GTS OWNERS CLUB

MikeHolland · Last edited by MikeHolland on Fri Jan 25, 2008 10:33 pm; edited 1 time in total

My J.Costa variator gave up on me yesterday.

I went for a long ride, and noticed that the engine was revving higher than usual, and making a new noise - oooooooAAAAAAoooooooAAAAA. So I rode home very gently - no more than 50kph.

Today I opened up the transmission, and found that one of the slugs in the variator had worn its rounded end away completely, and the inside of the bell that it rubs on was badly scoured. Tiny bits of metal scattered about the transmission case.

So I have refitted the original Piaggio variator. I have learned my lesson. The only way to tune a GT is to replace it with a GTS. And then don't do any tuning to the GTS (except maybe an exhaust). The only tuning left in my scooter is a Malossi camshaft, slightly larger main jet, and stiffer clutch springs.

But I shall ride my slow GT for another 6 months or so, waiting to see whether anything comes of the rumoured GTS Super. I hate the saddle of the GTS, but also hate the idea of buying an expensive scooter and then having to spend more money replacing the saddle. Fingers crossed on the Super.

Mike
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Scooterist007 · Posted: Mon Jan 14, 2008 1:00 pm Post subject:

well why dont you buy a gts before selling your gt and then change the seat over then sell your gt! Laughing

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ChevySoul · Posted: Mon Jan 14, 2008 6:45 pm Post subject:

Was talking to Jerry at Readspeed this weekend. The subject got around to variators. I mentionad the J Costa, and he just laughed. Seems that he had tried one on an auto a few years ago and was not impressed (quality). He thinks they are made in Taiwan, but not 100% sure.

Unless they have changed in the last couple of years, we could be seeing a few more failures Rolling Eyes

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suit scoot · Posted: Tue Jan 15, 2008 2:41 am Post subject:

i was gonna buy one as well!

before i got the polini.

th eonly reason i didnt get one was because theyre hard to get over here.
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CheekyThomas · Guvernor Joined: 18 May 2007 Posts: 1374

Not seen one do that before... seen a few of the Aprilia Atlantic guys with them suffer from belt debris issues with the sliding pins, making them jam in or out at times...

Its a shame considering the price.

Have you contacted Jcosta and seen what there opinion is? Free warranty replacement maybe?

MikeHolland · Posted: Fri Jan 18, 2008 7:49 am Post subject:

Well, it seems that the J.Costa variator is absolved of causing any of the problem. But it is a long story.

Some time back I tightened the crankshaft nut with an impact driver, and stripped the thread. I had a spare nut, so fitted that and tightened it correctly with a torque wrench.

The damage to the Costa variator indicated that it had been loose, and the bell had twisted, so I presume that the impact driver also damaged the thread on the crankshaft, and I had torqued the new nut against the damaged thread, not against the variator.

Whern I tried to refit the Piaggio variator, the new nut just kept turning.

So now I am sending my scooter in to be fitted with a new crankshaft ($AU1500!), and I will keep the J.Costa variator in, but with a new set of pins - the bell cleaned up all right.

Important Lesson - Impact drivers are for UNDOING, not for TIGHTENING!!!!

Mike
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AlexHancock · Joined: 22 Nov 2007 Posts: 12

I'm happy that you've resolved the problem BUT your post could have lost J Costa some business so please start a new thread to try to reverse the damage as not everyone will revisit this thread.

suit scoot · Posted: Fri Jan 18, 2008 11:31 pm Post subject:

Innocenti · Posted: Sat Jan 19, 2008 9:56 am Post subject:

i have been reading on other forums and this is the first i have heard off with probs, and like mike has said not variators fault, i have only heard off them over last 6 months and was looking to get one , Confused

intresting
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CheekyThomas · Guvernor Joined: 18 May 2007 Posts: 1374

Ive never heard of one fail... just the sliding rods get gummed up by the belt debris... so you have to clean it more often than the standard type.

suit scoot · Posted: Sun Jan 20, 2008 10:18 am Post subject:

this is wierd, when my variator nut came loose before no damage was caused at all to the variator. luckily i was doing about 40mph and managed to stop almost instantly.

did the variator nut fly off and bounce round the casing causing the damage?
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MikeHolland · Posted: Sun Jan 20, 2008 12:48 pm Post subject:

No Suitscoot, the variator nut did not come loose.

1. I fitted the Costa variator, and did the nut up too trightly using an impact wrench. I tried a new nut, and it went on with a little difficulty, but torqued up to the correct tightness. So I assumed there was little damage to the crankshaft thread.

2. I was wrong, and the nut had just tightened up on the damaged crankshaft before locking the variator up tightly. So the variator was a little loose.

3. Because of this looseness, the variator bell managed to twist slightly, and things started to go wrong in the variator.

4. When I opened the transmission case, I saw the damage to the variator, and assumed that the variator pins had worn drastically and unevenly, with the end of one of them disintegrating.

5. When I then tried to put the original Piaggio variator back, the nut just kept turning, and I realised that the crankshaft was shot. Further examination of the Costa variator bell showed that it had been twisted and was scraping on the transmission case behind and on the inner part of the variator.

6. I still cannot explain the symptoms I experienced on the basis of the above, but I am sure that is the whole story.

Mike.

NB. I have had a variator come loose once, and the friction against the metal plate inside the transmission cover melted the black plastic thingummy that holds the filter. That was why I took to using an impact driver to tighten tht nut.
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Smudge210 · Posted: Sun Jan 20, 2008 1:17 pm Post subject:

I would not use an impact wrench to tighten one, only to loosen it if really needed. You put all the stress onto the big end pin and risk twisting the crank. I know lots of garages use them but I'd still go with a torque wrench to the manufacturers spec.

igarratt · Posted: Mon Jan 21, 2008 8:53 pm Post subject:

Innocenti · Posted: Mon Jan 21, 2008 9:22 pm Post subject:

spoke to Sticky(scootering) today they are doing a review and test as we speak with all types of variators and exahust so be intresting to see what comes out best, he stated that J costa was best low down but not hot top end Confused

but thats on a dyno think you would just have to try yourself Wink

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