Worked up 670 tuning

[corblund]

A 670 with a crank issue, wierd. My instincts have been telling me it's got to be an ignition fault somewhere. When I get back to town I'm gona try new cdi and coils just for kicks.

 

[corblund]

Check to make sure the crank isn't out of phase

What do you mean by out of phase? would someone be into explaining this to me please.
Thanks

 

[corblund]

nevermind, I got it figured.
Thanks for all the help everyone.

 

[vendetta]

you really dont need to run av gas. its to high of octane for a pretty much stock motor. it wont burn hot enough cause of the octane.

Rob

p.s. what was the problem?

 

[corblund]

you really dont need to run av gas. its to high of octane for a pretty much stock motor. it wont burn hot enough cause of the octane.

Rob

p.s. what was the problem?

What I meant by nevermind, got it was I figured out how to phase my crank. still havent figured out the problem. I'm about done messing with it out here at work so I'm gona wait till I get home to my shop and pull the motor and give it a tear down and start from scratch, which I probly should have done in the first place, seeings how it was a blind purchase of a "mod". I'm gona go with the jetting that was mentioned earlier but compensate for my lower elev. replace my cdi and coils, keep trying it with premium pump gas and see how it goes.

 

[HANDSOME]

Check exhaust valves and bellows n springs"

 

[nuttyn01]

Pull the filters off an do anything with them other than putting them back on. Never had luck with them on much of anything let alone a R/V engine. Too much to explain, but pull them off and run open carbs and see if it wicks up like it should.

 

[Reeb]

True story on the filters. We bolted a 670x onto our track dyno back in the day and tried every combination we had. Stock, pipe, can, pipes, pods, etc etc. Ran best with the stock airbox no matter that we bolted on. It was a stock bore tho. Even when I bought a Union Bay 670 years later it too ran much better with the stock airbox.

Best bang for your buck on those sleds was to run a Cat roller secondary. Immediate improvement. But that's later.

A crank being out of phase isn't anything new but before I would go down that road I'd check our RV disc first. Even if it's off by a tooth it can cause you havoc.