Low compression, hard to start: Related?

Well this is my first posting. I've been browsing TT ever since I got my bike one year ago. I think this is a great site and have learned tons. Thanks to all of you! On to the problem...

The bike is a well worn (cosmetically) 92 XR600R. I believe it is stock except for a SuperTrapp exhaust and Uni air filter. When I got the bike it was spitting oil out of the exhaust - literally. I put in a new (.25mm over Honda) piston and had the cylinder rebored to match. That took care of the oil spitting problem. While I had the top end off, I lapped the valve seats because the were somewhat pitted.

After that I'm having a lot of trouble getting the bike started. When I do get it started, it runs really bad a low rpms (I have to continually rev it to keep it started). When I take it out for a test ride it runs rough and "surges" under constant throttle. I took the bike to a local Honda shop and they cleaned the carb and verified the jetting but that didn't do a thing (at least they didn't charge me for the "work").

Here's what I've done to try and figure this out:

- Changed out the gas (worth a try)

- Spark has tested good

- Timing has been triple verified

- Valve adjustment also triple verified

- Air filter is clean

- Plug is new and properly gapped

Any suggestions would be greatly appreciated. I see how passionate you all are about this bike but I have just had some really bad luck with it...Make me a believer!!!

Sorry...I forgot to say that the only thing the Honda shop could tell me was that the compression was low (about 100 psi). Could this be at the root of my problem?

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