Rattle on deceleration

[Arfdog]

I took the missus to Brighton for the weekend last weekend, this was the first longish trip on the GS450 with a pillion. I could not find parking near beach front, so rode up into hove and parked on a steep hill outside some houses, and we got a cab to the beachfront.The bike was pointing uphill, but little did I know at the time, because of this, overnight most of my oil leaked out of the clutch pushrod seal. I only deduced this once I returned home unfortunately, which means I rode about 80 miles at top speed with very little oil. The oil light never came on (must check it actually works), and I didn't think to check the oil, as I had checked it the day before going down there in the first place.

Anyway, the long/short of it is that a number of things have popped up. The first - the exhaust is blowing, right at the outlet manifold. It's a MOTAD. Is there a manifold seal of some kind that is prone to rupturing on most bikes? I checked to see if the bolts are loose, but they're not. Neither are they seized in, luckily.

Problem number 2 and far more worrying, is that if I am riding a decent speed, say 50 in 3rd gear, then suddenly turn off the throttle, a rattle eminates from the engine. sounds like a chain rattle. I am guessing cam chain. Is there anything else that can rattle like this under deceleration? There was no such sound before..

Thanks, Arf
____________________
I'm a lover, not a fighter.

[stinkwheel]

Rattling could well be detonating in your exhaust due to it leaking making the baffle rattle about.

These days they use fiber washers (well, a kind of sandwich of thin steel and fiber) to seal the exhaust headers. In my experience they are pretty crap and do blow after a while. When you take them off you are left with a few slivers of rusty metal and some crumbly dust. They do however have the advantage of being remarkably cheap (less than the cost of a pint).

Copper crush washers do a much better and more permanant job, they can be harder to find and more expensive though.

If it were me I'd fix the exhaust first and see if the noise goes away.

I would expect a camchain to flap about more at idle to be. If you listen carefully, you should be able to hear the camchain whirring as you rev the engine.

[Arfdog]

Thanks Stinky, I'll fix the exhaust over the weekend and hope it stops.

I've not been able to check camchain condition since I've have the bike, because I have a morbid fear of cam cover bolts. I will snap one, I'll bet my arse on it. I've been tempted to look, but lost my nerve whilst trying to crack the second bolt loose. Maybe it's just time to face my demons, but it'll end in tears for sure...

Anyhow, what is promising is that the camchain whirs beautifully (or did before this - more difficult to hear now with loud exhaust!). I guess it would be unlikely for a chain to stretch by a huge amount over 100 miles, even if the was very little oil.
____________________
I'm a lover, not a fighter.

[Arfdog]

OK, I took exhaust off, the metal ring that comprises the flange has snapped off most of the way round the end of the pipe. This is a motad exhaust on a '86 GS450, don't think it'll be easy to find spares.

Any suggestions as how I could try repair this?

https://i112.photobucket.com/albums/n190/arfdog/Clipboard01.jpg
____________________
I'm a lover, not a fighter.

[stinkwheel]

Well, what I personally would do with that would be to take it down to the blacksmith and ask him if he can do anything with it.

Huh, huh, check it out Beavis. He's really showing us his flange.

[Arfdog]

WooHoo!

Just popped round to the neighbours, he welded the bust lip back on, and built it up good and thick, then grinded it down. Worked perfectly and looks about 4 times as strong as it ever was.

Thank god for neighbours that build hot rods in their spare time!
____________________
I'm a lover, not a fighter.

[Bezzer]

Nice one and you might find your rattle has gone as well, loose headers can cause it
____________________
I used to be indecisive but now I'm not quite so sure.

[Pete.]

That would definately cause a rattle.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Arfdog]

Aye the rattle is indeed gone (only got to go for a proper ride this morning after doing stuff all weekend), great stuff.

I wish I took a photo of the newly welded flange before putting it in, real good job..
____________________
I'm a lover, not a fighter.

[Pete.]

Don't expect it to last long buddy, it will crack again along the edge of the HAZ (heat-affected zone). The best way to fix them is to make new swaged flanges from mild steel tube that slips over the original and weld them to it.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good