Main jet? Yet to take carb off. Suggest size please.
Power valve - not checked yet
Will update on jet size, carb model and gearing later today.
Off the line the motor is bogging down and through 1st & 2nd it is dog slow. Throttle wide open and clutch dumped when the flag drops. Nearly last off the line .
From 3rd onward it takes off in each gear with only a bit of a flat spot then it flys.
Any information to help get this bike moving will be appreciated.
Could the bogging down be because the power valve has been jammed open?
Pre mix for racing applications i would suggest a 30/1 oil/fuel mix. The numbers as far as i know are for a pre '97 DTR.Where is your cdi attached.If its the bigger one that bolts to the oil tank then you have a restricted cdi for sure. I run with the powervalve open on my bike which i use on and off road and have no problems with acceleration in any gears.Tractability is very good below the powerband too. Although most guys prefer the DEP pipe i much prefer the standard front pipe when it has been derestricted.Using a DEP can kill the bottom end power with the PV open The carb should be put to standard manual settings.Main jet ideally should be a 240.I've never had to modify or upjet a DT. Also has the bike got good compression.If its low then you will have bottom end power troubles.Are the crank seals leaking? An air leak here will also cause power problems
240 jet is the standard size and thers no need to upjet even with a full DEP system.Keep the powervalve open.Give the carb a real good service.New spark plugs can make the world of difference on a two stroke as well.Is your cdi unit bolted to the oil tank?
did they up the jet size in the later models cos according to my manual which covers up to 95 its a 210 ?
ive always ran pre mix cos i dont trust oil pumps but ive always ran 20/1 the advice i was given from a bike shop a while back was 25/1 for running in then as little as 18/1 after but 20/1 safer ive never had piston issues but thats not to say its right
210 jet was only used in the 88 model dt.20/1 is really rich mate.Think of it like this.Your effectively using 20ml of fuel to 1ml of oil.50/1 is using 1ml of oil but it is now mixing with 50ml of fuel. I used to use a 35/1 mix on my stage 3 tuned 350 ypvs and that was ridden hard against RGV and KR1S mounted buddies. Never had lubrication or plug fouling issues
hi mate im not sure if im working it out wrong but how i ment it was 5 litres of fuel around about 100 ml of oil which is 20ml per litre thats where im getting 20/1 from im cofused now lol
5 litres is 5000ml.5000 divided by 20 will give you the amount for a 20/1 mix which would be 250ml in this case.Running 100ml of oil to 5 litres makes a 50/1 mix.
Managed to bolt the DT back together for the weekend but it didn't go well.
Trying to find out as much as possible but obviously it wasnt enough for the weekend.
Ran with the full DEP system, upped the main jet to 260 (as advised), PV has been jammed open previously so i left it be. Fuel at 30:1
It would rev at a standstill but trying full throttle would have it stuttering and it would not rev out. Under load it died it just did not want to know. Tried the needle jet up and down in desperation but this had little effect.
Next i plan to whip the carb off, put the 240 back in and start again.
Spoke to a guy at the local bike shop who races YZ's and he advised to run Super Unleaded (i'm doing that already) at 40:1 and to add 100ml of Pro Boost to the 5lt. He also advised to take out the securing bolt holding open the PV, plus cut off a few inches off the DEP silencer to give it a bit more bottom to midrange.
Is the airfilter clean? Have you tried a new spark plug? It maybe that its an electrical problem causing a weak spark I would advise going back to the 240 main jet Get a manual and change the carb back to totally standard settings.The stock carb works well when derestricted I wouldn't take out the securing bolt on the PV 'cos it will turn in the barrel on its own and make contact with the piston crown DEP cans work well on a dt without modification.All two stroke cans are very similar in construction.Basically just a perforated baffle tube wrapped in wadding.Actual lenght is unimportant
as i said before mine has a 210 and i know gixergav said a 210 was for an 88 bike but my bike is a 90 i have a manual that covers up to 95 and it states the jet size is 210
i have also just checked the online manual on this site for the later 2005 onward model and the jet size is 210
CDI is fastened to the oil tank but i'm told the 3RM/20 is the derestricted one. True or false? Also been told that the TZR 4DL CDI would work and unleash the revs.
Well after the nightmare weekend i finally managed to work on the DT again.
Still with the full DEP installed. Out with the 260 main jet (have a 25 pilot jet by the way), carb cleaned and back in with the 240. Needle is on middle notch. Revs to the stop without any splutter.
What now? Need to test with this setting and will try the 40:1 mix with some octane booster in the super unleaded.
Does anyone know of a 'performance' power valve servo?
Other info:
No power valve servo is fitted. Do i need a battery connected for this to work.
No battery fitted.
Wiring harness looks like a crap version of the London Underground but the little bugger always starts.
Any dt cdi that is designed to fit on the oil tank is a restricted one.You can either try and get one from an unrestricted import or change the loom and cdi for a pre '97 one. The jet needle should be on the fourth clip from top but if your revving freely now leave it as it is for now Yes you need a battery for the servo to work and a 'performance' servo does not exist.All the servo does is move the valve to match the engine revs.By constantly altering the exhaust port size it allows good bottom end torque and high rpm power. As far as i know none of the tzr cdi units are compatible
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