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

Members Login
Username 
 
Password 
    Remember Me  
The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Loud noise on start up
Post Info TOPIC: Loud noise on start up
dlee22


Senior Member

Status: Offline
Posts: 414
Date:
Loud noise on start up
Permalink  
 

Hi there,

I have searched for my problem on here and found a few comments within a different (unrelated) thread and thought for future reference and people it would be useful to have a separate dedicated thread.

When starting my bike recently I have had a few loud bangs,  once running the bike is fine.

I have inspected idle gear 1 and it looks fine. I noticed a shim was on the inner side, I think this could be wrong based on a schematic drawing but has survived 15k miles like this. Can anyone confirm this?

The starter pinion is showing wear but nowhere near as much as other peoples on here.

Gear 2 looks okay initially, yet to pull off the casing off to look further.

I have replaced the sprag clutch a few thousand miles ago. When I did the large boss gear 3 looked okay, occasionally on turning off there is a bit too much noise for comfort.

 

It's difficult checking this in the rain under a motorbike cover, but needs sorting, but I'm expecting that gear 3 has warn a depression and the sprag is struggling to reach. Although the starter isn't great gear 1 is okay so I will not change that yet.

 

Hopefully once I've sorted it this thread will be of some use to someone 

 

 

 

 



Attachments
__________________

Thanks

Daniel Lee
ttr steve


Super Guru

Status: Offline
Posts: 2682
Date:
Permalink  
 

Keep us posted matey, any info is always goodsmile



__________________

totallyttrs.com

 
TTRfan


Super Guru

Status: Offline
Posts: 8606
Date:
Permalink  
 

Sorry to hear of the problem Dan.

If the boss on Gear 3 is worn or damaged then it may still allow backlash even with a new sprag clutch. 

What can happen is that, on shut down, the engine kicks back and the teeth on the sprag go over centre and jam on the boss. When you engage the starter, the bang could be the sprag releasing from its jammed position?

I know from changing sprags in the past that they can be jammed hard on the boss and can take a lot of effort to free them. Not much help I guess but I took a photo of a jammed one a few years back but not sure you can see how the teeth have rocked over and jammed.

jammed sprag clutch.jpg

I am pretty sure there shouldn't be a shim on Gear 1 - see the fiche diagram below.

Starter clutch.jpg



__________________

Exeter, Devon, UK

http://www.ttr250.com  - The one and only dedicated TTR250 FAQ!  

TIP: For easy viewing bookmark the "Recent Posts" view - http://ttr250.activeboard.com/p/recent/ 
dlee22


Senior Member

Status: Offline
Posts: 414
Date:
Permalink  
 

Cheers Brian.

 

I saw that diagram before, but thought I'd ask to see if anyone else had found one, if you haven't I doubt anyone else will have! Hopefully i remove it now the wear lines tie in with the gear okay...

 

I really can't remember there being any wear when I put the gear back together which is frustrating... I'll have to double check. The noise makes sense so chances are that it the issue.... I seriously hope it's not ruined the sprag as I keep throwing money at the bike. I do love it though!



__________________

Thanks

Daniel Lee
dlee22


Senior Member

Status: Offline
Posts: 414
Date:
Permalink  
 

So I investigated further today and the gearing shows no lipping or anything unusual, the sprag looks like a sprag and certainly wasnt warn on the teeth like the old one it replaced. I did find that the "woodruff" key was warn and immediately dropped out when I pulled the magneto off.

 

I'll buy a new one and hopefully that tightens everything up so the noise disappears.



Attachments
__________________

Thanks

Daniel Lee
TTRfan


Super Guru

Status: Offline
Posts: 8606
Date:
Permalink  
 

The boss on Gear 3 that the sprag rollers run on looks a bit marked up Dan - maybe from the old worn sprag slipping on it.

Is it OK or just the photo?

Check the taper on the flywheel and the end of the crank to make sure no damage as the Woodruff key shouldn't have got damaged like that if they are clean and a good fit - assuming the flywheel bolt was torqued up correctly.

Brian



__________________

Exeter, Devon, UK

http://www.ttr250.com  - The one and only dedicated TTR250 FAQ!  

TIP: For easy viewing bookmark the "Recent Posts" view - http://ttr250.activeboard.com/p/recent/ 
dlee22


Senior Member

Status: Offline
Posts: 414
Date:
Permalink  
 

I'll go double check but gear 3 is smooth with no lip, I think it's just the photo.

 

The tapered end looked fine, maybe I didn't torque it up correctly... I usely torque it up in increments, eg 30nm then higher.... I sent know why it's a weird habit.... maybe I missed that.



__________________

Thanks

Daniel Lee
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.
The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Loud noise on start up


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard