'New' '88 DT200R - Issues

[Paper Mache Man]

Hey guys,

I've recently bought a DT200R '88 and am working through the process of bringing it up to roadworthy status. The first hurdle is getting it working mechanically speaking as it has a few niggles here and there.

It has apparently been bored out to 250cc so in this respect should be fairly newish engine wise (new gaskets etc).

The first problem one is to do with the carbi (I hope). It refuses to run if the choke is off. It feels like it's running too lean so I'm trying a new pilot jet (current is 25, new is 35) to see if that helps things along.

I have a small leak in the radiator, but I'm hoping stop leak will fix that.

Removing the rear wheel was a *nightmare*. The thing would NOT budge even after all the screws had been removed. I had to virtually chisel it off the rear forks. I'm thinking all the gunk that's no doubt been left in it for years is the cause. I'm hoping now it's off I'll be able to get in there with WD40 and free the main shaft from all the bearings/spacers/wheel and give it all a good clean out and regreasing.

ANYWAY....

My main quick question for now is to do with the power valve. When I accelerate the valve doesn't move at all. It seems ok to move myself although I didn't disconnect it first to really see (I'll do this tomorrow). The real thing I'm wondering about though is will the servo operate without a battery? The manual for this bike says there is a battery but mine doesn't have one. The was apparently working until a wire fell out (although I still get highbeam showing in the dash) but that's it as far as the electrics go. What I'm trying to work out is how much of the electrics are dependant on having a battery.

I also wanted to know how dependant the power valve is on the ignition system (which has been stripped out). The workshop guide I have is for a 125 and doesn't get into the powervalve because they were restricted in the UK. So I'm at a bit of a loss with this one issue.

If anyone can shed some light on this I'd appreciate it!

[Airhead]

Hi and welcome

I'm no expert on power valves as i've never had a bike with one (soon to be ammended), there are others on here who will soon give the lowdown on these things...However i'm sure you are right in your suspicians that it wont work without a battery. You need to get a wiring diagram but its a rare bike and might be hard to find one.

[Cynic]

Crikey where do you start?

First off if the battery is missing and the ignition has been stripped down then the powervalve will do precisely cock all unless the looms has been modified with care and it doesent sound like it.

Secondly bored to 250cc, i doubt it. More like its been taken out to 224cc like the european DT230 Laval (i think thats what its called).

As to your manual, i'm surprised it doesent mention the powervalve. I would have thought it should be in there somewhere as the kit was easily available from yamaha at the time to de-restrict the bike. In any event the bike is basically a DT125 with a bigbore motor in it. So the manual should cover most of your needs.

[Paper Mache Man]

Ok so I think it's been rebored (well I know it has) but not too 250cc.

I'm going to pull the power valve out and take a look at it.

I have 2 questions.

Does the power valve need to be modified during the reboring process (i.e. to fit inline with the larger cylinder) or is it fine left how it is. I'm not sure what's happened there. I just don't want to 'fix' the power valve so it's working but find it explodes my engine as soon as it rotates for the first time.

Secondly, we use 12V battery packs at work for spotlighting. I'm assuming I can use one of these to check the power valve operation and perhaps even fit one to my bike. They are sealed lead-acid units rated at 12V7.5Ah/20HR. Generic crap that probably wont be any good in the long term (I can't just nick the good ones after all, these are the ones no longer holding a charge over 20 mins etc).

[Cynic]

Does the power valve need to be modified during the reboring process (i.e. to fit inline with the larger cylinder) or is it fine left how it is. I'm not sure what's happened there. I just don't want to 'fix' the power valve so it's working but find it explodes my engine as soon as it rotates for the first time.

Nope the power valve is (in engineering terms at least) miles away from the cylinder, the old RGV ones could desroy the cylders as when they wore out they fall onto the piston, the yam system works differently and wont affect the piston at all.

Secondly, we use 12V battery packs at work for spotlighting. I'm assuming I can use one of these to check the power valve operation and perhaps even fit one to my bike. They are sealed lead-acid units rated at 12V7.5Ah/20HR. Generic crap that probably wont be any good in the long term (I can't just nick the good ones after all, these are the ones no longer holding a charge over 20 mins etc).

Depends, if the loom is mutilated then there is no telling what may happen, you can use any 12v battery really just make sure you have a fuse on it to protect what wiring you have. Dont forget you said the ig had been chopped and the PV links to the ignition, so don't hold your breath.

As to removing the PV for a look. If its not leaking why bother, if you do though note what you do as its incredibly easy to put it in upside down.

