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

nelly · Senior Member

pilot ??

nelly · Senior Member

No ideas peeps , I've also tried the pilot screw from a spare carb, both look the same but no difference
I'm open to any ideas

locky · Guru

I had a very similar problem that took me ages to sort out. It needed a bigger pilot jet. this is my setup with aftermarket exhaust and snorkel removed (snorkel hole opened up)

Mikuni jets.
Pilot 52.5 part number VM28/486.
Main jet 40 part number N102/221.
Idle mixture screw 2,5 turns out from fully in.

Note that mikuni jets are sized different.

With the above it runs sweet, so smooth.

nelly · Senior Member

cheers locky
so you reckon a BIGGER pilot jet then ?
il have a look for them
thankyou

nelly · Senior Member

where do I get them without getting from the usa ?

TTRfan · Super Guru

We used to stock the #52 pilot (43F-14342-26) but they are no longer available either in the UK or the States to the best of my knowledge

See http://ttr250.activeboard.com/t49951533/carb-jetting-information/

nelly · Senior Member

yes, since locky replied to my post,i think ive read every single word concerning carb/jets at least twice,trying to find this 52.5 pilot jet ,or equivalent
but ive not come up with anything yet,

I saw a thread where one guy tried drilling or opening up the pilot,i have 2 or 3 old ones in the workshop somewhere, I might see what I can do

TTRfan · Super Guru

I can't help thinking there is something else going on in your carb that won't be fixed by fitting a slightly bigger pilot jet confuse

When you had the carb apart did you take off the side cover and check all the petrol galleries were free of deposits? Is it worth putting it through an ultra sonic clean?

Could it be a non-carb related problem?

Is it worth swapping carbs with Haden's TTR to see if it solves your issue and moves it to Haden's bike?

Brian

locky · Guru

www.allensperformance.co.uk/shop/

Yes I'm not saying this is the 100% fix for your bike but mine had exactly the same symptoms. The jetting cured it..

locky · Guru

Can't link to the exact jet for some reason.
Go to shop
Mikuni Jets
Vm28/486 (very bottom of page on right)
Jet size 52.5

locky · Guru

Some light reading www.thumpertalk.com/topic/282432-ttr-250-modslinkspics/

nelly · Senior Member

thankyou to both of you,

brian ,I will try the new jet first,if that doesn't work then il have to persuade haden to briefly swap carbs,

locky,thats them....I thought I had seen a place locally mentioned a while ago, allens is a 20min drive from me so il see if I can collect the jets if they have them,

thanks again, I will post up soon

nelly · Senior Member

right
me and haden had a nice ride out to allens in bingham on the ttr,s, they both ran brilliantly there and back, I bought the jets that locky advised me on, when I got home I only fitted the 52.5 pilot ,buttoned it all up , pilot screw 2 1/2 turns out AND...............................its now even better, been for a quick blast on it and like locky says it does seem smoother,
I'm not sure if the starting issue is solved or not ,it did take a couple of attempts to start because I had drained the carb to change the jet ,
il let you know when I next come to start it from cold

thanks again for the help
nel

ttr steve · Super Guru

Keep us posted please smile

locky · Guru

yes im also interested how it's running.

nelly · Senior Member

sorry guys
ive been busy winding down the rear shock,

yes it seems a lot better now, started it this morning after 10am as its sunday!
it starts a whole lot better, popping and farting is now gone, it seems to ride more smoothly too
pilot screw at 2 3/4 turns out, atm , very happy for now,

however Ive got this urge ,I'm fancying a ccm 404ds,for those that don't know
drz motor,fcr39 pumper carb,more aggressive cams, wp suspension,brembo brakes, usd forks [ not sure if that's a good thing or not ]
40+bhp, only 5 cogs tho,

i understand they suffer from dodgy electrics,swing arm bearings,airbox fills with water,airbox brackets fall to bits and end up in the intake ,
lighter than a drz, 980mm seat height,[ might be a problem with a 30" inside leg, ]
and lots of stuff out of the parts bin, crf rad brackets /guards,acerbis plastics,ktm something or another, etc etc,
i do like the ttr but i wish it had a tad more oomph, i feel as tho I'm going to blow it on the road

whats your thoughts lads ? anybody got one,had one rode one ?

peteBLUEttr · Super Guru

Mod your TTR out to 325cc

TTRfan · Super Guru

I was just about to suggest the same Pete wink

nelly · Senior Member

i had thought about it guys,it might still be an option....in an ideal world....i would take the ttr to somebody who knows what theyre doing,leave it with them a few weeks,and then go and pick up a spanking 325,that way id know it was done right, after reading about the cracks to the cylinder caused by wrong size sleeve, wrong length,does it need an O ring etc etc,

if i could be sure .....maybe

-- Edited by nelly on Sunday 24th of April 2016 07:17:20 PM

petenz · Super Guru

nelly wrote:
sorry guys
ive been busy winding down the rear shock,

yes it seems a lot better now, started it this morning after 10am as its sunday!
it starts a whole lot better, popping and farting is now gone, it seems to ride more smoothly too
pilot screw at 2 3/4 turns out, atm , very happy for now,

however Ive got this urge ,I'm fancying a ccm 404ds,for those that don't know
drz motor,fcr39 pumper carb,more aggressive cams, wp suspension,brembo brakes, usd forks [ not sure if that's a good thing or not ]
40+bhp, only 5 cogs tho,

i understand they suffer from dodgy electrics,swing arm bearings,airbox fills with water,airbox brackets fall to bits and end up in the intake ,
lighter than a drz, 980mm seat height,[ might be a problem with a 30" inside leg, ]
and lots of stuff out of the parts bin, crf rad brackets /guards,acerbis plastics,ktm something or another, etc etc,
i do like the ttr but i wish it had a tad more oomph, i feel as tho I'm going to blow it on the road

whats your thoughts lads ? anybody got one,had one rode one ?

the big prob with the DRZ motor is the gear box 5 speed close ratio..

gear it for the road 1st gear is very high / gear it for the dirt 5 gear is to low..

Suzuki sort of screwed up there a bit... needed a 6 speed wide ratio box..

but it was designed as a dirt only bike.... then lights were added later on..

...

nelly · Senior Member

anyway back to the ttr pilot
as ive said the ttr is running fine,but I still think something is amiss somewhere, the 52.5 pilot jet has made a difference, its a lot smoother,but I think I'm having the same problem

same issue, at 2 1/2 turns out the bike starts instantly no problem... but feels sluggish .... at 1/2 turn out is runs a lot crisper and a lot more responsive ,its like a different bike, but from cold ,choke on,it fires straightaway but coughs and farts inside the carb and dies,i can feel it doing it whilst holding my finger on the choke knob,
it looks like brian was right to suspect there was a problem elsewhere,

I commented on another post from brian ,where he mentioned the pilot galleries,....where can I find them please ?
atm swapping carbs with our haden is not possible
thankyou

nelly · Senior Member

had the carb off AGAIN, I removed the 2 screws and the side plate thingmebob, it all looked clean,the galleries appeared clear, I poked them through with some 15a fuse wire, the top one I could easily see through, the other could have been clogged up because at first I couldn't get it through but did in the end, maybe this was because of the acute angle at 5-6mm down ,
I then completely removed the metering screw,there was nothing clogging it up, I checked that the tiny o ring was intact and not perished, all good, screwed it in and back out 1 1/2 turns,as I was refitting the carb, something told me to check the 2 breather pipes that run backwards from the carb along the top of the airbox, the ones with the little bracket that screws onto the top of the frame,i blew down them from the carb end and nothing, I then noticed that they were both being pinched closed by the little flimsy frame tab, after loosening them off I was able to blow down them easily,
back together it started much better,il take it for a spin if it stops bloody raining and let you know
cheers

TTRfan · Super Guru

Fingers crossed for you Neil!!!

Been catchy weather down here in Devon as well today cry

nelly · Senior Member

its only spitting now so I braved it, went to start it, couple of twists on the throttle,choke on full,and it started immediately,i don't like to leave it revving high from cold for long,so I gradually turned off the choke,at about half choke it coughed and farted again and cut out,full choke again and started right up again, I gave it a few blips gradually revving it higher,turned choke off completely and took it round the block, it runs ok, I turned the metering screw out another full turn to 2 1/2 and it still runs ok, by then it was pissing it down so its now back in the workshop for another day, il set the pilot properly next time its up to temperature and see how it starts from cold

theres something going off somewhere

I'm going to try it briefly without the breather pipes connected and see what its like then

nelly · Senior Member

I think ive got it.......
removed all the jets and diaphram and gave it a good blow out with the airline at my buddies garage,all galleries blown out,jets blown out,everything clear except that little one way valve effort that sits under the gasket on the float bowl,i cant blow down it either way with my mouth but if I hold the little ball away from either end with my nifty bit of fusewire it blows through
so whilst its in soak for a while in paraffin,i buttoned everything up without it,

I took it round the block and its a different bike, ive set the pilot screw the best I could while it was warmed up,

tomorrow morning after its been stood all night I will know if its sorted , FINGERS CROSSED

TTRfan · Super Guru

Hi Neil.

Fingers crossed for you but that one-way valve allows the diaphragm (accelerator pump) to pressurise fuel that squirts into the carb inlet when the throttle is twisted. In theory the diaphragm wouldn't push the petrol through without the one-way valve allowing it to pressurise the petrol.

Brian

nelly · Senior Member

ok brian, I wondered what adverse effect it would have if not fitted, just been for a blast and its a different bike, it now flies [ well as much as a lil ttr can ]
I will place an order shortly, thankyou