717cc timing

[hal5778]

Hello I have a 717cc motor that I have been slowly working on and my question is how do I determine the year and model this motor was originally in? I am unsure as to whether the flywheel cover is the original so not sure if the model # listed would work. I am currently replacing the timing disc (do not have the original) and unsure as to what degree disc needed. I have used the degree gauge wheel and the mark on the engine block is at 130 degrees but I have read on this forum where this should not be assumed to be assumed in determining the proper timing disc? Any info that can be given would be appreciated I dont want to have to remove and replace a second time because of the wrong disc was installed.

 

[NickCawks]

Everything can be discovered by the serial number on the back of the ski. Beyond that we need to know the year and model the ski is.

 

[hal5778]

Hi Nick and thank you for your reply unfortunately I do not know what year or model the motor came out of I got the motor only as a winter project

 

[mikidymac]

You use the model and year of the ski to determine the rotary valve. The base engine is the same but the rotary valve is determined by your mpem, intake ( single or dual carbs) and exhaust.

 

[hal5778]

The motor is a single carb (white motor) I dont have a mpem for this motor. Would this motor run with whatever rotary valve I use (130,147 or 159) and at such time it is used as a replacement motor just check the motor replacing to assure it has the same rotary valve and if not just swap them out before installation? What I am asking is if I was to put a 130 degree rotary valve in the new motor and the motor being replaced has a 130 degree rotary valve would all be good and if the old motor had lets say a 147 degree if I was to install a 147 in the replacement motor would that work?

 

[mikidymac]

It should run with the wrong valve, it just won’t run well.

 

[hal5778]

Thank You I think what I will do is finish assembly with the 130 degree rotary valve I have and when the time comes to use the motor as a replacement motor I will check rotary valve in bad motor and if needed swap it out into replacement motor. I actually have no reason to run new motor until that time it has good compression with new stator and flywheel so I assume all is good. Once again Thanks all the info has helped alot with my concerns. Happy Holidays to ALL!!!!

 

[mattsully]

I think you are wasting time with a 130 deg R V . At least put a 147 in or the 159 as they have a much better chance of matching up to orig.