[rr390]

Hey guys,

I've recently bought a DT200R '88 and am working through the process of bringing it up to roadworthy status. The first hurdle is getting it working mechanically speaking as it has a few niggles here and there.

It has apparently been bored out to 250cc so in this respect should be fairly newish engine wise (new gaskets etc).

The first problem one is to do with the carbi (I hope). It refuses to run if the choke is off. It feels like it's running too lean so I'm trying a new pilot jet (current is 25, new is 35) to see if that helps things along.

I have a small leak in the radiator, but I'm hoping stop leak will fix that.

Removing the rear wheel was a *nightmare*. The thing would NOT budge even after all the screws had been removed. I had to virtually chisel it off the rear forks. I'm thinking all the gunk that's no doubt been left in it for years is the cause. I'm hoping now it's off I'll be able to get in there with WD40 and free the main shaft from all the bearings/spacers/wheel and give it all a good clean out and regreasing.

ANYWAY....

My main quick question for now is to do with the power valve. When I accelerate the valve doesn't move at all. It seems ok to move myself although I didn't disconnect it first to really see (I'll do this tomorrow). The real thing I'm wondering about though is will the servo operate without a battery? The manual for this bike says there is a battery but mine doesn't have one. The was apparently working until a wire fell out (although I still get highbeam showing in the dash) but that's it as far as the electrics go. What I'm trying to work out is how much of the electrics are dependant on having a battery.

I also wanted to know how dependant the power valve is on the ignition system (which has been stripped out). The workshop guide I have is for a 125 and doesn't get into the powervalve because they were restricted in the UK. So I'm at a bit of a loss with this one issue.

If anyone can shed some light on this I'd appreciate it!

[rr390]

oops i stuffed that first post up. Paper mache man.hows it going with the dt200?with ur issue of not running unless choke on-my dt200 had similar symptoms-ended up being crankcase seal.you may want to check that.

[Paper Mache Man]

oops i stuffed that first post up. Paper mache man.hows it going with the dt200?with ur issue of not running unless choke on-my dt200 had similar symptoms-ended up being crankcase seal.you may want to check that.

I actually took it out this weekend. I'm having some pretty confusing issues right now. When it runs, it's running much better and I can even run it with the choke off although the idle is too low and will stall the motor so I need to adjust the clip. Before it would just die regardless though so it's improved things somewhat.

The hardest thing is just starting the damn thing! It also just kept dying sporadically but I think I fixed the underlying issue there. I think I had a weak spark so I replaced the sparky only to find much the same with the new one. Ended up stripping down the pickup coil and found I got a much stronger spark and the bike is a *bit* better at starting.

That's really my biggest beaf at the moment. The damn thing just refuses to start. I've gone through everything I can think of and am really at my wits end now. I think I'll have to check the crank seals just to rule that out.

I've checked:

Fuel pre-mix ratio - leaning it out (from somewhere around 1:20 to maybe 1:40 - planning to run 1:35) seemed to help the start and remove the plug fouling although fouling was only really evident on the new plug.

Pilot Jet - now 35 and the engine is running much better in the low range, currently set at half a turn out - couldn't start it all the way in or 1.5 turns out.

Floats - discovered these were jamed in the case. Messed with them and they now work as they should (had fuel pissing out everywhere at one point thanks to this).

Carbi - is clean

Air Jet - not having any real affect

Main Jet - shows 75 but I think it should be 175...the 1 looks like a scratch from a flat head though so I'm seriously confused about that.

General electrical check - all the wires seem ok but the spark plug lead had some gum around it and some connections had a lot of grit in the sockets...I've cleaned out the main components.

So yeah, bike is still hard to start. Although it seems better it also can go 20 or 30 kicks without starting which is *extremely* frustrating in 40C heat. I ended up getting a tow more than once.

I haven't looked at the power valve yet.

Also do I need to get a sparkplug with R in the numbers? I'm hearing conflicting things, some reckon it's just for radio interference whilst others suggest not having one will fry the power valve servo.

[Paper Mache Man]

So the rear axle is great now. I think I need to disassemble the swing arm and replace bearings/washers though as it's squeaking a lot.

On to bigger problems though.

I decided to give the spare carbi a go with the new pilot jet (35 instead of 25). It seems in alright nick and I gave it a good clean out...it was missing a few pieces and most of the o-rings needed replacing (all done).

