need help with rotary valve 94 657x

[alx401]

installed rotary valve using 149 and 65 degree. Problem is the plate will not line up on both. its at least 10 degree diffrence. Should i split the diffrence and both marks be off a little or one side dead on?

 

[racerxxx]

Did you try flipping the plate over? It's asymmetrical, it's just a few degrees different when you flip it. You want to try and be close to both marks if you can.

 

[68ragtop]

Also, did you confirm you have the right valve duration? There are a couple different ones depending on year & carbs. some have a longer duration than others. At least on the 580's I know there are a few different ones used. Never personally worked on a 650

 

[alx401]

according to the specs manual the 657x 5854 motor is 149 n 65. Thing is there's a factory timing mark at 130 degrees. When i set plate on that, both sides lines up perfect on the 130 and 65 degree mark. is there a way to confirm specs with the serial number on the engine to tell if its a 5854 or 5855? The code on back of ski is 5854 but theres always a chance the engine was changed before i bought. thanks

 

[68ragtop]

The valve size/duration is determined by the ski model, not so much the engine. Unless the exhaust & carbs, etc have been changed, I would go with the specs from the manual for your ski. Are you following the manuals procedure exactly? It can be confusing. Mag side piston at TDC, then for opening mark, align the wheel with the bottom of the mag inlet port, measure degrees counter clockwise from that edge & make a mark, then to get the closing mark, align the wheel with the top of the mag port & measure in degrees clockwise & make a mark. the wheel should drop on as close to those to marks as you can get it. Like racer said, flipping over the valve will usually move it a couple degrees +/- sometimes they can be dead on, sometimes off a bit. Closer the better, but doesn't have to be dead on.

First time I did one I was scratching my head a bit...... If you set your valve on the degree wheel with one edge on zero, its easy to see what valve you have.

 

[alx401]

its a 147 degree plate. which makes the timing 130/65, which is the timing for a 5855 motor. Mine is clearly marked 5854 on back of ski and 657x on motor. Totally confused about what i got but am sure i got this solved with help from all who posted on this thread. thanks