Yamaha NXC125 20,000km [Archive]

speedpro

1st July 2011, 22:19

As the title implies the scooter is coming up on 20K. I've checked the tappets to find them all a little loose and set them to about .003". Strangely it seems to have knocked a bit of performance off, most noticeably up the hill from Stanley St to the NW motorway. I'm gonna set them loose again to see what happens. I need an airfilter and the owners manual says the belt should be changed. Oil changes have been done.
Does anyone have advice on whether the belt really needs to be changed, or rollers? Is there an improved variator or other parts rather than stock Yamaha bits? I commute Henderson to Glen Innes every day. The only real performance improvement I'd like is to get away from the lights a bit quicker.
I haven't needed to do anything to the scooter since I bought it which is pretty good I reckon considering it regularly gets held full throttle from one end of the North Western to the other.

CrazyFrog

2nd July 2011, 17:35

It would be wise to change the drivebelt if it's already done 20,000km, I doubt it will last another 5000. A snapped belt is a pain in the ass and will lock the scoot rear wheel up which is always fun, especially not good on the motorway with rush hour traffic up yer date.:woohoo:
Do the variator rollers at the same time, if you want better jump from the lights, go 1-2 grams lighter from standard, but you may notice a drop in top speed. You may find your original rollers have flat spotted a bit by 20K anyway, so new ones will prob feel fresher on the acceleration. :scooter:

speedpro

4th July 2011, 20:05

Pulled it apart in the weekend to have a look. Half the rollers have flat spots but otherwise everything looks good. So, belt, rollers, and air filter is all that is going to be changed.
I did note there is a line of slightly scorched rubber on the pulleys in the high speed position so I figure these full throttle trips on the NW motorway may be pushing it a bit.

Spearfish

4th July 2011, 20:45

While your mucking around in there and if your inclined, pull the clutch bell off and rub off any glazing around it and the clutch friction plates.

speedpro

5th July 2011, 20:15

I did look at that but there isn't any obvious glazing and the clutch takes up nice and firm when you gas it up.
Looks like the rollers may be a few weeks away. If anyone in Waitakere or East Auckland has a couple of spare 20x12 9g or 8g rollers I could use you can have the new ones when they arrive. The scooter definitely has a problem where the engine revs get dragged down on hills and into winds because the variator obviously isn't working properly with the flat spotted rollers.

speedpro

13th July 2011, 22:46

I've still got the scooter off the road waiting for parts. It took 1.5hours to get home tonight in the car. :facepalm:

speedpro

10th August 2011, 12:41

Woohoo, back on the road. Fitted a full set of 8.5g rollers, standard are 9g. So far seems like a very good mod. Scooter is a bit nippier in trafic with that couple more revs on. Will probably drop a full set of 9g rollers in on the weekend just for comparison. It has a small rattle coming from the variator region still but I couldn't see any problems when it was apart. Will have to take a few back road trips to work til I get a few miles on to give the belt a chance to bed in.

speedpro

10th August 2011, 19:17

What a great day getting to and from. Why do people continue to use cars?

Zipping along in the bus lanes, cutting to the front at lights, and probably used $1 worth of petrol, and parked 10' from the front door of work. The magic of commuting on a scooter. :yes:

speedpro

18th August 2011, 08:03

The rattle seems to be worse and associated with the drivebelt jumping around. I've got it all apart again including the torque thingo and it all looks good, plenty of grease and free moving with no obvious notches where it could hang up. It also still has that problem where the revs get dragged down on hills more than I remember it did when new. The only "possible" problem I can see is what looks like a pattern of cracks on the outside cone of the variator. There is no matching pattern on the other side of the cone and I can't feel anything even when the cone is stressed. There is no indication of movement on the edge. I'm going to try the old belt just for comparison.

Thoughts and ideas are welcomed.

craisin

18th August 2011, 18:18

You may have to fatten up the mixture with a jet change.

I imagine going up long hills that the fuel pump that runs on vacunm on most scooter would be low due to the throttle being wide open and the float bowl fuel level too low for good performance

speedpro

18th August 2011, 20:25

It's a thought but the motor is standard and I'm sure Yamaha would have checked that. The revs are pulled down as the scooter slows on a hill. With the torque thingo it should rev more and I'm sure it used to. I knew a guy who used to have one so I'll try for a test ride on his for comparison.

I fitted the old belt but there was no discernable difference so it's all back together for the Friday commute.

craisin

18th August 2011, 20:49

check out Dr Pulleys sliders on You Tube

speedpro

26th August 2011, 20:09

The rattle is bad enough now that I started it this morning but turned it off and took the car to work. It comes apart this weekend. It sounds pretty much the same from both sides and is coming from the bottom end. There is more end float on the crankshaft than I would expect but as it's a roller bearing crank that may be just fine.

As I've got more miles on the new belt it seems to handle the hills a bit better. Maybe it just needed to be worn in a bit to allow the pulleys to move freely under load. The revs aren't being dragged down so much.

Depending on the problem I'll be replacing parts. I've found a very well priced Taiwanese supplier of oversize cylinders and pistons, stroker crankshafts, and heads with bigger valves, plus a selection of camshafts. They go right out to 288cc. I'm figuring 200cc would be a good size for what I use it for.

speedpro

28th August 2011, 19:32

Stripped it down without dismantling the motor. Removed all the variator etc and ran it with just the engine. The noise was still there. A very careful check of the oil which has only recently been changed showed a small amount of shiny flecks so it looks like the bearings are going away. I've ordered a new crank and while I was at it also ordered a new cylinder with larger bore. Standard bore and stroke is 52.4 X 57.9. The rebuilt motor will be 58.5 X 61.4 and 165cc. I would have gone for a bigger bore but that would require me boring the cases so it will have to wait. It's only about US$175 so pretty reasonable.

craisin

1st September 2011, 22:02

sounds good hope the compression ratio is on the planet

speedpro

1st September 2011, 22:27

They also sell hi-torque starter motors :laugh:

speedpro

6th September 2011, 22:04

The parts arrived today which isn't bad service. I paid for them with PayPal on the 29 August. They were very nicely packaged in seperate boxes and I must say the bits look the part. The cylinder has a chrome bore and the piston is a very nice looking forged item. It has two base gaskets of different thickness for altering the compression. The crank looks OK and has Japanese NTN bearings and seems to be reasonably well finished. The only piece I'm not 100% on the looks is the conrod which seems pretty short and "looks" cheap and possibly nasty. Markings on the rod would suggest it's from a Chinese clone :shit: Check the photos out. Anyway it's full steam ahead stripping down the scooter to fit the bits.

speedpro

6th September 2011, 22:19

I've got the engine assembly on the bench with the cylinder and head off. I found the cam chain was loose when I was disassembling it and after a bit of investigation found the tensioner wasn't extending under it's own steam. I pulled the spring out and prodded the ram out further with an allen key. It seems OK it just won't extend freely with just the spring tension. The head looks good with the valves being nice colours and even and consistent so I won't be doing anything to the head. The cylinder on the other hand has obvious signs of wear. The bore itself is chrome and has absolutely no signs of being used. The piston though has brown stains below the rings indicating blowby. If I was keeping that cylinder it would need new rings. This would be the cause of the lack of power I've been noticing. With everything disconnected the problem with the bearings is really obvious. When the crank is turned it is really easy to feel that the bearings are a bit stiff and badly brinelled as they are quite rough to turn. Just have to borrow a rotor puller and I should have it all apart tomorrow night and maybe even start on reassembly with the new parts. Once I've run it a bit I'm gonna put it on the dyno to tune up the transmission by playing with the roller weights. It'll be interesting to see what changes to the power at the back wheel it makes at various road speeds.

speedpro

7th September 2011, 22:41

More progress and a lesson learned.
Pulled the alternator rotor off and the crank got all smooth to turn. As it happens the stator has a lot more poles than I thought and the notchy feel is from the magnets moving over the poles. The crank is primo. All the noise must have been from the cam chain. I'm not totally convinced as the fresh oil that's done less than 100km has shiny flakes in it. The crank bearings all spin smoothly though.
The new cylinder is 72mm high and the old is 73mm high. The 2 base gaskets are totally different thicknesses. One is more or less stock and the other is 2+mm. I'll be checking and may even make some alloy shims to adjust the height. If the assembled height is less than the original I might need to replace the slightly worn camchain.

craisin

8th September 2011, 04:38

Short conrod like you say.
Must have a lot of angle on the rod with the bigger stroke

I run my china scooter with the cover off the variator and clutch so my mate can observe the workings and the timings of clutch springs and variator weights
He has to lay on the ground to see anything

speedpro

10th September 2011, 19:21

the scooter is back together. I used the thin base gasket so the compression is up there. There is a possibility the piston is just kissing the head now that it is all torqued down, it was pretty close when I measured it earlier. The piston is flat around the perimeter where the bore is larger. I thought about relieving the edge of the combustion chamber and opening it out a bit, but in the end just bolted it together. The starter spins it over OK but you can definitely feel the extra effort needed if kicking it over. With the extra capacity I figured I'd put the original weight rollers back in. Even so it gets off the line way faster than the 125 ever did. At about 30-40kmh it really gets going and is doing 80kmh way quicker than before. Having a larger capacity with the original valves/ports and cam will help the bottom end but whether it is restricted higher up I don't know yet. It isn't a high revver so maybe it'll be fine.
It's got me thinking about taking it out bigger now. :facepalm:

speedpro

26th September 2011, 21:28

Done a few miles now and starting to use a lot more throttle and revs. It has felt a bit weak over about 90k so time for a bit of a tweak. Changed the oil after riding home and took the opportunity to check the carb. The carb looks like it takes the small round head Keihin jets but actually the jet has a slightly smaller diameter thread. It was a 105 and trying a couple of different drills it was between 1.0mm and 1.1mm so seemed to conform to the drill size jet numbering scheme. I've drilled it out to 1.1 or 110 jet size. Giving it full throttle now results in way more go. It's got a definite bark to it now which is kind of funny considering it's a "125" scooter and has standard air filter and exhaust pipe.

speedpro

5th January 2012, 22:42

Couple of 1000K later and the noises were back. I ordered a new cam chain from Powersports in the USA and gaskets and rings for the original 125cc cylinder. Small change over $50 including freight so bloody good price. I pulled the motor completely apart and as before can find nothing wrong that would account for the noise, though the piston has been kissing the head. I got all the bits today and reassembled the engine with the thicker base gasket supplied with the big bore kit. This should give it about .8mm clearance piston to head. I've reused the head gasket but sprayed it with copper gasket stuff. The crank had a lot of end float and a barely discernable freeplay when dummy assembled. The bearings showed signs of turning in the housing and the housings had marks as well. I've put it together with Loctite 641 locating the bearings in the housings. Suddenly there is no more end float. It's still a bit noisy but heaps better. I've only given it a good thrash round the block so far but it seems to be going good. The noise could be coming from the alternator rotor area but I didn't notice anything when it was apart. I'll have another look once the rotor puller($22) arrives from Haldanes. I've found a listing on Ebay for some taller final gearing and have ordered some 14/38 gears, currently 12/40. The gears in the scooter are completely different ratios to what the Americans seem to have but it all looks to be similar design so hopefully they'll fit. With them fitted it'll be about 10% higher geared which should be good on the motorway. Check out "jiangwayne" for all sorts of goodies for scooters.

speedpro

9th January 2012, 19:22

Ordered on 3/1, payment from account 5/1, on the doorstep 9/1. Service doesn't get much better than that. $81.37 including freight. I'll be fitting them this weekend.

carver

11th January 2012, 08:46

bloody yamahas....high quality..:laugh:

speedpro

11th January 2012, 18:14

I don't know what the noise is but it isn't getting any worse and doesn't seem to be hurting performance. I gave it a bit of a run this morning and it went to 110Kmh pretty quick. The motor is definitely a bit softer with the lower compression so I will carefully measure the clearance next time and make a solid base gasket the exact right thickness to leave the minimum squish clearance, allowing for rod stretch and stuff. Though, the next time it's apart I can see it getting stretched to 200cc with a new cylinder, and head.

