GTS OWNERS CLUB

suit scoot · Posted: Fri Jun 27, 2008 10:23 pm Post subject: 300, engine parts query.

does anybody know how much the 278 barrel, piston and longer stroke crank, + main bearings are?

if its over 400 quid i'm gonna just go malossi on it and tune my 250....
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revolution deathsquad!

Maver · Posted: Fri Jun 27, 2008 10:32 pm Post subject: Re: 300, engine parts query.

suit scoot · Posted: Fri Jun 27, 2008 10:40 pm Post subject: Re: 300, engine parts query.

Maver · Posted: Fri Jun 27, 2008 10:45 pm Post subject:

so you're sure you can change the bearings then?

knock the old ones out and fit the new ones?

know anyone who's done it before?
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suit scoot · Posted: Fri Jun 27, 2008 10:58 pm Post subject:

Maver · Posted: Fri Jun 27, 2008 11:18 pm Post subject:

oh changing the crank bearings are easy on most engines BUT i believe the crank bearings are a little different on the LEADER engine (in it's many guises) i'd check things out with someone who knows before you get too deep into things....................
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CheekyThomas · Guvernor Joined: 18 May 2007 Posts: 1374

Your spot on chap, the bearings aint a easy changable item on these engines as they are machined into the crankcase so actually part of the engine, not a normal removable everyday bearing like most engines... you can replace them if you have to but its not a cheap experience, the crankcase needs to go to an engineers, the original bearing machined out and then a new insert fitted, and the success rate of doing such is often low as its not uncommon for the new insert to move slightly....

Dont forget on the 300 the head is different to the 250 as well...

GTS300 parts...

Crank is 8729755001 @ £199.12+vat

Barrel + Piston is 876457 @ £162.14+vat

We need someone to be brave and strip them both and see what fits, wheres old Russ when ya need him Laughing

From the part numbers its all different, crankcases, head etc etc so they might not fit??

Maver · Posted: Sat Jun 28, 2008 10:19 am Post subject:

as i thought then.......

new crank bearings realistically means new casings Wink

another reason not to over do the tuning.......

did have a very qualified person tell me that if you increase the revs on the engine by 1000rpm it doubles the load on the crank bearings....

ie going from 9000rpm to 10,000rpm (therefore overriding the limiter) IF the load at 9000rpm was 100nm this would be 200nm at 10,000rpm......

and guess what it would be at 11,000rpm......300nm???

no, it doubles again from 200nm to 400nm 12,000rpm would be 800nm

if this is true we need to forget about upping the revs like we're used to on 2 strokes and go all American, BIG cc's and low revs Wink

(i don't know the actual load on the crank bearings, my 100nm @9000rpm is just to illustrate the theory Wink

)
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Blackpool Paul · Posted: Sat Jun 28, 2008 12:41 pm Post subject:

They dont use big V twins in Top fuel Drag bikes for no reason do they?
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GTS250 its the future!!! A club wi owt a name sc. Bamberbridge.

martin68 · Posted: Sat Jun 28, 2008 1:16 pm Post subject:

Nick at Southwest Scooters (SWS) in Yeovil has done a complete engine rebuild new crank etc. (Engine failure due to lack of oil i believe)

Maver · Posted: Sat Jun 28, 2008 1:18 pm Post subject:

CheekyThomas · Guvernor Joined: 18 May 2007 Posts: 1374

All depends if the main bearings failed as well... ive done a few rebuilds needing cranks but mains have been ok, its the bigend that normally goes first.

Roadcaptain · Sargeant Joined: 19 Apr 2008 Posts: 65

was a complete bottom end failiure I think, it belongs to Davetheskin on scooter scene

CheekyThomas · Guvernor Joined: 18 May 2007 Posts: 1374

Its a good idea to ask him if they did get the main bearings machined out and relined, if so and it all went well, who did it as they would be handy to know for sure Very Happy

As the bearings aint ball race type like most they tend to take a bit of abuse before they fail, but if its a serious failure they can chew up and then its a very expensive tale....

CheekyThomas · Guvernor Joined: 18 May 2007 Posts: 1374

But back to the main topic... 30,000km on the bottom end wont be an issue anyway, they will take it no question... even if you wanna use a new crank, the bearings should be fine as long as they are within tolerances still.