Gt186 kit on lince 125

[swissdean]

Hi, couple of quickies, i am planning on home building a rally going bike for next years Italy euro..have just bought an 86' bog standard Servetta 125 lince...after pienty of great reading on here plan is:

- GT186 kit
- 25 mm dellorto
- MB Big Bore v3 (as i have new one and it made no difference to my casa 185)

questions:
- will this work/ pull,the quoted 60 mph cruising speed i often read about on here on the 125 box?
- as it is a servetta i am not sure if and how i could drill the airbox (toolbox type)..could/should i run a remote filter? which one?
- will i need to change the crank/front sprocket/clutch etc..and if changing the crank any thoughts on which one? 4 or 5 plate clutch?
- elsewhere it states go with static 12 v ignition, will the std servetta one (its 12v) suffice or do i need to invest in a new/different one?
- anyone have Rich Ts tel number as I cannot get onto his blueyonder based website to see how long to order the kit

thanks

[burnside]

Sent you a PM

[missing lynx]

the problem is the thin tapper crank and heavy flywheel are not man enough for anything more than a very mild tuned engine why not get the case machined to take a std 200 barrel and change the gearbox the you can keep the serveta electronics there far better than any others

[Warkton Tornado No.1]

the problem is the thin tapper crank and heavy flywheel are not man enough for anything more than a very mild tuned engine why not get the case machined to take a std 200 barrel and change the gearbox the you can keep the serveta electronics there far better than any others

I’m missing something here, probably because I’m stupid.

If well fitted, Serveta, thinner crank tapers really are prone to breaking, why would it be any more likely with a small block based mildly tuned barrel than a large block equivalent?

[missing lynx]

my understanding is the gt kit is not mildly tuned but a quite a high reving kit were as a standardish big block won't rev much over 6000rpm keeping it within the operating range of a std thin taper crank even with the heavy electronic flywheel

[speedy]

Firstly ditch the li crank, I tried to use one on my Jet 200 with a stage 4, Ancillotti and 30 Delly, whilst usuing the fantastic Motoplat electronic ignition [ I'm presuming that's what you have and bot the points version ], and I sheared my crank taper after 1600 miles. That was taking it easy without caning it or sudden quick down changes putting excessive revs on the crank, so get rid straight away. I replaced with the black web mec crank, which are reasonably priced and said to be fine for motors upto 25 bhp, so ideal for the gt 186.I have just built another bike using the big block gt 200 and used a similar crank in that and a bgm 120w stator, midweight flywheel and have static timing of 17 deg. The gt 186 kit has been tried and tested for many years now and are brilliant imo. A friend of mine has just bought a 198 muggello to use in a motor for touring 2 up, instead of my suggestion of the gt 186. I think he has made the wrong choice for his intentions.cheers,Speedy.

[Warkton Tornado No.1]

missing lynx:

"my understanding is the gt kit is not mildly tuned but a quite a high reving kit were as a standardish big block won't rev much over 6000rpm keeping it within the operating range of a std thin taper crank even with the heavy electronic flywheel"

speedy

"Firstly ditch the li crank, I tried to use one on my Jet 200 with a stage 4, Ancillotti and 30 Delly, whilst usuing the fantastic Motoplat electronic ignition [ I'm presuming that's what you have and bot the points version ], and I sheared my crank taper after 1600 miles. That was taking it easy without caning it or sudden quick down changes putting excessive revs on the crank, so get rid straight away. I replaced with the black web mec crank, which are reasonably priced and said to be fine for motors upto 25 bhp, so ideal for the gt 186.I have just built another bike using the big block gt 200 and used a similar crank in that and a bgm 120w stator, midweight flywheel and have static timing of 17 deg. The gt 186 kit has been tried and tested for many years now and are brilliant imo. A friend of mine has just bought a 198 muggello to use in a motor for touring 2 up, instead of my suggestion of the gt 186. I think he has made the wrong choice for his intentions.cheers,Speedy."

Thank you for clarifying your beliefs & you may be right. I know this will go against commonly held views, but do you mind if I explain my own take on crankshaft tapers?

I’m not completely daft, so don’t think I wouldn’t choose a GP 200 taper crank over any other if I was to build an engine from a ‘blank template’ but there are a lot of riders that use the Servetta/Li taper as the consequence of it being in the machine when they bought it, or that they prefer the Motoplat electronic flywheel.

The Eibar crankshaft has a smaller taper, but any reputation of shearing is probably not justified simply as the result of being subject to more power, or torque, of a tuned engine. Increased revs alone aren’t likely to massively increase that risk either, IMO.

With any crankshaft, it might be subject to higher loads in the majority of UK Lambretta engines as there must be very few unmodified, standard engines left!

As to what may shear the taper on a crankshaft, I believe that the reputation for LI type, smaller taper crankshafts having a tendency to shear was started as the result of 60/70’s tuning & racing & ‘running in’ meant that seizing was almost mandatory!

Badly fitted, badly lightened flywheels, unbalanced flywheels, crankshafts out of true are all likely to be factors in crankshaft shearing. Not power/torque alone.

The dynamic loading on the magneto side of the optimum, balanced (not out of true) crankshaft should only be that of a flywheel accelerating & decelerating with no adverse ‘shear loads’ as in the case of a piston locking up.

For the record, the GT186 produced about 16.6 hp & 13.1 lb/ft as tested by ScooterCentre on YouTube. The maximum RPM was 9100.

That’s quite impressive but I’ve known motors with not quite the same revs but more power & torque in tuned Jet200’s that flogged up & down the UK for years ridden by enthusiast owners with standard crankshafts that didn’t & never will break as the result of the crankshaft taper.

Like everything else, set up a Lambretta/Eibar engine to the optimum with no ‘bodgery’ & it will be as reliable as any V*spa.

The problem is that with such an iconic machine as, say, the Lambretta GT200 that looks fast when it’s standing still, there was/is the temptation for amateurs to increase the performance & not do it properly. Then, when something fails, they’re not likely to blame themselves, are they?

Us ‘Brits’ are a picky, weird lot that tend to herd. We have hang-ups that we hold on to for decades! Consider why most members on this Forum would advocate electronic ignition until their dying breath.

“They are more reliable than points”

I don’t think all of the problems I read about on this Forum would back up that myth…..

[lofty]

'back in the day' I had a Lince 200 with an Alspeed (I said it was back in the day!) 240, it had the later serveta/motoplat ignition with a flywheel that had more mass than the sun, and it would regularly shear the LI/TV crank at the taper..

Once I had attacked said flywheel in a lathe and removed a good chunk of alloy, and used a plastic flywheel it lasted until I sold the scoot a good time later..

Thus my considered opinion on this was that with a tuned engine and heavy flywheel there is a significant risk of the flywheel taper giving way, if you don't want to go the GP crank route, reducing either the tune of the engine or the mass of the flywheel will reduce that risk significantly ..

[Adam_Winstone]

^... agree 100%, having seen standard Italian 200s shear tapers off LI/TV cranks with the lighter Italian flywheel, let alone the heavier Spanish one (electronic even worse than Spanish points flywheel). I've personal experience of a number of mates shearing Spanish crank tapers and it has often happened after I've warned them that it is likely to happen.

Adam

[Warkton Tornado No.1]

We have to draw a line under this & I’ve already conceded that my choice would be to utilise the bigger taper, given a blank sheet of paper.

However, my strongly held belief remains that the smaller taper will cope given that there were no other factors that often get overlooked or ignored.

The bigger taper can unquestionably cope better with the scenarios I’ve previously outlined, but such cranks can hold true better with their larger big end pins, which I've failed to mention until now.

That & the fact I can’t be arsed to do the maths!

Thanks Guys.

[Vmakgp]

Hi, couple of quickies, i am planning on home building a rally going bike for next years Italy euro..have just bought an 86' bog standard Servetta 125 lince...after pienty of great reading on here plan is:

- GT186 kit
- 25 mm dellorto
- MB Big Bore v3 (as i have new one and it made no difference to my casa 185)

questions:
- will this work/ pull,the quoted 60 mph cruising speed i often read about on here on the 125 box?
- as it is a servetta i am not sure if and how i could drill the airbox (toolbox type)..could/should i run a remote filter? which one?
- will i need to change the crank/front sprocket/clutch etc..and if changing the crank any thoughts on which one? 4 or 5 plate clutch?
- elsewhere it states go with static 12 v ignition, will the std servetta one (its 12v) suffice or do i need to invest in a new/different one?
- anyone have Rich Ts tel number as I cannot get onto his blueyonder based website to see how long to order the kit

thanks

Hi chaps is there a problem with the site I've been trying to get on the blue yonder site to get info & price for the 186 kit crank, n carb for last two days but no joy !
I've been on the face book page but very little info ?

[Eden]

PM sent

[swissdean]

Update: bailed at the last moment and went for Rt195 , Delly 28mm and foam filter...already have the big bore clubman and it looks like it will pull similar 60 mph at curusing..will let you know how it all goes together..putting casa185 on the servata as it will pull the gearing (may need to change front sprocket) and by all accounts works fine with the static timing and the up speced crank..went this way as it involved minimal change and minimal cash outlay in the end..

that said thanks for the advice and an interesting rad in crank tapers! look out for an ugly re serveta next week in Germany..hopefully!

[Eden]

Hi, couple of quickies, i am planning on home building a rally going bike for next years Italy euro..have just bought an 86' bog standard Servetta 125 lince...after pienty of great reading on here plan is:

- GT186 kit
- 25 mm dellorto
- MB Big Bore v3 (as i have new one and it made no difference to my casa 185)

questions:
- will this work/ pull,the quoted 60 mph cruising speed i often read about on here on the 125 box?
- as it is a servetta i am not sure if and how i could drill the airbox (toolbox type)..could/should i run a remote filter? which one?
- will i need to change the crank/front sprocket/clutch etc..and if changing the crank any thoughts on which one? 4 or 5 plate clutch?
- elsewhere it states go with static 12 v ignition, will the std servetta one (its 12v) suffice or do i need to invest in a new/different one?
- anyone have Rich Ts tel number as I cannot get onto his blueyonder based website to see how long to order the kit

thanks

Hi chaps is there a problem with the site I've been trying to get on the blue yonder site to get info & price for the 186 kit crank, n carb for last two days but no joy !
I've been on the face book page but very little info ?

The old GT site is down and is moving to a new server. while this is being done the old GT site is now temporarily here on my web site
http://www.lambretta-images.com/granturismo/