Yamaha Neos 50cc build

it has a pickup and 3 small magnets which I think are meant to go on the brake disk. That's how it was set up on the youtube video the instructions referenced anyway. Not sure why they need 2/3 magnets vs just one but whatever... hopefully this vid shows the arrangement at the right point - look at 1:00mins in otherwise:

 

Last time I fitted one of those it had two magnets, may be they just can't count over there.

 

the instructions say you can set the gauge to use 2 or 3 magnets, but there's no option for just 1..hence my initial post..since the yam oem sender has two things..perhaps I can make that work whereas one would no doubt have read wrong or not at all.

 

With one magnet you may not be able to set the tyre size correctly to give the proper read out, I found that part a pain so used a gps to get the speed I was doing (they're normally goods for around 2mph accuracy), then adjusted the tyre size settings to suit.
All trial and error, more errors than anything with that part of it.
It might be worth a tickle taking some wire extensions from the (disconnected) speedo plug to the new clocks wires and see what happens first before getting into the realms of fixing magnets.
Just a thought.

 

that's almost exactly my plan.... play a bit of "guess the wire" with the existing speedo setup first - if I can avoid having to add non-oem bits then I will. If i can't get it to read right (or at all) on the oem sensor then I'll have to fit the sensor which came with the gauge. Tweaking the tyre size by using gps is a good idea tho - hadn't thought of doing that

 

So I got the oem speedo sensor working, though it does seem to read rather slow. I could only get the speedo to read up to about 4mph when spinning the wheel by hand vs about double that when using the sensor which came with the aftermarket gauge. I reckon I'll try and make it work with the oem one by fudging the wheel circumference, but if that ends up not being possible it looks like I can fit the aftermarket sensor with only a little adapter plate needed which would bolt on alongside the brake caliper..either way it's reading now and I'm pretty sure I can get it to work one way or the other even after it's all been painted & assembled.

I also got the low oil sensor wired in properly and tested, works great. On low oil you now get a flashing "N" on the gauge. So basically all that's left to do of the wiring is make the fuel gauge read right through the range and "optimise" the wiring since atm there's a shedload of excess wire..then the wiring is done \o/ (phew).

I got a little plastic "project case" to put the relays and whatnot in to protect them from weather and prying fingers, which will hopefully get tucked out of the way on the brace which joins the neck to the down-tube just below the ignition barrel. Once I know it's the right size I'll try and find a nice aluminium one but ali ones are bloody expensive so till I know exactly what size it has to be I'll stick with a plastic one.

I also started work on the rear wheel adapter to fit the mini classic wheel..and after that I have new found respect for how sturdy the yamaha wheels are. wow that took some doing to get it to bits!

I chopped the central section out of the wheel with a disc cutter and then stuck the leftover bit on the lathe to try and extract the centre section without damaging the braking surface just in case I needed it...



once it was at this stage I drilled each of the holes you can see out to about 10mm and tried cutting the "fins" with various implements. Made some progress but wasn't really going as planned so figured by then I might be able to brute-force the centre bit out by using my pipe bender as a press. It's a 12-ton bender but the hub was so solid I ended up bending the frame of the bender instead (!) .

So I ended up drilling the holes out more with taper drills till there wasn't much left and I could get the airsaw in there. Finally ended up with just the centre section...



Then took to it with a disc cutter...

and finally managed to separate the steel spline bit from the rest..mission though.



The steel spline bit seemed a little bit off-centre and didn't quite fit in the intermediate tube I'd got. I dare say that's not an issue since it looks like they cast the ali wheel around the spline so it doesn't have to be 100% perfectly round/balanced as long as the wheel balances as a combined unit. That didn't help my situation though.

I also hadn't planned for the "tangs" which didn't fit inside the mini-classic hub, nevermind the intermediate tube. So I ended up sticking it on the lathe and fingers crossed it's now pretty well centred and the tangs have been taken down a bit too.



unfortunately in order to make it actually round and centred I had to take the main body of it down further than I wanted to and as a result now the main body of the spline is too small for the intermediate tube, but the tangs now fit snugly inside the mini-classic hub which sorta make the intermediate tube less vital.

I think I'll end up getting the intermediate tube (or another random bit of steel tube) down to the right thickness to fit between the spline and the mini-hub and just cut a slice out of it so it works like a giant circlip. Once trued and welded in place it should make no difference. I'm hoping to heat/shrink fit it all together so that it's all snug from the outset and then weld it once fitted together.

I reckon the gaps between the tangs and the tangs themselves should make for good welding surfaces when it all gets stuck together. I'm hoping I can weld the tangs to the mini-hub but also pool molten stainless in the gaps for max strength.




The good news is that the spline and the mini-classic hub fit together (length-wise) as if they'd been designed to do so. Hopefully next session I can mock it up on the bike with the actual wheel mounted and see how the offsets are looking...I'm really *hoping* that it'll all just more or less line up (with the brake pads too) and no major offset adjustment is needed, otherwise it's anyone's guess what will need to happen to make it all fit right

 

so, managed to get the rear wheel/hub assembly somewhat mocked up today...

first thing is the splined adapter fits the other way around from how I expected it to, so the tangs on it will need machining down a bit more so it fits into the splined part of the mini-classic drive flange, but otherwise it actually all fits pretty well:



the inside edge of the mini-classic drive flange actually fits very neatly inside the brake shoes, and doesn't even stick out too far. I could perhaps do with machining a few mm off the end of it to make it fit even more snugly and reduce the lateral load on the axle slightly but I can't fit it on the lathe that way around without removing the wheel studs (unless I figure out a clever way of mounting it) so it'll probably stay as it is. I think I can live with it like this though.



and here's the wheel mounted on the scoot. Slight clearance issue around the lower exhaust mount but not too bad and was to be expected. Exhaust and mounts will need some redesigning anyway to get around the wider tyre.



eventually this is the sort of position I'd be wanting to have the rear wheel end up once stretched, though obviously the frame would be quite a bit lower since it's on the stand here. Rear mudguard will be removed and hopefully replaced with a small "hugger"-type fender.


and finally from the rear - some offset but again, that was to be expected with this type of mod and will be compensated for in the stretch metalwork.

 

Eventually got the fuel gauge working properly today, right throughout the range. Took a bit of fettling but now it works pretty much bang on. I ended up using 4 120 ohm resistors and dividing the resistance wire up into 5 sections which gives a pretty decent (and accurate) range of values from empty to full. It ended up being a bit more fiddly than expected because I couldn't ensure decent contact between the resistor legs and the resistance wire (which won't take solder), so the idea of aralditing it all into place with uncertain connections didn't sit right.



I ended up having to thread a single strand of copper wire behind each "segment" of the resistance wire and soldering that to the resistor legs but then contact was totally reliable. It's currently not got JB-weld/araldite on it bu it was all sitting pretty snug as it was. I may revisit that and add the glue but don't really think there's any need for it.



Once the range was working it just needed a little 30ohm resistor in series with it to trim the position of the "range" and it's good to go.



That also means the electrics are all working now \o/

There's still a big glob of wires hanging loose by the fairing bars but till I know where everything's going for sure with the frame I don't really wanna start trimming them down so I guess that'll wait till after final welding & paint.

I also managed to get the mini-classic hub heat-fitted (mini-drive flange in the cooker for half an hour ) on some steel bar in the lathe so can hopefully machine the extra few mm off the back end of it for a super snug fit to the hub, and also machine a groove for where the brake drum (currently a section of pipe) will sit. That should allow me to make ideal angles/grooves which should make welding a *lot* easier & ensure max strength.



Lots of lathe time tomorrow as I hopefully get the hub bits fitting together properly...

