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

leigh · Senior Member

I'm interested in what airbox mods and jetting you are running

petenz · Super Guru

cut the top out of the air box / new header pipe with a GYTR tail pipe.
went up 2 sizes on the main / droped the needle one groove..

but now i run a 32mm flat slide carb....

..

leigh · Senior Member

Hey Pete, did you cut the entire top out or just a section? If so roughly how much?

Cheers

BM Steve · Guru

Here's mine, did the std jet mod and tuned in the mixture screw, std exhaust, runs like a clock, ticks over at a much slower idle

have a look in the sticky's for jetting, can't remember sizes

petenz · Super Guru

yer pretty much like that

..

PlumasDude · Senior Member

137/50 with the box cut up like Steve's, needle clip one notch to the lean, stock US pipe, runs great - that's stock US except for the box and needle. I still don't understand you all can run with those big main jets, unless maybe it's the pipe set up.

ttboof · Super Guru

I stayed with the standard main and up one size on the pilot .

Found it Way too rich on the larger main .

Opened up airbox and staintune pipe

leigh · Senior Member

Thanks for the input everyone.

leigh · Senior Member

ttboof - about how high did you make the lip on the plumbing fitting you used on the airbox?

ttboof · Super Guru

leigh wrote:
ttboof - about how high did you make the lip on the plumbing fitting you used on the airbox?

With out taking the seat off I think around 15 mm maybe more I can take it off and check if you want I'm on a weeks holiday

ttboof · Super Guru

Whipped the seat off it's 20mm

asap88 · Member

Reading this post makes me think i should check the jetting on my bikes as one has a pipe and modded air box. what can the problems be with running stnd jetting with these mods?
Also what part of Tassie are you in Leigh? I'm also in the sunshine state

TTRfan · Super Guru

If your TTR is running OK (check the plug colour if you think there may be a mixture issue) then I would continue to ride it wink

leigh · Senior Member

Great, thanks for taking the measurement ttboof.

They seem to be pretty flexible on jetting, as Brian says, if the plug looks ok, light brown or darker I wouldn't worry too much. The problem you might have with standard jetting and the mods is that it might be running lean (hot). Plug will look light grey or white. I don't think its common in Aus though as they seem to be jetted rich from standard.

Sunshine state hey? :) Its been wet this winter hasn't it. I'm Hobart based whereabouts are you?

Cheers Leigh.

-- Edited by leigh on Wednesday 12th of October 2016 12:48:42 AM

ttboof · Super Guru

I'm in taree about four hours drive north of sydney

I've been riding this week all in the dust the shed thermometer hit 42deg on Monday but the days are back to cool high twentys now

I wonder if the Aussie ttrs were jetted a bit rich due to the header restrictor Mr Yamaha fitted to get round our design rules

asap88 · Member

I will pull the plug out and have a look before the next ride I have noticed the header pipe does get a little warmer on the bike with the aftermarket pipe than the stnd piped bike. Thanks for your help

Wets an under statement we had around 35 minutes of hail today, I'm about 45 min from you Leigh down south of Hobart near Cygnet .

ttboof · Super Guru

The only indication i needed a larger pilot jet was the bike was hard to start and a slight hesitation when snapping the throttle open quicly and the ocasional flat spot at higher revs around third throttle, plug colour can be influenced by the fuel and additives from state to state and definatly country to country but is stil worth a look

once changed it starts first go and pulls better right from idle

just did the google earth search down your way looks good ive only got western australia and tassie left to ride. It will happen but not sure when

leigh · Senior Member

TT- a lot drier where you are than where we are at the moment, hence the thought of the airbox change for me. I'm not going to change the jetting but want as much "cover" if you like for the airfilter without effecting performance. I'm pretty sure I'll end up with the same airbox mod you have done. Better sing out if you ever get down this way, happy to show you (or anyone) around.

asap88 - I know the area well, I lived in Gardners Bay, so just down the road from Cygnet. Lived in the Huon for 15 or so years. Love it down that way, I used to be a farrier and had my own horses, its a long story but now just ride the iron steeds instead. Did you know there is good riding up Blue Gum Road in Gardners Bay? I learnt to ride up there, good single track, I lived on the corner pretty much. Small world!

Leigh.

asap88 · Member

There are some great fire trail's up the back of Blue Gum Rd I have spent a lot of time at there with the Tas Fire Service, clearing the tracks and also earlier this year fighting a fire. I'm just down the Rd In Garden Island Creek, have been meaning to open up some old trails that run from my place all the way up to Glue Gum rd.
Back on topic I seem to get a miss at around third throttle in second and third gear when im trying to get the power down could this be a sign of jetting ?

ttboof · Super Guru

It was in my case just went up a size on the pilot and it went away

the aussie ones seem to be lean on the pilot and ok on the main

my brother has a ttr thats still stock he hasnt ridden it enough yet to find out it was bought new three yers ago still hasnt done 100ks

just stits and waits

-- Edited by ttboof on Friday 14th of October 2016 05:35:33 AM