The cam timing is a bit out as well. Without slotting things it wasn't possible to get it exactly right. It was timed better with the old cam chain but the tensioner was nearly fully extended with the old one. Should really put a DTI on it and really see where things are. Silly really, the last time I degreed cams it was on an 1100 turbo and a Moriwaki 1100 before that. Now I'm thinking of degreeing "a" cam in a 125 scooter. I must be getting REALLY old.

spinnanz

12th January 2012, 21:03

good posts, like seeing someones progress like this!

speedpro

14th January 2012, 14:09

Got the new gears fitted. Managed to press the gear off the old shaft and onto the new one using a big vice at my mates engineering workshop. There was a good selection of steel pieces with holes in the middle etc so easy as. Only been for one ride and not on the motorway. The NW motorway is all screwed up at the mo' so I'm keeping away. Just tootling along it seems about the same. Open the throttle and it gets going more or less the same. When taking off from an intersection from a dead stop it may be just a little slower but as soon as it's moving at say 15-20K it's all the same. I only had it up to 90Kmh and again it may have been doing a few less revs. I was accelerating so the CVT could/would/should have been pulled back increasing the revs to compensate for the higher gearing. It's good enough to take to work next week and I think it'll be good on the motorway, as long as the motor will pull it and the CVT adjust for it. Coming home on Fri it was full throttle at 90Kmh into a pretty stiff headwind.

speedpro

14th January 2012, 20:41

I've been for a ride down the NW m'way to Gt Nth Road and back. On the flat with a little tail wind it pegged the speedo without too much effort. The needle went to about 112Kmh but the scooter went a bit faster. It holds 100K quite nicely and isn't revving so hard and will accelerate to 110K nicely. Coming back it was into the headwind and would only do about 100Kmh full throttle but it held 90Kmh without too much drama. The gears seem to be a good modification. It's quite noticeable that the clutch gets a little bit more of a workout taking off. I never noticed at what speed it disengages when slowing down before but it disconnects at about 25Kmh now which I'm sure is higher than previously. It's only any sort of a problem in stop/start traffic, which isn't a problem because I never stop/start with traffic as I'm on a scooter.
I have the standard weight 9g rollers in the variator and I'm thinking I'll try some 8.5g rollers I have. I've been giving a bit of thought to how the variator works with engine revs and speed and load. The lighter rollers will mean the motor will rev a bit higher to counteract the ratio change brought about by me asking the motor to make more power which will move the rear pulley against the sheave effectively lowering the gear ratio. The lighter rollers will raise the revs at all speeds except when the variator is at it's highest speed position. Once the scooter speed is obtained where the variator is maxed out and the engine doesn't have the power to work the sheave against the force from the rollers, the rollers don't make any difference and it'll be down to engine revs and gear ratios. I wish there was a way of checking the variator and seeing when it topped out. It would need to be checked loaded and unloaded. I do have access to a dyno but it doesn't have a brake. Still, it might be useful to lock the variator in the high speed position and do some runs to see where the motor is making it's power and then do some runs with everything back to normal.
To think, I bought a 4-stroke scooter so I wouldn't be tempted to mess with it. Now I'm thinking of trading to a 180cc 2-stroke or something similar. I could really make one of them fly.

Sable

15th January 2012, 00:45

Good read. Do it! Stupid 4 strokes with those valve things

ICE180

17th January 2012, 19:08

great read

I have a 2t Runner 180sp with
172 head for higher comperssion
polini clutch
MHR racing varatior
PWk carb 24mm
Pm tunning expansion chamber
Racing stroke crank
Pm tuning bushes

The list goes on it is fun though when you turn up to a ride with bikes on a scooter and overtake them on twisty roads or chase them down

I just wanted a bit of extra speed for overtaking in the open,now I do DYO days at the drags and get 2nd overall to the disbelief of some harden drag peeps

keep up the madness love it

spinnanz

17th January 2012, 19:48

great read

I have a 2t Runner 180sp with
172 head for higher comperssion

my DNA180 could do with that motor!

speedpro

18th January 2012, 22:09

Took the scooter to work today. Sat on 100Kmh easy with traffic without sounding too busy. Accelerated just fine at pretty well any speed and pegged the speedo no problem. Cruised along from the bays up along Kepa Rd heading to Glen Innes. Sitting at the lights at the top of Apirana Ave thinking to myself how good the scooter was going when the light goes green. As I gave it a handfull to take off it hesitated just a fraction which got my attention and then got going fine. It had a few more really minor faulters going down the hill and then at about PaknSave the motor just cut. I've got it home, on the trailer, and have started looking at it. The starter motor has real problems turning it over but it spins fine with the plug out and makes a good spark. I wired the car battery in parallel with the same result. The starter motor really struggles. I put my finger over the plug hole and hit the starter and it blew my finger off the seat strongly. I've suspected, because of the noise returning, that the crank was floating around again and it has end float again so the loctite didn't last. My only real suspicion is that the cam timing has slipped somehow. It has been noisy but with a new chain and the tensioner only going out a couple of clicks I was thinking the noise was something else. Hopefully this lesson won't be too expensive. Full confession after the motor comes out tomorrow.

speedpro

19th January 2012, 20:57

Motor out, oil drained,?? what are those sparkly little chunks in the oil ??. Turns out the big end in the new crank has toasted itself. I think somewhere back in this thread I expressewd reservations about the rod as it had "GY6" stamped on it. I will fit the original crank over the weekend so it'll be back to 150ish.

I'll have a look at dismantling the crank. If a stock rod kit is cheap enough and long/short enough I might look at rebuilding it, or maybe a Pro-X kit.

speedpro

19th January 2012, 21:00

Post 17 refers to the rod, must have known something!

speedpro

22nd January 2012, 18:17

After having a good look at the crap in the bottom of the crankcases I have decided to hold judgement on the rod. What I think has happened is that the Loctite was unable to hold the bearings. It has broken out into the oil and made it's way into the bigend where it has done a job on the bearing. The oil pump is scoured and I'm guessing the other bearings have had flecks and chunks through them as well. I've put it back together with the original crank as I still can't see anything wrong with it. I'm using the big cylinder so the motor is about 150-155cc, I can't be bothered working it out. The piston had been roughed up a bit as well and there was a bit of alloy stuck on the bore. I've sanded it smooth and taken the alloy off the bore to the point where I'm happy with it. I assembled it without a base gasket to make up for the shorter stroke crank so the compression is back up there. Even with the new cam chain the tensioner now only has about 4 clicks left to go. When running the engine makes some horrendous noises. The only thing it can possibly be is the cases or more specifically the housings for the crank main bearings. I'm now checking out new cases from the USA or possibly a 2nd hand bottom end from NZ or Oz, though I'm wary of buying an engine with the same issues.

The other simpler option might be to convert it to chain drive with a reguler 2-stroke motorcycle engine in it. I had a look today and it wouldn't be all that hard. You just need a swingarm that pivots on the same place the current engine/transmission pivots and the new engine mounted on the swingarm so it pivots with wheel movement just like now. The hardest thing would be getting a suitable rear wheel and sprockets.

This is getting annoying and wasting my time. Does anyone know of similar issues with crankcases in other Yamahas?

speedpro

2nd March 2012, 11:37

I ordered the crankcases from the USA some time ago and got word yesterday that one is on order from Japan - yay!. The same one wasn't available in NZ either. The small crankcase cost more in NZ than I was quoted for both including freight from the USA.

If anyone knows where I could possibly get crancases a bit quicker I'd appreciate a call/msg. The commute is annoying and frustrating and expensive and a long time in the car.

Or another option would be a fix that doesn't cost more than crankcases and will last.

speedpro

30th March 2012, 19:38

Decided to have a look at the guts of the long stroke crank and see if there was a fixable reason why it stopped and got all hard to turn. The "Trimac" guys had an idea that the two flywheels may have squeezed together and be jamming the rod, which seemed reasonable whilst talking to them. We pressed the pin out about 1mm which completely freed the rod but it was still problematic so pressed it completely apart. It took about 4 tons to press apart which was a clue that it hadn't just squeezed up a bit. What a mess. The pin has major damage with serious brinelling and the rollers all fell out in pieces and the cage was mostly gone. Seeing the damage I've had another very very careful look at the genuine Yamaha crankshaft and there could be freeplay in the big end on that as well. I'll degrease it tomorrow and jig it up to measure with a DTI. General concensus is that with such a lousy oiling system ther ehas been some crap fed to the bearing which has wrecked it. Not many options there unfortunately. I will check the TKRJ and ProX catalogues anyway. The cranks only cost US$122 so it's hard to justify a rebuild and could be a really good excuse to get another (longer) stroke crank. Will need another (bigger) cylinder if I do that, and a cam, and a carb, and a pipe, and somewhere else to live when the wife finds out.

speedpro

2nd April 2012, 22:16

Rob at ESE pressed the Yamaha crank apart tonight. The pin has serious wear but the bearing seems good. It looks similar to the other crankpin but not as bad so it would seem that is where the noise has been coming from. It could be just the extended thrashing on the NW motorway but I really didn't expect a roller crank to wear so badly on the pins. I've raced old Z1s which have roller cranks and Honda MB100 2 stroke bucket racers and never seen the wear like in the Yamaha scooter.

So now comes the decision on what bore and stroke to make the motor. They go all the way to 288cc but that would raise a pile of other issues. Hopefully I can cancel the order for the crankcases.

speedpro

3rd April 2012, 19:22

Hopefully I can cancel the order for the crankcases.

They arrived today.

I also got an email from Brad at MrCycles replying to my email from last night. He offered to take them back if I didn't need them and noted that they had been shipped. Pretty good I reckon.

speedpro

17th April 2012, 20:19

I have to commute to Manukau every day now, 30Km each way. I was getting a ride for a week but that isn't happening any more so I have to get the scooter going again. I've ordered another +3.5mm crank and a bigger 65mm cylinder and forged piston. It'll be about 200cc so will require a bit of tuning to get right, maybe even a new carb. I'll set it up so it revs lower to hopefully make it last.

speedpro

27th April 2012, 23:00

Bits arrived from Taiwan on Thursday 26/4. I only ordered them on Tue 17/4. It looked like they put everything in a box and put about 50 stamps on it. It was going to be 2 weeks until they were sent but as I'd been emailing them about some other stuff my bits got bumped up the order. Great service, kept me informed and with the tracking number it was easy to follow.

The crankshaft is different to the last one. The new one is fully machined and "looks" a lot flasher. The machining of the spline looks a lot cleaner as well. Like the last piston this one is a very nice forging but strangely the cylinder has a steel sleeve whereas the last cylinder was chromed aluminium. Wish I could afford a good cylinder head but realistically I don't need it, I hope.

speedpro

28th April 2012, 20:23

It lives. I dummied it up to check that nothing was going to go "bump". With the low compression base gasket (thick) I couldn't get the cam sprocket onto the cam as the chain was too tight. With the high compression gasket (thin) I can just get it on with a real good shove.

It's actually hard to turn over by hand. Once together, and with some fuel tipped in to fill the carb, I hit the start button. I have discovered the next thing I need - a high torque starter motor. If I give it a couple of goes it will turn the motor over but it isn't a sure thing. I have to give the kick start a pretty good prod to turn it over and you definitely couldn't turn it by hand like before.

It all sounds good which is a relief after all the mucking around. A few good lessons have been learnt. I'll need to sort the jetting tomorrow and after a few miles I'll see if I can put it on a friend's dyno and check the timing as well.

speedpro

8th May 2012, 21:53

Done about 125Km on the new motor and it's running sweet. Still only using 1/4 - 1/5 throttle except for short bursts. I've just topped it up with Mobil 98 but it still pinks a bit I think though less than before. I'll try jetting it up probably this weekend and I'll slot the pickup mounting holes so I can adjust the timing. I've got the technique for starting it now. You leave the throttle completely alone and just let the starter motor struggle with it. If you touch the throttle it stops the motor turning and seems to flood it after which it needs to be turned for a while on the starter until it clears out and then it slowly catches and starts running. If I've messed it up and had to turn the motor for a bit, it quickly gets to the point where it won't start turning the motor when you press the button. In that case I stand on the kick start and then hit the starter. The combination is enough to turn it over and generally it'll keep turning until it fires.

The motor was genuinely tight to start with but it is noticeably freer spinning now.

speedpro

29th May 2012, 21:56

250-300K on it now. I've given it a good handful here and there only to discover that it is severely limited. General concensus says it is the exhaust primarily but it needs a bigger carb as well and ideally a new big port head and cam. I'm leaning toward a complete variator, pulleys and clutch upgrade as well. There are plenty of writeups extolling the virtues of aftermarket bits. I've dropped the timing back a couple of degrees which has stopped the pinking with the added bonus that it seems a little easier to start.
Stock pipe will be off this weekend and I'll spend a bit of time machining a new exhaust spigot and hopefully find a bit of pipe to use. I haven't decided to buy or make a muffler yet. I might possibly go for 2 pit bike mufflers stacked, very styley.

awa355

15th July 2012, 14:14

Just finished reading the complete thread. .

It's a credit to you and your perseverence. Most of us would've taken the easy way out and traded the scooter long before now.

speedpro

3rd August 2012, 20:13

I've finally stopped pissing round with other people's buckets and have yanked the motor from the scooter again. It only takes me about .5 hour now. Took the head off to have a look and it is all good. I fitted a piece of perspex with a hole in it to the head with the gasket still in place and measured the volume using a syringe and some oil. It is only 12.5cc. Taking into account that it is sitting on top of 203cc of swept volume and just taking the piston as flat that gives a compression ratio of 17.6:1. Possibly just a smidge high. I'm gonna take to it with the grinder and take out up to 8cc which will be about 11:1. The good thing is it will improve the breathing as well as lower the compression. The intake valves are badly masked around their outside edges so I'll open that right up. The exhausts are nearly as bad. It will affect the flow pattern big time in the cylinder with intake charge coming from both sides of the intake pair rather than more or less just from the cylinder inner side. I intend to leave flat sections where they are now to promote turbulence towards TDC so it shouldn't be a problem, though I may reduce their size if I run out of aluminium to remove from other places. Might see if I can take a picture showing what I mean plus for a before and after comparison.

speedpro

4th August 2012, 19:11

Been busy. Compression is now about 13:1 which is about as low as I can take it with just grinding out the head. The black circle outside edge is the size of the new bore. On the modified combustion chamber the black parts are untouched flat portions forming squish areas similar to the original chamber. I've advanced the ignition timing to stock and taken it for a thrash. It handles full throttle now but is still flattish. To be expected with the small ports etc. The valves look quite small in the modified chamber I think. In the original photos you might be able to see how badly shrouded the valves were originally.

speedpro

1st October 2012, 20:30

Things have happened and I've decided to sort it out properly. US$399.60 has been sent to Taida and a new cylinder head with big valves, big cam shaft and grunty starter motor is on the way. I'm going to order a 30mm PWK carb kit from Jiangwayne. The kit comes with everything including a new throttle cable and a selection of jets and a new intake manifold - US$149. I'll weld up some sort of exhaust for it. If anyone has a 250cc scooter muffler they want to get rid of PM me. I want to keep it quiet and discrete.

speedpro

8th October 2012, 20:15

3rd October, sent payment, got email back with photos of goods and documents.
8th October, parts on doorstep.

Carb is machined a bit funny but is still workable. Manifold has a sharp change in direction on the inner radius which I'm going to fix. The original Yamaha intake manifold was hand finished and was nicely curved. All the new bits are 3-4mm larger diameter so should flow heaps more on a suitably sized port.

speedpro

10th October 2012, 21:43

I've started looking at how to run the new throttle cable. So far it has eluded me how to remove enough front panels to run the cable in place of the original one. Even getting the throttle apart to attach the new cable is a mystery. If anyone can help with a diagram or instructions I'd really appreciate it.

Got a note from customs today. They need $132.57 before they release the new head and cam. $94.50 GST, $22+GST import transaction fee, and a biosecurity levy of $11.10+GST. The GST is on the goods plus freight so thats added 15+% to the cost for . . . . . . . . . not a lot. I suppose we have to protect that local spare parts industry.

speedpro

13th October 2012, 18:52

It felt like Christmas this mornng. Big box of goodies arrived. As I expected the hardest job has been running the new throttle cable through the frame and cables behind all the plastic. I pulled most of the panels off to get access and even then needed help from my son. The engine could be back together tomorrow and back in the scooter. I can't fit a thicker base gasket in and without measuring it I think the compression will be a bit higher with the new head.

The bits look good though. Nice big valves and decent ports.

speedpro

15th October 2012, 18:47

New motor all together and fired up nearly straight away. Ran sweet from the start though I am using the stock exhaust at the moment which has a much smaller pipe than the port. I've taken it for a quick squirt and it's sooo much better. The only annoying thing is the noise from the carb intake as the filter doesn't quieten it much. I'll give the original airbox and connector a try after I have the new pipe fitted. The throttle is sweet and I'd say it is marginally rich towards full throttle. It pulls to 80Kmh easy up a reasonably steep local hill and shoots to 100kmh on the flat. I thought it was running sweet accelerating around 80K and then the it came on the cam. Even the variator seems to be in the ballpark for thrashing round the block sort of riding. If the exhaust is as restrictive as I've been led to believe for larger motors it will be real interesting to fit a free flowing pipe.

speedpro

17th October 2012, 21:20

First short run on the motorway today. Quiet run at 80K to Royal Road on the NW motorway using hardly any throttle. Coming down the on-ramp back to Lincoln Road I gave it a squirt and it was up over 100K halfway down the ramp. Took it back to 90K and cruised back with the slow cars. It'll handle taller gearing easy and I already have "up gears" fitted which are about 10% higher gearing. The carburation is faultless as far as throttle response goes. If it's moving it does whatever is asked with no hiccups or staggers. Even from a stop at lights I can just nail it and it leaps away which could be expected I suppose considering it's 200cc with good ports, carb, cam, and a variator transmission geared for only about 120K tops.
Hopefully I'll get some time in my mates workshop this weekend and come up with a better exhaust then I'll check the jetting. I wonder just how bad the standard exhaust is considering how well it runs now.

I've been thinking this setup would make an awesome bucket sidecar power plant though the engine would have to be smaller and some support would be required to handle the loads when cornering.

speedpro

28th October 2012, 12:24

Put it on the dyno. As it was it only made 11.?hp but over most of 70-120Km/h.
It did seem rich just going by how the graphs looked so dropped a jet size. Immediately picked up 2hp.
Dropped another jet size for another hp and the same again.
A further jet made no difference so back to the previous. We suspected the pod filter may be restrictive so did runs with it off and it definitely picked up .25-.5hp. Then we tried a couple of velocity stacks which showed promise but none were long enough.

It's making 15.?hp now pretty well between 70-130km/h which was the only range we were checking on the dyno.

There's clearly something holding it back looking at the graphs which is most likely the stock exhaust complete with the catalytic converter so that puts the pressure back on to finish the new one.

The stock transmission seems pretty good. It picks up nice and holds the motor off maximum revs until about 100-110km/h when the transmission maxes out after which the motor revs further until it pops on the limiter at 130Km/h - on the dyno at full throttle. I'll have to check which rollers are in the variator as it seems it will pull heavier rollers without too much fuss.

Riding back home it is definitely perkier and much happier at full throttle. The intake noise is getting really annoying so I'll have to look at an airbox or something and include a velocity stack.

speedpro

3rd November 2012, 20:26

I've finished the pipe and have the new muffler fitted. Now it really does bark. It sounds really similar to a bucket racer FXR150. We actually compared it side by side to a 20+hp one today in the workshop. It's running lean at larger throttle openings now so should make more power when a bit more fuel is tipped in. Photos to come.

speedpro

4th November 2012, 15:54

Nice looking pipe, shame it doesn't work.

I've gone up in the jets to the point where it really didn't want to know and it simply doesn't work. Possibly if I could clutch it and get it over the stumbles it might be OK but with a CVT transmission it isn't an option. I will try a few extensions to see if it simply needs to be longer but I think I may need to make another one.

I put the original pipe on and went back to the smaller jet we figured was best on the dyno. It runs sweet. I gave it a squirt on the NW motorway and it pulled 110Km/H easy peasy.

I'm thinking the exhaust needs to be freed up but not tuned at all as if there's a dip in torque the variator won't let the engine get over it.

speedpro

18th November 2012, 21:26

The new starter has always seemed to kick off well but if the engine didn't catch pretty well straight away it then struggled. I added some new hefty wiring in parallel to the existing starter circuit from battery to solenoid to starter motor and paralleled the ground wire from the battery to the engine. It "seems" to spin a little more energetically and this arvo when it didn't catch straight away a 2nd push of the button caused it to turn faster than previously and it fired up fine. No way of measuring it but it seems to start better.

I took my son to town for a look at Motomail on Saturday. We cruised in at a steady 90Km/H until we came across a few cars really crawling along. With the traffic in the middle lane I needed to speed up to merge without causing a disruption. A bit of throttle saw 110Km/h easy. On the dyno it was hitting the rev limiter at 130K and I'm reasonably confident it will pull it even with the stock exhaust.

Off topic - Motomail have an Aprilia 850cc scooter which makes 75hp. Supposedly it will do 200Km/H. Cool looking bit of kit.

speedpro

23rd December 2012, 17:01

Dead flat bit of private test track, no wind at all, and it pulled round to the "oil change indicator" no problem. Just changed the oil, Mobil1 4T, and loosened one intake tappet a whisker. I've taken it to Manukau to work and back to Henderson recently. Just cruised along at about 90K without any problems, just taking it easy.

One little issue I've found is that in the new road works going to Maioro Rd where it's only one lane the traffic really crawls. It isn't always possible to sneak past and I just have to stop/start creep along with the cars. It gets a bit ragged as the clutch takes up and I figure it's getting a bit overheated with the continual slipping. The stock lower gearing would probably be better in this situation as the clutch could fully engage at a lower speed.

I've had a good chat to someone that knows "stuff" about this style of engine and I've got some good pointers for the exhaust. That'll be a little project once I'm back from holiday.

frogfeaturesFZR

25th December 2012, 04:25

Good work !:2thumbsup

speedpro

19th February 2013, 21:12

Awesome weather for scootering. I'm taking it to town to attend Tribunals lately. SOOO much easier to get out afterwards especially if it's a bit close to 4 or 5pm. The thing is running great even though it still has the standard exhaust on it. Me and my boy have been to Kohimarama for gourmet burgers a few nights back for dinner. Good fun blasting back down the motorway. Quite funny how cars merging in have to get in front and then travel slower than I was going. Zipping past with the speedo pegged past the oil change indicator is a bit of a laugh. Met a Harley type just off the motorway at Te Atatu turning towards Henderson. Did the usual leap away from the lights only to be passed 50m down the road in a blast of sound and smoke, only to pull up beside him at the next lights. Process repeated and looking at a repeat at the next lights by the Caltex but he ran the red. You have to laugh.

speedpro

15th March 2016, 20:48

Hard to believe it's been so long. The scooter has been running great but on the way to work last week the belt finally let go after about 12,000K. New belt and new 10g rollers in place of the standard 9g rollers and away we went again. The 10g rollers pull the revs down nicely and the 203cc engine seems to prefer it. 95-100Kmh cruising is effortless going to & from Manukau down the SW motorway and the crawl through the back of New Lynn seems to be less hassle on the clutch, possibly because of the lower engine revs though the clutch rpm should be the same at the takeup point. It has developed a sort of flat spot which seems to be carburation, probably move the needle one notch. I never noticed it before with the 9g rollers as the motor jumped to higher revs past the stumble. It isn't a problem and the speedo needle continues to scoot around. It seems to get better fuel economy as well though it is a bit early to tell. I'm pretty sure the fuel gauge didn't dive as far as usual on the trip. Possibly the 9g rollers were letting the motor rev past the ideal engine speed as I actually prefer it with the 10g rollers. I'll put it back on the dyno and check it out

speedpro

16th May 2018, 20:21

It had to end.

It stopped when my son was riding back from Uni. Probably the crank again but I can't be bothered checking.
Just got a box of stuff from RC Scooters today.

Big list including +8.8mm crank, 66mm cylinder with forged piston, most of the transmission, oil cooler, heat sinks, roller cam with 2mm more lift. Out to 229cc when together. I'm sticking with the Taida 24/22mm valve head. The crank is a good looking piece, fully machined and with a pretty serious looking forged rod. Chris from RC says it should be good for 11,000rpm so should be fine at the standard redline. Just a bit of machining to do to fit the cylinder to the cases and a missing bit to come and we'll be away.

It barked pretty good with the old 5mm lift cam and my homemade exhaust. I'm thinking with the new cam I'm going to have to quieten the exhaust.

speedpro

2nd June 2018, 17:31

Some machining done to fit the cylinder to the cases and a bit of unpacking and assembly now going on. Gotta find someone with a valve spring compressor so I can fit the new valve springs. Oil cooler not shown. It's going to be fun finding somewhere to mount it

speedpro

2nd June 2018, 17:34

Lovely little piston

speedpro

18th June 2018, 22:14

Making slow progress. Had to grind the head as the cam lobes are so big that the cam chain side lobe got jammed against the head and stopped the cam lining up the bearing at the other end with the bearing pocket in the head. Then the valve springs are a bit fatter, and heaps stronger, and touched on the inside of the head. I took to the head again with the die grinder. While I've been messing with the head it became obvious with the valves removed that the ports were terrible. Turns out that a lot of these heads have lots of meat left in them for tuners to work their magic. I've done some work, not sure about magic but the ports sure look and feel better. The intake manifold was equally terrible so I fixed that as well.

WALRUS

19th June 2018, 10:20

Weird.. I've got a 2008 NXC125 (called a CygnusX over here) and I've not had any dramas like this with it. I've had a coil pack in and the ignition barrel has broken on me (some solder broke and wouldn't complete the circuit properly) but nothing mechanical, which is surprising considering the life it's had.

It used to be owned by someone who refused to look after, maintain, or service it. After that it was used for paddock bashing and general drunken shenanigans at festivals, now I've ripped the airbox off it and put on a "sports" exhaust and a handful of obnoxious cosmetic "upgrades" and it gets thrashed pretty much everywhere (even the odd trackday, for shits and giggles). I've not had any mechanical maladies..

I hope you get yours sussed out soon!

speedpro

27th June 2018, 19:33

CygnusX is what this is.
The thrashing this thing got was for extended periods down the motorway, sometimes from the city to Te Atatu offramp, 10-15 minutes with the throttle pinned.
Anyway, motor is coming together. Took a few photos of various bits, in this case the cams and rockers. The smaller cam is a Taida T6 so a bit of a hotup part which worked well with the 203cc kit. Compare that to the new cam, lift and duration. Matching rockers in the other photo. The Taida rocker is a step up from the standard ones and as you can see the new roller rocker is a big jump up from that. Lift is going from 5.1mm or 5.2mm to 7.?mm or roughly a 40% increase in lift.
The crankshaft is a neat fit in the cases. Not a lot of room to go bigger.

husaberg

27th June 2018, 20:19

speedpro

28th June 2018, 22:03

It's the sequins I don't like

speedpro

20th July 2018, 19:57

Engine is together and in the chassis. Trying to find where the oil cooler goes is a mission. Surprisingly little spare room. Have also ordered a new Mikuni TM33 pumper carb. That should perk it up good and proper being about a 40% increase in size and a proper carb. More work to fit that as well. I'll build a custom intake manifold, then we'll cut chunks off the underseat storage until it can be fitted. Once sorted I'll need to seal up the underseat area again.

Link to carb: https://www.mikunioz.com/shop/tm33-8012-33mm-tm-mikuni-carburetor/

Had a good chat to the guy on the phone. Very good to talk to. Very quick service as well. Paid for the carb online at about midday and had a message from the couriers saying it was on it's way before I left work.

Interestingly the pumper TMs are completely different to the non-pumper models. Different jet types, different slide mechanisms.

speedpro

25th July 2018, 20:21

Dropped at work this morning, thanks mikunioz.

speedpro

4th August 2018, 22:15

Ran it with the oil cooler line looped back just to check the engine for leaks. It was in the chassis so seemed a good idea. It seems pretty perky, and we all like it when they are perky.
Got it back out now to fit the new belt, manifold, and throttle cable that we got from Webike in Japan. I was scrolling through the site and discovered a manifold that's 32mm at the carb and 28 at the engine. Unfortunately the carb mounting rubber thingy is a bit tight and the carb doesn't fit securely but a proper 33/40mm mount from Mikuni will sort that out. The pictures show the manifold and carb mounted in the conventional manner. I will make an adaptor to raise the manifold 10-20mm and rotate it towards the left of the bike so it is on the other side of the cam chain tensioner. This will require less to be cut from the bottom of the seat storage plus the air filter will fit on the left side more or less where the standard filter housing went.

speedpro

1st September 2018, 22:08

It's all together and we've been riding it around. It gets happy at about 60kmh on the speedo. The clutch takes up nice once the revs come up. It takes more revs to engage initially but then seems more or less the same as it used to be. I do think the clutch disengages at a lower speed than it used to which is odd considering the difference in revs for it to engage. It pinks with more than about 50% throttle at certain revs. The carb seems pretty good so I'm looking to put the Ecotrons ECU I had for my turbo FZR125 on it but just to run the ignition. I'm pretty sure the teeth on the rotor are the same as the FZR arrangement so it should work and I'll then have a tuneable ignition advance.
Had a little ride from Glendene to Rosebank Road and then back on the motorway to Lincoln Road. 80Kmh on the motorway was a breeze and even 100kmh was probably less than 25% throttle. A quick flick to 50% saw it jump past 100kmh real quick. Supposedly the engine is good for over 11,000rpm rather than the standard 9,200rpm. With the Ecotrons ECU I can increase the rpm limit easily. This variator has an overdrive pulley set. with the original set and the taller gearing it hit the rev limiter at about 135kmh, measured on the dyno, and would happily do this over the causeway. With the overdrive it should do 140kmh and if I add 20% to the engine revs it'll go faster than I'd want to.

caseye

2nd September 2018, 15:20

Curious as all hell now, come on pics or it aint happened! Insane, but bloody good fun I'd wager.
:yes:

speedpro

4th September 2018, 18:47

I'll see about putting a gopro on it this weekend but have attached a picture of the underseat storage in the meantime. there was nowhere else to put the Mikuni. It's just a bit bigger than the original 25mm CV carb

speedpro

16th September 2018, 18:59

So funny. Another little trip down the motorway from Rosebank Road to Lincoln Road. Seems there is a road rule I was unaware of that says if you need to exit at the next off ramp that you need to be in front of any scooters on the motorway. One pushed in and another was looking to follow. A quick squirt saw the speedo past the oil change light and me 4-5 car lengths ahead in a space between cars. Both guys came down Lincoln Road and were looking to be somewhere near so I split to the front at the lights. At the green I gave it a bit of throttle to make sure I was clear of cars and totally unexpectedly the front came up and only went down when i closed the throttle about half way across the intersection. So much fun.

speedpro

30th September 2018, 21:06

It gets better with distance. Beautiful day for scooter ride so did the loop Glendene, Rosebank Road, Lincoln road and back home. Along Gt Nth Rd snuck to the front at the lights. Took off sharpish to get away from cars and the front came up, closed throttle to put it down and then opened it again and the front came back up.
110-120K(oil change light) is about 1/2 throttle and easy as. It does pink hard in certain circumstances so I really need to get the Ecotrons ECU fitted so I can programme the advance. Spent time today making an enclosure around the carb under the seat. Just need the lid now and we can get back to using the underseat storage. Can still fit a helmet under there as well. I want to fit a bung to the exhaust for the lambda sensor and then we'll have a look at some dyno time.

speedpro

9th October 2018, 18:41

Tried getting the Ecotrons ECU to work in the scooter. Managed to get spark but couldn't change the timing using the standard Load/RPM table. Also had problems with it connected to the scooter battery and scooter ground. My ECU was one of the range that had contact between the leads on the board touching the case. Despite giving me the run around for a year denying there was a problem I finally figured a cure by completely isolating the case from ground. Later I trimmed the wires so they didn't touch.
Anyway, i can't be bothered struggling with it any longer and will fit my Ignitech DC CDI and feed the MAP signal in on the TPS input. It should work OK but I'm thinking will need a bit of smoothing. I'm hoping to use a 3D map with the variable MAP signal being used in place of the variable TPS signal, versus RPM.

speedpro

15th October 2018, 21:03

Hooked the Ignitech up and ran it. I can map it OK and adjust the timing. The MAP siganl bounced around way too much to use so i pulled a hose off my vacuum gauges which has a little restrictor in it to stop the gauges fluctuating too much and that cured it nicely. Still using the standard ignition at the moment but should be able to get it fitted in the long weekend coming up.

Oh yeah, damn, pesky speed cameras. Must have been parked in the church carpark just heading out of Henderson up the hill.

speedpro

22nd October 2018, 20:10

first - that speed camera is a new fixed jobby. From the lights it sits behind a "school" sign and isn't obvious.

Ignitech is in and running the bike now. Set the idle timing to about standard and just added some advance as it revs. I haven't enabled the TPS/MAP input, just keeping it simple at the moment. It may be just a whisker harder to start but runs fine once fired up. Blips clean from idle which is 2000rpm and I think I'll add a bit of advance to make it real crisp. I've tried big throttle settings and the motor is a lot happier with no sounds of pinking. I'll add a bit more advance through the middle until the noises start up again.
Ideally I'll be able to get it on a dyno. At the moment i have 10g rollers in it which seem to work fine on the road but for the dyno I'll put 12g rollers in so the variator tops out as early as possible. Then we will be able to see the power the motor makes at certain revs which is what is needed. It might even be worthwhile making some heavier rollers to max the variator out even earlier in the revs.
Taking off from an intersection it isn't too hard to make the front feel light. It's the wrong word but the motor is feeling a bit "lazy" so I'm expecting good things once I get the timing right.
The plug is looking text book light tan so the jetting is not far off at normal riding speed.

speedpro

5th November 2018, 18:00

Still not seen a dyno but have given it plenty of full throttle runs. Got it so I can consistently hold it with the front light away from traffic lights. Have also given it a good full throttle burst and it went off the clock real quick and just kept going. I wouldn't say it is a lot quicker than the old motor, it's real hard to tell with the variator and the spread, but I suspect it's making good power, for a scooter.

speedpro

7th November 2018, 20:48

Arranged some dyno time at ESE on Saturday arvo and thought I'd swap out the 10g rollers for the 12g rollers. Took it apart and looked for the 12g rollers and couldn't find them. A couple of the boxes of rollers I got with the new transmission kit were 3 of one weight and 3 of another. Turns out I had put in 3 10g rollers and 3 12g rollers that were in the same packet. I've now replaced the 10g rollers with 11g rollers so not much of a difference but as good as I can make it for the dyno.
Looking at it now I can see how it would be even quicker accelerating with a lighter set of rollers. It is quick even with the 2nd heaviest combination I had. Going lighter and letting it rev harder should be a real giggle. My son is taking it for a ride tomorrow with the 11g & 12g rollers in it. Will be interesting how it goes, especially at lower speeds like 50kmh

speedpro

15th November 2018, 20:45

On the road with the heavier roller combination it is a bit slower away from the lights. Once moving there isn't much difference, evidently. On the dyno the plot is very jittery and very difficult to determine a change. We played with the timing and ended up with a few more degrees from 8000rpm up. I took 1degree out after my son rode it on the road and he thought it pinked pretty good at certain revs and throttle.
On the dyno the change that was really obvious was when I refitted the 10g/12g roller pair. As the throttle was opened from about 40kmh on a run there was a significant increase in power as it ramped up. Once at full throttle and spinning the roller up there was little to tell between the 2 setups.
Theoretically with the lighter rollers the engine would rev harder at the exact same speed and the CVT would obviously be at a lower ratio. This seemed to be born out on the dyno with the engine limited to 8000rpm on a run with the 11/12 combo and sitting on 8500-9000rpm with the lighter 10/12 combo.
I bumped the rev limiter up to 10,500rpm. This had the road speed going out to 170kmh on the dyno. It's very unlikely on the road for 2 reasons - it's not really making enough horsepower, and I'm not that stupid.
The horsepower tailed off as the speed went up. I figure this is due to inefficiency in the CVT transmission. The transmission case gets too hot to touch in use so it sort of bears that out.
We also tried a jet up and one down. There wasn't any real obvious difference. I will fit the Lambda meter and see what fuel ratio it is actually running and just tune for what is typically a good power setting, something around .8-.85.
I tried giving it a handful from stopped on the dyno but it just spun the tyre and wanted to go sideways, hence doing runs from 40kmh.
Back at home and I've been out riding. It does seem a bit more frisky, licence losing frisky. It launches off the lights and even with the speedo pegged it keeps on going real good. Not 600 good but OK for a scooter. I've also given it a couple of degrees extra advance around 2-4000rpm and it is back to being real perky when blipping the throttle. It'd be hard to mistake it as standard for sure.

speedpro

19th November 2018, 21:08

Lambda meter fitted and taken for a test ride. All warmed up at idle it is sitting on about 11:1 so a bit rich. Next time the carb is out I'll wind the idle air screw out 1/4 turn. Cruising around suburbia at 50K it's sitting on about 10:1 so proper rich. A touch of throttle and up to 60K and it drops to a more respectable 12-13:1. This is probably the reason it's so snatchy right down low, that transition from real rich to less rich when it perks up nicely. It's at hardly any throttle so probably a combination of idle air and pilot jet. On the motorway at a steady 80-100 it sits around 12-13:1 as well. Full throttle sees it moving around a bit but still on the slightly rich side so basically I don't think there's too much to do. I'll look at putting it on the rolling road I built and run it at a stable speed and load and see where it settles. One interesting thing is how lean it indicates when you close the throttle. Even at only 60k it goes full lean, something over 20:1 and as the revs drop to close to idle speed it jumps back to rich. Same on the motorway, closing the throttle fully and it goes super lean. Easing off it just varies about a bit. Probably because the main fuel source - main and needle, are closed leaving only the idle and pilot jet supplying fuel. With the motor still turning quicker than idle it manages to drag in air but not so much fuel.

speedpro

3rd December 2018, 17:56

Time ran out and I never got it on the rolling road so I've only made adjustments to the idle mixture. When I checked the idle adjustment on the carb it was 1 turn out from bottomed. This idle adjustment is for fuel not air so I gave it a 1/4 turn in. The AFR went to 12-13:1 so looking good. The only problem is that when giving it really small amounts of throttle it was going lean, really really lean. I turned it back so it was only about 1/8th of a turn in and this seemed to work OK while still making it a bit leaner. I still wasn't completely happy with how it felt so went back to the original setting. It was here that I checked how far off bottoming it was and found it was 1 turn out. The instructions say it should be 1-3 turns once adjusted. I have a few pilot jets so will try one smaller and make the adjustments again. It might make the progression just off idle a bit better. It still barks when you blip the throttle but i haven't ridden it on the road yet so don't know how it takes throttle if I have it leaned off. The WOF is due which will be interesting.

speedpro

15th December 2018, 17:28

That didn't go so well. Bit noisy, even with the decibel killer insert, the throttle cable a bit stiff. Cable is all sorted and the stock muffler is all but refitted. With the taller big block none of the mounting holes line up so the pipe has been cut and I now need an adaptor to fit over the cut ends and join them up. The header pipe is way smaller than the port but I ran it like that with the last motor and cam. Be really interesting to see how it goes.

speedpro

22nd December 2018, 18:08

WOF all sorted. Son had ridden with the stock muffler and reckoned it went OK. I just got back from a ride and it is OK. Did my usual test loop to New Lynn, Rosebank Road, NW motorway to Lincoln Road and home. Pretty happy puttering about at 50-60k though it feels richer than ever. Launches off from the lights but I'm guessing it is missing a bit as it doesn't pick the front up like it was. On the motorway it was no problem getting the speedo round to the oil change light and just cruising happily at that. Giving it a handful resulted in a bit of pinking. It might be more obvious as it isn't being drowned out by the exhaust. It also might be worse because of the restrictive stock pipe. The header is at least 2-3mm smaller diameter than the port. As OK as it is I'm going to put the other pipe back on but leave the decibel killer fitted as it knocks the noise right down with no obvious detriment to power.
It's a bit of a "stealth scooter" as my son has called it. Nearly as quite as stock but still goes like the clappers.

speedpro

23rd March 2019, 19:55

Starting has slowly been getting more of a problem. The starter one-way clutch was slipping worse and worse. I had a look and it was past it's best-by date for sure. Another one was ordered and when it turned up it wouldn't go on the boss in the crankcase that it rotates on. There's a roller bearing that goes on a hardened sleeve on a boss in the crankcase and the starter cog rotates on that. The trouble was that the boss the bearing was supposed to fit in was something like .15mm smaller than it should be. As is usual with bearings it looked hard, as in hardened. Anyway, chucked it in Kev's 3-jaw chuck and checked runout. It was only .02mm so we decided to not mess trying to get it better. The whole thing is not that precise anyway. A new ceramic bit was fitted to the boring bar, speed 1500rpm, and away we went. Very impressive cutting hardened steel at speed. Took it out to precisely where Kev thought it would work and ended up with a very nice finish. Good enough finish for intermittent use anyway. Brought it home and fitted it together and it works great.

Seems I might not need that new battery that is now on the way.

speedpro

1st April 2019, 16:37

Went for a ride in the weekend with my son on his Yamaha Scorpio. He followed the whole way up through Swanson to Taupaki and then Blossoms Cafe. The Scorpio is good for 18hp(claimed) and he was saying the scooter walked away from him in places despite him being in the right gear and giving it a handful. He's done a bit of racing so knows what you need to do to get along. He doesn't weigh much either so all the better. Away from lights on the way to Swanson he reckons no way he was staying with the scooter. No surprises really.
Starting is way better with the new clutch and gear and it still goes off the clock plus a decent bit more so it's still fun to ride.

frogfeaturesFZR

3rd April 2019, 17:03

speedpro

7th April 2019, 09:36

Page 5 has a lot of the new motor bits on it. Otherwise the scooter looks pretty normal except the exhaust and the oil cooler

speedpro

4th June 2019, 07:16

Scooter is going good and it was a nice day yesterday. Out for lunch with my son. Quick video of throttle and speedo, private test track etc etc

https://www.youtube.com/watch?v=2yVU_WdTlaU&t=2s

speedpro

15th June 2019, 11:23

Small problem with muffler let all the packing out so had to fix it and repack. Noticeably different tone and a bit quieter with the fresh packing. I put the little end piece in as well to quieten it even more. My son has taken it into town and back and was saying he thought with the cooler weather that it may have been going better than before which is what I have been thinking as well. Speedo able to be pegged down past the oil change light no problem evidently. May be time to put the Lambda meter back on and check the full throttle readings. Probably should sort out a smaller pilot jet as well.

speedpro

23rd June 2019, 10:41

Got a bit of time so had the carb off. It already has the smallest main jet I have in the range. I do have smaller but they are 4-5 steps smaller and I prefer to sneak up on things. I did put in a smaller pilot jet and unwound the idle mixture screw 1/2 turn. Still starts easy but noticeably the idle is a bit lower and rougher. I need to make a very short screwdriver to get to the screw as it is on the bottom of the carb throat where it enters the engine. On the scooter it is a close fit with the cases, see the attached photo. Being on the engine side of the carb the screw is a fuel screw, winding it out adds fuel. On the air filter side it would be an air screw.
I took it for a ride to be sure it was still good and didn't have a stumble off idle. No obvious problem with fueling but did have a couple of little problems at lights. I snuck to the front at one set and gave it a handful on the green. There must have been a slightly damp patch as the rear spun and launched sideways, just like it has on the dyno. At the next set of lights I didn't give it such a sudden handful and was most of the way across the intersection before I got the front back on the ground.
Must say I prefer it now that it is a lot quieter. Even giving it throttle the noise is reasonable and I haven't noticed any real drop in performance. Power wise it is still happy on the motorway with the speedo pegged with plenty of throttle to go.

speedpro

28th June 2019, 19:36

It's good having a bit of time off and being able to play with things at leisure. I've made a 10mm long screwdriver from a 6mm bolt by filing the end of the bolt into a screwdriver shape. Works great. I also fitted the lambda sensor to see what fuel ratio it liked and also to confirm what I said about the screw adjustment. The screw adjustment is quite sensitive. Even with the smaller pilot jet it was still a bit less than 1 turn from bottomed at the ideal position. I went down to the next jet and adjusted the screw to 1.5 turns from bottom. Once back together it fired up after a few cranks getting fuel back in the carb and settled down nicely. It was sounding rich and the Lambda meter confirmed it so I screwed it in until the meter said it was in it's happy place. Less than 1/2 turn had it indicating about 14:1 and the idle getting a bit uneven. At idle it seems to like about 10:1 which is attained with this jet when the fuel screw out just over 1 turn from bottomed. Not road tested but it responds to throttle OK and the Lambda isn't jumping about too much apart from when the throttle is snapped closed and it goes lean until the revs drop.

speedpro

9th August 2019, 18:25

Damn.

Scooter came home on the trailer today. Son took it to Uni, lectured cancelled, came straight home. Possibly going a bit faster than usual down the NW motorway. Made funny squeeking noises as he went up the Te Atatu turnoff and stopped at the top. No compression when tried starting it.

speedpro

10th August 2019, 19:58

It's toast.

There was a small oil leak from the crank seal behind the variator into the transmission cavity and out the back. Oil level was real low, and it got real hot, then it stopped. It's completely wrecked inside.

So, does it get rebuilt, binned, or something else?

Parts are being costed as I type.

speedpro

25th August 2019, 21:59

Decision made. Same bore and stroke but with a slightly bigger cylinder head running the same cam. Cylinder is watercooled, head is left on it's own for cooling. The fan will be removed along with all the shrouds. Supposedly it's all good like that. Just got to sort out a radiator and pump and fan and controller. Looks like it is going to have to be under the seat in the storage compartment but we'll see once it is together. More power :drool:

speedpro

9th September 2019, 13:58

Box of interesting bits has arrived at work. Almost pulled a "sicky"

sidecar bob

9th September 2019, 17:09

Here's an easy to source 12v water pump that could be useful in this application.
Every '90's 5 & 7 series BMW had one.

speedpro

10th September 2019, 12:22

Pump all sorted thanks. I went with a Davies Craig EBP15. Brushless Bosch motor and magnetically coupled. 1.4A current draw depending on load so should be manageable.

speedpro

11th September 2019, 10:43

Interesting the bits that have arrived. The watercooled cylinder has had a jacket welded on over the fins which I wasn't expecting. I've been there so it really doesn't worry me.
The crankshaft is the same as the old one but has an even longer rod. The old rod was 97mm long and the new one is 103mm long. The cylinder is very slightly shorter than the old one but there is a spacer plate and 2 gaskets to go under it making the whole thing even taller. 6mm taller probably. There is less stud poking out the top for sure. The problem is that even though I had a longer cam chain for the last motor the extra height requires an even longer camchain which I will need to get. Unless it is packed in with the long stud set that came with the motor which we haven't opened yet.
The cylinder head is apparently a blank canvas with metal left in to be removed by the tuner. I'm going to have to dismantle it to remove metal from the valve pockets and to blend the valve seats into the ports. The intake valves are up .5mm at 24.5mm but the exhaust valves are down .5mm at 21.5mm as compared to the old Taida head. The exhaust port is a good 1.5mm smaller diameter at the gasket face. I've asked if that is the hot setup or if they have just shipped what they had on the shelf. The motor went real good with the Taida head and from experience I can't see smaller valves making it go better. As usual all the bits look real good. The little 66mm forged piston is real nice.

speedpro

30th September 2019, 20:59

Okay, bits have been dummied up to get an idea of clearances. The flat perimeter of the piston to the matching flat area of the head is 1.2-1.3mm clearance which seems fairly generous to me. This is with both base gaskets and the spacer plate and a used head gasket. The piston has reasonably sharp edges around the valve pockets so I'll be removing those edges and smoothing it out with wet&dry. The head needs lots of work. As you can see in the photos the valve seats are sunk into sharp edged pockets. I'm no expert on the desired combustion chamber shape but I'm going to be unmasking the valves and blending the pockets into the chamber. I'll leave as much of the flat head gasket surface that protrudes into the chamber as possible. This will aid turbulence and keep compression up. Retaining turbulence will speed combustion and reduce the need for ignition advance both of which are good.
The intake port on the head has an angled cut centred on the manifold mounting studs. The outer diameter matches my adaptor I made. I'll be taking the port out to match the outer circumference.
The exhaust port is small. There is a lot of aluminium that could be removed. Unless there is something crook with the exhaust ports which becomes obvious when I remove the valves I won't be taking much out of the port. It seems like giving the small port a try won't hurt. I am however mindful that a while back Chris of RC Scooters did mention that they use heads with 26mm & 23mm valves but I think that was on their race motors. This head has 24.5mm & 21.5mm valves which seems like it might be a better option for the street. I certainly had no complaints about the Taida head with 24mm & 22mm valves.
I've thrown in a photo of the connections for the oil cooler.
As much as Chris maintains that the head will be fine with no ducted cooling going to it I'm having problems with the idea. Chris says they have been running motors with watercooled cylinders and no fan or ducts for years with no problems. Maybe I'll clamp a CHT sensor on and monitor it with a Mychron date logger. I do have a fan controller with oil and water temp sensors so will be able to keep an eye on things. No logging unfortunately but may be able to run a sensor to the Mychron and log it that way.

husaberg

30th September 2019, 21:05

speedpro

30th September 2019, 21:07

Couple more photos. the crank and head are SD branded and the piston is FJN. Everything seems pretty good quality and nicely finished apart from the previously mentioned porting and piston surface.

speedpro

30th September 2019, 21:18

Is there only two squish areas rather than 4 on that piston head combo?

More or less. There is just a small perimeter each side with matching flat surfaces. With larger valve sizes for the given bore having a squish area between exhaust and intake each side would mask the valves I would think. The only time it wouldn't be masking the valves is if the valves were at a very shallow angle and the valve seats were more or less in line with the flat plane of the head. Then as soon as the valves lifted they would be in free space with no combustion chamber surface close to their perimeter. This sort of thing: https://www.psychobike.com/forums/1000s/50881-skull-installations-gsxr-1000-combustion-chamber.html.

The downside might be a lack of swirl in the chamber which back in the old days was a big deal. I'm thinking of Suzuki's TSCC system. I think in that case that the majority of flow was from one side of the valves which probably happens in any case with port directions and valve masking though good port design should reduce it a lot.

husaberg

30th September 2019, 21:20

More or less. There is just a small perimeter each side with matching flat surfaces. With larger valve sizes for the given bore having a squish area between exhaust and intake each side would mask the valves I would think

I was just basing it on say a CRF150R
which would be similar bore.
22.5 and 26mm valves
I think even the old VT250 were similar to the CRF150R
https://www.campbellenterprises.com/honda/pistons/cp-crf150-piston-300.jpg
https://i.ebayimg.com/images/g/p5YAAOxy--NRqFrv/s-l300.jpg

What size is the pin on the piston 15mm or 16mm

speedpro

1st October 2019, 06:07

Those valve seats are a lot further out and closer to the plane of the head gasket surface compared to the scooter head, by the looks. I would think it would flow better but would need to see it on the cylinder to see if the side of the bore would have an effect. Flow bench wouldn't lie of course. Being a very flat valve angle would also effect the piston dome profile and as you say the CRF has the flats between the exhaust and inlet valves and there's a bit matching it on the head. The scooter head is probably a bit older style.

speedpro

6th October 2019, 21:26

Some real nerve wracking grinding this weekend. I had to grind down real close to the valve seats without touching where the valves seal. It wasn't too bad cleaning out the ports and I only had to take out a small amount to clean up where the valve seats and the actual port meet. Comparing it to the old Taida head I actually think the Taida head has slightly a better intake port. The exhaust port is about the same. I've got it sitting on the vice at the moment with the combustion chamber full of WD40. There may be just a very small amount got through on both sides but it may also be oil from fitting the valves in the head. I'll know tomorrow morning. The final photo looks a lot worse than it really is but I would still prefer it to be better.

speedpro

17th October 2019, 18:02

Coming along. Getting the roller rockers in were a mission as usual. It's a tight fit inside the head and the rockers have to be slipped in more or less to where they go and then pushed up out of the way to fit the cam. Once the cam is in the rockers can be slid down to where they go and the pivot pins put in. Everything else just bolted together like normal with the spacer plate and extra gaskets.

speedpro

16th December 2019, 16:47

As usual when an aircooled bike is converted to watercooled it turns into a mission. Just finding a radiator that was probably an acceptable size and had hoses in more or less a useable position and angle was a problem. In the end I went with a FZR250 radiator I had lying around. It's hopefully too big but the way I've mounted it makes it easy to downsize. Any pretense of being just another scooter is now gone. A smaller radiator may be able to be tucked out of the way but this one only had one place to go and that was out front.
There are 2 studs that the front fairing mounts on. I made extensions to screw on and to which the bracket for the radiator then mounted to. The radiator mounted to the bracket using the standard radiator mounting points. Hoses are run down inside the front fairing on both sides.

speedpro

16th December 2019, 16:59

The watercooled cylinder came with 90deg fittings. In the end, in conjunction with a collection of odd bits of hose, it seems like the hoses on inlet and outlet both connect OK and allow for motor movement without causing a problem. I only have the one temperature sensor at the moment which I've used to connect 2 bits of the engine inlet hose. Until I get the other sensor sorted the fan is going to be run from a switch. I have a fan controller which checks both oil and water temp. The oil cooler is going to be put back exactly where it was originally which isn't ideal.

speedpro

16th December 2019, 17:10

I wanted the water pump low down in the cooling system. The pumps aren't self-priming. I've ended up jamming it inside the front lower left corner of the bodywork. Cool water from the radiator drops into the pump and is pumped back to the motor inlet. It's far from ideal as the cool water is taken from the top of the cross-flow radiator which isn't too much of a problem from a cooling perspective. The issue is if the water level drops for some reason the first thing that will happen is the pump will suck air from the top of the radiator. The temp sensor location won't help alert you to a problem as it is on the inlet side between pump and motor and without water circulating will probably indicate a low temp. If i stick with this radiator the hoses will definitely be swapped over somehow.

husaberg

16th December 2019, 17:13

I am pretty sure i have a Cr80 one kicking about,the smallest square one i have ever seen is what the KTM50's run. 2001-2009
https://i.ebayimg.com/images/g/4MQAAOSwAhNa1hay/s-l1600.jpg
that pic is about life size.
the 2009 ones on run these
https://sc01.alicdn.com/kf/HTB1RSXjacfrK1Rjy1Xdq6yemFXar/Alloy-Radiator-Kit-for-KTM-50-SX.jpg

I can measure both if you want Mike.
I would have thought for a 4t cylinder only it doesn't need to be to big?

speedpro

16th December 2019, 22:53

I'm hoping the radiator is oversize and will allow a smaller one to be fitted. Supposedly this combination of watercooled cylinder and aircooled head does not need any forced air to the head from the fan. I'm going to keep the fan and direct the air to the head to assist with cooling antway. Dimensions of those radiators might be useful. I have an RG50 radiator which would fit nicely and has the radiator cap on top. It just looks too small and probably is. Given the engine is probably making more power than a CBR150 I'm thinking it needs at least that size radiator and the FZR250 radiator seemed like a good starting point.

husaberg

17th December 2019, 18:39

KTM50sx 2001-2008
Radiator approx 200mmx115mmx30mm 690,000mm3

Honda CR80 olderstyle 310mmx100mmx30mm 930,000mm3

all sizes approx core not including neck..
i would suggest that the CR80 one would be good for mid 20 at least HP. when covered with mud operating at low speeds sustained loads.No fans
I think the KTM50 were arround 12hp they all ran hot but ran tiny amounts of oil with slipper clutches at low speed covered with mud and no fans

speedpro

21st December 2019, 21:29

I've been working on it for most of a week and finally it's alive. Still more to do but the motor runs and sounds as mean as before. The water circulates and when it gets to the temp set on the fan controller the fan is turned on and immediately starts dropping the temp. I'll take a few photos tomorrow after it's sorted properly.

speedpro

22nd December 2019, 20:01

All together and taken on increasingly longer rides around the area. I taped off more and more of the radiator and currently only have a section 90mm wide by 160mm high uncovered and it still runs way cold. There is a tiny oil leak which may be coming from under one head stud. I did have a problem riding along Christian Road. It started running quite rough and eventually stopped. It felt like fuel and refused to even kick when pressing the starter button. Turned out the air filter had fallen off and disappeared. This wouldn't have been a problem except that the carb had come off as well. So it was a fuel problem. Gary came and rescued me with a few tools and I was back riding in a short time.

It runs great, pretty much like before. If anything it may even be a little better. It popped an unexpected wheelie down the drive and even at minimal throttle is doing 80Kmh pretty quick. The engine is tight and requires running in so that is as far as I went.

husaberg

22nd December 2019, 20:11

speedpro

22nd December 2019, 20:17

I'm going to try my RG50 radiator. It is slightly larger than the uncovered area so should be near ideal with the radiator cap and the pipes being in more or less the right places and angles.

speedpro

24th December 2019, 14:41

Carb falling off problem sorted. With the taller cylinder the head and carb were 6mm or so further forward. At a reasonable amount of suspension compression the carb was pivoting forward with the engine and the hard part of the throttle cable where it fastens to the carb was hitting the enclosure I've made for the carb under the seat. I've rotated the curved hard part to the side more and it seems OK now. Only problem now is that the enclosure lid won't fit on now because the cable sticks up too far.

I phoned Mikuni Oz(https://www.mikunioz.com/?v=787739c35a69) yesterday at midday to enquire about a new filter. The only guy there was sounding a bit stressed and said he had about 80 orders to get out before he went home for his holidays and that it would most likely be sent on 7 January when the shop reopened. I wasn't worried about that and went ahead with the order anyway. Early afternoon and I get a message from the couriers saying I had a package on the way. Another example of the fantastic service from MikuniOz.

speedpro

29th December 2019, 22:19

RG50 radiator fitted and about 1/2 covered with duct tape. Even with the warm weather and the odd traffic light it still doesn't warm up properly. Generally it sits around 60deg. I'm still taking it easy and running it in. I changed out the oil today with more of the same lower grade stuff. I'll run a couple more tanks of petrol through it then put in better oil.

It really doesn't like 50kph. It's just too slow and the carb is barely cracked open making it difficult to control. Even 60Kph is a big improvement.

The filter arrived on Friday. Unfortunately it won't fit very well. It was suggested that I return it and they would send the right one but I pointed out that I was in NZ so not so easy with courier satchels etc. Tom from Mikunioz has been replying to my emails despite being on holiday. Turns out he is in Taupo and he suggested I drop it off and he will sort it out. Then it sounds like they don't have a filter for the 50mm carb spigot, but there is a way.

It's running reasonably well. It gets to 80kph with hardly any throttle real quick, and even 100kph is quick. It still does wheelstands though so far only down my drive.

speedpro

2nd January 2020, 09:58

husaberg

2nd January 2020, 12:40

Few more rides and it seems that a radiator 100mm X 25mm would be spot on. Unless stopped for a few minutes it doesn't overheat. In fact it doesn't overheat at all, it just gets a bit warmer. That's with the radiator out the front anyway.
Had a longish sting at a steady 80kph and no sign of warming up, just sitting on a steady 60-70deg.

Is any heater cores fom cars that small? you could likely get away with few of these. Be easier to package

https://cometkartsales.com/WildKart-Aluminum-Inline-Water-Heat-Exchanger.html

344066

looks like people use these for tig welder coolers
https://www.mindfactory.de/product_info.php/Phobya-G-Changer-120-HPC-Radiator-1x-120mm_1128745.html

https://klozey.com/products/80mm-straight-mouth-water-cooling-row-radiator-heat-exchanger-computer-pc-cooling-row-industrial-row

techy types water cooler computers with tiny rads

sidecar bob

2nd January 2020, 14:44

A barrel alone will take very little cooling.
Most of the heat in a four stroke engine is produced in the head & that's the part that needs cooling most to prevent detonation.
Here's an example of an engine that I'm familiar with that has a water cooled head & air cooled barrels, which would be the usual route for a air/liquid cooled engine.
https://en.m.wikipedia.org/wiki/Rotax_912
How difficult would it be to water jacket the head as well?
The amount of cooling you require for this application currently, demonstrates how little heat is produced in the barrel compared to the head.

speedpro

9th February 2020, 13:44

Got about 1000km on the new engine. Changed the oil for good stuff and gave it a bit more of a handfull. It may be better than before. The rod length is about 6mm longer but I doubt that would be obvious when riding. Bore, stroke, & cam are all the same. The head is all new with a smaller exhaust port & valves but slightly larger intakes. Whatever, on the motorway cruising with the speedo off the clock is effortless.

speedpro

10th March 2020, 20:58

It's getting a good thrashing now. Been along the motorway for a good distance with the speedo needle buried in the bottom of the gauge without a problem, except for one little one.

I pulled off the motorway and the revs weren't coming up like they should with throttle. Stopped in a driveway and gave it a bit of a rev and it seemed OK but when I went to leave it was labouring and was vibrating. The vibration went away with a bit of speed and the engine revs came up as the scooter gained speed. I was thinking I might have melted rollers in the variator so just rode it home carefully.

Took the transmission cover off when I got home and it looked OK except the belt wasn't in the low ratio position but rather it was at about 3rd gear position. I pulled off the front pulley and found that one roller had managed to jam itself sideways and was stopping the variator from moving to a low ratio. It was probably holding one pulley face at an angle causing the vibration of the transmission on the belt.

I had been planning to fit a new belt anyway so went and replaced all the rollers and the belt. I have slightly lighter rollers in it now so it should be doing a few more revs everywhere which from the dyno will make it more interesting but will stress things a bit more on those extended motorway thrashes.

The water temp was solid on about 60 on the motorway and only rises when I get stuck in bad traffic. The guy I bought the bits off, Chris from Race Concepts Scooters(RC Scooters) maintains I don't need the fan to supply air to the head and has suggested an oil temp in the head around 100-120 works well. I have the fan controller still fitted and currently only monitor the water temp but it has a 2nd sensor for oil so I'm going to screw that into the exhaust tappet cover where the oil pools a bit. I'm running Hobao billet valve cover heatsinks one of which already has a threaded hole for a temp sensor.

The back tyre has worn out. It didn't last that long.

speedpro

29th March 2020, 20:57

I've put a proper back tyre on it now and it handles a lot better.
It does rev a bit more but I hardly notice it after a few rides. Giving it a handful at 60K sees it really get going now. Taking off from the lights got a bit erratic with it not always taking throttle. There was also a reluctance to take full throttle on the motorway. I had a bit of a look at fuel, checked the float bowl and the idle fuel adjustment but it was all good. The plug looked OK but I noticed black stuff down the outside which might have come from the tool. I put a fresh plug in anyway and checked inside the plug cap and found more of the black grime. After cleaning it all out went for a test ride and it's back to it's old snappy self but with the extra revs is just a little bit zippier away from the lights. Down a side street off Rosebank Rd testing starts was a bit of fun. It'd wheelie without too much effort and even come back up after you put it down, probably catching the bounce. On the dyno it definitely liked smaller rollers, making more power everywhere with the extra revs. I had it booked in for a WOF on Saturday but that didn't go ahead of course.

speedpro

8th June 2020, 20:58

Done a little bit more finessing. I always thought that it wasn't really happy at full throttle. Rather than piss around going up and down with jets, I installed the lambda meter. Took it for a cruise down the motorway and back and it was going lean over about 3/4 throttle. Definitely main jet. On the way back coming up Te Atatu Rd there was a pile of traffic stopped at the lights just by the Caltex. I could see a small bike and a scooter at the front but blocking the gap between the rows of cars so i decided to sneak up between the right lane and the right turning lane. I'd just got to the front still rolling and the lights went green. Not wanting to be jammed in or impede traffic I gave it a bit of a handful and had the front up right across the intersection. The clutch had disengaged so giving it throttle still made it take up with a bit of a snap.

I went up 2 jet sizes, 125 to 130, and took it for another ride. It was doing a few odd things like going really lean at times so I never got as far as the motorway, just doing a few laps round the block sort of thing. Pretty obvious though that it's a lot happier at full throttle and the lambda is staying around 11.5-12:1. I might try one size up just to see. I have to double check for leaks anyway so may as well.

I have also wound the idle up. It's still nowhere near engaging the clutch but it seems to have made the takeoff even more consistent. You can give it as big a handful as you like blipping it and it just jumps. No hesitation at all. Chris from RC Scooters did say it wouldn't be a good idea putting the stock gearing back in. I was thinking of doing it for a bit of a giggle. He said he had customers who had flipped them.

speedpro

2nd August 2020, 19:12

The scooter has been going really well but had odd response sometimes and when cruising at any speed has missed a bit now and then. I found the plug cap more or less off and pushed it back on. It is the type that grips the plug threads and felt like it had plenty of tension when pushed on. After another ride it was playing up again and when I checked I found the plug cap off again. After playing around and trying to to pull the cap off I found that with the cap at just the right angle it came off with absolutely no resistance. That cap is now in the bin and I have fitted the original Yamaha cap. Engine response is now totally reliable and cruising at any speed is dead smooth with no misfires.
One thing I have found is that taking off from the lights, and not snapping the throttle open but opening it about 1/4, and then rolling it open about 1/2 way across an intersection, will see the front coming up in a nice controlled wheelie.
The temperature also seems to be pretty happy to sit at about 75C even when thrashing about the place. Coming off the motorway after a few Km with the speedo pegged and having to stop at lights for a bit doesn't cause problems either.
Quite a bit of fun at the moment

speedpro

15th April 2021, 17:51

Registration time is coming up and I had a WOF check done. The tested failed it on the radiator out the front(pedestrian hazard) and he had a question about the engine capacity. I took it to a Low Volume Vehicle Certifier type of guy today to get checked over for proper compliance. I can collect it tomorrow and will have a list of stuff to tidy up for compliance. The little compliance tag must be mounted on the frame in a position that is visible on the side of the road and does not need tools to inspect. Bit hard on a full coverage scooter so possibly a little tag off one shock mount.

F5 Dave

15th April 2021, 20:57

Really? My 496 RZ / RGV LVV is mounted under the seat. Can't get to that without an Allen key.

mulletman

15th April 2021, 21:00

https://lvvta.org.nz/documents/infosheets/LVVTA_Info_01-2021_Introduction_of_LVV_Electronic_Data_Plates.pd f

https://lookup.lvvta.org.nz/

speedpro

18th April 2021, 18:54

That's the thingy that's being installed. I've gone over the scooter and the only place to put the radiator is under the seat. I'm going to move the pump, fan controller and relay, radiator, and fan to under the seat and fabricate support and ducts. I was trying to retain use of the underseat area but there is no other place to put the radiator. The good thing is that it will be even stealthier.
Came off the motorway at Te Atatu Rd today and went to the front of the queue at the lights beside a loud Harley with ape hangers. Did my usual "smart" getaway and got to the lights at Covil Ave before the Harley. Rinse and repeat as they say up to the lights by the Caltex. Same again up to the left turn at the lights by countdown. This time on the green light the Harley was off making a huge racket. Boy, he showed me.

husaberg

18th April 2021, 19:46

speedpro

20th April 2021, 20:59

The leg shields have barely enough room to run a 5/8 heater hose. Talking to the certification guy the requirement for something up front is all curves to deflect a pedestrian. It would have been difficult to make and probably ended up ugly.
I have the scooter stripped down and have more or less worked out where everything is going. The trick is allowing for engine movement with rear suspension travel. The hoses have to be able to move without putting strain on anything or getting jammed. I'll have a look at a warning light on the front to let me know when the fan is running.

speedpro

22nd April 2021, 19:51

I've been able to make a bit of progress. The radiator is going to be fitted in the rear of the underseat compartment. The perforated plate is going to attach to small brackets to be installed onto the enclosure walls. The RG50 radiator is attached to that using the standard mounting points. On the other side of the radiator is another plate attached to what used to be the mounts for the plastic shroud and the fan is mounted on that. I will cut a couple of 50mm(?) holes in the back of the underseat to let the air out. It's going to be pretty tidy with only a bit of black rubber hose visible on the left side which I doubt most people will even notice.

F5 Dave

23rd April 2021, 07:42

So why the big plate blocking off 30% of the area?

Big fan I assume?

speedpro

23rd April 2021, 08:24

The big plate is simply a way of mounting the radiator. If needed there is a FZR250 fan mounted on the smaller plate on the other side of the radiator.

speedpro

26th May 2021, 20:14

It is now fully legal with WOF, rego, and LVVTA certification. I replaced the fan with a 120mm fan which moves 124CFM and the temp is well under control. I had to fully enclose the air path through the radiator and fan to the vent holes in the back of the storage area to stop hot air simply recirculating under the seat. I'll have to take it for a few rides on the motorway to be sure but the temperature is under control when thrashing around the suburbs.

speedpro

30th August 2021, 10:42

husaberg

30th August 2021, 18:05

Numbnuts lockdown here at the moment. It looks like I'm going to cave in to temptation and take it for a ride later today.
I have given it a couple of good thrashes on the motorway and the temperature stays wherever I have it set. I have a gauge on the handlebar to keep an eye on things and it hardly varies. It is surprising how long it takes to get fully warmed up, maybe 10 minutes of casual riding or more.

i seen an inline bypas therm on TM last night it was $25
I cant remember what it was off.
OKay $35 and a Ducati
https://www.trademe.co.nz/a/motors/motorbikes/parts-for-sale/engine-components/listing/3241621352?bof=3kIYdJCK
https://trademe.tmcdn.co.nz/photoserver/plus/1446627860.jpghttps://www.ducati.ms/attachments/p1010093-jpg.68943/

speedpro

31st August 2021, 13:57

That might be useful on my twin. I have an electric pump on the way for it as well

speedpro

14th December 2021, 19:48

The radiator now mounted under the seat out of site. a high speed fan is mounted at the back drawing air through the radiator and expelling it out the back through holes in the storage compartment.

pete376403

14th December 2021, 22:51

That might be useful on my twin. I have an electric pump on the way for it as well

If you're not interested in paying Ducati prices, there is an aftermarket product for KLR650s that does the same thing, but is probably higher quality - google "thermobob"

speedpro

15th December 2021, 08:55

The little silver box you can just see to the left of the photo is the fan controller. The temp it turns on is adjustable in 2deg steps. Once on it stays on until the temp drops 5deg. So far it has been very good. I like to have the pump running continuously as my theory is that the water flowing all the time eliminates hot spots. Either way it seems to work well.
The only minor problem I have experienced is that once in a while the fan controller defaults to 100deg. It doesn't seem to affect operation, if anything it may even improve throttle response. All it does is pump a bit of water out.
Currently I'm running with the baffle out. The noise is just fine when idling at the lights but as soon as you touch the throttle it rivals a Harley with straight pipes.

husaberg

15th December 2021, 10:06

If you're not interested in paying Ducati prices, there is an aftermarket product for KLR650s that does the same thing, but is probably higher quality - google "thermobob"
https://www.agskartparts.com.au/image/6287/INLINE-THERMOSTAT-BYPASS-RETURN

https://fastech-racing.com/thermostats/

https://infernoheaters.com/product/thermostat-bypass-valve/

speedpro

15th March 2022, 18:19

After much thrashing it was finally time for a bit of maintenance. I'd been adjusting a bit of duct tape on the cooling shroud on the engine and disturbed a ground wire from the ignition. This made the bike less than enthusiastic about starting with the result that I spent a bit of time cranking it over which it doesn't really like. It got really reluctant to catch and turn the motor and when it did start was making a few rattly noises. It was time to check rollers and the belt anyway so I stripped it down which turned out to be a good idea. The starter clutch was toast with one roller even turned sideways. The brass inserts on 3 variator rollers, all the same weight, had come loose and slid out the end of the plastic and rubbed hard on the alloy of the alloy pulley.

I ordered a couple of clutches some time back so cleaned the whole lot and fitted one. I fitted the variator rollers back in but facing the other way. I will replace them as soon as replacements arrive. I do have spares but they are a bit lighter and it already pulls plenty of revs on the motorway. It's supposedly good for 11,500 rpm but I don't think that applies to continuous on a motorway. I think it would also make it more wheelie prone away from lights and I don't need that.

350791350792350793350794

speedpro

16th April 2022, 19:40

Found another problem on the way home today. The belt is in a number of pieces and the scooter doesn't want to go any more. Luckily I was close to Patiki Road on ramp and after coasting across from lane 4 where it happened i pushed it back up the on ramp to my mate Kev's workshop. I have already asked about getting a replacement so hopefully it'll get sorted pretty quick. I have an old spare so hopefully that will do until the new one arrives. I'll be taking it easy.

speedpro

19th June 2022, 13:57

It's gone really quiet in Scooter land.

Thankfully my scooter is doing it's bit to wake up the neighbourhood. I got a new belt which is slightly overlength. It sits very slightly out of the rear pully at rest and i suppose when I get round to thrashing it the belt will sit just out of the front pulley as well. I had to skim just a little bit off the inside of the case to provide a bit of clearance for the belt. I have been for a ride since doing it and then inspected it afterwards and there were no marks from the belt so it seems good. Supposedly, the belt being overlength is to give it a bit more top speed. I don't need it as I already have "up-gears" with the scooter geared for about 170k at 10,500rpm. It doesn't seem to be hurting anything. I've already ended up doing a wheelie away from lights without even intending to.

It's a perfect day in Auckland for a ride so I shot out to get lunch and went the long way home. Now I'm procrastinating instead of getting back to sanding and painting windowsills

speedpro

14th March 2023, 21:20

The scooter ticked over 45,000K yesterday. It was time for an oil change and I checked the valve clearances as well. All the valves are a little bit loose, probably about .001". Given the difficulty of adjusting them I haven't bothered. With the old engine I could get a spanner onto the tappet locknuts but this engine is even taller and there isn't quite room to get a spanner on without the frame getting in the way. Getting the engine free is a bit of a mission with the radiator under the seat and a few other things. The transmission is working sweet so I haven't bothered to look at it. It's still doing wheelies away from the lights. Some guy on a flash adventure bike joined me at the front of the queue. He got left behind initially but zoomed past when I backed off at about 80k. Next lights we were off side by side with the front wheel about 50mm off the ground. I backed off at about 80K like previously but he carried on quite a bit faster. Good fun.

The weather in Auckland lately has been ideal scootering weather. I took it up Old North Road heading to Helensville in the weekend. So friggin glad I wasn't in a car. There was long slow queues at the roundabout by Soljans Winery which I just slid past and then weaved my way around the cars blocking the roundabout. Apart from the cars, not a bad ride. They've cleared a lot of the forest up the road. If you want to see an example of the "slash" that has been wrecking bridges head on up Old North Road.

speedpro

19th March 2023, 18:04

Had a good ride down and around Point Chev then back down the NW m'way. Gave it a good handfull before turning off at Te Atatu and got a couple of good bangs from inside the pipe. That's not common but also not uncommon. Waiting at the lights and I could hear a ticking noise which was still evident at home. My suspicion was that in my effort to get a spanner on a tappet locknut I might have loosened one off which finally came loose. I pulled the intake rocker cover off and managed to alter the clearance using a different spanner than before. Once finished I was cleaning prior to refitting the tappet cover and found the sparkplug cap had come loose. The ticking I could hear was the spark jumping over. Those Ignitech DC CDIs are mean

F5 Dave

19th March 2023, 18:39

What's a Tap It? Some Milf?

speedpro

10th July 2023, 13:24

Only criminals ride scooters.

https://youtu.be/VMfb0B7k3uY

speedpro

11th July 2023, 19:33

The scooter has a bit of competition in the garage. My son has left me his bike to look after while he's in Oz. Rowdy DRZ400sm, slide valve carb from trailbike version and fmf muffler(?) which doesn't do much muffling. Lots of fun.

speedpro

12th October 2023, 21:29

There may be competition but the scooter still gets used. It's always been difficult to start after a long period when it has not been used. I now have a kart starter which is very useful for the FZR bucket which I've modified to allow me to turn the motor over with the kart starter. On the scooter there's a nut on the end of the crankshaft to hold the fan on. Turns out I can use the kart starter to spin the motor without shagging the starter clutch on the scooter. The first time I tried it the kart starter let out a big puff of smoke but then spun the scooter motor fine after an initial big hesitate. Today I tried it again and all that happened was that the wires on the kart started got nice and warm. The scooter must have been just coming up on compression and the kart starter wasn't up to it on it's own. I gave it a helping hand with the scooter starter to get it started turning and it was away.

The scooter is still rowdy. I can hold the front a small distance off the road leaving the lights right across an intersection and a distance down the road, up to about 80kmh or so. Coasting down a hill like Waikumete Hill it pops and bangs and burbles away in a manner that would please a Volkswagon Golf owner. You might need to be in Auckland to understand that reference.

It's over 45,000K now. It's been through a few motor bits but the rest of the chassis etc seems just fine and it's still fun to ride

speedpro

9th March 2024, 18:10

Consideration is being given to moving the scooter on. If the hoped-for new toy becomes available it'll mean a bit of pressure to rationalize bikes. The spectrum of hoon bikes will be fully covered but rego costs will mean something has to go. Kinda sad to think of it.

F5 Dave

9th March 2024, 18:14

Trials bikes don't need rego. Just sayin.

speedpro

22nd March 2024, 15:46

Cruising down Rosebank Road at about 10:00 today and was pinged for 67k in a 50. The truck directly in front of me pulled over as well. Obviously thought the lights and siren were for him. Line of cars directly behind had to get around as I stopped at a bus stop on Rosebank rather than going a bit further and turning off. Had no interest in anything else apart from my speeding. Supposedly I'm supposed to do 50k irrespective of any tradies zipping about doing tradie stuff. It was a typical mid morning on Rosebank Rd. Those familiar will know what I mean by that

speedpro

29th March 2024, 10:31

20 points and $120. The ticket received in the mail this morning has the road incorrect and the suburb. Simple things you'd expect to be correct when issuing a notice.

speedpro

29th March 2024, 10:52

FREE engine bits.

On a different note, I've been rearranging boxes of bits and have decided to clear out bits I'm never going to use.

Parts to go(free) are:
+3.5mm stroker crank
65mm cylinder with forged piston.

Combined these give an engine capacity of 203cc. A new cylinder head will be required. The stock head simply does not flow enough to work.

There are also Taida rockers to suit a big head where the valves are spaced further apart, and a Taida T6 camshaft. I did have a Taida head which from memory had a 25/22 valve size combination but unfortunately that head was destroyed in a later engine dissasembly.

There are also a small stack of gaskets, clips, and other random bits.

The engine bits are all good. There was a problem where the scooter more or less died which in the past had been due to crank problems. New bits were ordered before disassembly. The problem turned out to be a broken needle in the carb. By the time I discovered that, the new parts were already on the way. Cylinder heads are available from a few suppliers, commonly from Taiwan. The quality is at least as good as OEM. The only thing to watch for is that sometimes metal is left in the ports and combustion chamber for the tuner to remove as they prefer.

Link to Taida heads - http://www.td-motor.com.tw/product/51145.html

Parts are located in Glendene Auckland