STRANGE NOISE

[robsgreen]

Hi Guys
i wonder if anyone can shed any light on this issue I have.

Im still breaking my bike in from a full re-build and all seems OK apart from one thing? When Ive covered around 10 miles or so and its hot, there is a strange clatter seeming to come from the top end of the engine. This occurs if you blip the throttle gently. The rattle comes in as the revs drop back to 1000rpm from about 2500rpm. Its a strange sound, like there are marbles inside the cam cover. Once the bike has cooled, it stops doing it. bike goes really well otherwise. When started from cold, the engine is nice and quiet. you can also hear this noise sometimes as you pull away. I very sure its not the alternator as this was fully rebuilt and shimmed. Its had new cam chains and primary chain as well. My crank and rods were rebuilt by a motorcycle engineer specialist so I don't think its a small end or detonation etc. I changed the oil and filter and had the sump pan off at 200 miles and there was nothing inside the bottom of the engine or oil pump filter - super clean. Should I strip the top end down again? Ive done about 400 miles so far. I'm at a loss what to do next.

Martin

[daves79x]

It's probably the clutch basket rattling. Does it change in neutral when you pull the clutch in?

Dave

[robsgreen]

Hi Dave
No, its def not the clutch, makes no difference clutch in or out. Im sure its coming from the cam area. I still have not set the pulsar positions accurately yet and wondered if they were out, could it cause this problem, like the cylinders firing are working against each other?

[daves79x]

Carbs out of sync can cause this, also loose Oldham couplers. Installing an oversize set greatly reduces the top end noise.

Dave

[steve murdoch icoa #5322]

Maybe try a long metal rod or screwdriver as a stethoscope to isolate the area that racket is coming from.

[robsgreen]

Hi Guys

Def coming from middle of cam cover area - but not always there. I think Im going to take the cam cover off to see if anything is obviously wrong. I took it out last night and it went pretty well.

There is a little blue smoke (oil) on start up but this goes completely once the engine is warmed up. I'm told it will probably stop once the bike is fully broken in, but I dont think this is anything to do with my vibration issue.

cheers

martin

[Little mate]

Pull the valve cover and check the cam chain the tensioner may not be adjusted properly . Did you set the tensioner a per the manual.???? If the chain slaps the cover it makes a racket check the inside of cover for marks .

[Little mate]

Or you could just adjust the camchain.

[robsgreen]

I did adjust the cam chain during the rebuild and have set it since as per the manual.
When I start the bike, you can hear one of the chains rustling but this goes once the bike has warmed up. I do really need to get the cam cover off to check all is well. Took the bike out for a 60 mile run today and it ran pretty well. Still making the noise on the top end so will need investigation.
cheers

[Little mate]

As Dave said carb cync can cause this. Did you balance the carbs ? As you said this goes away when bike is cool . This leads me to think check mixture and sync carbs if that doesn't fix it then look at cam bearings or sticking valve lets hope for carbs . Good luck post your findings

[herdygerdy]

If you set the cam chain tension as per manual, just by undoing the 10 mm chrome dome nut on the back of the cylinder barrels, and re-tightening it, if the tensioner itself is sticky (not at all uncommon), it may not have done very much adjustment at all and the chain could still be quite loose, hence the mysterious internal rumblings.

I find it best to set the cam chain tension with the cam cover off and follow this process. A second pair of hands holding a torch (or wearing a head torch) helps.

Remove both cam cover and RH crank end cap.

Take a 17 mm ring spanner and slowly rotate engine forward (clockwise) while looking down the front run of the long A chain that runs from crankshaft to exhaust cam. You will see the run of the chain pulled very tight as the crank 'pulls' down on the load of turning the camshafts. All the slack in the chain will be moved to the rear run of the chain.

Now turn the motor backwards slightly and you will see all the slack now move to the front run of the chain. (Doing this just to share the principle of removing slack).

OK, now loosen off the 10 mm chrome dome nut on back of barrels a few turns (don't take it all the way off).

Now put as much forward rotational pressure on the 17 mm spanner as necessary to move all the load onto the front of the cam chain. Just enough for the crank to be pulling down on the chain, but not enough to actually rotate the crankshaft.

While holding that forward rotational pressure, on the end of the crankshaft, now push down very firmly with your thumb on the rounded very top part of the 'A' tensioner, so that it bows down and in towards the crankshaft and takes up all the slack in the back of the chain. While pushing down on the top of the tensioner, now tighten the lock nut so that it is just firmly nipped up - ie; not too tight.