Right now I'm running a 35 pilot (1 turn out) and a 175 main. I got it up and running perfectly (really good response etc - no dead zone like with the 150 main) except that the idle was too low and the engine would stall when I let go (idle screw all the way in). It also ran great with the choke off - which it wouldn't do before. It was all a bit too good to be true though and it flooded after 5 mins with fuel dripping out the carbi pretty fast. Fixed the floats, put it all back and then nothing, bike wouldn't start. Checked spark, seemed to be getting a decent one (albeit yellowish but put this down to daylight).

I came back to it yesterday and adjusted the main jet needle clip to try and raise the idle. I changed the clip from 2nd from the top to 2nd from the bottom so 2 down.

Bike started first kick but responded very strangely. The idle seems to be surging from low to high revs and still wants to stall if I let go of the throttle. It also had a popping sound, as if it's misfiring (odd bang from the muffler too I think). I also noticed some fine misty smoke coming out from the bottom, that's really worried me. I think it must be the lower gasket or else the power valve. It's annoying because whilst leaning down I let go of the throttle and once the bike stalled I couldn't start it up again.

So basically my bike will start once, stall (flooded presumably) and then not start again (presumably until I pull the carbi off and give it a breather).

I'm just not having much luck, every time I go to fix one problem another one seems to come up. Undecided

If anyone can give some advice...like yes the smoke means a leak somewhere which will make it misfire (instead of say, a weak spark)....or a reason as to why it keeps flooding (only reason I can think as to why it will start once only) that would be great.

More than happy to rip this thing down step by step testing as I go. Main issue now is that if I can't reliably start the bike I cant see what affect my changes are having.

Main changes/stuff checked so far have been:

Pilot jet changed from 25 (all the way in) to 35 (1 turn out).

Main jet changed from 150 to 175

Different carbi (pretty massive I know but at least the choke works on this one)

Spark plug pick up and leads checked - spark at plug checked (fires 2-3 times on each kick)

Checked and adjusted floats - petrol level same as pilot/main jet base height (using clear tube on a level surface)

Things to do:

Get new spark plug (currently B9ES...getting BR8ES)

Check effect of raising/lowering main needle clip

Check effect of turning pilot in/out (previously results in bad results)

Check source of smoke (gasket or power valve)

Check effect of manually adjusting power valve

Check effect of autolube system (connected but not in use/running pre-mix = source of air?)

Check electrics (ugh, not so keen on this one)

Put rubber around right footpeg to save on shoes.....(seriously I've wrecked 2 pairs)

Ok so that's where I'm at.

If I can't get anywhere I'll pull the motor apart and check it out (I've never seen inside it so it could be ratsh_t). I've been putting it off because I don't want to fork out for a new head gasket just for a look see but at this stage it's probably stupid not to.

[Cynic]

Don't know if this helps but this is the carb specs for a DT230.

Carburettor Type / Manufactured / I.D. Mark: TM30x1 / MIKUNI / 4TP00

Main Jet: #165 M.J.

Jet Needle, Clip Position: 6DHY40-4 J.N.

Needle Jet: O-0 N.J.

Pilot jet: #22.5 P.J.

Pilot / Air Screw (Turn Out): 1-1/4 P.S. (A.S.)

Float height / Fuel Level: 12.4-13.4/- F.H / F.L

Idling Engine Speed: 1,300-1,400 r/min

Thought if you looked at your specs and this it might help, i think (tho don't quote me) that going by the id the carb is a 30 mm.

The bike being a bugger to start and running a bit hap hazard is a pointer towards the crank seals. Have you tried zaping all the possible leak areas around the carb with WD to see if it helps.

A good drenching behind the coils can help to see if its the generator crank seal too.

[bob-c]

I have to agree with Cynic, I have the same bike a 88DT200r . At this age there is 99% chance the crank seals are leaking . If you don't fix them 1st you will never get the mixture right . Watch out for pattern seals , they are cheaper but imho not up to the job , get yamaha ones.

There is a fair bit of info on here but you need to post a few times to get access to all sections

www.yamahait.com.au

[Paper Mache Man]

I have to agree with Cynic, I have the same bike a 88DT200r . At this age there is 99% chance the crank seals are leaking . If you don't fix them 1st you will never get the mixture right . Watch out for pattern seals , they are cheaper but imho not up to the job , get yamaha ones.

There is a fair bit of info on here but you need to post a few times to get access to all sections

www.yamahait.com.au

How much of the bike do I need to pull down to get to the crank seals?

Any advice before I do so?

Any parts/gaskets I'll need to replace as soon as I venture this way (i.e. use once items)?

Found that despite having a lot of fuel in it, the tank wasn't putting any out...just the smallest trickle. Turns out what I was seeing was all reserve, no main. As soon as I filled the tank up the carbi started spewing it out again. Stupid mistake which has made the last week of troubleshooting close to useless.

Also had another person mess with my carbi so gah...square one atm.

[Cynic]

How much of the bike do I need to pull down to get to the crank seals?

Any advice before I do so?

Any parts/gaskets I'll need to replace as soon as I venture this way (i.e. use once items)?

Found that despite having a lot of fuel in it, the tank wasn't putting any out...just the smallest trickle. Turns out what I was seeing was all reserve, no main. As soon as I filled the tank up the carbi started spewing it out again. Stupid mistake which has made the last week of troubleshooting close to useless.

Also had another person mess with my carbi so gah...square one atm.

Hmmm, there are 2 schools of thought on this. Personally if the crank seals have had it then there are plenty of others that will be past their best, also the main and output bearings are probably worn too. So i would strip her down and do the lot.

The other view is pull the duff seal out and stick in a new one in situ, i havent done this but i know bob-c has.

Before we dash down that particular road try a couple of things. Take off the left side engine cover and get the motor running as best you can, now spray LOADs of wd40 or similar at the back of the generator so it covers the seal. Does it improve things. Secondly pop the gearbox breather into a glass of liquid, parafin, white spirit or similar with the engine running again see if there are any bubbles, or conversely the fluid level appearing to drop.

Those 2 can give a reasonable indication of crank seal health.

While you have the WD out blast all the possible leak areas on the motor, the reed cage is a favorite as well as the carb rubbers as they can perish. Again with the motor running and see if there is any improvement.

[rr390]

How much of the bike do I need to pull down to get to the crank seals?

Any advice before I do so?

Any parts/gaskets I'll need to replace as soon as I venture this way (i.e. use once items)?

Found that despite having a lot of fuel in it, the tank wasn't putting any out...just the smallest trickle. Turns out what I was seeing was all reserve, no main. As soon as I filled the tank up the carbi started spewing it out again. Stupid mistake which has made the last week of troubleshooting close to useless.

Also had another person mess with my carbi so gah...square one atm.

I hav just recently replaced crankseals on my dt200.bought genuine yamaha,cost-$114-or $76 for the stator side-$38 clutch side. i had to buy a 27x1 lefthand male thread flywheel puller also as i could not find someone with correct size.cost-$55.

[Paper Mache Man]

I hav just recently replaced crankseals on my dt200.bought genuine yamaha,cost-$114-or $76 for the stator side-$38 clutch side. i had to buy a 27x1 lefthand male thread flywheel puller also as i could not find someone with correct size.cost-$55.

Well I might not need to do it, maybe. I put in a 45 pilot and the bike seems to be running properly now. Runs with choke off properly now and also has no issues starting any more.

I have a problem with my radiator though, it's leaking a bit - I get steam, can't see water drops so it must be small.

Just wondering what the best way of dealing with this is. I put stop leak in but it hasn't stopped the leak. The water is boiling despite my pump working and the thermostat seeming to regulate properly. It seems to only boil once the bike has stopped and the internal pressure is relieved through the leak in the radiator...so it might not be that bad.

However does anyone else get a temp warning when running the bike at idle(i.e. stationary) for about 15 minutes? I had to hose the rad down with water to prevent that happening. Once I drove off it was ok though.

Any ideas?

[Cynic]

Well I might not need to do it, maybe. I put in a 45 pilot and the bike seems to be running properly now. Runs with choke off properly now and also has no issues starting any more.

I have a problem with my radiator though, it's leaking a bit - I get steam, can't see water drops so it must be small.

Just wondering what the best way of dealing with this is. I put stop leak in but it hasn't stopped the leak. The water is boiling despite my pump working and the thermostat seeming to regulate properly. It seems to only boil once the bike has stopped and the internal pressure is relieved through the leak in the radiator...so it might not be that bad.

However does anyone else get a temp warning when running the bike at idle(i.e. stationary) for about 15 minutes? I had to hose the rad down with water to prevent that happening. Once I drove off it was ok though.

Any ideas?

Personally i would replace the rad. If it fails you could loose the motor, especially if it goes on a fast stretch it can dump all its coolant in seconds and sieze.

Any bike will protest if its left to idle for 15 minutes, it is the airflow from the bike moving that cools everything down. Newer stuff has fans, yours may have had one could be worth checking. My TDR heats up readily enough in traffic, can't say i have ever left it running for 15minutes though.

Can't imagine thats good for any 2 stroke. I suppose it shows your motor is running pretty good now. I know the DT would never idle for that long without doing a plug. I wouldn't fancy it with the TDR.