 

well that lathe was a good purchase..I'd have ben f**ked if I'd tried to do this without it or it would have cost a fortune to get the bits machined by someone else due to the many slight plan adjustments needed along the way.

However, we do now have a snugly-fitting centre section for the mini-classic hub \o/

main piece of wisdom I've learnt from this process:
Just because things have come from a manufacturer and are rotating parts..don't presume they'll actually be round/balanced. They're not.

aanyway...

so the first sleeve bit I made ended up being a smidge too loose and didn't allow for the non-splined section of the hub being a little wider, so I made a second one which fitted better and allowed for the non-splined bit. It also appears that the mini splined hub has everso slight a taper to it which just makes all the measurements extra fun.

Back side of the mini-classic drive flange evened out and now actually round...


yamaha drive-spline-tangs machined down to fit inside the mini-classic splined bit..


finished collar and how it fits onto the yam drive spline...


and how it all fits inside the mini drive-flange. The collar gets compressed slightly to ensure a snug fit, hence the cut in it.


all assembled and test-fitted onto the scooter...


It turns out the collar assembly needs to stick out a few mm from the back so it all clears the bearings


despite machining a few mm off the back of the drive flange I still have this gap (due to the stickout). I'll probably leave it like this though.


wheel fitted onto the whole assembly...I loooove how the wheel looks on the bike.


need to sort this proximity issue, can't get the wheel on with everything assembled as it stands..


drive flange from the back...


One new issue I encountered is that the wheel studs expect there to be a brake disk between the drive-flange and the wheel so they run out of thread before the wheel is actually securely fastened. I've ordered some shorter studs (presumably from a drum-brake version) which should solve that. It does mean I'm going to have to remove the current studs though and all but one are *very* stubbornly fitted. Will have to cut and drill them out before fitting the new ones. I wondered about fitting some metric studs while they're out so we can ditch the whole imperial sizes nonsense but have yet to find any m10 ones which will fit (which aren't hideously expensive).

I think eventually the welding will be done in two parts...the collar will get fitted into the drive flange and welded from the front (inside the splined bit of the drive flange) and around the exposed bit at the rear. Then the yam splined bit will get fitted and welded to the collar (on the rear) and to the splined bit of the drive flange (from the front). Hopefully that should be plenty solid to take the abuse it will no doubt receive

 

Got the new wheel studs fitted yesterday so now the wheel should bolt up to the drive flange properly, and faced the drive flange on the lathe too while they were out (so now it's actually round/even), which basically I think that means the rear hub section is ready for welding together.

However given I'm still pretty new to TIG and it's going to be several quite tricky welds both in terms of placement as well as variety of metal composition, I think I'm gonna finish up the underbody/sump-protection frame and the new downpipe for my golf first. Both of those parts will require extensive TIG work in ascending order of difficulty, both are under the car and out of the way (so don't get seen if they're not so pretty!) and neither are quite as safety critical as making sure the scooter wheel don't fall off, so should be good practice all round.

By the time I'm done with both of those I reckon I'll be a lot more confident with the TIG and should be fine welding the scooter hub with no issues. I'll have also had chance to see how the 312 stainless flows since there's some dissimilar steel joins on the downpipe too so will be using some of that in the process. It's still not quite the same as what I'll be facing metals-wise with the scooter hub but similar-ish ballpark.

Whilst annoying to have a delay, hopefully it shouldn't be more than a week or so out and having taken such care with it so far I'd rather do it right than fudge it and have to start over.


on a side note: It's kinda scary how out of whack the mini parts were - these are heavy, rotating parts and they weren't even close to round or balanced. Having a wheel attached would have only amplified any imperfections too. I dunno whether it's an "Austin/mini" thing or a "Cast parts in general" thing. This is the first time I've dealt with Austin/mini parts though so I'll be interested to see how VW bits compare.

