Clouds of smoke DTR125R

[Sheddybiker]

Hi, Newbie here, Have recently bought an 89 DTR125R, which wasn't running too well.. I firstly cleared out all of the old fuel,filled the tank with a good semi synth 2T, stripped and cleaned the flatslide carb. and cleaned and oiled the air filter. New BR9ES plug slotted into place, hit the button and off I went,, But not too quickly, it was stuttering and mis firing, then clearing a little but would not go past 40mph, My immediate suspicion was the power valve. Taking off the cover i was confronted with a short length of threaded bolt but no head and the pulley floating about doing not much. I removed the (DEP) exhaust and, following suggestions found on this site, reset the power valve to normal operating settings.

All back together and....... Revelation, crisp, free revving, quick,(up to 65mph) and soooo much fun.

I returned to the garage laughing like a loon in my helmet. It was like being 17 all over again.

Now for the bad bit. Having used the bike for my daily commute to work (10 miles each way) for a few weeks, I was on my way to work, lightish traffic, bimbling along at 30 - 35 when the bike started stuttering again and bogging down and I couldn't get much more than 20mph. with a rooster tail of dark blue/grey smoke engulfing the countryside.

Luckily, not too far from work. I let her cool off and at lunch time fired her up and revved her out a bit, after a couple of minutes she was running cleaner so i ran her up a fairly steep hill for about 1/2 mile, keeping the revs up, and returned running fine. Made it home with no problems. Following day and she is running badly again,Checked the plug, which was sooty but with a cocoa coloured electrode and again smoking like a frenchman.

My thoughts are that it is burning too much 2 stroke, but again, using info found on here, the pump settings seem ok, and why so suddenly any way??

Suggestions please

[Airhead]

The right hand crank seal may be fauty, this side of the crank is in oil for the transmission, when these go it will burn transmission oil and not perform well. Take out the oil filler plug...can you smell petrol?...has the level dropped?

[2 Wheels]

It could also be that 10 miles a day is too short a journey. Sur she's only getting warmed up and then your turning her off again.

2 strokes dont like pottering along slowly all the time. They get all carboned up,,,,,,exhaust,,,,,,power valve,,,,,piston crown,,,,,,head,,,,,,exhaust port.

This weekend,,,,, take the bike for the ride of its life for about an hour. Keep her lit when you start to see a trail of smoke behind you.This is the heat burning off the carbon build-up from everywhere. When the smoke clears keep going another bit, you will then feel the bike freeing up and becoming more lively. Job done, so you can now head home happy !

Obviously Dont go mad and keep the bike screaming in the red-line, you will damage your engine by doing that.

But it could also be like what Airhead says,,,,,,so start checking things out

[Sheddybiker]

Thanks guys. the trip is 10 miles each way but no real chance to get her lit up. I was having some suspicion about the crank seals. I have some memories of if you change the 2T it's been used to it can cause problems. I went for a semi synth as the safer bet not knowing what's been in previously. I'll give it a good sniffing at in the morning.

One suggestion that was put to me was to disconnect the oil pump and run on pre mix for a couple of days. Any idea what ratio?? 40:1 ? Then if she runs OK therein lies the problem?

[Airhead]

I doubt the 2T oil change is the problem, anyway it would be easier to smell at the trans oil and watch the level than disconnect the pump

By the way...is there a breather on top of the motor transmission area?

[Sheddybiker]

Just had a good sniff but all I can smell is transmission oil. and no there doesn't appear to be any crank breather. There is a blanked off orifice on top of the cases just above the gear box fillercap but this looks like a factory blank?

[Sheddybiker]

Well I think I've got the problem narrowed down to the power valve not functioning properly. The oil burning cleared up but the bike was still running rougher than a big rough thing on 'Rough Tuesday'.

I decided to have another look at the power valve set up, and it doesn't look good.

Setting up, using the drill bit to align the pulley was fine, turn ignition on and it completes it's cleaning sweep and returns to where it set off from. But rev the engine enough for the valve to operate and it comes to rest quite a few degrees off, but re aligns when i turn the ignition back on. Also, when running the engine with the pulley cover off, the valve fluctuates,opening and closing even on a constant throttle.

I'm (obviously) no expert but surely this can't be right?

The upshot is that I've unplugged the servo. The bike now runs without the farting and belching (unlike myself) and the spread of power is fairly smooth and even, if a little down, until higher revs when it still hits the power band.

Any ideas what the problem might be?? Bad signal from the ECU?

[2 Wheels]

Setting up, using the drill bit to align the pulley was fine, turn ignition on and it completes it's cleaning sweep and returns to where it set off from. But rev the engine enough for the valve to operate and it comes to rest quite a few degrees off, but re aligns when i turn the ignition back on.

Also, when running the engine with the pulley cover off, the valve fluctuates,opening and closing even on a constant throttle.

I'm (obviously) no expert but surely this can't be right?

That is what they do, so this bit is fine. You set them up with the drill-bit and thats it. Ignition on and it does its cleaning / checking cycle and returns to its drill-bit setting,,,,,so all ok. When the engine is started it closes more than that setting,,,so ok there too. If you turn ignition on, it does cycle, then kick the bike over but it doesnt start first time, you will notice that the valve has moved from the drill-bit setting and closed off a little, this is to give more back pressure and aid starting............So all is well there.

Yes, this is not right,, dout if its a ECU prob,,,,so check out the cables to the pully, are they to tight,, to loose,, one tighter than the other. I'm thinking now off the top of my head but is there another little junction box further up underneath the fuel tank on your bike,,,,,if so have a look at it for stiffness.

If its raining 2moro ill go out and have a look at me bike for ya, see whats what,,,, have u a manual,, i cant find mine at the moment to look up cable setting.

[Sheddybiker]

Thanks 2 wheels,I have adjusted both cables as evenly as I can, even played around with different tensions and lengths but there is still the fluctuation on a constant throttle. had the bike stripped down and checked that the servo was strutting its stuff. No I cant see another junction box anywhere along the line after the servo.

Does the servo get its signal from the ECU ?

I would have expected the valve to remain open on a constant throttle?

And to be fair to the bike it almost always starts at the first push of the button

[2 Wheels]

Thanks 2 wheels,I have adjusted both cables as evenly as I can, even played around with different tensions and lengths but there is still the fluctuation on a constant throttle. had the bike stripped down and checked that the servo was strutting its stuff. No I cant see another junction box anywhere along the line after the servo.

Does the servo get its signal from the ECU ?

I would have expected the valve to remain open on a constant throttle?

And to be fair to the bike it almost always starts at the first push of the button

Sorry me bad,,,, there's no other junction box after the servo.

The PV does nothing else after it is setup propperly so it must be ok.

It could be the servo acting up,,,, but you have tested it and it seems ok.

There's nothing else really amafraid.

Dont know if power comes directly from ECU/ CDI,,,,,sorry

Your bike is a 1989 ???? How come it has a starter ??? Or come to think of it,,,, how come it has a servo either,,,,, that year a bike had a non working PV.

Didnt get a chance to look at mine yet mate, but i will 2moro

[Sheddybiker]

I have been wondering myself about the age thing. log book states 89 but i think it's a later engine. The kick start is blanked off as is the Rev counter drive, rubber seal where I think it should be.

I had thought that it may have an electrical tacho but on checking the clocks you can see where the drive cable should be.

Markings on the head read 3MB, and 3MBOO 125cm3 on the base of the barrel

[2 Wheels]

A Yes,

Here lies your prob,

Your bike might be 1989 but your engine is a 2004 onwards, you have a DTRE engine.

So whats happening i think is this.

Your CDI on the 89 bike is not brainy enough for your engine, basically.

CDI is sending power to the servo,,,,,servo works,,,,,signal goes back to CDI but it isnt smart enough to know what to do with it. Hence your PV keeps fluttering. The older CDI's have the slots to plug in the servo electrics but not the capicity to make them work. The 89 bike's might have had a PV but they were pinned in one place and couldnt move, they also didnt have the servo fitted. Somone did a fair bit of work to the bike to hook up the electric start and servo and all that. All DT's were kick start up untill the year 04.

What you COULD try is to get a CDI for a DT125RE 04 onwards. Then your CDI will be brainy enough to make the PV work propperly. The down side is, i wonder is the wiring harnes of the 89 bike compatable for the newer model CDI (brain). DONT quote me on this if you buy a newer CDI and it all doesnt work,,,,,,, but thats what i Think is happening.

Check out your V5, the engine and frame numbers should match up, but in your case i think the engine numbers will be different. If there not then previous owner didnt tell the DVLA about the engine change.

Anyway all is not bad, you can still pinn the PV say half way open if it comes to it. This will give you the best performance in low revs and high.

Pat.

[Sheddybiker]

Thanks for that Pat, It's all starting to make a bit more sense. Do you know if there is a way to check which CDI is fitted, any tell tale numbers or markings?

At least at the moment the bike is running and useable.

The previous owner had done the green/black wire to earth.thing, which I had disconnected whilst attempting to get back to base settings as it were. Would this be worthwhile reinstating do you think?

[Airhead]

just a thought though!

when someone fitted an elec start engine...did they fit the earlier magneto stator to maintain the status quo for the early ignition system?