TOPIC:

A member of this forum for merely a few days and the first troubles start emerging;
This week I was riding my bike on the highway, It was handling all right and everything seemed completely in order. Planning to perform an overtake when suddenly the engine stopped pulling in response to the throttle. I pulled over and the engine died. Upon a startup (it would restart immediately) I noticed a pronounced rattle when revving the engine. It appeared to come from in between the cillinders so my first thought was an issue with the cam chain. I chartered a friend with a trailer to repatriate the bike to my 'garage' and did a short routine check to eliminate some possibilities;

Valve clearence is OK, Timing advance (transistor, not mechanic) is OK. Bike still starts all-right. Clanging and rattling sound still present at any RPM higher than idle.
I also checked the automatic cam chain tensioner and it appeared to be in working order; The shaft was not bent and the spring tension was quite firm.

I still suspect an issue with the cam chain; It could have jumped a tooth on the valve timing sprocket, it could be past its service limit or the automatic tensioner chain-guide might have failed. The bike has only 23.000 km's on it's odometer so it would surprise me if the camchain is worn-out.

I'll have time this weekend to take the head (decapitate) off the engine to visualy inspect the forementioned parts and i'll try to take some pictures of what I find. Is anyone familiar with this issue or am I just unlucky and is it an incidental breakdown?

(note, I have the factory maitenance manual and will (dis)assemble the engine according to instructions)

Would first do a leak-down test, which will also aid later diagnosis.

Next, remove the valve cover (not the head) and inspect for anything out of the ordinary.

Results of the leak-down test will likely indicate any valve issue and and identify which valve is involved.

One possibility could be a broken valve spring.

Good Fortune!

If needed, here's some info about leak-down testing .

A leak down test injects air pressure through the spark plug hole to pressurize the combustion chamber.

Can perform a poor man's leak down test by introducing compressed air into a spark plug hole and listening to where it escapes from the combustion clamber. This may be done at TDC or any other cam positions where both valves are fully closed. Top dead center (TDC) is when the piston is at its highest position. An easy way to tell TDC is by alignment of the T mark with the case mark when viewed through the timing window.

May introduce a spurt of compressed air by using a rubber cone-tip blow gun (rubber air nozzle) held into the spark plug hole. And of course keep holding it in position to keep air from coming back out the spark plug hole while listening for escaping air at other places. The air compressor should not be running while listening because the noise will likely drown out any sound of escaping air. Or just use a portable compressed air tank.

Air heard escaping from exhaust port indicates exhaust valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from carb intake indicates intake valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from crankcase breather indicates loss of compression past rings into crankcase (perhaps worn piston rings or cylinders).

Air heard escaping from head gasket area indicates indicates loss of compression past head gasket (perhaps due to a blown head gasket).

A leaking valve may sometimes be resolved by adjusting the clearance to within specs.

A leaking head gasket may sometimes be resolved by torquing the head fasteners when the engine is stone cold (such as after sitting overnight).

Good Fortune!

Puzzled;
I checked the valve cover; Valves were just fine, no leaks and good compression. Cam chain was well within specs and tensioner does its job as it is supposed to. The timing of the chain was found to be correct as well.
Could this be a carb (synch) issue that causes a rattle of e.g. the primary chain? I'm getting a bit lost here...

Janklaassen wrote: ... riding my bike on the highway...everything seemed completely in order. Planning to perform an overtake when suddenly the engine stopped pulling in response to the throttle. I pulled over and the engine died. Upon a startup (it would restart immediately) I noticed a pronounced rattle when revving the engine. It appeared to come from in between the cillinders so my first thought was an issue with the cam chain...Valve clearence is OK, Timing advance (transistor, not mechanic) is OK. Bike still starts all-right. Clanging and rattling sound still present at any RPM higher than idle.
I also checked the automatic cam chain tensioner and it appeared to be in working order; The shaft was not bent and the spring tension was quite firm.

I still suspect an issue with the cam chain; It could have jumped a tooth on the valve timing sprocket, it could be past its service limit or the automatic tensioner chain-guide might have failed. The bike has only 23.000 km's on it's odometer so it would surprise me if the camchain is worn-out....

Janklaassen wrote: ...checked the valve cover; Valves were just fine, no leaks and good compression. Cam chain was well within specs and tensioner does its job as it is supposed to. The timing of the chain was found to be correct as well.
Could this be a carb (synch) issue that causes a rattle of e.g. the primary chain?....

Although carb sync might be questionable, am pretty sure that poor sync isn't causing the rattle at rpm above idle.

If not already done, would check for possibility of a loose spark plug, and assure that the plugs are the correct heat range.
And also assure that the crankcase oil level is correct.

Questions -- when first starting the cold engine, is the same rattle present?
Is the ignition timing owner-adjustable? And has it been checked with a timing light?

Haven't yet ruled out the possibility of broken valve spring.

Good Fortune!

The rattle could be from a misfire. Battery. Ignition coil. spark plug or spark plug wires???
Maybe fuel delivery???

My bike started running poorly at high rpms, then quit.
It would restart but ran poorly at higher speeds --- the battery electrolyte was low.
Another time, same thing --- the battery was bad.
The next time it was the ignition coils --- they were getting very hot (pressing hard w my fingers).
Another time it was a defective petcock diaphragm.

This part:

It was handling all right and everything seemed completely in order. Planning to perform an overtake when suddenly the engine stopped pulling in response to the throttle. I pulled over and the engine died.

Sounds like a carburetor or fuel system problem.

I just ran home 80 - 90 and had a rattle loss of power get home and looked and have no nuts on 3rd header

yeah some guy said your bike looks fast lets race . oh hell yeah lets go , he had a jap 650 I have a machine gun lets go . ELR wins wins no problems lmao

An image says more than a thousand words. At 30 frames per second, I present you a mere 810.000 words. The noise only seems to occur when there is an increase in the rpm's or at higher rpm's. The location of origin is very hard to pinpoint. Anyone familiar?
LINK to VIDEO

Check your exhaust pipes where they attach to the cylinder head for leaks. Ed

Sounds like an exhaust leak