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

Members Login
Post Info TOPIC: Cold starting problem


Super Guru

Status: Offline
Posts: 7933
Date:
Cold starting problem
Permalink  
 


I have had some cold starting problems on my 325 whereby it starts but quickly dies.

I raised the pilot jet size up from 48 to 50 and it seemed to make an improvement but I haven't run the TTR often enough to test it thoroughly.

I came across this video this morning and, even though the guy is dealing with a TTR125, I recognised the poor cold starting symptoms. 

I looked at a dismantled TTR250 carb and, sure enough, there is a small jet in the float bowl that meters fuel to the brass choke tube and hence the choke itself. I had not realised it was theredisbelief Every day is a school day biggrin

I checked the circuit on my own carb and think I may have cleared a partial blockage but I will need to get the carb back on to check.

But, irrespective of whether I fixed my carb, it is a useful tip to any other owner stripping and cleaning their carb to check this circuit is clear. 

Choke_fuel_supply2.jpg Choke_fuel_supply1.jpg

Choke_fuel_supply3.jpg

 

I have updated my carb rebuild tutorial accordingly wink  See http://ttr250.com/Carb/TTR250_carburettor_strip_and_rebuild_guide.htm

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/ 



Senior Member

Status: Offline
Posts: 262
Date:
Permalink  
 

Haven't had this issue with 250, still good to know, but I never thought about this on the 125, golden! Cold start and idle problems are common on the 125 I always just go to the pilot jet (on my third pilot jet cause they don't clean well). Thanks Brian!

__________________


Guru

Status: Offline
Posts: 923
Date:
Permalink  
 

Good find Brian! Youtube - home of video wonders. I suppose a bigger pilot would have similar effect when cold - putting more fuel in instead of the choke circuit, but then when warmed up, the pilot is bigger than necessary.

__________________


Super Guru

Status: Offline
Posts: 7933
Date:
Permalink  
 

OK - so I cleaned the newly discovered jet in the float bowl, put back the 48 pilot jet (and fitted a new diaphragm and O rings as the rubber on the old diaphragm had "died" and was virtually solid) and gave it a try.

Choke fully out and it started first time, but, this time kept running without the usual cough/stall business! I am well pleased to have fixed this irritation biggrinbiggrinbiggrinbiggrin

The power of Facebook (where I found the tip and link) and YouTube combined eh?

One happy bunny here wink

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/ 

Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard