Hi...i have decided to take apart and clean the carb on my DT 125R 1989.
This is because it leaks petrol out the breather pipe that come down from the bottom of the carb(the one from the drain screw) while it sits idle, and although not that fst will empty the tank over a few days if i dont turn the fuel tap to off.
After reading about it on the web it sounds like i have a sticky float and the carb is gummed up and seeing as its never been cleaned in nearly 20 years its probably right.(i bought it from a bloke who stored it in his garage from 89-06 with 1800 miles on the clock...it was mint)
I just need to know if its an easy job or not and when i put it back together is there anything i need to know about. I do have the haynes manual and it goes on about resynching it or something.
I am a total novice and this is my 1st bike so any words of wisdom greatly appreciated.
Thankis.
P.S. I am selling this bike once i have done this carb clean, anyone interested???? its great cond.
If you have the manual then you will be fine.Just take your time and don't rush it.Its most likely the float valve has dirt under it preventing it from closing fully.Theres nothing to resynch on a dt carb.Only two or more carbs require synching.
I just attempted to remove my carb, but when i removed the 2 rubber hoses that connect on the same side as the rear brake fluid resevoir(warmer hoses?) , coolant started pissing out of the hose and carb.
Do i have to drain the radiator first or something?
Cheers.
p.s. Please wait until i have pics up and make me an offer as i will have this on e bay as auction also.(i am expecting a decent price )
Cheers... i just did it today.... i took off the float bowl and cleaned the float needele... htere was alot of varnish .
But now 20 mins after putting it back together again and putting fresh petrol in it wont start...wont even kik over.
I only took the bottom of the carb(float) off and sprayed carb cleaner up the jet(i think it was the jet) and the spray came out of one of the breather pipes.
Any reason why this might be? or do i just have to let the petrol run through from the tank? ( though after 30 mins i would have thought it would have.)
i mean when i kik start it it wont even make a single starting/engine sound.
But i dont really understand what i could have done by only taking off the float chamber thingy and cleaning the needle.
Is there anything that im supposed to do when re-assambling the carb? it said something about it being upright in the manual but i didnt really get what it was going on about.
the 'varnish' will be the deposits left when the petrol evaporated at some time in the past, if the bikes not been run for a while [month or over ?] There are all manner of addatives to petrol & thats what remains after evaporation..
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Blue - DT 125 RE - '04 - First Of The Leccy Start Lanza'Like Bikes !
pull fuel line off carb, open NEW fuel tap at petrol tank & make sure flows out ...
See if this works in ON & RESERVE positions ... and make sure stops when in OFF position ...
If ok ...
leave fuel in ON position, though to fill the float chamber from the tank would take 10 seconds.... not 30 mins !!
Did you squirt cleaner into carb in direction of engine ??
Not sure what you done, carbs are very fragile once opened ...
Pull spark plug out & hold thread against engine for earth ... kick over & make sure spark . .. [carefull if petrol about & dont get a shock .. harmless, but about 16 thousand volts ! Hurts ...]
Fit new spark plug ... don't overtighten .... [you got manual ? Download links on here ...] Try again ... kick over for 10 / 15 goes .. no fire ? Remove plug & see if wet with petroil ... [petrol / oil mix] from carb / oil injector !!!
Two stroke motors .... 50 % headaches cured by new, properly gapped plug !!
Keep us up to speed ...
You didn't bend owt / lose owt from carb ???
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Blue - DT 125 RE - '04 - First Of The Leccy Start Lanza'Like Bikes !
you got fuel down line to carb [in both on + reserve] ??
When you said wouldn't turn over, i imagined you had squirted cleaner + filled your crankcase / space above the piston with liquid + when you tried to kick over it will shag your head / gasket .. !! The piston / crankcase compress the air / fuel / oil mix before the stages of combustion ... and carb cleaner / liquid etc can't be compressed ... well they can, but it takes huge equipment & the resources of British Petroleum !! not a 125 aluminium engine !!!
Get spark ... get fuel to carb ... then worry about next step ...
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Blue - DT 125 RE - '04 - First Of The Leccy Start Lanza'Like Bikes !
Im just about to check things above.. but why would my spark plug be the problem when 2 hours before i did the work the bike worked.
All i did was remove the float section and spray carb cleaner up the hole from where the floats are.. and it came out one of the breather pipes above(halfway up the carb) then took out he float needle and cleaned the varnish off it.
the carb was never in bits.... i kept it attatched to the throttle cable.
Will update soon... going out now.
(all this over a leak! i wish i just sold the thing leaking)
mmm. fuel is coming out of the fuel tap, but as said above there is no fuel coming out when i turn the drain screw at the bottom of carb. Is there any chance there is trapped air somewhere? do i have to bleed something?
When i tried to get the fuel line off the carb i saw tiny bubbles coming out of the gap tween the rubber and carb, but i couldn't get it off (bike is still in one piece, trying to solve without taking everything off again)
The float valve is stuck and not letting petrol enter the float bowl.Take the bowl off again and clean spotlessly the float valve and measure the float height to make sure its right.
Ahhh.. thanks, that sounds like it might be right. is the float valve the pointy thing that looks like a sharp bullet? how do i measure the height and is it adjustable?
thanks alot.
I did notice it wasnt very smoth in going up and down once i reassembled it.
chhers mate
btw when i put it back it was in the down position is this open or shut?
Yeah the pointy thing is the float valve.Make sure its spotless.Also clean the tube where it sits preferably with a blast of compressed air to make sure there is no dirt at all. To measure the float height you take the bowl off and turn the carb upside down.Put a ruler on the gasket base and measure to the top most part of the float.I can't remember off hand what the measurement is but i can check in the manual for you. When the carb is sat upright the float valve will be in the down position.This is open.When fuel fills the bowl the floats rise and the valve moves to the close position.Your carb sounds as though the valve has stuck there. The float is adjustable to a degree by bending the tab where the valve attaches but its unusual to have to do this.9/10 times a good clean will sort it. A little tip.Open the drain screw and give the carb several taps on the side.This might free the float valve.
Bits of carb in crankcase .... Crankcase full of fluid .... Carb cleaner is a fantastic solvent & strips all oils away in seconds, so if you splurged the crankcase & barrel you would have no Remanant Oil, and when you kicked it up agin & again it could damage the bore if metal on metal ..
Keep us posted ... but if the float valve feels grindy & rough to your touch, the ballast of the float will find it hard to operate too !
Iv'e only had a DT a couple of weeks & not stripped the carb yet, but on all the other carbs iv'e had apart, you can actually remove the float, then open the valve itself to clean it ...
Im assuming same on dt carb ?? Gix ... ???
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Blue - DT 125 RE - '04 - First Of The Leccy Start Lanza'Like Bikes !
If so, does this reduce the volumetric efficiency of the engine. Installation of a heated air intake system maybe beneficial to engine emissions but is it detrimental to performance ?? Is it just on the later DT's with cat's ?? or all DT's ??
I don't want hot air into my motor ! [We've talked about this before ? ?] ... Would an inline valve on the supply, closed off in summer do any harm ??
Thoughts ?????????
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Blue - DT 125 RE - '04 - First Of The Leccy Start Lanza'Like Bikes !
Running the carbs hot is not ideal.It was common on older carb race bikes to manufacture heat shields to prevent this. It is there to prevent it icing up in ****ty weather but i've never known any other yamaha single to suffer with it. Easiest way to bypass it is to run one hose between the water pipe stubs on the head, eliminating the carb circuit Oh, and all DT and TZR carbs had this feature
Ok... got it started again, after cleaning the float needle housing.
But my leak is now worse than ever!!
will try again and bend the metal tab that pushes the needle up to see if that helps.
I did notice that a rubber seal around the main jet was very worn but surely that cant cause the leak can it?
Is it correct that the only way petrol comes in to the carb is via the float valve? im starting to get my head round the carb thing now and from what i can see the petrol comes in via fuel pipe and through the float valve which should close once the level in the bowl gets to the right height, and then the petrol gets sucked UP through the main jet ( is this right???) but today it was leaking more than ever .
I think im going to have to have the petrol tank connected while i have the carb open to see if anything comes through while i push up the needle.
Anyway your help is greatly appreciated and ill carry on and let you know how i get on.
BTW... what is the plastic thing that goes over the main jet and into the hole next to it? and as the rubber seal is worn what will this do( i mean a small black rubber seal that is behind the main jet after you unscrew it from the carb.)
What you have to do is get the float height setting correct.Take the bowl off and hold it upto the carb body with your hand.Connect it to the fuel line and turn the fuel on.After 10 secs turn the fuel off and pull away the bowl.This will show you what level the fuel has risen too. The rubber seal is to prevent air passing through the jet with the fuel and ideally should be replaced if damaged. The plastic part is to allow the pilot jet to suck fuel up from lower in the bowl
?] ... Would an inline valve on the supply, closed off in summer do any harm ??
