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Discussion Starter · #1 ·
I just finished up rebuilding my 670 after a pto bearing failure, I put in new pto bearings, new skidoo seals and went .020 over with new pistons and now it doesnt sound right at idle, it almost sounds as though I have a fouled plug which a changed twice and it stays the same but as soon as I give it throttle it bogs slightly then goes great. Once it hits 4000rpm it turns into an animal but below that.....blah doesnt have the same rumbly stout idle it had before the rebuild.
Could this problem be the rotary valve set wrong? I put the mag side at TDC and lined the edge of the valve up w/the line scribed inside of the rotary housing so at TDC the mag side rotary opening is open. The carbs are clean and adjusted and the only thing different is I ported the case to match the head....very minimal, any suggestions would be great! oh and btw the motor has the 44mm carbs with the 501 rotary and the twin pipe exhaust from the factory.

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