Yamaha Neos 50cc build

so does anyone know why I might be quite excited to have received this ~20-year old scooter wheel in the post?

 

Because it's all steel, not alloy?
Looks like it might already have the bolt hole markings on it, but not drilled yet, and they just happen to be in the right places?
Chromed it could come out really nice?
Centre boss is exactly the right one for your needs?

Is it a tubed rim or tubeless? Can't really tell from that valve position.

 

I like the look of this, but cornering must be a right dodgey thing, looks like it'll scrape if you go too far over.
Unless of course there is air ride suspension that rises on start-up.

 

And the first prize goes to SteveP \o/ exactly right! And yes, bonus points re the spot welds being marked in exactly the right places too.

The only issue I can see with it so far is that the brake drum diameter on that wheel is 100mm or thereabouts rather than 110 so I think I'm going to have to lose the drum and weld on my own. However I was expecting to have to do that on the Plan A approach anyway (mini classic drive flange etc) and this way at least I have the splined bit complete with an already-aligned vertical which I can just turn down to size and weld onto.

This also looks to be the most "slimline" fitting I've found so far, so as long as the vertical and the spline don't foul the newer brake assembly it should mean I need to add less offset for the wider wheel, and thereby put a bit less lateral load on the wheel bearings...which has to be a good thing imho.

The brake shoes have a bit of "float" in them anyway so i think the alignment of the welded-on drum, whilst it obviously still wants to be on straight, is not *quite* as critical as the alignment of the overall wheel.

I've also bought a used drive axle to build/lathe it on since the brand new Jasil one seemed to need a bit of "bedding in"..I'd noticed a couple of the splines didn't fit snugly out of the box which isn't a problem I've had with the (used) axles on the bikes. I'm hoping the used axle isn't bent but that's something I'll find out when I get it on the lathe.


In other news...today's mission is dusting off the sprayguns and airbrushes and seeing what still works and what needs replacing, and hopefully doing some testing as to what type of paints stick to the scooter plastics, as well as what paints go over what other types of basecoat, and what types of lacquers go over all the above, preferably without crinkling or peeling off.

Hopefully that way I can get an idea of what's going to be possible paint-wise. It's been a while since I've used any of this kit and so far it looks like my (favourite) HVLP gun and one of the mid-sized guns are knackered which is a bit annoying, but both airbrushes and a two other mid-sized guns look to be ok...which is enough to be going on with for the moment, though the HVLP is king for nice thick glossy coats of lacquer.

 

and re that japanese scoot - I think it's aired down in the pic. Looks to have an air-shock on the back.

Re the old jog wheel I dunno if it's tubed or tubeless, makes little difference to me since I'm cutting the outside off anyway. Why do you ask?

 

REF the jog wheel - angled brass valve, common on tubes.

2 pac paint it what you want to use, goes on better and thicker, and gives a nice finish.
Don't rub all the way through the stuff thats on there, if you get to the core of the plastics then the primer will crinkle, so might be an idea to get some stopper as well.
High build primer is good stuff.
Have a look at HouseofKolor.co.uk
They have some lovely paints.
If you want to paint the engine as well, like I do, then you will need a VHT primer and VHT topcoat and laquer.
If you dont use the VHT stuff the laquer goes yellow quite quickly.

Use an air fed mask as well for any painting, but especially 2k paint as it contains cyanacrolytes that are poisonous to your lungs.

 

yeah I'm hoping to use 2k for most of it, ideally the basecoat but especially the lacquer/topcoat since there's nothing like the heavy gloss from 2k lacquer . I'd like to try some more detailed airbrush stuff in between tho and am not sure 2k will run through those little airbrushes plus having to buy a whole range of 2k colours would be a pain (tho hok do some lovely paint!), so am testing to see what I can get away with using based on what I've got to hand...e.g. acrylics as well as rattle cans etc. I know from experience some combos are a no-no but really until you test it's all theory.

Many moons ago, before the days of photoshop I used to do quite a bit of airbrush illustration but that was generally all water-based...so whilst I've done both 2k on cars and airbrush stuff, I've never tried bringing the two together, which is what I'm working on atm.

Dunno what happened to my air-fed mask but it never really worked out that well since then needed a second compressor to feed it, plus all the relevant air filters so you're not breathing oily air etc, and I only have the one comp now which I think would struggle to feed both me and the spraygun. In the past I've used a voc-compliant respirator+goggles which worked pretty well, plus I'm painting in a well ventilated area so it's not like the fumes linger..but yeah the cyanoacrylates are not good to be breathing in.

I didn't know that, cheers . I've done a bit of stuff on plastics (the odd bumper & trims) but most of my car painting has been refurbing (old golf) engine-bays & replaced sills so generally on metal and going over a zinc-based primer - so the plastics thing is somewhat new territory for me.

Turns out the base of the can of high build primer I had lurking had rusted through so when I went to stir it suddenly it developed a hole and I had a mad scramble for coffee jars to scoop it out of the can before the primer all leaked out and redecorated my shed floor. yay! I guess that's sorta the point of today though - seeing what's still usable and what isn't. Managed to save much of the primer tho \o/

 

I just tested the ancient jog wheel and the smaller brake drum fouls the brake-shoe mounting pin and the bit which operates the rear brake...At this point I can't tell if it'll line up properly even with the brake drum removed (i.e. whether the depth will be right) but I guess there's only one way to find out. I'll trim it off and see where we're at...otherwise we're back to plan-A (mini drive-flange-based) or plan-C (turned down neos wheel - currently best option but has more offset than I'd like).

 

interesting session today...I got the ancient jog wheel cut down and once it was on the lathe it was clear that it was also not straight. It wasn't anywhere near as bad as the carenzi adapter (I'm still amazed just how bad that was) and I tested it on both the brand new axle and the used one, and it was still wonky on both..not massively so but wonky nonetheless.


fortunately I didn't need much of the wheel and what I do need could be machined straight relatively easily.



I've ordered a nice 6mm steel plate which would get welded to the now-straight face of the wheel, then tapped for the wheel bolts, braking surface welded on etc, all groovy.

*however*...although that would work this has led me to the conclusion that there is no such thing as a perfectly straight scooter wheel, and the degree of wonk which seems to be commonly deemed as 'acceptable' is way more than I would normally be ok with, plus every axle seems to be different so the opinion of what's "straight" is subjective, and the only opinion which really matters there is the one of the actual axle its getting mounted on (and im not pulling that one off the bike)...so perhaps I'm over thinking this....

I do currently have a turned down neos wheel which has the rim mounted on it and when tested ran with <1mm deflection at the edge of the rim. yes it has a bit more offset than I'd like but people run fatty ruckus tyres 8" wide and mines only 6" so perhaps that's not such a big deal.

I was going to fill the back-side of the threads on that adapter with weld but on reflection applying such a lot of heat to such a critical part of the structure might mess with the heat treatment of the aluminium..so in trying to make it stronger I may actually make it weaker. The wheel bolts have 100% thread engagement for at least 4mm and partial engagement for an additional 8mm+ so again, probably trying to over-engineer it.

so the conclusion is...I've got an adapter with a rim & tyre which I've checked and runs true on the axle which counts, seems sturdy enough, and i dont think im going to get better than that any time soon, so stop digressing and just stick it onto the bike...

which is cool because that's also the 'least work' solution and the easiest to repeat for other bolt patterns/rims in future

 

bunch of pics from the other day - got the back end stuck on (tack-welded for now), so far all looks good and straight

I had to cut up my nice sports exhaust to extend it sideways by a little bit (eek!) and whilst I'm sure it'll mess with the power band somewhat there wasn't really a lot of choice since it doesn't even slightly fit otherwise.

Lastly I also got the basics of the air-ride in place. I'm not sure if it'll stay like this as I have a larger diameter pneumatic ram on order with a longer stroke, but the current one has a stroke of 10cm which seems to be enough to go from laying the frame down to max ride height. The bigger cylinder is a bit wider though and I think it might just give a slightly better ride (plus I wanna use a paid of these ones to control the front suspension eventually).

I (think) I've ordered all the necessary bits to make the air-ride work - there's a gazillion little adapters for npt->bsp and vice versa in various sizes but I think I covered everything...just gotta wait for it all to arrive now, and some of it's coming from china so will be twiddlign my thumbs for a bit.

