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Sick Hawk, timing?

Old 10-07-2007, 10:54 AM
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Sick Hawk, timing?

Aloha Thumpers-

I have a '99 superhawk that had catastrophic failure after the front CCT broke. The front exhaust valves hit the piston and bent the hell out of them. I pulled it all apart and replaced the valves and installed APE manual CCT's. When I set the timing, the RI/RE cams lined up perfectly when I aligned the index lines on the case and flywheel. When I set the front, it seems like the closest I could get it was when I had the FI/FE lined up to the head but the case index was lined up with the "T" (flywheel has index line " -- , F, T. That sort of seemed to make sense that it was a little past rotation as the cam chain may have stretched a little. When I lined up the two index "lines" it was not as close as it was with the "T". Does this make sense to anyone? When I put it back together it started and I can ride it. But I can hear the valves tapping, I checked the clearance and I was about .050 too high at one cam (manual has a .030 tolerance) I did not shim, no shims, thought I would ride it and see how it felt. Main problem is that between 2000 and 3500 RPM there is a bad stumble/studder/popping/jerk. This only happens when I am at cruising speed with steady throttle or little acceleration. Bike has plenty of power and it doesn't have a problem during idle or rapid acceleration. I want to think it has to do with valve clearance or timing, but it had a bit of this before the melt down, but not as bad. Could this be carborator syncronization problem or maybe some electrical thing? If anyone has any REAL experience with this or knowledge, PLEASE HELP. Not quite sure where to start except back to the valve lifter shims and timing.

Thanks everyone.
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Old 10-07-2007, 11:50 AM
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I'm not sure I understand the situation you have with the cam timing: you might have some stretch, but that should only be a few degrees at the timing marks on the sprockets. You may need to re-align those. It soundslike you must have a shop manual, andif you are following the instructions for verifying the cam timing, it should be OK. I think its best when you are setting in the cams to be sure to pull the chain taught (from the crank) on the side opposite the CCT (toward front of bike in both cylinders, to be sure you have taken up slack that side, the CCT will take care of the opposite side slack. Be sure you level withthe timing hole so you aren't miss reading the mark - the mark itself if separate from the letters RT or FT, but there is a separate small line near them that you line up with the mark at the nine-o-clock position. I would recheck all of that. Remember too that when you are setting the chain/sprockets, the CCTs should be released, but ANYTIME you are then rotating the crank, they need to be tight, or you will skip a tooth or more. Finally since you now have manual CCTs be sure the tension is set to the right chain slack between thesprockets as per APE instructions.
Regardless, for the symptom at 2000-3500, like 1/8th throttle, that doesn't sound like the cam timing, more like carburation. Does it idle smoothly, or is that also off? If its out of synch, it would affect idle and steady very small throttle openings the most, so checking it is easy enough to do. what is the airbox and carb set up - all stock? unsure? did the bike sit for a long time? Its easy to gum up the pilot jets and cleaning would be wise - if its stock otherwise, making sure its at stock setup at the same time. What do the plugs look like?
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Old 10-08-2007, 09:56 AM
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Originally Posted by superchicken View Post

But I can hear the valves tapping, I checked the clearance and I was about .050 too high at one cam (manual has a .030 tolerance) I did not shim, no shims, thought I would ride it and see how it felt.
I hope this is just a typo as the factory spec has a .003" tolerance not .030"
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