Maintenance and repairs

Autumn 2002

The drive chain and sprockets as well as the oil seal and o-ring on the shaft were replaced at 49000 km. I found out that the previous drive sprocket had been wrong shape, letting the spacer tube move outwards on the drive shaft, opening a way for oil to escape. Frank Nyman MC service in Kauniainen, Finland, fixed the problem on the second try. I was puzzled by the relative lack of power at high RPM. Max speed 140 kph on the speedometer, perhaps 130 kph real speed, was clearly too little for this bike. The engine might have been worn (cylinder or valve leaks) by this mileage, but if this were the case, the problem would have shown up at low rpm rather than the high register. The engine did not blow through the breather tube either. My first theory was that the air filter might have been clogged. It was filthy indeed, and some bush mechanic had tried a quick fix by punching a thumb sized hole through the element. I washed the element clean and fixed the hole. No effect on top speed. My next theory was that the bike would have been a reduced power model. The papers say 30 kW, but as the earlier history of this bike in Germany was not known, the engine might contain surprises inside. Kawasaki USA's web pages contain good parts diagrams of the engine. I did a search on the Internet and found two different explanations, how the engine power is supposed to be reduced. Both had to do with the carburetor. I opened the carburetor but did not find any nonstandard or modified parts. The valve had signs of wear, so I replaced it and the spring.The test ride was a disaster. The bike did not go anywhere - now it was reduced power for sure. Luckily the problem turned out to be an assembly mistake. The diaphragm was displaced and leaked air. On the second try everything worked all right. Tachometer reading 140 kpl on the expressway.

There is a thin "flute" at the end of the muffler. I made some mental math and concluded that the exhaust gases must blow some 100 m/s through that pipe at full power. The pressure loss is not huge, but it might have an effect. I drilled four 10 mm diameter holes at the end of the silencer as an experiment. My idea was to give twice as much cross section (and a shortcut) for the gases to blow through. The sound was momentous but the speed did not increase. When idling the engine bore some romantic resemblance to Wickström engines found on old fishing-boats. In the name of neighborhood harmony I closed the holes. In some moment of despair I tried driving with the air filter element removed. No effect whatsoever. Now I had run out of simple means. Wrong ignition timing might have an effect, but the timing is controlled by a black box with a transducer at the side of the alternator. One would think it either worked right or did not work at all. By the way, as the transducer reads the crankshaft, there must be a spark on every round!

Winter 2002/2003 findings

Summer 2003

I detached and opened the carburetor and installed a #150 main jet instead of the original #145. I adjusted the pilot screw to give smooth idling and no popping at coasting. The pilot screw is in a very tricky place on the bottom side of the carburetor. You cannot reach it with a normal screwdriver, so I shaped an adjustment tool from an M6 bolt. I may still burn my fingers against the exhaust but it is possible to adjust the screw with engine running.

After these modifications I again went for a test drive. The bike went smooth and nice - excactly as fast as before.

One final change: The air entering the air filter box is sucked from behind the battery through a very small opening. The filter box itself is quite large and complex plastic structure. I guess it must be somehow acoustically tuned for minimum noise vs. performance. I experimented by removing the side plate covering the air filter. That had an effect on the power, and an even more marked effect on the sound, or roaring. Open the throttle and imagine you are riding a lion..
I put the cover back on and cut an L shaped opening on top of the air box inspired by mike's carb mod pages. I did not do Mike's other carb mods, because I did not like the idea of giving a free passage to anything smaller than a sparrow to fly into the engine.

A new test ride confirmed that the speed rose easily to 140 kph and ca 6500 rpm on 5th gear. Not a huge improvement but a step in the right direction. The sound at full throttle had become masculine, to say the least, but when idling the machine was as socially correct as ever.

Winter 2003/2004

The engine consumed more than one liter of oil per 1000 km. It had a small oil leak, but most of it blew out through the exhaust, which some fellow motorists kept reminding about. I had to do something to the oil consumption. With kind help from the motorcycle shop Powerkings in Lohja, Finland, I did a thorough repair during the winter weekends. I detached the engine from the frame, removed the cylinder head and took the valves apart. The valve seal on one of the intake valves was defect. I replaced all seals and ground the valves gently against their seats. The valve clearances had been below limits in the exhaust valves, and after the operation the intake valves were at the limit, as well. I replaced the valve shims with 0,1 mm thinner ones on the exhaust and 0,05 mm thinner on the intake valves.
The cylinder did not have scratches but the piston ring clearance was on the bigger side. I mounted a new piston ring set and honed the cylinder surface lightly.
I removed the flywheel (magneto) to be able to inspect the balancer mechanism. I learned not to try this without a proper puller and special tool to hold the flywheel ;) The balancer chain and the idler lever "doohickey" were all right. The doohickey is a weak point of this machine, see full story here.
The cam chain stretch was well within factory limits. Cam timing was completely wrong, however. BINGO !! Now finally I knew what had been wrong with the engine. The cams and the flywheel have aligning marks that are used to get the shafts right relative to each other. Having the whole flywheel visible I noticed that it in fact had three aligning marks in different positions! Whoever assembled this machine before me had aligned to the wrong mark, causing that the valve timing was one full tooth (15 deg on the crankshaft) early. This had slipped my attention, too, when I had checked the timing through the window in the engine cover a year earlier. A wonder that the engine had worked at all!

In order to stop an oil leak I replaced the copper seals to the oil pipe leading from the gearbox to the cylinder head. The bike got a new battery and then everything was ready for a test ride.

The test run proved to my delight that the engine had changed remarkably: in the upper register there was a lot of more power and the bike was now running the way it is supposed to do.

Summer 2004

Since the first test run the engine had sort of hesitated on low throttle at 60 - 80 kph. This was best felt in cold weather. This looked to me like lean mixture. I raised the carburetor needle by ca 1 mm with the help of two shims. It helped but did not completely take the phenomenon away. The mixture is certainly not too rich - on longer distances I sometimes get below 5 l/100 km (20 km/l).

The outside of the engine kept getting oily and after a harder run there was a rather unpleasant smell of oil around. I noticed that one of the rubber seals of the cylinder head cover screws was wrong size and it let oil mist escape. When running at full throttle it sprayed oil droplets all over the engine, the rear suspension, and my boots got their fair share of the oil as well. After replacing the seal the leak stopped and I have since been able to drive a full 5000 km oil change interval without adding oil.

The rear tyre punctured at 55700 km. I replaced the tube myself, and mauled the new tube beyond repair in the process. In the end I had to fix the old tube and put it back, this time very gently.

I replaced the seat cover at the same time. The old light blue cover had been dirty and I had cleaned it with a solvent that was obviously too strong for the vinyl. The surface had became permanently sticky, like sitting on a piece of adhesive tape. Very uncomfortable indeed. I removed the old cover and stapled a new cover in the plastic seat frame. Anyone trying the same, go get a _heavy_ duty stapler.

On my Summer vacation I did a 4000 km journey from Espoo to Nordkapp and back. Far up in the north I began losing my rear brake - brake pads worn out. I phoned from Hammerfest to Sumeko (Kawasaki Finland) and got the replacement parts sent to Kuusamo, where I was heading on my way back. After picking up the parts I drove to the local hardware store and replaced the parts on their parking lot. It turned out to be a good idea, since in the middle of the work I had to go and buy a wrench I did not have with me.

I went south along small roads of Kainuu, a district by the eastern border of Finland. At one point far from everything the rear of the bike started feeling strange, as if the suspension had broken. It was not the suspension but the rear subframe. In Tengai, the seat, battery, exhaust, and rear fender are carried by a subframe, which in turn is attached to the frame by four bolts. The upper two had broken and the rear part was kept from collapsing by the battery cables alone. I was able to improvise a temporary fix by using pieces of steel wire, electric wire, and rubber band I had with me. As I drove along I got more confidence in the fix and ended up driving all the way back home, some 500 km. Just 20 km from home the temporary fix broke. The remaning distance I practically sat on the gas tank and hoped that the frame would last just a little longer. It did and I got safely home.

In my opinion the mounting of the rear subframe is designed wrong. The subframe is kept in place by friction alone. If the bolts pressing the parts together loosen up a little so that the parts slip, the bolts themselves will carry the shear load. The bolts had broken right at the point where the shear load is highest, and the threaded ends of the bolts were stuck in their holes. Luckily I got them out without damaging the threads. It appears that some other KLR owners have experienced the same problem. A Scottish colleague did not take any risks but welded the subframe in place. I did not change the structure but just put fresh M8x30 bolts in with some Loctite. If the old ones lasted 50,000 km, perhaps the new ones will, too.

At 60500 km I had the rear tyre replaced. Bridgestone TW48 again. The previous one had lasted 10,000 km, not bad. The front tyre had about 50% left.

The bike had little by little begun to sound quite ugly, as if something was loose inside the muffler. The sound could have come from the engine, too, which would of course be quite alarming. I was looking for a suitable muffler but did not want to invest in the original part. I got hold of a used Marving silencer, whis was actually built for the Yamaha XT 600. The engine power and rpm matched and the front pipe diameters were the same, so I gave it a try. I had to make an adaptor between the rear frame and the muffler, because the new muffler had a different shape. It fit in place without problems. The result was pleasing at least to the ear. The rattling noise had disappeared and instead there was a low pitched sound with some substance but not too loud. When it comes to performance I could not tell a difference.

At the end of the season I closed the opening on the top of the airbox by a steel sheet. After all the cut seems to give little, if any, benefit when it comes to max horsepower. Restoring the airbox cured the running problems I had experienced at low throttle around 60-80 km/h.

Summer 2005

Before starting off I replaced the drive chain and sprockets. On my last ride the previous season I had noticed that the chain was hanging very loose and it made noise and jerked as if it wanted to jump off. I had not examined it closer at the time but I decided to buy a new chain+sprocket set for the Spring. When removing the old chain I found out that the master link (the one with the clip) had half-broken and the chain was just barely kept together by the clip side of the link. I had been very lucky on my last ride that the chain had not broken.

I installed new sprockets and chain, this time with a riveted link, as recommended by the manufacturer. The secondary drive was now back to standard condition with the right sprockets and standard drive ratio 15/43. A

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