 

you think british parts are bad? you should see "high end" american racing parts... in a box of con rods you can have over 12 thou difference in length between any 2. oh and the piston pin to skirt height is differnt on every single poston when you buy a box (which come in 10 for some reason?)

 

oh dear... I had no idea. that's insane.Maybe come in 10s so you can throw the worst two away

 

so - I've done a bunch of TIG welding since last post, and reckon I should hopefully have a decent shot at not making a total pig's ear of welding the hub adapter together now...so with a bit of luck will give it a go tomorrow/sunday. *fingers crossed*

In other news - my god how much easier is it working on bikes than cars!

 

So a bit of mixed bag of success/failure today - on the upside - the welding side of things worked pretty well, and I did ultimately end up with a working adapter, but on the downside it doesn't run quite as true as I'd like. "It's good, but not quite carling".

The issue seems to be that I had assumed all the individual parts were round/true from the manufaturer, which it later transpired they weren't, but by the time I found this out I was already partway through machining, which was really too late. So I think I will actually end up making another adapter with the other drive flange I've got (they came as a pair) but this time I'll build and machine it all on a yamaha drive axle (minus the gear) so that I know it runs true before it even leaves the lathe, rather than making sure everything is individually round, but relying on things coming together perfectly at assembly, which they definitely didn't.


First off I did a test of welding some mild steel to some carbon steel to see how the 312 stainless held up joining the two dissimilar steels in practice, and what to expect during welding. It's a 2.5mm thick offcut from a bit of box-section which I welded to the end of an ancient adjustable spanner/stilson-type thing. Although the weld wasn't pretty (wasn't particularly well prepared/cleaned beforehand), after welding I hammered the crap out of it to try and break it and the steel bent rather than the weld failing - which was a pretty good outcome.



encouraged by that I put the mini-classic drive flange in the oven for just over an hour at 230C (it's supposed to go at 250 but 230 is as hot as our oven will go) as suggested by the info I'd gleaned online about welding mild to EN24/carbon steel, then set about welding the collar, which was made all the more fun by the workpiece being super-hot before I even started welding.

These welds actually turned out really well, the 312 filler flowed nicely and the weld looked pretty decent, some of the nicest TIG welds I've done so far (i've not done many)...there's even a hint of "fishscale"/"stack-of-dimes" going on as I started to find a rhythm. Witht he types of steel being so different I wasn't sure they would "blend" together so nicely but looking at it I don't think strength of the join will be an issue like I thought it might be..



After that things got a bit tricky as I tried to weld the other end of the collar to the inside of the drive flange (I'd figured for max strength), but that didn't really work as I'd hoped and I ended up with some blobby bits which needed grinding down before the yamaha splined section would even fit back inside the collar. arg! The blobby bits were mostly the stainless steel filler which is b***ard hard and very tough to grind, so trying to weld that bit actually ended up causing more problems than it solved.

Possibly as a result of the blobby bits and subsequent grinding, when fitted, the yamaha splined hub centre-bit seemed to have a bit much play for my liking, which is obviously magnified when you add the larger wheel onto it, resulting in a fair bit of play/wobble during rotation. Not ideal :-\

I was pretty frustrated by this point and as a last-ditch attempt to get things running true I ended up using tiny self-tapping screws screwed into the gaps left between the drive-flange splines and the "tangs" of the yamaha splined hub thing to try and centre the wheel as best I could. I wasn't really having much luck with this but it was enough to get it pretty close and hold it long enough to get a couple of tack welds in place.

With the screws removed I still wasn't over the moon with the alignment but by then was committed and daylight was fading so thought "sod it" and finished up welding the yamaha spline in place properly. Working down inside the recessed bit was super tricky and the welds weren't anywhere near as pretty as the ones above, but again, seemed to get the job done. Then finally I welded up the back part where the yamaha splined bit meets the intermediate collar. Again, not that pretty but by then daylight was on its way out and patience had worn pretty thin. At least it seems relatively functional (planned to grind it smooth afterwards.



I already didn't have high hopes for the alignment at this point but figured I'd come this far so I may as well bung the wheel on and at least check it all fitted. Much to my surprise (somehow!) it ran a lot truer than I had expected from the measurements during mock-up, but I'm still not 100% happy with it, and given I plan to ride this at reasonable (yet still life threatening) speeds "close" isn't really good enough.



So...the idea does work and the welding went better than I'd expected but I think a do-over is in order to get it perfect. This time I'll build and machine everything on a yamaha axle from the outset so that I know 100% everything is running true before it even gets near the bike. I might also try and take more off the back of the drive-flange so that I'm not trying to weld "down in a hole" to the same extent as on this one. It seems like every mm counts there. It will also mean slightly less offset needed by the stretch metalwork and slightly less load on the wheel bearing so I guess that's a bonus.

It is annoying though because now I need to buy an axle and another rear wheel to destroy but it seems like the lesser of several evils at this point. I also know this time around to start off with the wheel studs removed and not fit them until I know it all runs true, since once they're in place there's no hope of fitting the adapter back on the lathe, and also to skip trying to weld the collar to the inside of the drive flange since that seems to be where things started going off track...

Whilst doing some head-scratching afterwards and looking into other options and figuring how to proceed I actually found that there is an adapter (albeit for the zuma/BWS) which even has the 4" (101.6mm) PCD/stud spacing so would even take a mini-classic rim directly...but a) I don't know if the zuma hub will fit the neos axle and b) at $275 it's a bit beyond my budget at this point anyway

https://www.steadygarage.com/store/chimera-unlimited-yamaha-zuma-125-rear-drum-hub

The end result is that my adapter is actually very close to what I need (less than 0.5mm variation at the edge of the rim), but the wrong assumption about things being round from the manufacturer probably made all the difference there.

Ah well, lessons learnt (the hard way, of course)...we continue.

 

w00t! new rear wheel and drive axle ordered - feeling a bit more hopeful today \o/

 

Heat bricks from an old gas fire or three.

lay them out making yourself a small box using the fire bricks keep a couple back to seal the chamber up when build, grab a propane tank and burner if you have one laying round, and if possible a temp gun. your going to be making a somewhat pottery kiln that will reach temps up in the high 1000 degrees.

when built pop the burner though a space in the back wall , half a heat brick to hold item away from the heat flame and a brick or two to seal the front chamber opening , start up your burner and let it cycle through a couple of heatings first, when you remove the front brick you should see a cherry red chamber. for a small chamber for hub adaptor its gonna take around 45 mins to bring upto full temps, so you will want to open the front brick block slightly and heat gun the temps .
Its how we tinkers make homebrew kilns and smelting ovens .

temps can get really hot, ie hot enough to melt brass / iron / copper / alloy , steel will require even hotter temps but it will get any mild steel / stainless upto temp fairly quick. a lot better than the home oven and will reach temps way beyond what the home oven can produce

 

cheers tamita the preheating was only to try and prep the metal/hardening pre welding...250 is ideal temp apparently so I wasn't far off...I don't think I need to go quite as in depth as you're suggesting, esp since he work piece got even (way!) hotter during actual welding....tho it's got me wondering if I can cast stuff now too

 

would want to do a couple trial runs but casting ......... cant see why not .
can also make a forge using an old car brake hub a cheapy old 12v blower fan and a few bags of coals

 

why would you need the old brake hub? as a thing to hold the sand or whatever for casting?

 

Brake hub with blower fitted to a pipe leading to its center, the grill covering the blower feed in so hot coals dont fall back into the air inlet. the hub acts as the holder for the coals . deeper the hub more space to get a crucible in to melt metals. you could use a drum hub to make a holding pot for your casting sand to , but better to clamp to wooden forms to create a casting mould. we got as far as melting drinks cans and casting alloy ingots , but used the same hub type idea to get coal hot enough for smelting