Shift Fork Replacement in The DS650 Tranny


  Before we get started you should already have at least a shop repair manual. This manual will be needed to get the proper
torque settings and what to use loctite on when putting the motor back together. Special tools needed are an impact gun,
a clutch hub holder tool, (like the one in the manual or like the one I used), a magneto puller, TDC bolt, and good set
of snap ring pliers.
You will need other tools also but these are the ones you might not already have. If you don't already have impact sockets
that go up to 32mm. Then you better pick them up to.



  The first thing to do is remove the motor from the quad. Then remove the head and cylinder. Once you have that done you'll
need to remove the left side case to expose the clutch basket. Now remove the clutch basket. First remove the 6 bolts,
washers and springs. Lift off the pressure plate and slide out the fiber and steel disks. I kept them in the same order
for reinstallation.



  Remove the inner hub of the clutch. To do this you'll need a special tool for removing clutches. You can get one at just
about any bike shop for about 30 bucks. Or order the one bombardier recommends from your bombardier dealer.
 


Now you can lift off the inner clutch hub.
Lift off the clutch basket. Pay attention to
the two needle bearings sequence that they
are in for reassembly.



  You also need to remove the lower cam chain gear on the end of the crank and the cam chain itself. The TDC bolt should
already be in place from when you took the top end apart. If not then thread it in now so that it goes into the slot
in the side of the crank. This holds the piston at "Top Dead Center" and keeps the crank from turning. And that is what we
need here. The picture below shows the TDC bolt in place. It's just below the lower cam chain gear on the outside of the
clutch housing area. You can click on the picture below for an inlarged view



  Next there are three plastic gears. The two smaller black ones do not need to be removed. To remove the larger orange
one use your snap ring pliers. Keep the gear and the snap ring together and place them in your bag, tub or box of
clutch side parts.



  Unfortunately with the DS motor you also have to remove the magneto. The reason is that there are two bolts that hold the
cases together that are under the starter gear that is in the magneto side of the motor. You cannot get that gear off without
removing the magneto itself. So flip the motor over and pull the right side case cover off. Below is a pic of the gear that is
on top of the two bolts. There are also two bolts in the oil filter area that need to be removed as well.



 
There is also a washer and a sleeve that we need to pay attention to and not loose.



 
To get the magneto off you'll need
the special magneto puller tool.
The first thing we need to do is remove the
nut and lock washer that holds the magneto on.



  You don't need to remove the 10mm flange bolts that hold the magneto to the one-way bearing and the starter / crank gear.
After the nut and lock washer have been removed thread on the magneto puller.



 
Now using an impact gun only!!! No wrenching here!!! Pop off the magneto.



  Pay attention to the way the gears come off and the placement of the large washer for reinstallation.



  Before we go any further flip the motor over and remove the TDC bolt. We don't want that sucker pushing on the crank as
we remove the bolts that hold the center cases together. Once you have done that. Flip the motor back over to the magneto
side. Remove all the bolts holding the two center cases together except for two. Just loosen them so they will be easy to
remove while upside down. Now flip the motor back over again so the magneto side is down. Set the motor on blocks for
this and arrange them so the motor is steady and stable.



  Now tap on opposite side with a mallet as you lift the case. Maybe even once or so on the crank to make sure it stays on
the magneto side. This will help keep everything on the magneto side of the case as you lift to seperate the cases.



  This is what you should see. Granted this pic shows the new shift forks. But don't worry I'll walk you through that.
As you can see in the pic there are three shift forks. Two are on the right. And one is on the left. There is a shaft
running through the middle of the forks on each side.



 
The first thing to do is remove the shift fork shaft from the shift forks.



Remove the upper shift fork. Match it up with the new one and mark the new one upper right



 
Remove the lower shift fork. Match it up to
the new one and mark it lower right.
Remove the shift fork shaft
from the shift fork on the left.



  Remove the left shift fork. Match it up with the new one and mark it left.



  Now unless you have gears to replace just reverse this process to install the new shift forks.

  Once you have the new shift forks intsalled you should make sure everything shifts properly. Put the shifter back on and
make sure you can shift through all the gears without any problems. Spinning the gears as you shift.


  I was also advised to use red loctite on the magneto shaft and threads for the nut. You don't want that sucker coming off.
I also used blue loctite on the lower cam chain gear nut and the clutch inner hub nut.

If for any reason you removed the crank. Before re-assembly make sure you line up the marks on the balancer gear and the
marks on the crank so they line up with the marks on the case.See that Pic here

Here is a list of the part numbers and a description of the item.
420 250 920 Magneto cover gasket
420 230 581 Clutch cover gasket
420 250 910 Center case gasket
420 650 010 Base gasket
420 650 020 Head gasket
420 258 018 Updated Shift fork
420 258 028 Updated Shift fork
420 258 038 Updated Shift fork