It's alive!! But clunking starter clutch?
 

Hi all,

In hindsight I should probably have made one big topic instead of several smaller ones but oh well - at least my problem topics might be more easily found on google so who knows it might help someone :ban:.

Anyway, yesterday while (succesfully) checking for oil pressure from the oil bleed I noticed a clanking sound that wasn't there before when turning over the engine.
I already saw doomsday scenarios but then realized the sound was coming from the starter clutch.

When I removed the spark plug, the sound would disappear. I opened the flywheel cover and saw why. Cranking by hand, right after TDC compression stroke, the starter clutch would get a 'shock' and rotate backwards for a bit. It would then hit the smaller gear which makes a huge clunking sound.

Both my smaller gear and the starter clutch gear have huge play on them. Is this normal?
I can move the smaller gear 0.5mm axially (as if a spacer is missing) and the big starter clutch gear more than 1mm. I didn't forget the spacer ring behind the starter clutch gear, and flywheel is torqued to 120nm.

Basically I think I have this problem , only in my case, it goes away when engine has started:
http://www.horizonsunlimited.com/hub...learance-97481

Well, knowing it's "just" my starter clutch, I went ahead and tried starting it anyway, and to my surprise it started almost right away :thumbup1::clap:
Here's the video from the first start:
https://www.dropbox.com/s/sxrqwhjwpg...0001.mp4?raw=1

In the beginning you can hear the starter clutch clunking away. After start it goes away and it sounds great.

Thanks everyone for helping out :thumbup1:

Yes, there are similarities, like gap and clunk, but also some differences, that sound on my bike still went on while engine was running. here's the other part of that story - https://www.horizonsunlimited.com/hu...594#post596594

if I guess correctly, there's a linear free play, along their axises (not radial). I think that 0.5 mm for smaller gear is not extraordinary. less certain about >1 mm play of big gear. mine had >2 mm that time.

how is starter clutch itself? I know, sometimes it gets uneven wear, but not sure if it might be the reason of any instable movement...

Yes, it's not identical behavior but looks like the same clearance on the starter gear and in your thread it looks like this shouldn't be the case. Also it's definitely my starter gear making crazy hammering noise.

My starter gear has so much play on it (yes, along the axis) that when I push it all the way towards the crank, the big starter gear is almost 50% misaligned with the smaller drive gear:

https://i.imgur.com/fyT2Q9P.png

When I pull it towards the flywheel, it sits almost straight with the small drive gear.
This makes me think the flywheel is in the correct position.

I was thinking, instead of making a custom new ring, why not add 2x the OEM ring? that should also be approx right.

One question on the subject. How exactly does the big gear transfer it's rotating to the crankshaft? Since I can move it away from the flywheel, and it's not fixed to the crankshaft either. Is it just friction with the flywheel?

Thanks

Well, even there wouldn't be any noise, I'd consider filling this gap only because of ~50% misalignement.
Thing is that unless you try, you don't know exact width of the gap. Having just another oem ring as extra spacer and hoping that 4 mm would be the exact size seems risky for me. When dealing my case, I prepared up to 5 different rings (inner diameter is essential, outer might wary slightly, gears will tell how much), some even from the car's engines and ended up with best setup. in my opinion, being just approx right is not enough in this case - that free play needs to be minimized (important - without completely jamming).

about transferring a rotation - despite of free play, since you had successful engine start, - that big gear will spin freely only in one direction; yes, because of friction, created by starter clutch (sometimes also called one way bearing).

Hm yeah, I can get some rings made too. Agreed, would be look for having minimum amount of play when the flywheel is at 120nm. Problem is I don't have a flywheel puller... and it's not a quick job:(.

I know the clutch spins freely in one direction. But I don't understand how it grabs the crank when I rotate it the other way. I can move the big gear away from the flywheel - so how can it ever have the friction to turn the crank?

edit: I think I got it.

This:

https://i.imgur.com/ETqoqCl.png

Goes into this:

https://i.imgur.com/NZUtmQz.png

skip to 1:00


https://www.renold.com/company/lates...nimation-news/

Thanks that animation makes it quite clear. I just forgot that the big gear had an extended piece in the middle that would fit in the flywheel/sprag.

Anyway, I also found this:
https://drriders.com/starting-noise-...650-t3713.html

This is pretty much exactly what I have and what I noticed when manually cranking the engine. They all say it's pretty normal, and some also had it on their XT600... hm.

I think I'll see how it goes once the bike is fully up and running and decide if I want to get some rings, flywheel removal tool etc...