Crankshaft information please?

[tigkid]

Hi;
I hope you don't mind me asking what may appear to be a simple question, but I'm going to anyway!
I've just bought a TRX which has stripped some of the teeth from the timing chain drive cog on the end of the crankshaft.
Is it possible to replace this cog and re-use the crankshaft, or do I need to source a new crank? (or is it easier just to replace the complete engine?)
In either case, could anyone suggest a source of the part(s) needed please?
Thanks for any advice offered.

[youngy]

You cannot economically replace the timing gear. It is machined into the billet of the crank. All the othe gears are shrunk on, but not that one - it is the one that commonly fails.

I have a crank sat in my garage if you want one. Otherwise Yamaha can supply a crank for around £800.

There is a braker in France that specialises in TRX and TDM. He has a crank with rods on his website... http://www.gn-moto.com/boutique/product ... 14aedc964c but even that is £475.

Let me know if you're interested in the crank I have.

[steve speed]

this has happened before ,,but i cant remember if anyone has had a go at having the old cog machined off , a new one made and welded back on ! i feel sure it must be possable ,,,is this phatt,s old bike that you now have ?

[HansJ]

I can recommend the French guy, I bought a 2nd hand cylinder head. Speedy service, and in better shape and more parts included than I expected!

[youngy]

this has happened before ,,but i cant remember if anyone has had a go at having the old cog machined off , a new one made and welded back on ! i feel sure it must be possable ,,,is this phatt,s old bike that you now have ?

There's very little meat under the gear steve. not enough to machine off and weld to easily.

the French TRX group were looking at having a bunch repaired, as a one off repair was astronomical, but even for a number of cranks the price was still prohibitive.

[brockzila]

what are the chances of it being blue and brought off phatvr6???

[tigkid]

Thanks very much for the info guys, and the offer of a replacement crank.

There is indeed a serious chance it may have been bought from phat, just hope I can get it all back together and have some fun on it.

[youngy]

don't put the camshafts in 180 degrees out!

[steve speed]

what are the chances of it being blue and brought off phatvr6???

every

[Quan-Time]

with the right machinist, you would be able to cut it off on a lathe, get a new gear, heat it up, freeze your crank, shrink it on. Its possible to do, but, still.. risky.

2nd hand might be one of the only options.

[youngy]

you'd have to remove the oil pump drive gear first, then machine down the crank to get a gear on there. the gear is so shallow to the crank though the new gear would be dead thin.

[steve speed]

as you say its a bit thin , but my idea would be to weld it on as well

[stormy]

Even if you could somehow machine the old gear off, make a new one to EXACTLY the same dimensions, how can you 100% guarantee that it would be aligned exactly so that when the chain runs around it AND the camshafts, that the timing would be spot on? Just getting the gear half a tooth out of alignment with the crank would cause you loads of hassle.

I know there is a little adjustment on the sprockets, i.e. bugger all, but that would have to be some serious retro engineering.

Take Youngys crank IMHO, save you a lot of grief!