Could someone please explain how to adjust the valves on the Ds?

 

A shop manual, about $70, would help you quite a bit for this job, but I will try to help.

First remove the fuel tank to gain access to the valve cover. Remove the valve cover, and one spark plug. Set the engine up at top dead center by either putting the quad in gear and slowly moving the rear wheels, or by removing the slotted screw plug on the side of the case (I can't remember if it is on the clutch side or the other side, but it is inline with the center of the crankshaft) and insert an allen wrench into the socket head bolt to turn the crank to TDC. Top dead center will be when the lines on the cam sprockets are facing each other horizontally and none of the cam lobes are contacting the valve cups.

At this point you simply slide a feeler gauge between each cam lobe and the respective valve cups to measure the gap. The factory setting specs out a clearance of .004" to .006". There are other schools of thought out there as to what the "best" setting is. Some say .006 on intake, and as much as .009 on exhaust. The theory is sound in that the exhaust valves run hotter, therefore they require more clearance. Personally, I run .004 - .005 on intake and .006 -.007 on exhaust.

If the measurements are within your desired range, you are done and can re-assemble. If not, it gets a little more involved. If for instance you get a measurement of .002 on a valve you need to record which valve needs whatever change, in this case it needs .002 to .003 more gap. Then you would remove the cam cover, remove the chain tensioner, and remove the cams - don't let the cam chain fall, tie it off with a piece of wire to the frame. Remove the valve cup and the existing shim or shims. Measure the existing shims in order to determine what shim sizes that you will need to achieve the desired clearance. Sometimes you can simply remove a shim to get where you need to be, other times you must do the math to determine the correct combination.

At this point you will need to purchase the proper size shim(s). They are cheaper at BMW M/C dealers than they are from Bombardier. Replace all of the parts in reverse order and re-check the clearance. If it is now correct, you are finally done.

A word of warning do not attempt to remove the cam sprockets from the cams, it is not neccessary. Also, during the process do not allow the motor(crankshaft) to move from TDC. Bombardier, and possibly BMW, sell a crankshaft TDC locking bolt for this purpose, a good investment. Just don't forget to remove it when your done.

Good Luck,
Ken

 

Very well stated Ken.

By the way, the bolt is on the clutch side, just to the left of a small oil line.

One little thing you left out though, it's always best to check the clearance with the motor as warm as you can work on it. Once I get the fuel tank off, I run the motor untill the carb runs out of fuel.

 

What's the recomended interval for checking the valves?

 

Knutz,
That is the logical approach. The shop manual actually states that the clearance is a cold measurement. I'm certainly no engineer but I would speculate that temperature expansion is already factored in. If however you have increased the compression and effectively increased the cylinder head temp, then that must be compensated for.

Thanks for the kind words,
Ken

 

Quicksand,
I believe the initial interval is 10 hours, then after that it is every 100 hours. It is listed in the owners manual, and it's probably more acurate than my memory.

I must say though, if you ever experience hard starting when cold, it is a good time to check the valves. This isn't the only cause of a cold-hard start symptom, but it is overlooked by many. When the valves get tight the compression at cranking becomes too low to fire off without the help of starting fluid, or a jumper battery to increase the starter rpm at startup.

I'm not recommending this, but I removed the compression release on my DS and it starts much better in all weather, so far. If you do this, don't use the throttle when starting. First it's not neccessary anymore, and secondly, opening the throttle increases the cranking compression to the point that the starter really drags.

Ken

 

Thanks for pointing that out Ken. Since I don't use factory specs, and I've done so many of them, I've never looked that up in the manual. Thats an intresting trick you did with the compresion relief, I'de not thought of that befor. I'm a little conserned obout trying that with 12:1 compresion though. I understand that the cylinder preasure would stay lower as long as the throttle stays closed, but that 760 piston is huge.

 

Knutz,
Your probably right. 12:1 might be over the top for what the starter/battery can handle.

I, like many others are watching impatiently to see how your 760 kit program works out. When you get it down, please let us know about the dyno results and pricing info. To me it sounds much more interesting that the Ron Woods, EFI, or Turbo approach.

There is never a replacement for displacement!

 

thanks for all the info guys i really appreciate it. I ordered a shop manual but i need them adjusted today and cant wait quad is all ready apart.

 

I bought an inch-lbs torque wrench to accurately set the torque on the cam bridge (I think the spec is 10 NM). If you over torque the cam bridge you can burn up the cams.

When you remove the cam chain tensioner (it is inside the large bolt on the side of the cylinder head), be sure to insert it the correct orientation or the cam chain will not be tight and will make clicking sounds that make you think your valves are hitting the pistons.