Now when you slowly rotate the engine backwards just a little, you should have much less slack in the chain.

For the shorter B chain, undo the lock nut and pinch bolt on the front of the cylinder head. Now push down firmly on the bottom run of the chain and then release the downwards pressure. The tensioner should bounce up and down freely and you will observe the rod on the front end of the tensioner sliding in and out of the hole in the cylinder head.

By slightly rotating the crankshaft back and forth, you will see the slack in the chain move from the top to the bottom runs of the chain.

So, once again, holding that forward rotational pressure on the end of the crankshaft, the tensioner should automatically spring up to take all the slack out of the bottom run of the short 'B' chain. While holding that forward rotational pressure on the crankshaft, just nip up the pinch bolt on the front of the cylinder head, then do up the lock nut. They just need to be nipped up firm. Not too tight at all.

If, after doing this, you still have noises coming from the middle of the rocker cover, suggest you may be up for a set of oversize Oldham coupling joints to join the pairs of cam shafts.

Good luck with this and let us know when (not if) you get it solved.

Cheers...Tony

[NobleHops]

If you set the cam chain tension as per manual, just by undoing the 10 mm chrome dome nut on the back of the cylinder barrels, and re-tightening it, if the tensioner itself is sticky (not at all uncommon), it may not have done very much adjustment at all and the chain could still be quite loose, hence the mysterious internal rumblings.

I find it best to set the cam chain tension with the cam cover off and follow this process. A second pair of hands holding a torch (or wearing a head torch) helps.

Remove both cam cover and RH crank end cap.

Take a 17 mm ring spanner and slowly rotate engine forward (clockwise) while looking down the front run of the long A chain that runs from crankshaft to exhaust cam. You will see the run of the chain pulled very tight as the crank 'pulls' down on the load of turning the camshafts. All the slack in the chain will be moved to the rear run of the chain.

Now turn the motor backwards slightly and you will see all the slack now move to the front run of the chain. (Doing this just to share the principle of removing slack).

OK, now loosen off the 10 mm chrome dome nut on back of barrels a few turns (don't take it all the way off).

Now put as much forward rotational pressure on the 17 mm spanner as necessary to move all the load onto the front of the cam chain. Just enough for the crank to be pulling down on the chain, but not enough to actually rotate the crankshaft.

While holding that forward rotational pressure, on the end of the crankshaft, now push down very firmly with your thumb on the rounded very top part of the 'A' tensioner, so that it bows down and in towards the crankshaft and takes up all the slack in the back of the chain. While pushing down on the top of the tensioner, now tighten the lock nut so that it is just firmly nipped up - ie; not too tight.

Now when you slowly rotate the engine backwards just a little, you should have much less slack in the chain.

For the shorter B chain, undo the lock nut and pinch bolt on the front of the cylinder head. Now push down firmly on the bottom run of the chain and then release the downwards pressure. The tensioner should bounce up and down freely and you will observe the rod on the front end of the tensioner sliding in and out of the hole in the cylinder head.

By slightly rotating the crankshaft back and forth, you will see the slack in the chain move from the top to the bottom runs of the chain.

So, once again, holding that forward rotational pressure on the end of the crankshaft, the tensioner should automatically spring up to take all the slack out of the bottom run of the short 'B' chain. While holding that forward rotational pressure on the crankshaft, just nip up the pinch bolt on the front of the cylinder head, then do up the lock nut. They just need to be nipped up firm. Not too tight at all.

If, after doing this, you still have noises coming from the middle of the rocker cover, suggest you may be up for a set of oversize Oldham coupling joints to join the pairs of cam shafts.

Good luck with this and let us know when (not if) you get it solved.

Cheers...Tony

Another gem Tony, respectful request to make this into it's own post with a suitable, searchable title? Pretty please?

N.

[herdygerdy]

Tks Nils, happy for you to do that as Moderator on my behalf? Not 100% sure precisely what you mean, but pls go right ahead and put it where you think it would most benefit our inmates.

(and I think you many need an update to your Avatar pic!) Still got my DL, but have not ridden it at all this year. Sorry for temp hijack, normal transmission will now resume....

[robsgreen]

Well Guys, Fantastic support as always. Really interesting and informative.
I plan to take the cover of soon so will give this a try once I have checked everything else.
I have had the carbs balanced and bike does go well, but low throttle openings, constant cruising, the engine doesnt run very smoothly. I can feel it missing slightly so I think as Dave says, carbs need to come apart again.
Despite this, I love the bike, still great to ride and will resolve eventually I guess!
Martin