Introduction. / News. /  Spares.  / Cylinder. / YPVS. / Oil pump. / Chain. / Carburettor. / Ignition. / Battery. / Fuel cap. / Piping. / Cooling. / Wheels. / Steering head and lock. / Brakes. / Paint. / Future projects. All links are within this page, so you may choose to go off-line. To return to the top, press the 'Back' button in your browser.
 

Introduction.
This page will be my own personal addition to the Haynes, or any other, workshop manual. Which means in time it will contain the information left out there. This will be things like how to setup the YPVS, things to note when riding it trough the salty season and other things I've noted or had to discover myself.

The page will never be finished. Unless of course the bike disappears in another bottomless swamp with no bulldozer around. (That was one expensive weekend and I don't even have pictures of it!). I am not new to motorcycling in general, but green when it comes to the green stuff.

Unlike my other pages, this will be kept in english as not to narrow the reading audience too much  : ) . And nobody is proof-reading this.

Also NOTE: Any information in this page is given without warranty (who would claim warranty from an unknown person anyway?)  and is valid for the 3RM2 model (1989-1991, 29PS) which was sold in Denmark. However this was sold in other countries as well, and is very similar to other year- and country-models. (Differences i know about is colors and restrictions). Check with your users manual and local dealer. Don't expect Yamaha to publish or answer anything via the net. I wasn't lucky.

News. 3/1/00.
Added 'oil pump', edited 'cylinder', 'spares', 'brakes' and 'piping'.

I have no idea how many people use this page, so please drop me a note with comments. eMail adress at top. I was thinking maybe to make a 'now there's an update' mailing list?

Bike is running. Just needing a new chain. Importers are closed for christmas. As if they don't have enough vacation in the summer. Yes, at the height of the season they slow down to a crawl.

Found a 45/40W halogen headlight bulb with a Bilux socket at a supermarket. Haven't tried it yet.

Spares.
Go wait. Go on vacation. Get grey hair. This is my last (italian build) Yamaha. And I'm not too happy with Suzuki either.

I've often had to wait for months for parts to arrive. My friendly/trusted(?) dealer tells me there's a number of reasons for that.

Yamaha, Kawasaki and Honda each have a european parts warehouse, and can therefore get parts out fast. If I place an order with the dealer for a Yamaha part before 10 AM, he'll have it in next day before noon. Sadly my particular Yamaha was built in Italy and has an unrestricted engine, and parts and their numbers differs slightly from other DT's. This has had me waiting long periods for a part to get in, only to find out it's the wrong size/colour/shape/etc.

The story with Suzuki is different. European importers haven't agreed on a common warehouse, and each importer will order parts directly from Japan. So if a part is not in Denmark it will be put on a list, to fill a sea container. Denmark being a small market this can take some time, although I've been told there's some collaboration with the german(?) importer. One summer I'd been waiting for something, and was one day told the parts were at the importer, but due to the holidays it took them two weeks to unpack the containers. DOOOH!.

In the three years I've had two bikes, for one month, in all, I've been able to choose which one to ride. This has often taken me close to the point of giving up riding altogether, especially when I see how car owners get cheap same day delivery of parts.

Cylinder.
Thanks to a broken piston ring at circa 15500km some engine components got to see daylight. Except for a large new scar the cylinder wall looked like new with clear honing marks.

At 19000km the engine blew up a second time. See Oil pump for details.

Strangely (to me), only the piston wrist pin bearing showed signs of oil starvation. It had no play but was discoloured. I haven't seen the main bearings, but they and the big end bearing have no play and the latter has no discoloration. Maybe I've been lucky, or maybe the piston and cylinder interface really is the weak point of a two stroke?

Whenever possible I'm using original spares. For the DT I'm particularly aware of this, as I don't want to end up with a restricted machine. However, after the first seizure, Yamaha wasn't able to deliver a piston of the correct size. Two pistons, each one millimetre larger than stamped on them, got to the shop, but the rebore service found the error when determining the new bore size. They measure the new piston and then calculate the bore size.

