The Diagnosis

Tonight I decided to see what was keeping the YFM225 from shifting correctly. If you will remember the former owner claimed the YFM stopped shifting after trying to pull start it. With the engine on the bench I pulled the crankcase cover and inspected the shifting shaft and shift cam. This all looked good so I decided to open the sub-transmission cover. As I cracked the cover I noticed the remains of a bearing sitting in the lowspot of the sub-transmission where the shift cam comes through. I pulled the middle set of gears out and found the bad bearing. Luckily the outside race was still whole and the structure around the race, although beat up, was not damaged to a point that if could not be used. The inside race was almost completely destroyed but surprisingly the shaft had no damage. I was able to slide the damaged race off the shaft and with a little work, pull the outside race out of the case. I was very lucky that there was not more damage done to the sub-transmission with a gear jumping around inside. I split the case and inspected the primary gears, shift cam, and shift forks, which all looked good. With the debris not impeding the movement of the primary shift cam, the gear movement worked well and slipped into all five gears. I put the two halves of the case back together and called it a night.
I will not only order the bearing that came apart but will replace corresponding bearing on the other end of the shaft.

The tear down

I got home tonight and decided to start tearing down the quad to make it easier to work on. I started with the racks and the front guard. I noticed it had been damaged fairly bad in a collision and could probably not be repaired easily. I was able to find a good used replacement on ebay for $35 with shipping and so I purchased it as a replacement. After all the racks were off I uninstalled the rear fenders. This gave me good access to the left hand side of the engine where the clutch and shifting mechanism is located. I drained the oil and pulled the left cover. I removed the clutches and started inspecting the shift rod and cam. I did not see any physical damage but while manipulating the gear I noticed I could shift out on neutral into first and second gear. I could shift back into first gear but not back to neutral with out a lot of messing around, and could never get the quad into third gear at all. This has lead me to believe that either the shift forks are damaged or the shift cam grooves are damaged. Not the best news considering it means I will have to split the case to get at the damaged equipment.I pulled the front fenders, which meant pulling the handlebars and unhooked all the cables and tubes from the engine and carburetor. I removed all the mounting bolts and with a little muscle I was able to pull the motor and get it onto the bench.

I am again impressed with how well this quad is put together. Everything is heavy duty and well thought out. Although the frame is dirty the powder coat has protected the metal very well.

The pick-up

Well here is how it all happened:

Last Saturday I was looking through the classifieds and spotted the quad, a 1986 YFM225 Moto4. I have a weak spot for these old quads, not only because they are bullet proof, but because you can get them for rather cheap. I called up the owner and made arrangements to stop by on Sunday before the Vikings playoff game to take a look.
Like many wives with husbands that have to have a greasy project, my wife does not share my love of old quads and bikes and so whenever I start itching to start one of these projects she starts figuring out a way to deter my ambitions. I had schemed in my little brain on how we could take the truck to my sister in laws to watch the playoff game without making it obvious that I had already slipped the 300 bucks into my pants pocket and planned to bring my project home. Like most wives, my wife is also much smarter and craftier than me, and as I tried to announce we would be taking the truck, she had already loaded up the Sequoia with the veggy pizza and bruschetta we would consume later that day.
After stuffing myself with enough chicken wings and buffalo burgers to keep Tyson in business for another month. I grabbed my brothers in law and out the door we went.

The quad was parked by the side of the owner's house and after some small talk I found out that Clark was the original owner! The fenders have a little sunburn on them from sitting outside the last couple years, but all in all the quad is in great shape. I looked under and inspected the swing arm boot to avoid the nightmare and expense of rebuilding the rear-end like in last years project. Clark explained that the last time he had been out riding it was a little cold and it was not starting. He tried pull starting it and when he popped it into gear it stayed in gear and would not come out..... hum. After thinking of the many things that could have bent and broken, I figured it was a project and had fixed worse. I gave Clark my money and told him I would be back on Monday evening to pick it up.

Monday came quick and I stopped by, got my bill of sale signed, and title in hand. I had Vern (brother in law) help me lift the old quad into the truck. After tying it in and dropping Vern off I headed home.

A little history of the YFM225 Moto4

Yamaha first introduced the YFM225s Moto4 in 1986. This was an upgrade model from the YFM200DXS. The 225 not only had more power but also a dual range transmission, dual headlights, speedometer, trip meter, and was a larger machine all the way around.
The cylinder and head used the same basic overhead cam configuration that Yamaha introduced into the 200cc four stroke motorcycles starting in 1980. Below is listed the model numbers and corresponding years.

1986 YFM225S
1987 YFM225T
1988 YFM225U