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Post by zig on May 2, 2022 10:38:58 GMT 1
I s there a reason why the idle gear is slack/loose on it's shaft ?
even though i have replaced mine with brand new it is slightly better but still loose
i can only assume it is designed like this for a reason ?
Has anyone ever tried an extra shim to take out the jiggle or is this a bad idea ?
ZiG
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Post by 4l04ever on May 2, 2022 10:50:51 GMT 1
It appears that the shaft is slightly undersize, so even a new gear or new bush will still have some play.
The only fix is to get a custom bush made which matches the size. I found a local engineer who can do these. He has also replaced bushes in the main gears too.
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Post by zig on May 2, 2022 21:27:40 GMT 1
it's surprising that Yamaha got it wrong with the shaft either undersize or just plain wear and tear adding to the issue ....
i think i might have a look at placing another shim behind the circlip , seems to have the space to fit
ZiG
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Post by 4l04ever on May 2, 2022 22:07:14 GMT 1
The bush is designed to fit an exact mm size shaft 12mm or 14mm?? The shaft is about .1mm undersize... Measure your shaft to see.
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Post by zig on May 3, 2022 19:56:00 GMT 1
The bush is designed to fit an exact mm size shaft 12mm or 14mm?? The shaft is about .1mm undersize... Measure your shaft to see. i dont think i have ever came across an idle gear that fits without some movement and so always thought it was just the way it was manufactured do you think it would be a good idea to double shim the gear , do you see any problems arising from it ? ZiG |
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Post by midlifecrisisrd on May 3, 2022 20:41:54 GMT 1
I had it in my head that it was supposed to have some play in it to aid the kickstart gear engaging
Steve
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Post by zig on May 3, 2022 21:23:57 GMT 1
I had it in my head that it was supposed to have some play in it to aid the kickstart gear engaging Steve you are probably correct Steve when you think about it , would make sense ZiG |
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Post by jon on May 3, 2022 22:25:11 GMT 1
I had it in my head that it was supposed to have some play in it to aid the kickstart gear engaging Steve I’m not sure that’s the case? I could imagine if it had chamfers on the teeth that this would aid engagement. Personally I think it’s a case of after very little use the bush gets worn as the gears smash into each other before the cogs engage? Jon |
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Post by 4l04ever on May 3, 2022 23:11:32 GMT 1
There is too much clearance between the bush and the shaft.
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Post by Tobyjugs on May 3, 2022 23:14:29 GMT 1
Normally gear wheels on big engines will have between 0.06-0.09 mm oil clearance between shaft and rotating gears.
I have often thought why should it be more sloppy?
Maybe because it has to engage another gear?
I have spoken to Nova gears in the past and they can make needle bearing conversion but I wasn't sold on the idea.
I agree with midlife as it must engage another gear.
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Post by 4l04ever on May 3, 2022 23:17:25 GMT 1
A needle bearing conversion will also end up being loose, as the shaft is undersize.
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Post by 4l04ever on May 3, 2022 23:18:40 GMT 1
It may be Yamaha erring on the safe side,as too tight would seize, but too loose would just rattle around a bit.
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Post by jon on May 4, 2022 7:30:08 GMT 1
I’ve had one that rattle around so much it wore the tolerance etching off the secondary gear.
Jon
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Post by zig on May 5, 2022 10:41:42 GMT 1
with thanks to Dave @mutts i now have me a fresh set of shims and circlip which on inspection of the old one has revealed is has severly worn the back of it so much it has a lip on it so needless to say the shims must be equally worn as much
down thru the years....building up for the weekend and will let everyone here know the outcome of the upgrade and new Yamaha parts go as regarding the rattle
ZiG
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Post by zig on May 7, 2022 16:43:58 GMT 1
update so fitted the idle gear upgrade from Norbo along with the new genuine idle gear shim's purchased from Dave muttsnuts carried out the slector star mod advised by everyone here as regards selecting Neutral ditched the clutch rubbers and upgraded the clutch plates to EBC DCR043 as seen and used by Dusty and glad to say after building her up today she is a different bike , no noise or rattles of any kind AND the star mod was a great call i now have Neutral without any problem  just want to say a big thank you everyone who gave me feedback to fix something that really worried me to the point it was going to be a complete engine strip thanks everyone ZiG |
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