I don't really know how air ride in cars etc normally works but this one will have a pump with a one-way valve which pressurises a tank and is controlled by a pressure sensor so it keeps the tank at 100psi or so, and then solenoid valves to air-up and down. It could be done more simply with just hooking the pump up to the shock but I reckon this way the pump will only run when needed and airing up and down should be instantaneous and not necessarily accompanied by pumping sounds or limited by the capacity of the pump. Besides I gotta fill all that blank space underneath with *something* now don't i

I'm just doing air on the back initially till I know the setup works but if it does I'll expand the idea to the front - which looks like it'll be a lot more fiddly to get right.

If I can find an adjustable pressure sensor then it might be possible to set it so that front and rear stay at a certain pressure e.g. when you start the engine it auto-airs up to a given psi (right height) and maintains that, so that you keep a preset height while riding...but then when you engine off it auto airs down...

I dunno if actually laying the frame on the ground will work since the lowest point is currently the exhaust and I don't think dumping the weight of the bike on that is necessarily a great idea, but given there's a pressurised tank there's no reason it couldn't deploy little assistive "feet" (like a spaceship) when you set it to "park"

 

am still waiting for the bigger rear shock from china so wasn't much I could do on the neos this weekend, but I did get the cross-bar fitted. It's a nice 2" section of exhaust pipe which will give me ample room to route all the cables to just where they're needed.

Given no fairing etc there's going to be a little box mounted to the side of the neck area which will house all the electronics, and the placement should mean all the cables can go from there directly into the crossbar with minimal fuss and be mostly invisible.

Where bottom end of the bar meets the cross-bar i've deliberately left a slight overhang to the top since that's where all the cables will come out..

 

air-ride system finally almost complete


I'm just waiting on a 1-way valve for the pump (open connection bottom right) and have to extract the pump from its current location (in a tyre-inflator type thing).

from the top down..

- pneumatic ram
- "air-down" solenoid
- "air-up" solenoid
- pressure gauge
- safety relief valve
- pressure switch (to switch the pump on and off between 90-100psi and keep the reservoir at pressure)
- pump in
- reservoir

The order of a few of the things will perhaps change depending on how it works in practice but that's roughly how I think it's gonna work..
May need to add a variable valve to the open side of the "air-down" solenoid to control the rate of descent. Ditto the valve on the welding cylinder/reservoir should allow me to adjust the rate of "air-up" speed.

I'm wondering whether it might be possible to add a pressure adjuster (like found on any compressor) to set the actual system pressure and thereby the ride height. Then I think it would only need one button to control - up (to set pressure/height) and down.

Depending on how it performs I may add another tank just before the cylinder to act as an accumulator, but I've got a bigger ram on route from china so that may not be necessary.

Obvs this would need expanding slightly if I add the air-ride to the front and the air-operated "feet"/stand, but I've not figured that side of things out yet.

That's the theory anyhow!

 

been a while since I've been able to post any progress - had lots of non-bikes work on :-\

However...I have not been idle, just too knackered to post pics after being out working on the bikes.

The larger diameter rear shock finally arrived from china, and I've adapted where it connects to to give a steeper angle and the right amount of throw to take the bike from on the deck to riding high (as high as it can go without the auto-choke fouling the frame anyway). It's set so that when it's riding on the bump stop it's bottomed out so that if there's a loss of air-pressure while riding, I'm not suddenly gonna be dragging the exhaust pipe. That wouldn't be good. There's now a rubber bump stop in place of the spring. That said when it's aired down it's **low**



it looks a bit deceptive in the pic below because the frame is on axle stands so that I can adjust the rear wheel up and down to get the measurements right, but when it's actually supporting its own weight and on the bump stop it's proper slammed. But when it's where it would be when "aired up" it's at a nice usable height so should be plenty of clearance for potholes, kerbs etc. It's a good range of motion and only uses about 1/3-1/2 of the stroke of the air cylinder.



Latest mission was getting the stretch frame off and properly welded up so that now it can support its own weight. Not the most beautiful welding but it's all TIG welded and I've gone from strength over prettyness. Some fo the welds need dressing a bit and a couple of ends need trimming back slightly, and a couple of the open ends will get capped off for neatness but the basic structure *works* and is now back on the bike.



Next up I kinda need to see it supporting its own weight so that I can extend the fairing bars rearwards and have them rejoin the frame but obviously I need to see it at a "natural" angle so that the lines all flow right. Then I can weld up the fairing bars & cross bar too (it's all just tack welded atm).

