DT125R ARCHIVE

carl13671 · DTR Senior Member

CARB MIXTURE PROBLEMS.

.... · Guru

sounds like an air leak mate, as its sounds like its getting too much air in, thats why it wont idle and when you put choke on it dies etc also the fact that mixture screw should be no less than 1 1/2 turns out, try check for an airleak between carb and airbox, i would always do the following

start the bike, let it idle
get wd40
spray over the carb to airbox rubber
if the engine suddenly revs high then its defo an airleak

the reason it will race faster is because wd40 burns quicker than fuel causing the engine to race

hope this helps

Seiki · Admin

RAC guy finished a can of WD40 on my car once thinking the very same thing . 1 Week later it turned out to be the immobilizer lol

carl13671 · DTR Senior Member

Cheers for that,
Is this the connection with the jubilee clip round it on the back of the carb as i gave the screw a few turns today just to make sure it was tight,wheres the next likely place to draw air from
When i got the bike (august) i noticed the mixture screw was a bit mashed up probably through being messed with alot,i think it has had this problem for a while but could not pin point it as the head gasket was blown when i bought it.

.... · Guru

anywhere from carb itself, to carb to engine rubber,where reed block is

carl13671 · DTR Senior Member

Ive leathered the WD40 all over the carb today.Paid special attention to filter and reed block clips and around the top where the gaskets are.
Unortunately i got no raise in revs.
I loosened the clips either side of the carb and twisted it slightly to acheive a possible better seal and removed the mixture screw hoping for some wear but nothing,it was still the same when i started it up.
I suppose the next thing to do is remove the carb.Do i remove the throttle slide first before i get it out or will it come out with it still attached?
The reed block is still fastened with the original Yamaha bolts the torx type with a bit in the middle is there a special tool for removing these or can this stay attached when removing the carb?
What am i to look for when i strip it down or do i just give it a good blow out?
Will i need new gaskets when i build it back up?
Surely it has got to be something blocked if there is no air leak?

-- Edited by carl13671 on Sunday 6th of December 2009 05:49:00 PM

.... · Guru

it will be dirty jets possibly then, yes you can remove carb with the slider still attached although it needs to come off anyway

the carb will not need new gaskets too,

undo the 2 jubilees(1 each side of carb
rip the dam thing out lol
undo the 2 screws on top(if they round-moldgrips on the side of bolts all good)
then you will need to unscrew 3 screws on the bottom
be careful not to damag4e the floats(black plastic peices)
there will be 2 jets on the bottom
blast these with carb cleaner and everything else for that matter
reassemble
job done

.... · Guru

ps reed block can also come out, the 4 bolts that are there will remove and dont need re torqued back down as the will just nip up fine

might be worth a look and make sure the reeds are all in tact while ytou have the carb off too

let me know how you get on

carl13671 · DTR Senior Member

Will do,
Thanks for your help,your a diamond,every thing i needed to know.

carl13671 · DTR Senior Member

UPDATE.
Took the carb off and took it to a friend where it was blown out and inspected for any wear etc.
While i was stripping it down i noticed the mixture screw has no tiny rubber seal on it only the idle screw had one,so i swapped it on to the mixture screw (maybe this might solve my problem).
Also i have noticed something might be missing from the side where the fuel pipe connects,could somebody please advise.

.... · Guru

that hole doesnt have anything fitted into to it mate, so just ignore that

hope all goes well mate

carl13671 · DTR Senior Member

What about the tiny rubber o-ring seals,will it make a big difference taking it off the idle screw and putting it on the mixture screw or am i better getting a new screw complete with o-rings.

-- Edited by carl13671 on Friday 11th of December 2009 05:06:24 PM

.... · Guru

id have new o rings on both, they make things airtight and work properly, without them it will cause all kinds of problems and can affect engine after time too, try buy a multipack of o rings will work out alot cheaper, saying that they could be cheap for just the 2 from yammy, have look mate

carl13671 · DTR Senior Member

Carb back on after a good clean and blow through.
Still exactly the same,all im missing is the tiny o-ring seal off the idle screw,cant see this will make things right.
I thinking of trying a new carb off ebay the trouble is are they selling it because they have had problems with it.
Anybody on here got one i can try (DTR125CRAZY).

-- Edited by carl13671 on Saturday 12th of December 2009 12:50:21 PM

.... · Guru

110% percent that this could cause it, this is why your bike wont idle mate, everytime you pull the throttle etc the ratio is different because the air getting into the carb

when a bike hunts the revs its an airleak or incorrect oil mixture, i have a spare carb but has been repaired

carl13671 · DTR Senior Member

Cheers for that,
Ive just come back in from a good ride out and it seem very slightly better,still doesnt seem to be hitting max revs and still a bit lumpy on idle.
Im going to try and hunt down a complete idle screw with all trimmings.
If this fails ill go for the new carb.
Cheers again.

.... · Guru

sounds a good plan

carl13671 · DTR Senior Member

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=180350075345&ssPageName=STRK:MEWAX:IT

Found this kit on the bay,seems to have the o-rings i need.
Does anyone know if they will fit my 2005 DTR.

.... · Guru

thats a dt125mx mate, completely wrong kit

.... · Guru

yamaha sell each individual part seperate, probably best find a local dealer

carl13671 · DTR Senior Member

UPDATE.

Phoned my local dealer today and the o-rings dont come seperately.

I had to order the complete assembly for both the mixture screw and idle screw,should be with me Thursday all being well it should be running properly Friday.
(i dont know why but i have a funny feeling im trying to convince myself and this wont solve my problem).

-- Edited by carl13671 on Monday 14th of December 2009 07:56:58 PM

.... · Guru

how much did you pay? also have a little faith

carl13671 · DTR Senior Member

Idle screw asembly £13.
Mixture screw assembly 10.
Ive had my arse slapped i know.
My lack of faith disturbs you young jedi,lol
I have big sausage fingers and little farty things like these do my head in.

-- Edited by carl13671 on Monday 14th of December 2009 09:58:36 PM

.... · Guru

lol

carl13671 · DTR Senior Member

When replacing the mixture and idle screws starting from the base is it washer,o-ring,spring or o-ring,washer spring?
Ive looked on OEM MOTORPARTS and it looks like the washer then the 0-ring with the spring sat on the o-ring.
Surely over time this would tear the o-ring.

carl13671 · DTR Senior Member

carl13671 wrote:

When replacing the mixture and idle screws starting from the base is it washer,o-ring,spring or o-ring,washer spring?
Ive looked on OEM MOTORPARTS and it looks like the washer then the 0-ring with the spring sat on the o-ring.
Surely over time this would tear the o-ring.

NUDGE

carl13671 · DTR Senior Member

Bike now sorted.
The idle screw o-ring is bigger than the mixture o-ring.
Replaced them both with new genuine parts.
Bike now idles properly and mixture setting is more near the 1-1.5 turns. biggrin

.... · Guru

ideal, faith pays off in the end lol