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I need a red powerband. (and a new big end)

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wr6133
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PostPosted: 23:08 - 21 Nov 2014    Post subject: Reply with quote

Curiosity.... did it have a variator restriction? All the Chinese 4T's I've seen had them but I've never seen a Chinese 2T in the flesh.
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stevo as b4
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PostPosted: 01:20 - 22 Nov 2014    Post subject: Reply with quote

Are you going for std weight rollers Iain?

I guess the trick race pipe will need some lighter rollers and possibly stiffer clutch springs to get off the line as quick as std?

Your pics of a motorway bridge reminds me of speed testing my Speedfight 100 before and after tuning. I picked a long downhill section of motorway between 2junctions. With everything std except the Malossi Variator I managed to get 58mph down hill, but just 54mph on the flat, using a digital push bike speedo.

All tuned to 11.8bhp r/w, I got 73mph downhill and 68mph on the flat. That was with:
1, Doppler pipe
2, High compression skimmed head& cooler plug BR9EIX
3, lightly ported std barrel
4, Polini oversize reed block and 4petal reedvalve.
5, Dellorto PHBG21 with 102 Main jet and K&N clamp on filter.
6, Malossi Variator& torque spring, lighter rollers, strongest clutch springs available, and swiss cheese drilled clutch shoes to try to get more rpm before engagement.

Huge fail for £700 including dyno set up! Thumbs Down
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stevo as b4
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PostPosted: 17:08 - 22 Nov 2014    Post subject: Reply with quote

yeah, I bet the off the line and first 100m are massively affected by how good the transmission set up is, and also with a pipe etc, how good the jetting/carburation is? If it's stuttery or has a flat spot then that's only going to make it worse.

I have no idea how best to go about tuning the carb and transmission on twist&go's as one thing could affect the other, and you might go round in circles?

My Speedfight had peak power at 7800rpm, but I reckon the clutch was biting before 4000-4500, and with a peaky pipe it probably wanted 5500rpm+ before starting to engage.

On a tuned 50cc, I guess you'd want 6500-7000rpm? before take off as a minimum. Not good for the neighbours early in the morning though! Laughing
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speedy
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PostPosted: 04:08 - 23 Nov 2014    Post subject: Reply with quote

generally speaking variator exhaust and inlet manifold need de restricting
at least with the pre 4t piaggios and gileras etc
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wr6133
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PostPosted: 06:53 - 23 Nov 2014    Post subject: Reply with quote

Curiosity again... what top speed you seeing minus the variator washer? On the Chinese GY6 based 4T's it gave about 4 Mph more on the few I've removed them from (my v-clic and a few neighbours assorted Chinese brands), for a top of about 36 Mph.

Are there bore kits available? Best cheap way to more power, mine cost 20 something quid sent from Poland, probably about £40 all in with rollers and larger jets, didn't do a lot for top speed (about 42 Mph..... eventually) but transformed it on hills previously it would drop to about 16 on hills for me now it'll only drop to mid 20's (I'm a little on the heavy side). That's on stock pipe (with a few holes drilled) and filter, people get more changing them out as well on 4T's so I imagine on your 2T you could see some real gains.

Also I think you are lacking monster stickers for genuine pedboi adventuring (each sticker is 0.5 bhp) Laughing
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evoboy
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PostPosted: 23:59 - 23 Nov 2014    Post subject: Reply with quote

I should of kept the NRG, that did pull wheelies off the throttle for fun. Laughing

The standard variator is junk.
Change the exhaust.
Buy a bigger carb.

The Piaggio engine your using the dyno graphs from is an far better base engine to start with so the exhaust graphs from that may not be suitable for the Minarelli copy that is in your scoot. That said, anything is better than the standard crap they come with. Even a cheap Q-tre pipe would give large gains.
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evoboy
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PostPosted: 10:44 - 24 Nov 2014    Post subject: Reply with quote

I found most gains from putting a larger carb ( 17.5mm) and an exhaust onto my stock minarelli engine. If you go for 70cc, even just a bad ebay kit, it made it far easier to tune the gearbox as the engine made a winder spread of power.

The variator was always a problem on the Minarelli engine so I cant see it being any better on a copy. When it gets hot, it seems to struggle to shift smoothly giving the impression of flat spots. I changed the one on mine to a cheap ( tunr) copy of a Malossi Multivar which meant using the larger diameter weights. It would hold the revs far more constant than the stock one which is key to getting the best possible acceleration. The stock chinese ramp plates also wear grooves into them from minimal use. I can see yours is also not using the whole variator travel...

What I see most from those dyno graphs is that the more expensive pipes give peak power for almost twice as long as the leo vince pipes, even if it is marginally lower overall output. You will have to be absolutely perfect with the gearbox tune to get it to stay on peak power and if the variator is unable to hold steady, youll drop off the power going up a hill and end up crawling. Same applies if you rev higher than peak power.

Overall power output is useless on a scooter unless you can get the gearbox to hold it at peak all the time. From when you first pull off, uphills, all the way up to when the variator runs out of travel.

Just go 70cc.
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stevo as b4
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PostPosted: 12:38 - 24 Nov 2014    Post subject: Reply with quote

I presume your keeping an eye on the drive belt, as I dunno on 50cc twist and go's, but a modest 100cc 11bhp machine seemed to chew through belts in no time. Could have been a bad set up as I never had it perfect.

Beware of stiffer or wider Kevlar belts. They IMO are a total waste of time, and stop the variator working correctly and reduce it's range of gearing too. They also sap too much power. Would be fine I guess on a 25bhp+ scooter but not on a lower powered one.

The 0-10mph thing is interesting too, as your having the same issue I had with the Speedfight. I could not get mine to not bog down in the 0-10/15mph area, and that was after professional setting up the Jetting and roller weights on a dyno.

I think rollers have naff all to do with low down bogging and it's all in the clutch springs/set up. The tuner who worked on my scoot said my Doppler pipe was peaky, yet only delivered 0.5bhp more or so than a Giannelli pipe and about the same as the PM tuning pipe.

I would never beat a de-restricted NRG Mc3 up to 40-45mph, but I had maybe 10-12mph more top speed on a good day. The Pug 100cc motors really sucked, and I think the Morini 100cc motor was a lot quicker even though there's no tuning bits for it. I wanted an Italjet Formula 125 and worked out a good deal on one, but everyone at the time said avoid it, as they were too unreliable though fast for a std 125.
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evoboy
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PostPosted: 19:55 - 24 Nov 2014    Post subject: Reply with quote

stevo as b4 wrote:

I would never beat a de-restricted NRG Mc3 up to 40-45mph, but I had maybe 10-12mph more top speed on a good day. The Pug 100cc motors really sucked, and I think the Morini 100cc motor was a lot quicker even though there's no tuning bits for it. I wanted an Italjet Formula 125 and worked out a good deal on one, but everyone at the time said avoid it, as they were too unreliable though fast for a std 125.


The Piaggio 50 in AC or LC is a much quicker motor as standard than any of the other makes. It is quicker than the 100cc Aerox/Pug too. Just from taking the washer out and fitting a pipe would see 50mph with ease. The gearbox is much better built, most of them come with a 17.5mm dellorto as standard and the porting in the cylinder is far better finished.

Everytime a Formula 125 pops up I have to stop myself from buying one as you just cant get the bits. But they really do fly for a 125 being 2 engines bolted together. Laughing



Quote:
How so? Photo was taken prior to the variator restriction washer being removed, and in the video the throttle was barely blipped - definately not enough to wind the variator all the way out.


If your still only doing 46mph flat out, which is the same as when it was restricted going downhill, then the belt isnt travelling any higher up the variator pully. The higher the belt travels, the higher top speed you will get. If you take the variator off again it may well have grooves worn into the pully faces where it has been ran restricted for quite a while. That will make it more difficult for the belt to travel up the pully.

Was that washer in the pics over the variator sleeve or was it on the end of it, between the sleeve and front pulley half?

I would just keep a look out on ebay for an exhaust. I never bought one new as kids sell them all the time. Paid £1.20 for a Gianelli, £5.50 for one for my old NEOS and £22 for the PM tuning 360 that was on the NRG 'race ped'. Laughing
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stevo as b4
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PostPosted: 23:50 - 24 Nov 2014    Post subject: Reply with quote

I agree with the Piaggio LC motor's being damn quick for 50cc. I MC3 I raced had a ZX pipe, and jetting/rollers changed to suit. It was neck&neck to 45mph, and as you say on the flat or the slightest downhill those 50's with a pipe would see over 50mph easily!

My Pug would get to 62-65mph eventually, and top 70mph just downhill, but it never felt fast due to the crap 0-10mph bogging issue.

I wish I'd had a Blue F125 or a new KMX125 or TDR125 or Cagiva W8 instead now, as there were some good deals on the last of the new 125's back then.
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evoboy
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PostPosted: 20:05 - 25 Nov 2014    Post subject: Reply with quote

Just keep all the rollers. You can mix 3 of one weight with 3 of another to fine tune the gearbox before shelling out for yet more rollers. Think i have about 20 sets. Laughing

Problem comes when your a heavy git like myself. The setup they give you in the box with the pipe is for a feather weight 16yr old/dyno tune.

Think i ended up using a Pedmoto White spring on a standard engine. If you go for a stiffer spring, you will need heavier rollers else the variator wont be able to overpower the spring. The contrast spring should only really need to go stiffer on a tuned engine where more power is involved and you suffer from belt slip.

A stiffer contrast spring will also rob the engine of power as it takes more effort to compress the rear pulley.

Dont think I'm trying to be negative in anyway. I spent ages messing around with scooters, so I'm just sharing the info!
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stevo as b4
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PostPosted: 00:18 - 26 Nov 2014    Post subject: Reply with quote

Sexy Spannie! Laughing

Looking forward to seeing the difference your tuning parts make, and the effect on speed/acceleration.

I don't feel half as bad now for wanting to buy/try some different pipes on my KMX now, as some of the gains those 50cc ped pipes are making are bloody good IMO.
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evoboy
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PostPosted: 11:12 - 26 Nov 2014    Post subject: Reply with quote

A pipe off an aerox or neos may well of fitted better, but hey ho.

When you do go for a 70cc kit, make sure you get a higher revving kit as it will match that pipe just perfect. The Athena HPR kit I had on the NRG was only happy at 11,000rpm Laughing

The cheap 70 kits dont seem to like high revs. ( again, after much experiment )
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UnspeedySam
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PostPosted: 22:33 - 26 Nov 2014    Post subject: Reply with quote

I just thought I'd pop by after seeing this on Facebook to say it looks like a seriously fun project. I'm currently commuting 3 miles on an 1100cc BMW through heavy traffic and can't help thinking that some kind of ped would be much more of a laugh (my poor bimmer clutch agrees).

Look forward to seeing the results of this cheap kit...
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evoboy
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PostPosted: 00:57 - 27 Nov 2014    Post subject: Reply with quote

_Iain_ wrote:

The streetrace is also significantly cheaper, £79.99 rather than £133. With this being a bit of a budget build/fuckabout toy I'm tempted to opt for that. The slight sacrifice in peak power is made up with a much better spread of power which I can't help but think will be good to have on the road especially as the variator is likely to be fully compressed by 8k and after that RPM=MPH

https://www.pmtuning.co.uk/stage-6-70cc-streetrace-cylinder-kit-minarelli-ac

My only concern is at that point I'm taking a chinese crankshaft & rod, putting three times the power it was designed to take on it & then revving it around 4k higher. This engine has likely only got a 10mm gudgeon pin too, and I've seen Firefoxes with the same motor shit small end bearings when ragged flat out downhill for extended amounts of time & I barely scraped 10k when I maxxed at 46mph Shocked


Think the HPR kit wasnt all that expensive and that made an easy 16bhp with the right pipe. If you are going to do it, it would be worth taking the engine apart and doing it properly (like I did in the thread about the NRG build ).

Once you start, you wont stop. At that point the engine probably wouldnt be strong enough to take what your trying to put through it Laughing
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