudoum New Member

    Hi Ludwig,

    I can see that you're following my blog :)

    The photos I took last wednesday are great, but It really needs a lot of cosmetic work to be truly beautiful.

    Today I reached my speedo top speed in a little downhill (a bridge over the railway, there is no hill here!) 60km/h. It's working better and better each time I use it!
  15. Ludwig II

    Ludwig II Member

    Be careful that that little old heart doesn't die of overwork.
  16. lillback44

    lillback44 Member

    Hi Poupoudoum, I've seen it's been a few years since you posted on this site, but I hope you will see this. I recently picked up a Vap 3 motor on eBay and came across your youtube videos for your Vap 4. I really enjoyed watching your videos and although I speak no French it was clear to me how passionate and excited you were about your bike! I've built 2 Whizzer motorbikes and have a newer reproduction one. The original whizzers are from the same era as the Vap.
    This build is going to be very difficult as I am missing some key drivetrain components. As I'm sure you know the vap3 does not have a clutch, but rather a drive pinion gear and gear type chainring. I'm hoping that someone seeing this may have some info on Vap parts. There is very little on eBay and almost all of that is literature in French.
    Anyone who has any info on parts can IM me on this site. I'm putting a picture that has the main parts I'm looking for. The small drive pinion gear in the bottom middle of the motor and the large ring on the rim.
    I also have a few pics of the motor temporary mounted on a 1950's Schwinn. Once I have the parts I need I can concentrate on getting a vintage European bike to eventually mount this on. Thanks

    Attached Files:

  17. Poupoudoum

    Poupoudoum New Member

    Hi lillback44 !

    Great look this VAP3 on this bike !!!

    I was also missing some of the parts on my VAP4 but as it is a chain drive I was able to adapt a chain a gear.

    Even in france it's really hard to come by parts for a VAP3. I've only seen an incomplete engine one time.
    The guy to contact about these engines is "Guy" : -
    I don't know if he speaks english but I think he might be able to help you.

    see you !
    lillback44 likes this.