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 -> Jetting reccomendations, running rich
Post Info TOPIC: Jetting reccomendations, running rich
ttr_paul


Member

Status: Offline
Posts: 24
Date:
Jetting reccomendations, running rich
Permalink  
 

My bike is running rich, as it splutters a lot on WOT. I have ran it with air box lid removed and it runs a lot better. Main jet is a 147, can anyone recommend what size main jet to change to? exhaust is a CRD open pipe. Is there a point changing pilot jet as it runs ok on low revs.

Many thanks.



__________________
TTRfan


Super Guru

Status: Offline
Posts: 8565
Date:
Permalink  
 

I am surprised your TTR is running rich on a 147 with an open pipe confuse

Main jets are cheap so it is worth trying a 137 else try dropping the needle down to the last notch (cheaper!).

As you say, leave the pilot alone.



__________________

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/ 
ttr_paul


Member

Status: Offline
Posts: 24
Date:
Permalink  
 

I agree its strange, was running ok before but recently not good. Needle already moved one notch but no noticeable difference. Worth getting any other sizes as well?

__________________
TTRfan


Super Guru

Status: Offline
Posts: 8565
Date:
Permalink  
 

If your TTR was running OK on the current jetting in the past then it's unlikely the jetting is at fault.

The symptoms you describe are the same as those when the cam chain has jumped a tooth on its sprocket or sprockets. 

Its a pain but well worth taking off the camcover, put the engine to TDC and check the lines on the sprockets are still parallel to the head casting.

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/ 
ttr_paul


Member

Status: Offline
Posts: 24
Date:
Permalink  
 

OK thanks will try this. If the timing was off would it still run better with the air box lid off? Its defnitely rich as its using more fuel as well.

__________________
TTRfan


Super Guru

Status: Offline
Posts: 8565
Date:
Permalink  
 

Check cam timing first and, if OK, try the airbox cover off then wink



__________________

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/ 
alanwebbo


Veteran Member

Status: Offline
Posts: 32
Date:
Permalink  
 

As well as Brian's recommendation i would be checking over the float too.. Have you accidently adjusted the float height ? Is the float valve sealing properly ? ( Does petrol leak for the float bowl if you leave the petrol tap on), has the float sprung a leak ?



-- Edited by alanwebbo on Friday 4th of September 2015 12:58:55 PM

__________________
ttr_paul


Member

Status: Offline
Posts: 24
Date:
Permalink  
 

Heres some photos of the timing, to me it looks slightly off but not sure?

20150904_155401.jpg

20150904_155447.jpg

20150904_155537.jpg

20150904_155513.jpg



__________________
TTRfan


Super Guru

Status: Offline
Posts: 8565
Date:
Permalink  
 

The chain may be a tad worn but not enough to be causing the misfire. 

Alan makes some good points.

Could there be an issue on the ignition side? Faulty plug/suppressor cap/lead/connection?

Brian



Attachments
__________________

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/ 
ttr_paul


Member

Status: Offline
Posts: 24
Date:
Permalink  
 

Have tried a new plug, and float seems ok as not leaking fuel. It runs a LOT better with the airbox lid off...... any more ideas?

__________________
TTRfan


Super Guru

Status: Offline
Posts: 8565
Date:
Permalink  
 

Main jet loose?

Seems unlikely but I am battling with the fact that your TTR ran perfectly OK on the current jetting until recently. So what can have changed confuse



__________________

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/ 
ttr_paul


Member

Status: Offline
Posts: 24
Date:
Permalink  
 

Main jet is fine :s

__________________
peteBLUEttr


Super Guru

Status: Offline
Posts: 1721
Date:
Permalink  
 

I'ts a misfire is it and not a splutter??..


__________________

Pete. South Somerset, England.
ttr_paul


Member

Status: Offline
Posts: 24
Date:
Permalink  
 

Bike runs perfectly witout the air box cover so I guess its not electric. Tried my spare carb and problem is the same, also have tried disconnecting the breather hoses and it still splutters. It feels like its hitting an early rev limited with the side cover on.

__________________
TTRfan


Super Guru

Status: Offline
Posts: 8565
Date:
Permalink  
 

Can't think it would cause your symptoms but is the carb inlet stub in one piece?



__________________

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/ 
peteBLUEttr


Super Guru

Status: Offline
Posts: 1721
Date:
Permalink  
 

Theres defo no sh** floating around in the carb??..



-- Edited by peteBLUEttr on Saturday 5th of September 2015 07:00:32 PM

__________________

Pete. South Somerset, England.
locky


Guru

Status: Offline
Posts: 625
Date:
Permalink  
 

Any of the air jets blocked ? Do you have a airline to give all the passages a blow through ?


__________________

2004 TTR250. White Brothers E series exhaust, modded airbox, rejetted, 13/48 c&s & many more mods..
ttr_paul


Member

Status: Offline
Posts: 24
Date:
Permalink  
 

Just discovered all the front welds on the race can have failed, think this might be causing the odd fueling! need to test some more....

__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.
The TTR250 FAQ web pages -> TTR250 -> Carb stuff -> Jetting reccomendations, running rich


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard