Aside from political & trade issues (which I agree are downsides too) I'd advise steer well clear of the cheap Chinese too.
A while ago at work at about the same time we got two 125cc road bikes in that young lads had come off & done a bit of damage, one was a 4 year old Yamaha & he'd bust the fuel tank, rad & a few odds & sods. The other was a Chinese thing & he'd bust the front wheel. Within a few days Yamaha boy was back on the road with bits from a breakers while the Chinese bike gathered dust for 6 months while a new wheel was sought in various ways. It left without being repaired & I dont know if he ever got it fixed!

I'd also think you want a bit bigger engine, a 125 bike is lively because the heaviest thing is the rider but the trike frame work, extra wheel, brake, steering gear etc will make it go like a 125 with a fat passenger!
What will a sub 600cc salvage bike cost? Too small an engine for many folk which would make it worth less but a lot more go than a 125!

Anyway, good luck with your project & welcome!

Some pictures of the chinq/seicento steering rack in use.
http://www.locostbuilders.co.uk/viewthread.php?tid=90143

Hi and welcome to the nuthouse.
Have a look in my photo archive, you are discribing my build apart from the chinese scoot, I have used a Piaggio 500 cc scooter, cortina uprights, and intend using all the electrics , fuel tank etc.
The car is on it's wheels now and I am just making plans for bodywork.
The idea is to make the frontal area as low ans small as possible.
Good luck with your build and keep us informed.
Regards Denis.

Hi there,

What are your requirements of the vehicle?

If you go down the suggested route then you might expect decent economy but actually these bikes are not that economical (the 125's from the major manufacturers are little better than the larger [non sports] bikes). (say GSF600).

The power from these engines is in the 10-20bhp range. (GSF600 78bhp)

You will do well to better 250kg weight, plus any riders. (300kg with the GSF600)

So performance will be sluggish (power to weight at maybe 60bhp per tonne, >200bhp/tonne with gsf600), and economy not that great (maybe 40mph in each case, with top speed limited to maybe 70mph depending on gradient with the 125cc).


But you will have built it yourself to your own design, and that is something to be very proud (and to my mind damned cool). Building something big is a great thing to do, but it is a long journey. Make sure of your destination before you start spending.


Matt

p.s. damaged repairable gsf600 2005 model on a £1600 BIN

I'll echo that a 125cc engine is a bit small. 12 BHP is barely enough for a scooter. 250cc was as small as I'd go. 22 BHP is OK in a light weight trike that I hope to keep to 220kg. Do what makes you happy though, that's the whole point.

What are my requirements? It's a city vehicle really. It needs to be:
Cheap to build
Cheap and easy to repair
Cheap to run (fuel and VED)
Cheap and easy to maintain
Capable of easily maintaining 40mph (top speed of 50+mph
Able to carry a few bags of shopping
Easy to park in small spaces

I wasn't expecting it to be much heavier than a scooter, but the front end would add a bit and increase the rolling resistance too. I may go for motorcycle tyres on the front like the MEV one in the picture to help reduce the rolling resistance.

One of my concerns with the electric one was that there were some expensive parts eg. batteries and motor. With a Chinese scooter there won't really be much worth nicking . I think Chinese scooters have improved and it seems to be quite easy to get replacement parts online. I looked at a Puegeot scooter which was double the price and the engine is the same design.

600cc bikes are a lot more expensive (about double the price 2nd hand) and VED would be a lot more (I think upto 150cc is £15/year).

I also want it to be reasonably quiet so that it doesn't upset the neighbours (I'm fed up with the noisey bikes and cars around here). I'm hoping that the Chinese ones are quiet enough for me, but I'll need to do a bit more research.

I'm also looking for a bit of fun. If it'll do 55+mph, then that would be great for the country roads. However, most the time it'll be doing no more than 40mph in the city.

Those other trikes are looking nice! One with a roof etc. would be better for me, but I think it's far too ambitous at the moment. If it all goes well then I may build something bigger and better

Of course, one of the best things about building it will be what I learn

Well when you lay your requirements out you do seem to have a slightly different goal to others on here which is primarily to have fun & go fast where you're putting more priority on practical town use. This is still a good place to look for advice though, loads of knowledgable folk on here!
Mabye best to speak to people who are involved a lot more with the type of bikes you're thinking of using as a donor to see what they suggest being the best donor?

It's good that you can get parts easily, you'll definitely need them I repaired my nephew's Chinese bike and the quality of the engine and ancillaries was abysmal, the carburettor is a joke. The only good part about them is the plastics, they are very good at plastic. I think you are a bit optimistic with your speed estimate for a 125 pulling extra framework, downhill probably Give it a go and leave your options open for fitting a bigger motor later in case you don't get what you need from 125cc.

Speaking of the Chinese and their plastic's industries...

I watched a program the other week showing folk collecting used condoms from the bins, streets and sewers, then delivering them to a manufacturing plant where they are washed and have the retaining band at the open end chopped off...

These are then used as the basis to make.. hairbands!

Eurghhhh!

And yes... they do export them!