Clunk noise on startup

People like to fight me on this, but the starter clutch just likes to clunk sometimes. Mine's been doing that from time to time for 150,000 miles now. My brother's does it. All the EX's I've built do it. I don't lose any sleep over it.

Additionally, the starter clutch itself doesn't fail. In all my experience and spare parts, I don't have a single failed starter clutch. The tiny springs for the 3 starter clutch pucks will get weak and tweaked over time, so it could be those need to be removed and stretched out a bit.
What DOES happen is the 3 allen head bolts securing the starter clutch assembly to the back side of the flywheel love to back out. After a while, they begin to catch the big starter clutch sprocket and make a ticking noise while running. Eventually, the bolt will back out far enough to grab the sprocket and effective engage the starter at all times. It will make the most horrendous whirring noise and you'll be inclined to immediately shut off the bike, which you should do. This is resolved by removing the 3 allen head bolts, thoroughly cleaning the oil from the bolt threads and the threads in the flywheel, applying red loctite and hammering those bolts in there. Long as you didn't replace your flywheel with another factory original exposed magnet flywheel, you will never have a reason to remove those bolts ever again.

Agree and disagree with Saabnut. Agree especially that the bolts can loosen, sometimes no indication until they hit the sprocket piece. But I have seen two things happen to the One-Way Clutch. 1. the pucks are sent back into the clutch assembly with such force that you can see an impression of impact at the outer edge of the clutch assembly; 2. the clutch assembly cracks from the inner diameter through one of the bolt holes out to the outer diameter.
[/QUOTE]
I think that the first thing you mentioned may have happened since there are three marks on the outside I just assumed that it was supposed to look like that. although I can't really see how that would cause the noise. here's a photo

In the photo @Carraig posted of the outwards dent on the outside edge of the starter clutch housing, I've seen that many times before. I honestly haven't specifically looked for it many times and can't recall if any I've had my hands on before didn't have such dents on them, but I do recall encountering them enough that I stopped paying attention long ago. So, I don't know if that's how they come or if it's damage like @haybaler says, but either way, I would not consider it anything to fret about.

That clunking happens when the starter clutch skips and grabs again. There's some debate as to the root cause of that. Some say that it's caused by running synthetic oil as it's too slick and causes it to slip. It could be cause by weak springs behind the pucks. But, it happens in engines with neither of those things. Hence why I tell people not to worry about it too much. The best thing you can do for that is to get the engine in top running order so it only takes a blip of the starter to fire it up in any weather. At the very least, you don't have to hear the sound as often.

haybaler said:

2. the clutch assembly cracks from the inner diameter through one of the bolt holes out to the outer diameter.

Click to expand...

That's a new one to me, have yet to see it on an EX500. Not saying it's impossible, I just haven't personally encountered or heard of it here on the forum. Have you seen it on an EX500 or some different application?

slightly off topic but relevant to the discussion. Fog has said on many occasions these bikes were designed to last 25k and little more, double that and your on a wing and a prayer.
however some bikes seem just to last a lot longer just because of sheer determination of owners to make them last longer. in theory when a EX reaches this milestone the best option would be to remove the engine strip it and replace any parts that show signs of wear including any other bike parts with wear on them.
this is not practical for most of us so preventative measures have to do. ignoring some of the downsides of worn parts like clunks and rattles and slight loss of power.
by checking the parts that often cause issues you can make these bikes last a long time. the winter non riding season is an ideal times for this. moreover a new owner of a GEN 1 with mileage on it is at a disadvantage from day one as PO's have had the benefit of the best of the bike when it was newer.
however if this owner when acquiring it goes through all the known issues one by one he can diminish the risk of later problems finding and eliminating these helps a lot.
on getting the bike or as soon as possible remove the CCT and bin it. replace with the GEN2 type.
drop the oil and coolant. then remove the valve cover inspect the cams and rockers for wear and check the cam chain is in spec do the valve clearances top back on remove the side cases.
on the clutch side check the primary chain for wear and the clutch basket also. you will have some wear in there in the basket bearings and some burring both on the basket and the plates this is to be expected but if it is not excessive it is not worth worrying about but will make some strange noises when running.
on the flywheel side check the starter chain for wear. and the exposed magnets for any signs of cracking in the epoxy resin glue. if any found redo the epoxy. but look for a gen 2 type and modify it for the gen 1 ignition ( I would do this anyway) remove the flywheel and the starter clutch inspect them for wear and stretch the little springs a bit and check for cracking in the weld of the starter sprocket replace the the three bolts with thread lock to the right torque.
and replace it all close the cases. refill with new oil and filter and add new coolant.

