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 -> Cracked generator cover
Post Info TOPIC: Cracked generator cover
dlee22


Senior Member

Status: Offline
Posts: 415
Date:
Cracked generator cover
Permalink  
 

Hi there,

I noticed a slight weep of oil had gotten a little more noticable so decided that it was time to investigate. I replaced the copper washer behind the neutral swtch thing and checked the generator covers bolts. I then rembered there was one hidden so I took of the cover for the gears between the starter and then sprag clutch area and sadly found that the casing had cracked and snapped, see attached photos.

 

Usually i the can be due to sprag clutch failure but i only put a nee one on 6 months ago and have barely ridden it! My only guess (as maybe stupid as it is) is that where the gears/shaft fit into the donut mount there was no washer. If there was direct connection could there really be enough tortional force to break this? 

 

Id be greatful for an opinion, im really glad that i found it now rather than when we leave for a trip! Im worried this could happen again.

If it does i imagine the best i can do is remove the gears, jb weld and cracks and use the kicker?



Attachments
__________________

Thanks

Daniel Lee
TTRfan


Super Guru

Status: Offline
Posts: 8607
Date:
Permalink  
 

It must be a day for weird sprag happenings!

I have never seen anything like that before. Usually a worn sprag lets the engine kick back against the starter gears when the engine stops and it cracks the casing - not take out the whole supporting casting for the starter gear that acts on the starter pinion. no

This is a photo of the usual scenario and you can see that the central boss is still intact where yours is completely broken off.

Damaged casing and gears2.jpg

Cracked generator cover 2.jpg

 

Another photo showing damage on reverse and the small starter gear.

Damaged casing and gears1.jpg

If you have a new sprag and the starter gears and  bosses are all OK then a replacement generator cover along with correctly fitted washers should fix it. No need to go back to kickstart only.

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: 415
Date:
Permalink  
 

Thanks Brian, i brought an old oe which sprag had gone before, it showed all the signs yours does!

It really must unsual if you haven't seen it before haha!

Thankfully i have a spare oe available so i stripped it and replaced the casing, i just wanted to see if anyone knew what happend 😊

__________________

Thanks

Daniel Lee
ttr steve


Super Guru

Status: Offline
Posts: 2684
Date:
Permalink  
 

Bad luck Dan

Do you think it could have been a loose bit of debris, like in the other sprag post?

Like you said if Bri has not seen it before, very strangecry do you think the missing washer could cause so much friction to heat weld the 2 components together??

Just an idea.

Steve

 



__________________

totallyttrs.com

 
mossproof


Super Guru

Status: Offline
Posts: 1436
Date:
Permalink  
 

I'd say your's was the result of something hard getting caught in the gear teeth Dan. Doesn't need much to jam the gears, and if they're spinning fast something's gotta give. Freak incident though for some detritus to travel that far up the casing either in the oil or stuck to various gear teeth. Bad luck. Glad you found it now though!

Brian's pics looked to me like someone tried to lever the starter motor out and put too much strain on that little spur casting, but then the broken teeth on the gear suggest again meshing with a foreign body in the teeth.

Ride safe all,

Simon.

__________________
dlee22


Senior Member

Status: Offline
Posts: 415
Date:
Permalink  
 

Still don't know 100% but thanks for the suggestions! Im glad i found it now, im very paranoid at the moment, i kerp checking it just in case!

Quick question too... i have a brand new yamaha sprag clutch on the bike but 50% of the time when turning the bike of its got quite a loud bang, is anyone elses like this? Also start up can be pretty noisy too:/ my gears all look to be in good condition!

I may just be paranoid like i said

Thanks

Dan

__________________

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 -> Cracked generator cover


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard