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Motorcycle rebuilding

(after the trip)

   One year after my return in Greece, I decided to rebuild my XR, which was just resting for all this period. I didn’t take that decision because I love that motorcycle, as most people would imagine. I did it because I wanted to become even more familiar with the mechanic parts of a motorcycle, in order to be better prepared for my next trip. Before this trip, I was working for free in a repair shop for cars, in order to learn the basics. I saw there the master disassembling and assembling many engines. I knew the procedure in theory, but I had never done it by my-self. So, it was time to give it a try!

   Rebuilding was not just on the engine, but on almost every part of the motorcycle. All of them had worked for many tens of thousands of kilometers and they had worked in tough conditions. So, they needed some care. I removed everything from the frame, except the handlebars and the triple clamp (also known as “triple tree” or “yoke”). I checked again and again the steering head bearings and they had no dents, roughness, looseness or freeplay. They have rollers instead of balls, so there is a bigger friction area that helps to keep the outer race of the bearings unworn (the head bearings of my Africa Twin, which use balls, were making dents every a few thousand kilometers…).

That’s the small engine that let me travel in Asia for 2 years and 2.5 months!Disassembly

I disassembled the engine with the help of the manual, to be sure I will not make any mistake.
Disassembly of the engine

That’s the manual (it was traveling with me in Asia and that’s why it became like that at the bottom of my pannier. Happily, I didn’t need it during my trip).
Bike's manual

I disassembled the engine and I was surprised to see that the reason it stopped working just 60 km. (37 miles) before I reached Greece was not what I was expecting. I knew that there wasn’t enough compression in the engine, but I didn’t know that the reason was a hole on the piston!
Hole on the piston!

   The question is “why did that happen”. I guess the main reason was that some fuel or air passages in carburetor’s body were partially blocked or oversized. I realized that at the end of this rebuilding, when the repaired engine had the same problem that it had during the last part of my trip. When they adjusted my carburetor in Kyrgyzstan (at the same time I changed the carburetor’s diaphragm), I noticed that the adjustment was wrong and I told it to the master. However, maybe the problem was not on the adjustment, but on the fuel or air passages. He told me to go to a specific master in the capital, but that one didn’t know either how to adjust a carburetor on a motorcycle like this. When the engine was cold and I was accelerating suddenly, the engine was running poor and it was nearly stopped. I had to pull once the choke lever for a moment while I was accelerating and then everything was working fine. That means that the carburetor was providing more air and less fuel, which leads to abnormal burning of the mixture and that caused the hole on the piston after a few tens of thousands of kilometers.

   Everything I tried in order to clean the carburetor during this rebuilt did not have any results. I removed it and I put it on the bike ten times approximately! Initially, I cleaned its metal parts just with cotton and alcohol, but it didn’t work out. Then, I cleaned its metal parts with solvent for carburetor cleaning and compressed air, but there was no change. I replaced the main jet with a slightly bigger one, but the problem was persisting. I cleaned the carburetor again and again, but without any success. At the end I gave it to a repair shop to clean it by ultrasonic bath, but that made it much worse! Since then, the engine could not start. It was behaving like flooded from fuel. I achieved two or three times to start it with many tricks, but it was working very badly and only while I was holding the throttle fully open.

One of the many times I disassembled the original carburetor in order to clean it in detail.
Old carburetor

   The problem was on carburetor’s body, so I could not fix it. I had to change the whole carburetor. Happily, lspyros, a member of the internet forum, offered me an old carburetor from a Honda XLR 250 1989. I am grateful to him for that. I did the required modifications to fit it on the air filter box and to install the throttle and choke cables. It worked immediately! I was so happy to hear my XR’s engine to work again properly!

   The hole on the air filter box is larger than the intake of the XLR’s carburetor. So, I put a rubber tube with a metal ring inside (from a cut seal) which resists on the clamp.
New carburetor

   Except this, it was clear that the piston was working without oil for a while, it was stuck and it got automatically unstuck in a moment. Look at the scratches on the piston’s sides.
Piston's side

Piston's side

   But why there wasn’t oil around the piston? That’s what surprised me the most when I saw it! Look at the situation of the cam chain tensioner and slider.

Camshaft-chain slider

You can see at the top the tensioner without the rubber, which was broken. At the bottom you see what was left from the slider. All this metal stick is surrounded by rubber normally and you cannot even see the metal!

   Don’t you wonder where all these rubber parts were? Well, they were all around the engine. I found them in the clutch compartment, in the oil pump, even in the seat of the oil strainer screen. That seat was blocked by the rubber parts and probably there wasn’t room for enough oil to pass through the screen.

Clutch compartment

Some of the rubber parts I found in the clutch compartment..

   Since there wasn’t any slider, look where the cam chain was sliding for some hundreds of kilometers (maybe even for some thousands of them).

Camshaft chain

There should be much more material on that metal part. That's why the oil filter was silver from the small parts of aluminium which were circulating around the engine.

   In addition, the oil strainer screen on the frame, at the bottom of the tube which doubles as an oil tank, was blocked from the small parts of aluminium. Look how it was!!!

Dirty frame's-oil-screen

How could oil pass through this mesh (or mess)?

Look at it after cleaning to see how it should be.
Clean frame's-oil-screen

    So, another reason that helped to make the hole on the piston was that it was working without oil for a while, the temperature in the combustion chamber got extremely high and preignitions occurred, which produce extremely high pressure in the combustion chamber and that’s why the hole was made. Except this, when I was preparing the motorcycle for my trip, some material from the top of the piston was removed, because this piston was higher than the normal. Don’t forget that this version of XR is so rare that it’s difficult to find spare parts in Greece. We had used an original Honda piston for the usual XR 250. In order to realize how much material was removed, look at the first photo of the piston at the beginning of the rebuilding chapter. At the inner side of the piston (up in the photo) you can see some small relief lines. Those lines were making the word “IN”. It’s interesting also to compare the holey piston with the new one.
New and old piston

New and old piston comparison

   Of course, even if material was not removed from the top of the piston, the hole would occur, since it’s inevitable when abnormal ignitions take place.

    In conclusion, our mistake during the preparation of the motorcycle for the trip was that we replaced the cam and the cam chain, but we didn’t replace the tensioner and the slider. The thing is that I was planning to travel much less than I actually did. I couldn’t imagine that I would end up traveling for 73,000 km. (45,361 miles). It was a pity, because I thought that the XR’s engine reached its limits. However, it’s clear that if the carburetor was adjusted right and if the tensioner and slider were changed during the previous engine overhaul, this small engine would offer me many more thousands of kilometers. During this rebuilding, instead of removing material from the top of the piston, I decided to give some more room to the combustion chamber by putting a second gasket under the cylinder. This way, the small height difference of the piston will not be a problem.

   The valves didn’t have as much dirt as I was expecting, because most of the oil I was adding in the engine liter by liter was just leaking through the gaskets and only a small amount of it was burnt in the cylinder. However, the two exhaust valves had some small hollows at the surface which contacts the head, so I changed them.
Engine's head

   I had written at the end of my trip about the excessive amount of oil that was leaking through the engine’s gaskets and that the wind was blowing it on my boot and even on my pannier. Look what a dirt I had to remove from the engine (and from any other part of the motorcycle).
Dirty engine

   The important thing was that there wasn’t any crack on the engine’s head, because in that case I wouldn’t be able to pay so much money to fix it. There is a rumor about the XR’s that a crack appears at the head close to the spark plug’s hole. Everyone was thinking that my XR’s head would definitely have a crack and that would be one of the reasons the engine was not working. I had researched a lot this rumor before selecting this motorcycle for my trip. An experienced and trusted man from Honda had told me that the crack appears because of wheelies. Oil doesn’t go to the engine because of its inclination during the wheelie. I have never made a wheelie even by bicycle, so that was not a problem for me. As it is proofed from the perfect condition of my engine’s head, the man from Honda was probably right.

   During more than two weeks my goal was to empty the left crate, which had the spare parts I was removing from the bike and to fill the right crate. After cleaning patiently everything, I was taking care of it and I was repairing it, if it was necessary. When it was ready, I was putting it in the right crate together with the new spare parts which were arriving day by day. So, I was very happy when the right crate was full!
Old and new spare parts

   I replaced preventively the piston seals of the brake calipers. The fluid seals were OK, but the dust seals were in a bad shape.
Brake calipers

Let’s talk about the frame now. First of all, it should be washed by petrol (diesel or whatever).
Cleaning the frame

…that’s my clean frame:

Clean frame

You see two different colors because before I left for my trip, I had painted the frame without removing all these parts I removed this time. So, I had painted only the parts of the frame that were not covered by the motorcycle's parts.

   Then, I used a magic paint remover! I spread it on the paint, I waited a few minutes and the paint was peeled.
Paint remover

…I scratched it by a slice and most of the paint was removed leaving this wonderful color of the naked metal. How enjoyable it is to remove the paint so easily without sandpapering for hours…
Paint removed

   Since the paint was removed, I took the frame to a welder. There was a big crack around the side-stand’s mount. It’s expected, if you consider that it was not designed to support the weight of the XR plus 90 kg (198 pounds) of load!

Then, I had to apply a primer on the frame and re-paint it.
Painting the frame

It’s ready!
Frame painted

   I had to paint the exhaust too, but first of all I had to sandblast it in order to remove the old paint, the rust and the mud which was grilled on the hot exhaust and had become a part of it.
Sandblasting the exhaust

The exhaust is ready too!
Painted exhaust

   It was time to try something I had never done before and I had never even seen someone else doing it, since I was working in a repair shop for cars and cars don’t use forks at the front suspension. I was only helped by the manual. I disassembled completely the fork legs, I changed their oil and their oil and dust seals, because a little bit of oil was leaking through them during the last part of my trip. I was very careful with all these parts of the suspension, but now I know how to do this too and I can do it again easily.

   After a lot of searching and waiting for the original spare parts, I finally had them on my hands! One of my favorite moments during the rebuilding was when I was opening all those unreasonably expensive packages from Honda and I was putting the parts one by one on the engine. Girls enjoy shopping therapy with clothes. I do the same with spare parts 😉
Assembling the engine

…I am putting the cylinder carefully.
Installing the cylinder

   In order to tighten the clutch nut, I had to prevent the clutch housing from turning. I applied the trick with the rag which blocks the gears when I was disassembling the engine, but I didn’t want to do that again, because everything would be full of rag pieces once again. So, I thought this:
Installation of the clutch discs

   I put a gear in the gearbox, I put the old sprocket on the shaft and I kept it with a pipe wrench. So, I did a clean and effective job!
Installation of the clutch discs

   Finally, the engine is assembled! I painted its covers, but not the cylinder, the head and the head cover, because I didn’t want the color to heat-insulate the engine and reduce its cooling effect.

In the next rebuilding of my XR I will turn it to a chopper! It will look like this:
XR chopper

The frame is ready for the engine.
The frame and the engine

   The day I installed the engine on the frame was a glorious day! I was very happy about it! I was feeling that my motorcycle will be ready soon and I will be on it rolling around the mountains and the plains again!
The engine on the frame

   I did another one improvement on the sidestand. The bigger surface at its bottom, which I welded before my trip, is useful in the sand and other kinds of soft ground. However, I had to give some height to the sidestand, because when I was parking the bike, it was leaning too much. Usually, I was putting a stone beneath it or whatever I could find there. So, I added 2 cm. (0.79 inches) of polyurethane at the bottom of the sidestand. It seems that’s the ideal material for this use, because it is elastic and it hooks better on the ground than metal or teflon.
Sidestand extended


   In the meanwhile, I got the K&N air filter I ordered from Germany. This XR version uses a very rare air filter, which Honda sells at the usual extremely expensive price. I decided to install a K&N filter which never needs to be replaced. It was difficult to find the right filter. I found out that the XR 250S (I think Baja too, but I didn’t check it) uses the same filter with XR 650L constructed on 1993 or later. The Honda part number for that filter is: 17214-MY6-670, while the K&N part number is: HA-6592.

Air Filter

You can see the original filter at the top of the photo and the K&N below.

Almost everything is installed on the bike’s frame.
Almost ready

   Finally, it was time to modify the bike’s electric circuit. There isn’t a switch to turn off the lights on this model, because it was designed for the U.S.A. market. In addition, the front turn signal lights are always on. When I want to turn and I switch on the appropriate turn signal, then that light is flashing. The battery on this bike is a small one, there isn’t a kick-starter and on top of these the lights were spending the electricity which was precious some times. The only choice in those cases was to unplug the connectors of the lights. So, I installed a switch to turn off the front and rear lights and the speedometer’s light. I did it on a way that allows me to have the front light’s low beam on when I switch on the high beam. When I need for a while more light, there are two 55-Watt bulbs working instead of one. The front turn signals are not always on anymore. They work as in the usual bikes we ride in Europe.

   After one and half months of hard work, the motorcycle was ready for the first road test. Last time it went out of that door was more than a year ago.
Out of the garage

   At the videos below you can watch the wonderful moments of my rebuilt engine’s first start. I was very happy when I heard after so long that familiar sound of my XR, which was accompanying me during my trip in Asia. The most important reason for a hobbyist mechanic to be happy in such an occasion is the thought that he took apart a whole motorcycle which was not working, he repaired it, he assembled it and it works!

   The rebuilding took me two months, 40 working days with an average of 8 working hours per day. The most time-consuming and less enjoyable work was the cleaning of all those parts I removed from the bike. I was washing them in detail with petrol or white spirit for more than a week. If it was necessary, I was using wire-brushes or sand-paper. The most enjoyable work was the engine’s assembling!


Exploring Epirus, Greece with Christina.


On the pass from Zagoria to Vovusa, Greece.

All the works I did during this rebuilding are reported in detail below.


  • Reconditioning of the cylinder
  • Replacing of piston
  • Replacing of piston pin and circlips
  • Replacing of cam chain
  • Replacing of cam chain tensioner
  • Replacing of cam chain slider
  • Replacing of cam bearings
  • Replacing of exhaust valves
  • Grinding of valve seats
  • Replacing of valve stem seals
  • Replacing of o-rings on the round caps for valve adjustment
  • Replacing of rocker arm for the exhaust valve which is closer to the clutch together with its adjusting screw
  • Replacing of oil pump
  • Replacing of gaskets between the gearbox and the cylinder, the cylinder and the head, the head and the head cover
  • Replacing of cylinder’s screw which is next to the spark plug at the side of the clutch
  • Replacing of cylinder head’s screw in front of the spark plug
  • Cleaning of oil strainer screens in the clutch compartment and on the frame
  • Replacing of washers for the tube which connects on the frame’s oil strainer screen
  • Replacing of o-ring on the oil filter cap
  • Construction of new thread for Ø 8 mm screws on the oil filter cap

Transmission and final drive

  • Replacing of clutch compartment gasket
  • Replacing of clutch nut
  • Replacing of chain slider on the swingarm
  • Replacing of chain slider below the swingarm, at the front
  • Replacing of front sprocket
  • Replacing of the seal behind the front sprocket
  • Replacing of gear lever’s seal

Fuel and air supply

  • Replacing of carburetor by Keihin PD 73A from a Honda XLR 250 1989
  • Cleaning of carburetor
  • Replacing of carburetor’s gaskets and o-rings
  • Replacing of carburetor’s pilot screw, its spring, washer and o-ring
  • Addition of choke cable
  • Replacing of the intake manifold which connects the carburetor with the cylinder head together with its o-ring
  • Replacing of air filter
  • Replacing of the right petcock on Acerbis fuel tank with a universal Acerbis petcock


  • Painting of exhaust
  • Replacing of the gaskets between the exhaust pipes and the cylinder head ports
  • Replacing of exhaust pipes studs


  • Replacing of swingarm bearings
  • Replacing of the left swingarm spacer
  • Greasing of rear shock’s arm & link bearings
  • Replacing of oil seals, dust seals and oil on forks


  • Painting of frame
  • Painting of the rack for panniers
  • Welding around the sidestand
  • Addition of 2 cm. (0.79 inches) polyurethane under the sidestand
  • Replacing of the red plastic cover for the rear lights


  • Replacing of front wheel’s bearings
  • Replacing of rear wheel
  • Replacing of rear wheel’s bearings and dust seals


  • Replacing of rear brake hose
  • Renewal of brake fluid on front and rear brake systems
  • Replacing of rear brake disc and pads
  • Replacing of brake fluid seals and dust seals on the caliper pistons of front and rear brake system
  • Replacing of pad guide on the rear brake’s caliper
  • Replacing of rubber boot on the front brake’s caliper
  • Replacing of bleed valve on the rear brake’s caliper
  • Replacing of dust seals on the rear brake’s lever

Electrical system

  • Addition of a switch to turn off the low beam of the front light and keep it on when I switch on the high beam and to turn off the rear light and the speedometer’s light
  • Modification of the front turn signals to stop them being always on and to make them work as the rear turn signals
  • Soldering of the fuse box for the GPS
  • Replacing of high beam indicator’s bulb


  • Cleaning of speedometer
  • Replacing of speedometer cable
  • Cleaning of panniers and repairing their lights


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