Points cam not turning - GT380

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yeadon_m
Posts: 7401
Joined: Sat Jan 02, 2010 7:10 am
Location: Canterbury Kent

Re: Points cam not turning - GT380

Post by yeadon_m »

Folks,
Anyone got any ideas for safe removal of part # 29 on the diagram? its a plain metal bush, parallel sided, pressed into the crankcase and into which the inner end of the points cam shaft fits. I'd expect that as the cheaper component, its the one that designed to wear out first, rather than the more expensive points cam shaft. The components have done 43K miles. I just idly calculated that the shaft has turned ~250 million times since being assembled (really). You can tell I have too much time on my hands :-)
I am not sure whether its worn enough to need replacing, but since its was only 3 Euros I thought I'd buy one with the gear, oil seal, circlip and bearing.
I've had a look today and I can just imagine me messing it up, so unless there's a safe way to do it in situ, I'm gonna leave it!
Cheers,
Mike
these methods look simple enough but have scarily high potential to ruin a crankcase if done by a non-expert (ie me).
http://www.neme-s.org/Model_Engineer_Fi ... Bushes.pdf
I'll bet Astrax knows how to?
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yeadon_m
Posts: 7401
Joined: Sat Jan 02, 2010 7:10 am
Location: Canterbury Kent

Re: Points cam not turning - GT380

Post by yeadon_m »

Update - as posted, left the pressed-in points shaft bush in place as still in good spec. Replaced the bearing that sits in the clutch cover and very glad I did. The old one had a lot of play in it and was rough as hell when cleaned and turned with a finger. It may even have contributed to plastic gear failure. Fun getting the old bearing out and new one in - the oven and freezer trick worked a treat. New oil seals and circlip too.
Put the clutch cover back on, momentarily being foxed by not recalling how to tension the kickstart string but all done now (and think this is why the kickstarter lever doesn't lie where it should on my GT550B - the last guy was as confused as I briefly was but put in on without tensioning the spring). Timing rough checked to ensure I have the points cam gears in the right mesh - confirmed OK and will be settable with a dial-gauge later. Tinkering with a few other bits now I have the carbs out but hope to have it running early next week. Fingers crossed!

Marksav also popped over - very nice GT750A mate and thanks for riding down!

Cheers,
Mike
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yeadon_m
Posts: 7401
Joined: Sat Jan 02, 2010 7:10 am
Location: Canterbury Kent

Re: Points cam not turning - GT380

Post by yeadon_m »

Hurray! all done, timed to agonised-back perfection with dial gauge and meter; bike fired up 3rd kick and idled on 3 pots even on choke and nice and slowly off choke.
I have also fitted a 1/4 turn on/off fuel tap as I am fed up with slowly failing fuel taps. Its tight under the GT380 tank but quite workable. At £8 delivered, they are a bargain.
Cheers,
Mike
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