DT125R ARCHIVE

Katie-Jay · DTR Respected Member

HELP!

carl13671 · DTR Senior Member

Get rid of that jet and put standard one back in and remove the mixture screw and replace with a new one and start again from scratch.
If that screw is chewed up its probably had problems for a while.
oh and put the needle valve in the middle.

-- Edited by carl13671 on Sunday 29th of August 2010 09:16:40 PM

seancullen · DTR Member

had the very same problems with my tdr last week, right down to the air screw being in ****e so i replaced the carb, turned out my flywheel side oil seal was gone. and letting in air

Katie-Jay · DTR Respected Member

carl13671 wrote:

Get rid of that jet and put standard one back in and remove the mixture screw and replace with a new one and start again from scratch.
If that screw is chewed up its probably had problems for a while.
oh and put the needle valve in the middle.

-- Edited by carl13671 on Sunday 29th of August 2010 09:16:40 PM

according to most info ive read on here 240 is the standard jet??? They changed it from 210 to 240 on later models did they not?

carl13671 · DTR Senior Member

my 2005 RE had a 210 in it,but it didnt have a DEP on it, but my 2003 R does have a DEP and that does have a 210 and both run ok.

-- Edited by carl13671 on Monday 30th of August 2010 09:50:00 AM

xGINCATx · Guru

Every carb i've opened has had a 210 main jet, there's just no need to change it as you dont get any performance gains. The only way your gonna get performance gains out of your carb is by selling it and buying a bigger one

Katie-Jay · DTR Respected Member

im very condused now, as everything I have read after googling has said that Yamaha changed from a 210 to 240 on a certain year.

From what Ive read also is that if it had a 210, and wasmeant to have a 240, then it would rev high (which it is), as would be running to lean??? and if had too big a jet would get flooded?

Im only going off what im reading as I really havent a clue, neither has my partner, hense why his mate had a look, but there into superbikes, and its a bit different lol.

Im thinking could there possibly be an air leak?? (Again, just what im reading on heree from other peoples experiences)

Im soooooooooooooo confused about all this, its doing my head in, if i thought I just needed a new carb, or a rebuild kit, id get one, but i dont just wanna buy stuff if i dont need it.

And I dont want to downsize the jet until im 110% sure it should have a 210, as ive read this will make it run lean, hot, and kill piston and rings.

Theres so much conflicting info about jetting, just on this site alone, and if I google and look at other site's like Yamaha owners club, there's even more conflicting info, its sooooo confusing!!!!

ARRRRRRRRRRGGGGGGGGGGGGGGGHHHHHHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!!

Katie-Jay · DTR Respected Member

At topic for instance ive dug up - http://www.activeboard.com/forum.spark?aBID=66365&p=3&topicID=27115053

Wheres Gixergav when you need him lol, id like to hear his opinions and evidence on jet size, its doing my head in, one says one, another says another, and Im lost with a bike I cant fully enjoy. Think i should have stuck to cars lol

xGINCATx · Guru

My haynes what covers DTs from the years 88-02 says on page 78 that the main jet should be 210 for a 3MB00.
Also if you go to page 24 on this manual that also says the main jet is a 210.
I've ran my bike on a 240 main jet and it ran like it used to but it just didn't go nowhere near as fast as it used to so i switched it back to a 210.
Unless you've got a different carb then standard i think you should change it to a 210 and go from there.
Jets are less than £5 to buy so you wouldn't be wasting much money if yours is a mysterious carb that does in fact require a 240 main jet

carl13671 · DTR Senior Member

If you put a 210 in it with your DEP you can adjust the air mixture with the mixture screw that is chewed up.This is where i think your problem is.The screw has been wound up and down that much trying to adjust the mixture with the 240 jet.
If possible turn the mixture screw just a quarter turn off the base with your 210 jet in it and it should run fine,as mine is a 2003 and set up like this and i have no problems.
Hope this helps.

-- Edited by carl13671 on Monday 30th of August 2010 02:51:43 PM

xGINCATx · Guru

I think the main reason i havn't had any problems (other then losing speed on top end) when changing jets is because i have never touched the air mixture screw.
I had one DTR and because the air mixture screw was so badly knackered it would only ride on the choke, but when the choke was on it rode like it should have without the choke been on if you know what i mean. Crazy stuff lol

Katie-Jay · DTR Respected Member

its all wayyyyyyy to confusing lol.

so why is there so many conflicting arguments about having to upjet when a dep is fitted etc??

I just feel like banging my head agaisnt a wall LOL

So if i order a carb repair kit, will that include a 210 main jet and a new mixture screw??

As my way of thinking now is, carb repair kit to eliminate and airleaks with seals, replace jet, replace needle etc to ensure no wear.

Then all I want is a standard setting, so does needle want to be on middle setting?

carl13671 · DTR Senior Member

I bought a new genuine air mixture screw from a yammy dealer and i think it was about £8.One thing to note on the RE there is a very tiny O ring seal on the end,yours could very well be missing.Id definately start with replacing this and a 210 jet.Once you have done this start the bike and spray WD40 all over the carb and inlet block and see if the engine revs any higher,this will tell you if you have any air leaks.

Katie-Jay · DTR Respected Member

will mine have the o ring though since its not an RE???

carl13671 · DTR Senior Member

Im sure it will as i think they use the same carb.

Katie-Jay · DTR Respected Member

cant buy a new screw until Yamaha dealer opens tomorrow, but checked O ring on tick over screw, and thats present, and have sprayed carb etc with WD40, and has made no difference.

Ill go to yamaha dealer tomorrow and get a 210 jet (and get them to clarify that this is infact correct for my model/year) and a new mixture screw.

Any tips on removing the old brass mixtures screw??

carl13671 · DTR Senior Member

I knew you were going to ask that at some time.
I have never tried to get one out but have often wondered how i would if i needed to.
They are only brass so should brake up easily,just go easy how ever you do it you dont want to damage the seat or threads,have you considered asking on wanted,some of the quys on here have alsorts lurking in dark corners,you might get one with a screw that is ok.

xGINCATx · Guru

Or you might just get a working carb? I sold one on ebay a couple of months ago for only about £20 and it came with throttle cable and throttle housing as well

Katie-Jay · DTR Respected Member

ive considered a second hand carb, but could just be buying someone elses problems, atleast if mine is rebuilt with new seals, jet, needle, screw etc, its gonna be like brand new.

Why do people say you need to upjet with a dep etc if you dont? Its unbelievable how much conflicting info there is regarding this, I appreciate haynes may say 210, but thats based on standard pipes and de restriction is it not??? Im just horrified of killing a perfectly healthy engine lol

carl13671 · DTR Senior Member

If the jets they supply dont make your engine run right or agree with your set up no matter what people say your going to get problems,where as if you uprate everything and make you bike run on its limits your also going to cause other problems.
I think your main aim at the minute is to get the bike running right.Then upgrade 1 thing at a time and give the engine time and see how it goes.If you try 270 jets,red power bands and cut chunks out of your inlet system all in the go something wont agree and you will be forever trying to put things right.

Spartan · DTR Senior Member

Katie, I had similar issues with my air screw - the head was mashed and the screw was jammed.

I ended up drilling it out. After I made a hole in the top of the screw I was able to get a screw driver in there and it just twisted out, carb will need to be out of the bike for this. Make sure your blow air down it afterwards just in case any little bits are left.

Made a difference when I replaced it with a new one as I was able to control the mixture again. Might just be what is needed for your bike once the mixture is correct. £10 for me from my local yammy store - came with o-ring, washer and screw.

Ask them to clarify the settings of the air screw too, haynes says for DTR between 1999-2003 air screw setting is 1.25 turns out. So screw it in until it lightly seats and then screw out 1.25 turns.

I don't mean to add fuel to fire, but again looking at me trusty haynes haha, main jet is 240 for 1999-2003 DTR. Jet needle clip position is 4th groove from top. Please correct me if wrong tho.

-- Edited by Spartan on Monday 30th of August 2010 10:38:56 PM

Katie-Jay · DTR Respected Member

I see your logic, but if the bike requires a 240 as standard (which some sites say it does on a certain year), and mine has a full DEP, which apparently requires upjetting (acording to csome sites, including MCN), then understandably, im a bit scared of downjetting to a 210, which will appprently run lean and hot and kill piston and rings.

Call me a worrier, but since im a woman, better safe than sorry IMO LOL

From what we can see, bike has full DEP system, 240 main Jet, Carbon reeds, removed reed switch in clocks, ands there is no V piece in inlet, whether mine should have or not.

Basically i need it looked at by a 2 stroke bike mechanic. My partner plays with cars, and his friends all have Ninja's, Bandits and R1's etc.....

Were armed with a haynes manual, and no clue PMSL xx

Katie-Jay · DTR Respected Member

Spartan wrote:

Katie, I had similar issues with my air screw - the head was mashed and the screw was jammed.

I ended up drilling it out. After I made a hole in the top of the screw I was able to get a screw driver in there and it just twisted out, carb will need to be out of the bike for this. Make sure your blow air down it afterwards just in case any little bits are left.

Made a difference when I replaced it with a new one as I was able to control the mixture again. Might just be what is needed for your bike once the mixture is correct. £10 for me from my local yammy store - came with o-ring, washer and screw.

Ask them to clarify the settings of the air screw too, haynes says for DTR between 1999-2003 air screw setting is 1.25 turns out. So screw it in until it lightly seats and then screw out 1.25 turns.

I don't mean to add fuel to fire, but again looking at me trusty haynes haha, main jet is 240 for 1999-2003 DTR. Jet needle clip position is 4th groove from top. Please correct me if wrong tho.

-- Edited by Spartan on Monday 30th of August 2010 10:38:56 PM

Agian, another conflict on jet size PMSL x

I was under illussion it was 240 too, and I think you may be right about screw, bike was off road atleast 3 years, surely mixture wants setting, and cant with duff screw, im off to yamaha tomorrow to clarify jet size, and get a new screw, may aswell get a carb rebuild kit too, and do it whilst its off, not gonna do no harm, and there only about £15 I think?

Katie-Jay · DTR Respected Member

just been reading the haynes, and it says for my bike -

3RME 1999 on

Type   -   TM28SS
ID Mark   3RME2
Main Jet    240

Can anyone elaborate on this??? as it contradicts both of the above advice????
Also is there any truth in upjetting whaen fiting a DEP?? as if so should this not mean I requirea 260?????

Now you get me point about conflicting info lol x

seancullen · DTR Member

my moneys on an air leak anyway,

craigbulmer · Guru

I really dont know about carbs and jetting, but I know on the DEP website, in the dt125 exhaust section they say themselves under testing you dont need to rejet.

Katie-Jay · DTR Respected Member

seancullen wrote:

my moneys on an air leak anyway,

thats what we thought, but where? I have followed advice on WD-40 ALL over carb, to no avail lol, its a proper head do'er lol x

xGINCATx · Guru

Bloody hell, she's right anorl lol. My Haynes says on page 78 that the main jet is a 210, but on page 139 it says 240. Conflicting info indeed... Hmmmm go to the Yamahaha dealer and see what they say.

I just cant see any reason to up-jet as it affects the petrol-air ratio so by adding a DEP pipe to the bike the air to petrol ratio is still the same.

I think there is alot of false info out there though, like cutting back the inlet manifold increases performance which it don't. Didn't work for me and someone on here did a test before and after and by cutting it back it increased BHP by absolutely nothing.

But my 2004 RE came from Yamaha with a 210 main jet, and i removed the airbox snorkel and was told to up-jet (to compensate for more air) and all it did was slow it down to about 65MPH instead of 80MPH.

Good luck with Yamahaha tomorrow and be sure to let us know what they say smile

Katie-Jay · DTR Respected Member

Will do, but i dont hold much faith as said Yamaha dealer told me my year was fitted withh an electric 2 stroke pump, so there was no need for me to use pre mix in tank after bike had stood for years incase pump had seized PMSL x

Spartan · DTR Senior Member

ahaha :) all armed with the haynes.

Yeah Gincat, fuggin realized this myself today. Page 139 has the info for DT's 1997 onwards and page 78 is info on the older models.

Give em your frame/engine number, it may help. If they still can't get the right info find another yam shop, i have two where i live biggrin