After half a year waiting I went for a Pro-X piston kit. This became necessary the second time, as the first blow up needed second oversize (+0,50 mm) which is the largest Yamaha stocks (Okay I don't know if they stock it; they didn't sell me one...). I'm now on third (+0,75 mm). Only thing obviously different between Pro-X and OEM is a missing small hole at the back of the Pro-X piston. I assume it's to circulate extra cool air/fuel/oil mixture to the piston bearing. I had the shop drill the same hole in the Pro-X pistons, and having done a little 'clean up' with a fine file and emery cloth it has shown no signs of weakness.

The following figure_1 is  from a dealers printer. The item numbers are my own.

Assembling: On my bike water had found its ways to the treads of the studs holding the cylinder (12) and head (2), corroding and ruining them and the locating tubes_4. Experimenting to avoid that happening again, all studs for the head, cylinder and exhaust were coated with a liquid gasket.

The head gasket has a tab at the rear with a blurred "UP" stamped in. The studs_12 are of different length were the locating tubes are fitted. Don't forget brackets_5&6.

If you are using a torque wrench (absolutely recommended), you will need a very small one (1/4") to get at the head nuts if the engine is in the frame, and some attachment to get at the cylinder nuts. My home made solution was to attach the torque wrench to a normal closed end wrench at a 90' angle. Se figure_2.

YPVS.
Figure_3 tries to show a schematic view of the YPVS.

When the ignition is turned on, the valve will do at least a low to high cycle. Probably to ease starting, it will stay there till the engine is idling when it will move to the low position. To _check_ the adjustment of the valve make sure that there is one or two millimetres slack in _both_ of the two cables_10&11. Turn the ignition on till the valve stops, and then off again. The notch on top of the pulley_9 should now align with a hole behind it. Use something like the blunt end of a drill bit for checking.

For setting up the valve I recommend removing the front of the exhaust system. This will allow you to feel the alignment of the valve with the exhaust channel. See figure_3. And don't forget the slack in the cables. Check it again _after_ tightening the lock nuts.

Oil pump.
So far my theory for the piston failures is lack of oil. Before seizing the second time, the engine used somewhat less oil than when new. First time the engine was assembled I checked the pump stroke as described in the Haynes, and it was OK. But the Yamaha workshop manual (YWM) described the procedure differently. Long story short; the manual also got the amount of oil it should deliver which I believe is a better check of the pump. (Anyone with an idea how to rig an oil flow/oil pressure warning light?)

The oil quantities given here are for an earlier model (Pump colour code 'Red'). My dealer didn't have other info and as only minimum pump stroke differs slightly, I guess these data are similar:
 

My actual pump delivered a little more oil (right column), and I will use these numbers for future reference. (Too much oil in premix will lean the fuel-/air-mixture but doesn't hurt with an injector system like this).

The check procedure is straight forward, noting three things:
    1. A two stroke engine with a pumping crankcase (OK, that would be anything else than marine diesels) will suffer from top end (piston rings) oil starvation if idled too long. During the test the engine should be revved from time to time. You will see blue exhaust as an indication that oil collected in crankcase is scavenged and expelled.
    2. Try as well as possible to keep air out of the system. The system will eventually purge itself of air, but you never know, and the check is faster and more accurate when there's no air to be passed.
    3. Keep an eye on temperature gauge. Mine didn't move, but...

Get a 5 ml syringe and a length of clear tube.

The tube from the oil tank must be blocked off (bend&zip tie, washing line thing(?) or tube pincher like chemists use). Remove it from pump. In it's place connect the syringe with the clear tube and fill it with oil. Remove the tube from pump shortly to let air escape. Air bubbles in tube may be tricked to raise up by tapping it with the finger, just like the doctor does with his needle while he tells you it won't hurt. Tie syringe to bike.

Now start engine, and idle it. Count the pump strokes and compare consumption with table or your own data. Don't forget to occasional rev the engine.

The full throttle check is done in the same way; you just turn the cable wheel on front of pump by hand to the full throttle position.

And if the pump doesn't check out right? Errm. Only thing to do is try and shim it to correct delivery. The pump can be taken apart (The one i discarded looked fine) but no parts are available, and I know now, a top end rebuild costs at least twice the price of a new pump.

There are two other things that could possibly cause too little oil:
    1. The throttle cable split box. It's supposed to be self adjusting, but self adjusting things has been seen before not to do so. It could cause the oil pump not to get on 'full throttle'.
    2. Oil pump driving gears. Don't know if it's a thing on the DT, but I've heard that some RD's(?), which in this regard are similar, had small pieces of clutch friction material come loose. In itself not a problem, but the particles could get caught by the plastic driving gears for the pump, and destroying them.

Chain.
Should be run slacker than stated in the manual. When the rear suspension is compressed to the point where the chain is tightest, some slack should still be in the chain. To find that point (not fully compressed) you might need help from two of your ..erm-hm.. "larger" friends. When the bike is unloaded the chain will seem very slack, but if it's not worn it will stay on. Make a note of the amount of slack unloaded so adjustment will be a one man job in the future.

Changing the chain, the nut holding the front sprocket is often difficult to loosen. Find a round drift or bar with the _exact_ same diameter as the holes in the rear brake disc, and lock the disc against the calliper anchor. No problem. And don't use copper grease to make disassembly easier. Copper, steel and (salt-)water don't mix. Copper grease should only be used where there is heat and no water.

As I use the bike mainly offroad I use a 16/57 final gearing. Note that this requires a 134 link chain.

Carburettor.
So far: Needle raised one to the highest notch. Main jet up one size to #220. Gives better throttle response.
Lowered needle again to remove constant speed stutter at light throttle.

Ignition.
I have some problems with lost sparks here, and work is still in progress. The original plug cap fell apart, and the replacement NGKs has a problem, that appears to be as follows: The spring clip holding the small tread on top of the plug is not strong enough to withstand vibration, and metal dust from the following rubbing helps the current past the isolator at high engine load. This doesn't happen with plug caps requiring the small aluminium nut on the plug. Instead they have been loosing contact or let water in with similar results :(  .

I have now found a different cap with a very strong clip, and the type worked faultlessly (~waterproof) on my moped for years. And as I've found now, it works absolutely perfect on the DT. 500 km of motorway, 20 km of wet beach, an assortment of mud and a garden hose didn't produce the slightest misfire or signs of above mentioned problems.

The Holy Grail of plug caps: 'Merit'I found it at http://www.thansen.dk/
 

Battery.
First: The battery has absolutely nothing to do with the ignition. I've always known this, but in the Haynes I stumbled on the notion, that a poor battery could cause weak sparks. Not True.

A replacement 'cheap' battery named 'Long' split between its lid and casing. And no, the breather was not blocked. Luckily escaping fluid only got in contact with the plastic battery carrier.

Fuel cap.
The vent in the cap has a one way ball valve, which can get stuck. Getting to and cleaning it is easy done by removing the two screws underneath the cap.

Piping.
I don't think it's designers intended the bike to go offroad. At least they didn't route the different tubes out of water, muds and the swingarms way. I still don't know what to do about the battery breather (except checking it often), but for the others:

Gearbox breather: It appears that when riding the warm bike through water, the cooling of the gearbox would suck in a small amount of water via the breather.  The working solution has been to take the tube up under the tank, where it ends in a paper fuel filter.

The carburettor drain/overflow tube has been taken to the left hand side of the engine, where it ends on top of the flywheel cover.
The two float bowl breather tubes has been left as they were. No problem.
Naive me. After i got the Merit spark plug cap I sat out to explore deeper waters (No I didn't, I found myself just there). The ignition works faultless under water, but the carburettor doesn't. The three tubes mentioned above will be taken up under the tank, with the drain tube fitted to be easily taken to a lower level when not out sailing.

The tube on the rear right hand side of the carburettor i still don't understand. When I bought the bike new in december 1996 (Yes, it had been standing for some years) it was just routed up under the tank. Shortly after i noticed that dust had settled on the inside of the tube meaning air was drawn trough it to the carburettor. After cleaning the carb I mounted a paper fuel filter on the end of the tube. The filter has apparently no effect on the engine.

Cooling.
As mentioned above, the new bike had been standing for some time at the dealer. That had caused the coolant to "harden" in the circuit to, in and from the carburettor (carb-heating). The main circuit wasn't affected. Nothing seemed to dissolve the blocking, until I tried my trusty aerosol contact cleaner. (Kontakt 60 from german Kontakt Chemie. Excellent grease, oxide or WHY remover. And it has never attacked any plastic or rubber).

Wheels.
Bearings are changed with the tyres. I use the 2RS type meaning they have a rubber seal on each side.

Steering head and lock.
The 'german' steering lock will let water into the bearings. This is a problem not limited to this bike, even road bikes will suffer. Fast solution: Don't use the lock, fill it with grease and tape it up/heat shrink tube it closed. I think sealing it in a way where the lock would still work is too time consuming as it is not much of a lock anyway. But removing it all together could cause legal problems in some countries/insurance companies.

For this particular bike it is not possible to get a conical roller bearing for the top as the clearances are too small for any (to me) available bearings. It's not a problem as the roller bottom and ball top works fine except it's a little harder to adjust.

Brakes.
Brake pads _are_ different front and rear. The rears is harder than front, probably because there is a larger tendency for mud to get at them and wearing them out fast. Some pad manufactures don't acknowledge this (ex. EBC ~ 400km pad life). I use SBS which last _much_ (10x) longer. And they are made in Denmark :-)

Keep an eye on the rear calliper. Contrary to the front, it has no rubber boot to protect the piston.

Calliper anchors were not painted or corrosion protected in any way on my bike. Not only did they very fast look really bad, but as the oxides of aluminium are thicker than aluminium my brake pads were getting stuck, not moving away from the disk when brakes were released. Also the rough surface of the corrosion bonded dirt to the parts, making cleaning difficult.

The point of the worst problems was between the anchors and the small stainless(?) clips of which there is one at each end of the brake pads. They are there to keep the steel backing of the pads from wearing out the aluminium anchors, and also to act as springs, retracting pads from discs. (Don't loose them, they cost a fortune, four pieces cost double that of a brake piston kit with seals!).

I cleaned the anchors with an electric wire brush, a file, emery cloth, soap&water and degreaser. I'm using ordinary spray paint on aluminium, which I'm told is not a strong combination. Therefore the thorough cleaning. However it has not shown any weaknesses and the anchors don't get really hot anyway. But if you have a set of calliper paint it would probably be the right thing to use (expensive, 2-component plus prep chemical).

When painting I was very careful only to get thin layers of paint (three), as not to have the pads stick right off. When the paint was dry and the clips cleaned, they got a quick spray of paint on their back and were immediately pressed into place in the anchors. In this way the parts were glued together and water and dirt is effectively hindered from getting between them and causing new corrosion. It works very well, and even pad change is easier.

Paint.
The bike seems to have relatively good rust protection. But japanese cost-cutting and italian production fortunately leaves some for the owner to do. Just like the annoying mix of fasteners: inner- and outer-hexagonheads, different crosshead and "european (13mm)" and "japanese (14mm)" heads.

The exhaust system will _not_ survive any salt, so if you go anywhere near a beach or ride in the winter, you should have it sand blasted and zinc sprayed. This will leave the surface rough and perfect for painting. Buy a good heat resistant paint intended for automotive use. Don't use the supermarket "200'C oven paint".

A note on zinc spraying. When I was having parts for my other bike at the 'sand shop' the other day, the manager told me that the zinc coating isn't expected to withstand heat above circa 80'C. Occasionally it will flake off. However, I have so far not had any problems. I'll see what happens this summer. But ask your local shop if they know of limitations of their product.

Where the seat rests on the tank and frame top tubes, in combination with dirt, it will remove the paint. If you are buying a used bike, you should check that no severe rust damage has occurred. My solution was to clean and paint the affected areas and cutting some bicycle inner tube to be contact glued on to the frame and tank. Done with a little more care than I, your work will not be visible with the seat mounted.

Future projects.
Halogen light via the battery. Combining the two generator windings gives a nominal output of 95W. Using a standard tree phase rectifier/regulator should work.

Rewiring the ignition cut outs.

Modifying side stand switch so my heel won't activate it. It's not smart to loose power in a deep sand/mud pit.

Larger fuel tank. Any ideas?

Aluminium rims.

Front page.

MC links.