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Start up (when cold) problems with Yamaha DT LC 2 125 1985

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So, i have a problem when starting my bike when engine is cold.

Funny thing is, it depends on the weather, when its hot outside i can start it easily, when degrees go down like 10 celsius then its more hard to light it up and it very easily wets the spark plug.

I never use choke, because when i have tried it, it never helps anything, and i have a feeling that it will only wet my spark plug more easily. Allways when my engine is hot, there is no problems with starting it up.

There is some little other problems too, that i think will have something to do with this too. Sometimes, when i run on idle, my engine goes off without warning. Allso, when i drive, i think when i use throttle, some areas of throttle are not so smooth. When i give just little gas its okay, but when i give a littlebit more it starts to get littlebit "unsmooth, maybe jumpy". Allso, when my engine is cold and i drive, the drive is not smooth, its very jumpy and sounds like shit and makes lots of white smoke.

but anyways, the main problem seems to be, that my spark plug gets wet very easily when i try to start up when engine is cold. i start it like this: I kick so many times until the engine gives a "promise" and after that i kick and give little throttle, when engine is hot, it works, but sometimes when its cold, its hard and my spark plugs can get wet. Allso if i try to start engine with choke or without choke without giving any throttle, the engine wont start.

One time i did this: i drove 5km, and after that i immediatly took my spark plug off.

When i look at it, i think the electrodes of the plug were fine (color of coffee with milk in top electrode, and the lower electrode is black), but there was just a littlebit some black stuff in the thread and some moisture in the thread, maybe the black stuff is 2t oil, i use 3% mix, maybe its too much? maybe i should change to 2% mix? Allso, maybe i have too rich mix because there is some moisture in plug? how do i fix too rich mix? i have allready tried to adjust my carburetor, i have opened my air mix screw 3 1/4 rounds, and i have adjusted my idle to about 1900 rpm ( sometimes it does "sailing" whys that?)

I put my idle so high (maybe 1300 would be good) because sometimes my engine turns off without any reason if i have my idle too low...but now sometimes my engine still does go off without reason in idle...

So, what im asking is, does anyone know any hints, what i should adjust to get these problems solved:

-Bad startup when cold

-Spark plugs gets wet very easily when starting cold

-Littlebit idle problems (sometimes turns off)

-some problems in some areas of throttle

-when driving with cold engine, lots of white smoke and bad motor going,

This is nasty problem because if i drive far away from home, and then i let my bike be in park for many hours, and then i want to go home, it maybe wont start and then i have to take the plug off and change it etc...i hate it.

Weird thing is, when there is hot outside it works fine, but only a little change in temperature and then the cold start starts giving me hard time...very sensitive.

Allso one thing is, my gear oil keeps coming out somewhere, i dont know where, i think some gasket is broken, i dont know if this got nothing to do with this problem, probably no. Coolant liquid seems to stay in same level.

I have allready:

-changed ignition coil, spark plug cap, and spark plug

-reloaded my battery

-build maybe 1/3 of my eletric wirings again

-clean my fuel tank with vinegar, changed my fuel pipes and fuel filter

-cleaned my carburetor with vinegar and with care

When my spark plug is dry, it gives a blue spark.

Is there a possibility that my spark plug has somehow gone broken because its been wet so many times? i have 2 spark plugs, and they have been both wet many times. another is regular, another is iridium. i have drive with them maybe 200km / each.

my spark plugs are NGK and their heat values are BR9. could i be that i need another heat value?? probably no??

My jet values in carburetor:




and needle is 406, and the pin in needle is in second slot from down.

One more thing, my air filter in carburetor is not a original one. its made from metal wire and foam. i have cleaned it with dish washing liquid and water, and then i did dry it and i put some gun oil to it.

Sorry for the long post and bad english!!

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If the gear oil is not leaking on the ground then it is getting sucked in past the right crank seal.

3.5 turns on the pilot screw is probably to much,,normaly it is around 2.

By the sounds of things you need to get a manual and set the carb up at the proper float height move the clip back to 3 rd position on the needle and replace the choke plunger seals.

If you post some pictuers of the spark plug it would help and changing to a br8 might help.

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Have to stick to english so here goes.

You say you have wandering with idlespeed. I had it too helped a lot when I adjusted the reeds I have a set of fiber reeds and they did not at first sit flat on the cage. After careful lapping they started to sit on without a gap and the idle problems went away.

The main jet might be a bit small. I threw away the original airbox and replaced it with foam pod filter. Now that is far more open than the original airbox. I found that out after burning one piston. I now have mainjet size 250 and idle 30 needle at #3. At this weather +32C or so it might be too much. Sounds like you have so called power filter. I think it's even more open than the foam pod.

Electric problems are a chapter of it's own. I my self have been struggling with a weak spark and such for a week or so. There's a topic about it.

The neutral indicator light and it's wiring is a common problem it's a light blue wire that runs from the magneto toward the rear of the bike. Check that. If you still have a sidestand swich check that too. All these work or dont work kinda like the kill switch.

The plugs. They tend to suffer from soaking. Expecially the racing ones with very thin electrode.

Keep in touch. And man. I feel your pain!!

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my dt days are over, my gearbox said bye to me yesterday,i had to push dt home 15km with 4rd gear in, it was hell

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Maybe, you dont want to buy the whole bike? You could build a perfect bike mixing my bike and yours :) i could allso repair my gearbox or get a new one, but i start to think, that i start saving money to a more big enduro bike, and spend the effort to that when i got the money. Anyways, my dt has many things working smooth.

-electrics ( i have build maybe 1/4 of wires or connections again)

-fuel system is cleansed, new fuel lines, and fuel filter, allso i did fix leaking in fuel tank.

-i removed rust from carburetor and fuel tank with vinegar and baking soda

-new ignition coil installed, new spark cap and plug. Good blue spark

-new seal set in front brake caliber, and front brake pads and liquid

-cleansed front brake master cylinder

-lots of other small things, dont remember what, new lightbulbs etc, flash and lights and ypvs are working good etc. Front wheel adjusted with fork, painted the plastic parts and fuel tank

-new battery

-both mirrors are new, and bar softener and stickers etc

-allso i have spare carburetor and 2 boxes full of random dt stuff and new enduro front tire and inner tube (not installed)

You interested of bying?

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And allso just before i blew the transmission, i did adjust carburetor needle that way that i put pin in needle to 3rd slot, it made throttle lots of smoother, when i drove in the freeway about 90km/h there wasnt allmost any engine sound, just the wind and chains :)

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Check your profile Juissi There's a private message from me. We can carry on with business on pv chat

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