A forum for owners of Yamaha TTR250 trail and enduro bikes!

South307 · Member

Strange metallic sound while starting/turning off

TTRfan · Super Guru

The symptoms are of a worn sprag clutch possibly causing damage in the starter pinion/idler gear area. How many miles has the engine done?

A quick check on what's going on would be to remove the starter gear cover and check on the state of the starter pinion and idler gear. See the first picture here

Brian

South307 · Member

Watched a bunch of videos of TTR250 running and heard this sound often while the engine is turns off, but never while starts....

South307 · Member

Just 17k done. The same sound heard from bunch of other TTR250 when turning the engine off oO

TTRfan · Super Guru

If the sprag allows kickback on shut down it can jam the sprag on the boss of Gear 3. If this is happening you will get a noise on start up as it frees itself off.

We can't hear what you hear so and my rule of thumb is if (assuming you are mechanically sympathetic wink ) it makes you wince then you need to take some action.

Brian

South307 · Member

What would you recommend assuming that I have no skills of repairing and no tools to do that and don't really want to spend much money on fixing something that don't really need it? In other words can it harm to my bike and make it worse and more expensive to fix with a time?

P.S. Will make a video soon so you can check this sound out yourself.
Andrew.

TTRfan · Super Guru

I would take the starter cover off and see if there is any obvious damage - only 4 Allen-headed bolts to undo and no oil will be lost - quick and easy check wink

Brian

ttr steve · Super Guru

I don't want to alarm you, but if you ignore a worn sprag* you will be looking at a massive rebuild of all the idler gears and a new starter motor. Just trying to help that's all.

dlee22 · Senior Member

When the sprag clutch is warn will it consistently clunk? Mines only a year old (original yamaha) and can vary from being loud, minor or almost silent.

ttr steve · Super Guru

Sometimes it can be the boss has wear on it, a new sprag should not make a loud clunk that makes you wince.

KiwiJeff · Senior Member

I'm with dlee22, I had a new, genuine Yamaha Sprag fitted about two years ago and from the start made the same sounds as the supposedly worn one.
When switching off, sometimes quiet and other times with a clunk.
Have never heard any clunk when starting.
Steve, what is the Part Number of the Boss that you mention ? (I've got a Yamaha Parts Catalogue)

Cheers
Jeff

leigh · Senior Member

My experience has been that no noise or a slight clunk to even a slightly loud clunk is normal. Particularly when it's really hot the clunk will be a little louder. (my DRZ is also the same)

The clunk when it's worn is different - it's more of a clang or bang- haha. Not sure how else to describe - however, Brian's explanation is the best, if it makes you wince - I bet it's worn.

When mine started to go every now and then when I shut it down the clunk was pretty loud - making me go WTF was that. Start and stop the motor again, no noise, or a light clunk....hmmm. After a while it just started happening consistently and then also on startup. Changed the sprag and it's back to normal now as above. Sometimes light clunk, sometimes nothing, sometimes a decent clunk is heard.

or maybe it's a Kerplunk? hehehe

ttr steve · Super Guru

No7 in the picture

https://www.fowlersparts.co.uk/main/img/assemblies/large/370b87b7f7f03c7d1b57c1f139232b25.png

So it is very important this is checked when replacing a sprag.

Cubber · Super Guru

ttr steve wrote:
No7 in the picture
https://www.fowlersparts.co.uk/main/img/assemblies/large/370b87b7f7f03c7d1b57c1f139232b25.png
So it is very important this is checked when replacing a sprag.

Steve, Fowlers won't let you play that game - playing Fowl, probably. biggrin

Is it No 7 in this diagram?

Martyn