Getting the closing shims out

I have measured all the gaps and I will need to replace all four closing shims on my '94 900SS.

Before I drop the valves into the cylinder or make another mess I thought I would ask you guys for some advice on the practical issues of removing the shims.

Do I need to rotate the engine to TDC on each cylinder when removing the shims? What is your prefered way of preventing the valves dropping into the cylinder? etc. etc.

BTW, I made a simple bikestand to carry the SS while removing the rear shock, maybe it could be of use to someone: http://sphotos-h.ak.fbcdn.net/hphotos-ak-frc1/882887_10200330775786233_1964736806_o.jpg The bolts are long 10 mm bolts that just slide into the holes in the engine. It is pretty easy to use if you lower the bike down on the stand using a rear wheel lifter.

tnx

JimR

 

Yes that's a pretty good tutorial, I was hoping to supplement it with some practical experiences from the DIY people :smile:

Jim

 

Thanks, someone else said the same and I don't fully get it as there are two cylinders and you can't get both on TDC at the same time. I am changing the belts so I am able to use that method.

And how to put the belts on correctly afterwards, is it just to align the dots on the cam wheels and the crank?

br

Jim

 

It seems that you HAVE to remove the belts as you can't get the open rocker to the side (after pulling out the clip) without turning the cam.

I just finished changing half rings on all closing shims and after inventing a number of new curse words I learned the art of holding the closing arm down while fitting those two small suckers. It was pretty difficult on the exhaust side on the horisontal cylinder but I got it in there at last.

I didn't have any clamps for securing the valves so I did each cylinder at TDC which prevents the valves from moving down the cylinder. I removed the belt on the cam wheel while messing with the shims, then remounted the belt to turn the engine to work on the other cylinder.

Next steps is to measure all gaps again, then order new shims and do the whole thing again.

Jim

 

Do you know how small increments in closing shim sizes you can get?

3 out of 4 closing shims could be rounded of to 5/100 but the last one needs to be 6.63 and rounded up to 6.65 I only get 0.02 mm gap left which could be risky. Haynes says 0.03-0.05 and I have aimed for 0.04.

br

Jim

 

Thanks everyone, I found use for just about every advice from you guys and after 3 trips to the dealer for parts I am finally done

I'll leave some of my experiences for future reference:

- FIRST: Plug all the oil return holes in the heads (earplugs work fine) or you WILL drop a half-ring into the engine, also cover the carb. air intake and maybe even the spark plug holes (while allowing them to breathe air)
- Get a couple of extra half-rings, they vanish when the screwdriver slips and the closing arm shoot them far away!
- Remove the spark plugs and the clutch cover, it's easier to turn the engine using the clutch
- You must remove the belts to be able to freely turn the cams in order to be able to remove shims and push closing arms down
- Don't worry, later you just align all the red dots and remount the belts Just be careful not to turn the engine without securing the valves!
- Use some kind of valve restrains to stop the valves dropping down (I used the cable tie method)
- Make an extra mark on the crankshaft pulley for vertical cylinder TDC (red dot facing straight forward when vertical cylinder is at TDC)
- Turn the engine to TDC of the cylinder you are working on just to be sure that the valve don't drop
- Start by changing the half-rings, then measure the gaps, then measure the shims and order new ones or modify the old ones if possible.
- Get, find or make a shim measuring tool. I measured the old ones with a part that did not fit into the new shims and that made a mess of everything and gave one more trip to the dealer.
- When mounting the new closing shims you can turn the cam and check that it runs free at TDC, while allowing you to turn the shim while holding the closing arm down. You can't really measure gaps in the 0.01-0.04 range very accurately but the practical method works fine.
- IF you feel resistance turning the cam you can wet-sand the shim on some 600-1200 wet paper on a glass plate or use an oilstone to carefully shave the last 1/100 of the shim. I did this on a couple of my shims and it worked fine.
- Recheck the open shim gaps after putting in new closing shims and use slightly larger gaps on the exhaust side. I also use larger gaps on the rear exhaust valve as it will get hotter than the front cylinder.

br

Jim