I also have to finalise the lateral position of the exhaust & mounts so I can weld in the little extension so it clears the wider rear wheel properly...which is gonna be a tricky one, but should hopefully be the last of the major metalwork.

I've also dismantled what I'm hoping to use as the air pump (was a tyre inflator) but it needs building into a case along with some sound deadening to make it quieter and more or less weatherproof. That's gonna be fiddly too I think.

I've still not quite identified what threads are in the air cylinders which is kinda annoying, I'd rather re-cut the threads on whatever fittings screw into the cylinder than re-thread the cylinder itself but that's only gonna happen if i can figure out what thread it actually has. The ebay description seems a little..er..wrong.

 

she runs! (again) \o/

i've been a bit at a loss of where to start to get this old girl moving along - so many things to do it's tricky to prioritise, especially as many of them require money which I don't have currently. But it was sunny out and I had the day to tinker so dammit I was gonna do *something*. I ended up moving the coil with a vague view to trying to get her running (again, after the stretch), since that's a fairly major milestone and all the rest isn't much good if that bit doesn't work.

as it turns out as well as the coil I only needed to extend a couple of wires and the oil hose (18" stretch) and she fired right up.

There's only the stub of the exhaust on at the mo so it's super loud but it runs. Welding in the exhaust extension is on the to-do-soon list. As it is the throttle cable doesn't reach but I could blip the throttle by yanking at the halfway-point on the cable by hand.

What is strange is that the carb now pisses petrol out like it did when I put it on the other bike, and I'm sure it didn't do that before. I've not relocated the carb on this stretch either (which I thought might be the cause on the other bike where I had to move the carb).

In fact nothing's changed other than the motor is 18" further back than it was..but now it leaks. hmm. Maybe it did before but I didn't notice it though it's quite a significant leak so I'd have thought I would have spotted something that obvious. Even with the airbox on it drips out the bottom of it.

I wonder if it could be something to do with the (now) excess fuel hose and the relative change in position of the fuel tank? Seems like a bit of a long shot but there's not really much else which has changed. weird. I'll figure it out eventually..

EDIT: been reading about carbs and I think the pissing fuel thing is to do with float levels - maybe something got upset in the swapping carbs around. will test the theory next time I get the chance.

 

Sticky float most likely.

 

that's the conclusion I was reaching too...or wrong float level perhaps. Shouldn't be insurmountable I've been learning as much as I can about carbs the last day or two since I don't seem to be able to avoid doing so much longer.

 

Carbs, they are not so complicated....

 

Been a bit slow going on this recently - work's been swallowing up my spare time...however..

One of the challenges I've been facing is what to do with the threads (for the air fittings) on the air shocks since I've not yet figured out what thread they are, and the thread the ebay seller says they are, they're almost definitely not.

However today I accidentally discovered that the shock ends actually unscrew from the body, which means I can take the ends off, re-cut the threads to something useful like 1/8 bsp (like the rest of my fittings use), clean out any swarf/shavings and then reassemble the shock. I wasn't wanting to try to re-cut threads in situ since there was the likelyhood of metal shavings making their way into the air part of the cylinder...which would obviously be a bad thing mmkay.

Once I've got the shock working on the right fittings I suspect it might be an idea to loctite the threads of the shock body so that they stay screwed together. That's not something I'd want to come apart while riding.

I've also ordered a bunch more tubing & bends so that I can extend the fairing bars rearward and tie them into the frame, thereby hopefully bringing the front and back halves of the bike together and giving a bit of visual/design continuity as well as producing a nice stable platform for my feets while riding. Obviously this wasn't something I could really do till I had the stretch frame figured out though. The plan is to put some checkerplate down over part of the bars so that it all ties together nicely.

At the moment the stretch frame is very much "functional" rather than pretty, but once I've got the fairing/foot bars in place and the exhaust mounted I'll look into the more aesthetic aspects and hopefully "blend" that somewhat with the surrounding metalwork.

pics as I have them



btw I've also done a couple of catchup videos which I've posted on youtube. There's more to come and I'll drop them in here as I finish them...

 

Bitch innit when work gets in the way of playtime

 

deffo :-\ gotta pay them bills somehow tho..