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Coose
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PostPosted: Sat Feb 27, 2021 6:57 pm    Post subject: Alternator Chain Slack Reply with quote

Evening all,

I'm chasing a strange whine on my 1990 EXUP, which is loud at tickover but gets quieter once you rev the motor. It does also get quieter once the motor warms up, but it's still there.
You can hear it here...

https://youtu.be/5xRCqZvuH8I

I've been scratching my head for a while and have checked the camchain and tensioner but all is fine. So, I bought a cheap endoscope which is actually quite good, where the only issue I think I've found is the amount of slack in the alternator/starter hy-vo chain. There's no mention in the Haynes manual, but does anyone know how much there should be?

Here's a link to a video I took with the endoscope, where you can firstly see the top run with the chain lifting off the guide, and if you bear with it you'll then see the slack in the bottom run (I accessed the chain through the sump, hence it may seem to be the wrong way up).

https://youtu.be/gwS4T_EaBc4
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creedxup
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PostPosted: Sat Feb 27, 2021 8:12 pm    Post subject: Hi-Vo chain slack Reply with quote

It’s normal to have some slack in the Hi-Vo chain, yours looks fine.

I couldn’t hear any excessive noise in your video, even when I bought mine new it was never a quiet engine.
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1992 RU midnight blue, Wiseco 1070, 6 speed, r1 calipers, ducati discs , 157 bhp crank, Ohlins shock
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Coose
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PostPosted: Sat Feb 27, 2021 8:35 pm    Post subject: Reply with quote

Thanks for your comments, that's reassuring about the chain. The whine you can hear in the video is quite loud, certainly louder than any other EXUP/Thunderace etc. that I can find on YouTube. Strangely, having gone around it with a garage stethoscope (i.e. a screwdriver and an ear) it's loudest at the thermostat housing!

I'm going to whip the clutch out and check the basket, although it doesn't get any louder when you remove the filler plug.
One other question, would you know the primary gear clearance value? In the box of bits I got with the bike was another clutch basket so I'm wondering if the primary gear clearance might be too tight if the baskets were "graded"?
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Coose
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PostPosted: Sun Feb 28, 2021 12:37 pm    Post subject: Reply with quote

I've just dropped out the clutch basket and there's nothing to report there. There's a sensible amount of primary backlash, and although the three yellow damper springs are loose they would tighten when you pull the clutch in, which doesn't make any difference to the noise.

Now, I can see the hy-vo chain where it runs on to the crank. The guide looks good, but if I pull the chain away from the guide there's at least 8mm of clearance. Does that sound about right for an EXUP as it seems a lot to me?



You can just see it in this photo, where you can also see a nice Carillo rod. cool
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creedxup
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PostPosted: Sun Feb 28, 2021 12:59 pm    Post subject: Reply with quote

Your Hi-Vo chain slack is normal.

There shouldn’t be any backlash between the gears of the clutch basket and the crankshaft.
If you can feel or see movement when you grab the aluminium part of the clutch basket and rotate it, then the basket is worn, the 6 radial springs that are mounted on the rear face wear into the aluminium of the basket which cause this wear.

There are no limits in the manual for this, all it says is to inspect for wear or damage, so it’s up to you if you want to replace it, I’d be surprised if you can still buy a new one and any 2nd hand basket will probably be worn the same.
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1992 RU midnight blue, Wiseco 1070, 6 speed, r1 calipers, ducati discs , 157 bhp crank, Ohlins shock
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Coose
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PostPosted: Sun Feb 28, 2021 1:37 pm    Post subject: Reply with quote

Thanks again for your input, it's greatly appreciated! cool

I think I may have had a breakthrough. I was just reassembling the clutch and noticed something which sparked off something that the guy who had the bike built had mentioned a while ago: -

"Just a point the clutch basket has cut outs on the outer ring, this was caused by the throw of the crank with the Carillo rods."

Here's a couple of interesting photos: -





Notice the marks towards the end of the fingers on the clutch jacket, and also the hammering on the outer friction plate. I think a little dressing may be in order.... sly wink
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Stig
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PostPosted: Sun Feb 28, 2021 5:50 pm    Post subject: Reply with quote

Those fingers def look like they’ve made contact at some point in time looking at the rub marks
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creedxup
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PostPosted: Sun Feb 28, 2021 9:39 pm    Post subject: Reply with quote

It looks like someone has already machined down the fingers of the basket to try to make clearance, that part of the basket is already a weak point and they’re prone to breaking there.

I’d be tempted to grind off a few mm of the head of the bolt instead.

The fingers of the basket should be full thickness all the way to the end like this one.


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1992 RU midnight blue, Wiseco 1070, 6 speed, r1 calipers, ducati discs , 157 bhp crank, Ohlins shock
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Coose
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PostPosted: Mon Mar 01, 2021 7:22 am    Post subject: Reply with quote

The other basket I have is the same, so in that case I'm assuming that they skimmed two baskets at the same time.

I'm not too worried about the basket as it's been in there for nearly 30 years, with the first few as a race bike. (Yep, 30 years! eek )

I put it back together yesterday afternoon and it still whines, although I did notice that the starter gears do "jangle" a fair bit so I'm wondering if it's a sum of the whole?

So, I think I'm going to fit a new sump gasket, change the oil again and ride it! sly wink

Thanks again to both for your input. smile
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