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

Members Login
Username 
 
Password 
    Remember Me  
The TTR250 FAQ web pages -> TTR250 -> Carb stuff -> TTR running rich on tickover
Post Info TOPIC: TTR running rich on tickover
TTRfan


Super Guru

Status: Offline
Posts: 8605
Date:
TTR running rich on tickover
Permalink  
 

I have a carb that runs rich on tickover. Just touch the choke and its stalls immediately.

I have set the float height artificially low - made no difference so it's not flooding.

I have checked that the choke is seating properly so that's not the issue.

I tried a smaller pilot jet and it made no difference.

The pilot screw makes no difference screwed fully in or out.

The slide is working as it should and the needle is properly fixed in place.

137 main jet on VO5 nozzle.

The TTR runs fine on other carbs.

What am I missing - what else could cause the problem - anyone got any ideas please?

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/ 
Cubber


Super Guru

Status: Offline
Posts: 2610
Date:
Permalink  
 

Could the throttle slide be NOT closing properly? confuse

Is there a scuff on its side - is it slightly oval - is it burred somewhere ???? confuseconfuse

Are the cables adjusted correctly to let it seat down to the slide adjuster???? confuseconfuseconfuse

Martyn



__________________

You're never too old to learn something stupid

East Budleigh. Devon
TTRfan


Super Guru

Status: Offline
Posts: 8605
Date:
Permalink  
 

Thanks for the feedback Martyn.

The throttle slide is definitely fully closing.

To check the carb I ran it without the cables attached.

Logically I can't think why the throttle slide/needle/nozzle/main jet could make the TTR run rich at tickover but I will strip out the slide assembly to make sure It's all OK 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/ 
JOHNYBOY


Super Guru

Status: Offline
Posts: 1094
Date:
Permalink  
 

hi brian i once had carb problems with a rd 350 lc that i had restoredi tried many things but no cure until one day i was removing the jets & noticed one hole in one jet was slightly bigger than the other but they were both stamped the same number so i removed the needle put it in one jet & marked it then the other they were different so i guess some one had drilled the jet larger which people used to do when they were young & stupid just a thought john

__________________
TTRfan


Super Guru

Status: Offline
Posts: 8605
Date:
Permalink  
 

I can't believe it's taken me 2 months to get sufficiently motivated to try again to fix the carb - although maybe having booked the TTR in for an MOT on Friday helped disbelief

Anyways up, after careful inspection of slide etc, I could see nothing wrong so, just for the hell of it, I swapped the nozzle for a nearly new one with a different main jet (taking on board John's suggestion that the main jet might be faulty).

I couldn't see any difference between the nozzles and the main jet was slightly bigger but, somehow, the different nozzle/jet seemed to fix the problem and the TTR ticked over sweetly without the bumbling that I had put down to an over rich mixture.

I then replaced the main jet with the new 137 one that comes in the All Balls kit that Steve sells and, again, the TTR ticked over nicely and runs strongly on the carb right through the rev range so I am a happy (although slightly bewildered) bunny biggrin

Thinking about it, maybe I hadn't screwed the original nozzle in fully? I know that I am nervous of over tightening nozzles knowing that they can snap off. There is no way of checking now but I will try the original nozzle in another carb to see if that one runs properly - in due course 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.
The TTR250 FAQ web pages -> TTR250 -> Carb stuff -> TTR running rich on tickover


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard