Open Heart Surgery on the DR 350

Looking at my newly acquired DR350, I feel a bit worried. After the oil incident, I think I might have made a mistake and should have kept on hunting for a bit longer. Shelving those feelings for a bit, I settle down to the relaxing task of removing the plastics, stripping it down to the main structure, and exposing its engine. Then sitting down on an empty wooden nail box, my eyes bore holes in the engine as time fell away. I had not moved but in my head, I have formed a rough plan of attack.

With a week to fine-tune my plan, I was back kneeling next to my motorcycle. Below me, I line my tools up with high hope of sustaining tidiness. Piece by piece I strip the engine down. Removing each piece with total care, while paying attention to every detail. I slid each bolt into its corresponding hole on a piece of cardboard mapped out to match the true location of the engine. Removing in the only order possible, working from the top down, I removed the head cover, the head, piston cylinder and the piston head and any everything else attached or in the way of the deconstruction.

 


Starting on the lower end of the engine, I remove the clutch cover to expose the clutch and lower cam chain sprocket. Giving my self a small treat, I pull out the impact driver, removing all the tiny bolts to release the clutch basket in no time at all. With one quick glance, I could see that the pervious owner told the truth and had replaced the clutch and basket recently.


Putting it aside I reach for the large socket and the half-inch drive placing it on the cam chain nut, I start to turn it counter clockwise. Failing to turn anything but all the cogs, I jam a screwdriver into between the oil pump drive gear and the cam chain sprockets. With one heave on the drive, I see the spanner fly out and skid across the workshop floor. Laughing I pick it up and replace it back in between the teeth, I try again. Again, it flies out with an odd pining sound. Frowning I look at the oil pump sprocket to discover I had broken one of the teeth off. Annoyed at myself for breaking the sprocket unnecessarily, I pulled out the impact driver out again. Within seconds, the nut was off the shaft and I was able to remove the cogs and sprockets.

On sunday, I laid every useable part out on the workbench. With the workshop manual turned to the correct tables, I settle down to accurately measure the wear on the parts using my uncle’s trusty callipers. I found that each piece was just past the worn specification stated in the book, which isn’t good enough for a long journey like mine.

With all the fairings in one corner, engine bits in another and no new parts were expected to arrive for a few weeks, I have to go on with other things. Len shows me how to remove my valves using a home made 'G' clamp which was built for my last DR engine re-build. We squeeze the valve springs down to release the collars from their locked position, allow me to remove the valve steam. With my workshop manual open to right page, I measure everything using callipers. All the measurements were coming up well within the specification. 


Len spots tiny pitting around the valve head, which becomes more evident once we put it into the lathe and give it a good clean. After a quick trip to the auto shop, I now have cutting compound, which we lightly put on the valve head and reinstall into the shaft. Using a cordless drill, we turn the head backward and forwards letting the cutting compound grind a new flat surface. After a close inspection and a wipe down with a clean cloth. The valve head and seat come up like new. Now its time to re-install.

Setting the 'G' clamp into the vice, we balance the head in the clamp and wind down the top. Making sure the shaft slides through the two springs. Once we see the groove that the collars are mean to sit into we stop winding. With a collar in one hand and a small screwdriver in the other, I proceed to push it down into the tiny gap. Hoping it does not fall down too far or the process has to be repeated once again. This happen about four or five times before we finally got it to work and quickly wound the spring back out into the locked position. We repeated this for all four valves.


Moving down, I check the piston head and rings. The head has the usual carbon stuck to the top of the head but this time, it is malleable, therefore quite easy to clean off. Again using the callipers, I measure the piton head diameter, the piston ring grooves and compare the clearances permissible. I discovered that the top piston ring had lost its spring and had a larger gap then what is tolerable. Taking the bore, into the sunlight to inspect the possible wear, or not wear in this case. It even had the original cross-hatching of the factory honing. This meant I only had to give it a quick light swipe with a hone to ensure it was round and had no major pits. Setting up the hone in the power drill, we swipe the bottom of the cylinder just to check we are on the right path. Seeing that we were not taking too much off, we carry on completing the tidy up of the entire bore. I then clean out the bore using several paper towels until the towel showed no dirt.

Time is running out, I only have Len helping me for the next three weeks. I can only work on my motorcycle during the weekend so that leaves me only three weekends! I needed to write a list of all the items I required to do on my motorcycle and highlight exactly which tasks I really need his help. I head back to the city with my list of parts to buy, hoping I could get them for the following weekend. I ring my favourite motorcycle shop ‘Tyres for Bikes’. Calling then I discover that I now had to wait two to three weeks for some for some of the stuff to be sent from Japan! I swear they are strapping the individual parts on snails and sending them on their merry way overland to Australia. Little adventurous wee suckers – didn’t they know that the Vietnamese love snails!