Scooterotica

Warkton Tornado No.1 wrote: ↑Thu Feb 28, 2019 11:36 am

holty wrote: ↑Thu Feb 28, 2019 10:48 am the one thing going against more plates is that ive already got a 10 mm packer so adding more will mean extending the kickstart shaft which I don't want to do, I will try stronger springs first.

....not if they are clutch plates & steels of a thinner variety.

If you can measure the existing springs gauge (wire diameter), free length, compressed length (in a vice) & number of turns, I will have a look for what I have here.

If I've anything that looks to be stronger, you can have them to try. Are you going to Wickies?

the plates are bgm pro 6 plate, disigned for a 5 plate type crownwheel, ive measered the springs, free length is 31mm, compressed is 15.5 and gauge is 2mm, and there are 7,25 turns im not going to wickstead

If you've got an easy lever pull then you could increase the applied force by using thicker steels. Not sure if that's an option on mb clutches as I've never seen one, but it seems an often overlooked but easy option to me.

It will make your lever stiffer but maybe only a little?

Made a huge difference to mine once.

holty wrote: ↑Wed Feb 27, 2019 11:25 pm
yeah I get the genral idea , im running a 3.7 to 1 final drive ratio at the moment and 7 bgm plates so both of those things are in my favour, I could extend my clutch basket more and maybe go to 8 or 9 plates if I had to, but im pretty sure stronger springs will stop the slippage, I may just add a centre spring and try that, the lever does pull in very easy at the moment as well

By the way, I've seen your work, so if I came across as patronising, it was unintentional. Just trying to be thorough.

hendy wrote: ↑Thu Feb 28, 2019 8:11 pm

holty wrote: ↑Wed Feb 27, 2019 11:25 pm
yeah I get the genral idea , im running a 3.7 to 1 final drive ratio at the moment and 7 bgm plates so both of those things are in my favour, I could extend my clutch basket more and maybe go to 8 or 9 plates if I had to, but im pretty sure stronger springs will stop the slippage, I may just add a centre spring and try that, the lever does pull in very easy at the moment as well

By the way, I've seen your work, so if I came across as patronising, it was unintentional. Just trying to be thorough.

I did not think you were patronising at all, everything you said made perfect sense and you put the points across well, im happy to have all sugestions of how I could improve it, I guess clutch slip is an age old problem in lambrettas and most folks will just buy an off the shelf high performance clutch and the job is done, the only one I know of with a cush drive is the casa one and its way out of my budget at £800 , im thinking center spring as well and could go hydraulic, ive seen a cylinder that would fit between the clutch arm and the adjuster block and pulls, just how the cable works on a lambretta.

I think one of the US dealers did a hydraulic thing that worked a bit like that for the front brake

Front sprocket spin under load? Surprising how many people with powerful motors mistake this for clutch slip.

Soft aftermarket sprocket, old worn original sprockets or ramp, old tiered spring, S1 spring fitted by mistake can all be a cause. Decent new hardened sprockets, new S3/GP spring and/or short S1 top (Front sprocket assembly) to pre-load front spring are all good ways to address this.

May well be clutch but don't overlook this issue. I've had it on high mileage standard Innocenti Innocenti motors but normally come across it in tuned motors.

yeah good call adam, I am pretty sure its clutch slip, but when I have it stripped I will reduce the height of the sleeve by a couple of mm and that will increase the loading of the spring, its easy to do when the side case is off.

Happens so often that I can see it being an issue with your beast of a motor.

This feel exactly like clutch slip, becoming an issue when working under load. Back off and the motor gets some traction back. Open the throttle and it starts to slip again.

Adam_Winstone wrote: ↑Thu Feb 28, 2019 10:31 pm Happens so often that I can see it being an issue with your beast of a motor.

This feel exactly like clutch slip, becoming an issue when working under load. Back off and the motor gets some traction back. Open the throttle and it starts to slip again.

yeah just as you describe, when the powervalve opens the engine just changes its sound and screams, I measured the exhaust timing with the valve open and its 205 degrees so no wonder it just takes off, however it does have more power at low revs than it had with the non powervalve cylinder fitted, realy looking forward to getting this sorted at getting it on the rolling road and seeing how much power it has, I can tell it a lot.

Adam_Winstone wrote: ↑Thu Feb 28, 2019 10:06 pm Front sprocket spin under load? Surprising how many people with powerful motors mistake this for clutch slip.

Soft aftermarket sprocket, old worn original sprockets or ramp, old tiered spring, S1 spring fitted by mistake can all be a cause. Decent new hardened sprockets, new S3/GP spring and/or short S1 top (Front sprocket assembly) to pre-load front spring are all good ways to address this.

May well be clutch but don't overlook this issue. I've had it on high mileage standard Innocenti Innocenti motors but normally come across it in tuned motors.

I think OEM front sprockets & the associated cams are as good as you will get, but they are all subject to wear.

To overcome the cams over-riding is something that can be achieved by a couple of methods.

One is to use only the splined element of the dished 'top hat' washer to preload the spring even more. If, like me(!) you have experienced the dished 'top hat' washer breaking, don't throw it away! Get it surface ground to fit.

The other, more obvious way is to use the opposite of what Adam intimates as a mismatch often overlooked. The SI dished 'top hat' washer with the S3 spring achieves the same result, but my belief is that the SI item is not as durable as the SIII as they are the type that I have experienced breakages with.

holty wrote: ↑Thu Feb 28, 2019 2:54 pm

Warkton Tornado No.1 wrote: ↑Thu Feb 28, 2019 11:36 am

holty wrote: ↑Thu Feb 28, 2019 10:48 am the one thing going against more plates is that ive already got a 10 mm packer so adding more will mean extending the kickstart shaft which I don't want to do, I will try stronger springs first.

....not if they are clutch plates & steels of a thinner variety.

If you can measure the existing springs gauge (wire diameter), free length, compressed length (in a vice) & number of turns, I will have a look for what I have here.

If I've anything that looks to be stronger, you can have them to try. Are you going to Wickies?

the plates are bgm pro 6 plate, disigned for a 5 plate type crownwheel, ive measered the springs, free length is 31mm, compressed is 15.5 and gauge is 2mm, and there are 7,25 turns im not going to wickstead

I will look through the sets I have today.

I should have asked you if you knew what the maximum length of spring could be tolesrated by your clutch assembly when coil bound (I.e. fully compressed)

One thing worth mentioning for others reading this, is that the inner bell of the clutch will actually deform if it is of poor manufacture. I have chased my tail trying to improve other people's pride & joy. You know the type, where the money spent was purely visual & the internals were only fit for the skip.......