gilera runner sp50 not pulling off

Hi can anyone help? I bought a project for my son and I to do up over winter. We have replaced the water pump main bearings and seals. engine runs really well just over 125 compression. T he problem we have is it pulls away very slowly and we are revving it really high. It has a leo vince tt exhaust 5.5grm rollers and blue clutch springs. Can anyone advise on what the problem is?
Thanks Gaz

 

Hi
Rollers are probably too light - unless there is an issue with the clutch -

 

hi thanks for your response, could it be the clutch springs being too hard?

 

Yup - that would do it. Or a wider Malossi variator without a re-inforced (wider) belt.

 

what type of springs would you recommend? Mate. I have ordered a kit off ebay 1000 1500 and 2000rpm. Would I be best starting off with the lowest? or the highest?

 

Hmm - If the motor and exhaust are standard - I'd go for 1500 - but I would try going for heavier rollers first -
Go up by - say 3G total weight. Measure them altogether and then do some calculations. An excel spreadsheet is invaluable. And you can use rollers of different weights - eg three 6 gram & three 5 gram - or whatever - to get your total. Just do them 'radiation symbol' style to get an symmetrical opening distribution.

 

The engine is standard it has a leo vince tt exhaust it idles fine. revs fine just when we try and ride it it pulls off very slowly. when my son went down the hill it picked up really well but no getting back up the hill is this rollers or clutch or both?

 

So just so have I have this straight - it screams like a banshee at the start and keeps on screaming if you try and go up a hill without actually getting anywhere ?
But going down it's OK (but still revving like mad) ?

 

yes to uphill screaming and getting nowhere downhill screaming at start then you hear the gearing so the revs sound normal. Hope that made sense>

 

It's definitely the rollers - unless the clutch has shed it's pads - or some such bizarre thing. Or stoopid-hard springs in the clutch - but I've never seen any hard enough to do that. Not even on a drilled Polini Clutch with Omega springs.........

 

That's great so heavier rollers? if you had this problem what would you go up to?

 

I'd start with 3 or 4 g total more than you have now. So if you weigh all 6 and you come to - say 20 then you need to find two sets of three rollers that get you to 24 g total. The best thing to do is get some accurate digital scales (these can be found for 15 quid) and then get measure what the rollers are now. Get a range of values above and below. I have a box full - and to get it right - you need to be able to go up or down in total by stages of a gram total (with a standard engine) at least once you're near a reasonable result. Highly strung engines are worse (much worse) in this dept. but you should be ok as it's only a stock cyl with a Leo pipe. But start out increasing by 4 g total.
Good luck -

 

Thank you for your help and advise I will try that tomorrow Thanks again Gaz

 

Cool -
One more thing - you may find that you need to fiddle with the carb once the scoot is laying down the power. If it's fine once it gets going but bogs at the start - think about riching up the mixture screw a tiny bit. If that has no effect - then you need stiffer springs in the clutch.
And watch the plug colour when it starts flying. More speed & power means more load on the engine and possibly a richer main jet.
Good luck -

 

If we do need a richer main jet where could I buy one from or a kit for a weber carb seems everything is dellorto cheers Gaz

 

these guys are great. http://www.dellorto.co.uk/contact.asp you can call. They are very helpful and they have it all.

 

That's great thanks again

 

Righto changed the rollers today no change I went up by 4grms. I am going to change the clutch springs tomorrow I will let you know how we get on. Cheers Gaz

 

That is really weird and I'm surprized. I am thinking that you might have the wrong bell for the clutch. What is the distance between the pads of the clutch and the bell (when you plonk it in the bell upside-down - off the machine) ?
If it is just the springs in the clutch - then take them out and I will have them ! Because they would be perfect for a big config.
But I seriously doubt that it's that.
It's either going to be that the bell is too big for the type of clutch you have - or the belt is too thin for the type of variator you have - and even that would calm down after 20 mph.
So it has to be the clutch - either springs or the wrong bell.
Or it could be jammed rollers in the variator - do they plop in & out easilly when you change the rollers ?
Let us know ! I'm intreagued.

 

I will let you know the gap tomorrow as I haven't got it here. The rollers drop in and out easy. When there is no weight on the back wheel the wheel flies round and it keeps picking up but as soon as we put ant weight on it nothing but if we throttle forward and back several times it picks up slowly any ideas? Cheers