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Okay, what could I have possibly screwed up?!

1111 Views 3 Replies 4 Participants Last post by  Calamarichris
It goes like this--

A few weeks ago I decided to do a valve adjust and a carb-sync, seeing my dad do it the week before on his Concour I felt relatively confident. I drain the coolant, get everything apart, get the cylinder head off and realize I have no idea what I'm doing. I'm no longer in denial about not being "mechanically inclined". I put everything back together with no problems.

I go for a test ride. It seemed normal at first, however once I get up to about 4,000 rpm, or when I rev it hard, It doesn't go. It's like it struggles to do so. If I hold it at full throttle, it will eventually get up there, but it certainly doesn't want to.

I don't get it, I didn't change a thing. What could I have possibly done wrong?
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Hey Brad. You only removed the headcover right? You don't have to remove the entire head to adjust the valves. If you actually removed the head (which would mean disengaging the camchain and removing the exhaust headers) you must replace the head gasket with a new one. A re-used leaking head gasket could conceivably cause what you're describing.

Assuming you only removed the headcover, made no adjustments to the valve clearances and the bike is still idling reasonably well, you most likely just have a leaky or uninstalled vaccuum line.
Other possible causes include:

~a leaky intake (which would only be affected if you removed the carb rack or loosened the clamps on the rubber carb-mounts)

~a maladjusted float level in one or both of the carbs (which, again, could only have happened if you've removed the carbs or the float bowls.)

~a blocked fuel tank vent hose (which would prevent fuel from flowing freely from the tank to the carbs--you can tell if it's this by opening the fuel cap after a higher-rpm run: if you hear a sucking sound when the cap is opened, it is probably this.)

I would swallow your pride and ask your Pa for help on this one. The mighty EX engine is basically half a Concours engine (same bore/stroke, just two fewer cylinders, AND the same locknut-type valve adjusters) so if your Pa has already successfully done his Connie, he's qualified to help here.

Sorry to ramble, but one of the things I really love about the 500 is that you can be very precise with the valve clearances resulting in REALLY synchronized carbs and REALLY smooth running. Us poor clods with the modern Ningines ("Ninja+engines", I just made it up) are stuck adjusting our valves using shims at .05mm intervals (and we have to :( remove our cams :( to do it . It's accurate enough but not as precise as you can make your mighty EX.
I've adjusted the valves on both my wife's former EX500 and my Pa's Concours,* and they're pretty neat designs.
Good luck and let us know how it goes.
-Calamari Chris in Carlsbad, CA

*And the mechanic at the dealership who previously adjusted my Pa's valves REVERSED the clearances on half the engine! Intake valves set to exhaust-clearances and vice-versa!
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