the bike will now be in the best possible shape for the year ahead if you do this every winter as well as other maintenance there is no reason it will not last a long time. and you will know that even with the odd strange noise nothing is going to fail. so can be almost ignored.
these bikes are old and should be treated as such, you wouldn't expect a granny to do the same things now as she did in her 30's so the bike won't either.
true some grannies are in better shape than others and this applies to bikes but keep up the maintenance and treat it with respect and you too will keep it going long enough to join the 100k club.

just my thoughts thought it may be beneficial in the context of worn parts.

yorkie said:

slightly off topic but relevant to the discussion. Fog has said on many occasions these bikes were designed to last 25k and little more, double that and your on a wing and a prayer.
however some bikes seem just to last a lot longer just because of sheer determination of owners to make them last longer. in theory when a EX reaches this milestone the best option would be to remove the engine strip it and replace any parts that show signs of wear including any other bike parts with wear on them.
this is not practical for most of us so preventative measures have to do. ignoring some of the downsides of worn parts like clunks and rattles and slight loss of power.
by checking the parts that often cause issues you can make these bikes last a long time. the winter non riding season is an ideal times for this. moreover a new owner of a GEN 1 with mileage on it is at a disadvantage from day one as PO's have had the benefit of the best of the bike when it was newer.
however if this owner when acquiring it goes through all the known issues one by one he can diminish the risk of later problems finding and eliminating these helps a lot.
on getting the bike or as soon as possible remove the CCT and bin it. replace with the GEN2 type.
drop the oil and coolant. then remove the valve cover inspect the cams and rockers for wear and check the cam chain is in spec do the valve clearances top back on remove the side cases.
on the clutch side check the primary chain for wear and the clutch basket also. you will have some wear in there in the basket bearings and some burring both on the basket and the plates this is to be expected but if it is not excessive it is not worth worrying about but will make some strange noises when running.
on the flywheel side check the starter chain for wear. and the exposed magnets for any signs of cracking in the epoxy resin glue. if any found redo the epoxy. but look for a gen 2 type and modify it for the gen 1 ignition ( I would do this anyway) remove the flywheel and the starter clutch inspect them for wear and stretch the little springs a bit and check for cracking in the weld of the starter sprocket replace the the three bolts with thread lock to the right torque.
and replace it all close the cases. refill with new oil and filter and add new coolant.

the bike will now be in the best possible shape for the year ahead if you do this every winter as well as other maintenance there is no reason it will not last a long time. and you will know that even with the odd strange noise nothing is going to fail. so can be almost ignored.
these bikes are old and should be treated as such, you wouldn't expect a granny to do the same things now as she did in her 30's so the bike won't either.
true some grannies are in better shape than others and this applies to bikes but keep up the maintenance and treat it with respect and you too will keep it going long enough to join the 100k club.

just my thoughts thought it may be beneficial in the context of worn parts.

Click to expand...

Thanks for the input I will be sure to check the cam chain since that part hasn't really been checked in a while but as of now, I am really itching to ride. everything seems to check out though I just had one question about the flywheel since I did notice some slight wear after riding it lightly. I am assuming that it's normal but I just wanted to be sure.