80 KZ650 LTD sat for 16 years

Long story short the bike sat since 2003 and i went through the carbs and saftey stuff when i got it, new plugs. I jetted it up because the previous owner put pods on (that blocked the ports on the carbs!) And straight piped. After some reading i decided to jet up, i believe i pit 115 main and 17.5 pilot in, but after riding during the summer i think its overly rich. But it did run good. The first startup after 16 years it ran on about two cylinders until i revved it up and cleared it out. The bike always ran good after it warmed up, but most the time upon first startup it would miss on one cylinder and burn oil, (it was either 1 or 4). This fall the bike started ticking on the exhaust side up by the cams louder than normal, and the starter clutch ( i believe) is going out and making some noise. Couple weeks ago i pulled the valve cover,plugs and checked lash. The exhaust lash was .25 mm for the two middle cylinders and .17 for 1 and 4. I found all but the 4 outside headbolts were loose, like less than 10 ft lbs. So i torqued the heads and have to recheck lash but i was wondering what else i should look into while im digging in? The bike has 9000 original miles and compression is decent across the board lowest reading was around 60/100 ( 40 degrees in shop). Hoping the head bolts were the cause of the base gasket leak it had also. Long post but just trying to see if i should stick with this bike and what il be looking to spend (i do all my own work)

Dan

Hi Dan. Here's my 2c:
Unless your head is warped you shouldn't see any difference in valve clearance (assuming that is what you mean by lash) after tightening up the head nuts. The loose nuts could explain the leaking base gasket and also the burning oil (although if the outside 4 nuts were tight the oil galleys shouldn't leak into your cylinders). From what you wrote I assume you don't have a clogged pilot jet as it would only miss a cylinder when cold and not necessarily always at low revs.
Now for some guesswork It could be down to the head nuts if they were so loose that there wasn't enough compression until everything expanded and tightened up. I would recheck compression after tightening everything up and see if the low reading corresponds to the cylinder that isn't firing when cold. Could be your problem disappears, could be that you need to look somewhere else (vacuum leak, plugs, rings, ...??).
The starter clutch isn't a huge deal, especially if you can get the oil pan off without removing the exhaust. If not it could be an adventure though - depending on the state of the exhaust. The exhaust studs on my 750 just sheared off when I tried to remove the headers, didn't even need any force. Basically you just need to get the oil pan and clutch off, then whack out the secondary shaft and sort out the starter clutch - FSM explains it a bit better
Whether or not it's all worth it is for you to decide I would try and sort out the misfiring when cold first. If it's just a vacuum leak or the loose head then the whole thing won't cost you much more than time.

A bike that sit more than a decade needs more attraction like rejeted for pots and straight pipes, you have to dig more deeper into cleaning, diagnostic, adjustment and rebuild the engine.

Normally I'd agree with scirocco. If the bike hadn't been started for 16 years I'd tear it down before trying to start it up. If, for example, one of the pistons had seized then you could do some serious damage trying to start it. As you've been riding it I figure it's a question of what you want to risk. You could tear it down completely, but I'd probably just take a good look at the top end and carbs.

I had a similar bike-- a 1978 KZ650SR. Similar story: it sat for maybe 12 years. I got it fired up (cleaned carbs, minor stuff), and it rode great for a little bit, then it started making alarming top end noises.

The timing chain was out of adjustment-- which is common for bikes resurrected from the dead.

Since then, it has become my experience that the most common source of top end noise is a timing chain in need of adjustment. It is not the end of the world (easy to do), but it could be catastrophic if you don't deal with it in time.

So, I highly recommend you take a look at your timing chain, try adjusting the tension. Maybe that will take care of your problem.