1990 project kat, couple questions

[blaaaaarg]

Ive got a friend that was looking to get a bike, and I spotted a 1990 kat listed on craigslist for $600 but not running. So I figured it needed its carbs/etc cleaned, basic stuff. Turns out the seller was the owners wife or ex or something and didn'nt know much about bikes whatsoever, so we offered 500 and got the bike.

The bike gets to my garage where I pull off the tank/etc, put some new spark plugs, change the oil/filter, I figured I would see if it started before I rebuilt the carbs.

The moment of truth? Well, the bike starts, but it sounds like an airboat. It was late at night when we were working on it so I couldn't let it run.

Any hints as to why the bike would sound so loud? I couldnt spot an obvious leak but... who knows.

[Black_peter]

Loud?
After market exhaust.
Leaking head pipe.
Missing head pipe.
Rusted out head pipe.

Airboat?? Interesting choice!

[blaaaaarg]

The exhaust system is still in place. Aside from a header leak/etc is there any reason, internally/etc that it would be so loud? This is my 3rd bike ive brought back to life (a ninja250 and a gs500 beforehand) and everything is still going well aside from being paranoid that something is wrong with this engine due to the noise.

[md86]

Feel along the pipe (especially around the exhaust ports) for air . You'll feel leaks . Probably smell them , too . If not ...... They ARE known to be kinda chatty bikes .

[blaaaaarg]

Assuming I find the leaks, is there any DIY way to repair this? or are my options (im guessing) a> buy a new exhaust b> take it to a welder

I think I was just paranoid about the gasket on the head to be bad, and letting me know by sounding insanely loud, but if that were the case I suppose there would be a small lake of oil beneath it by now, right??

and thanks again/in advance. i wouldnt be so paranoid if this was my own bike, but its not my money being used to fix it up so I dont want to waste somebody elses money.

all this help is greatly appreciated.

[newride]

JB WELD my friend.
I have used it on my old BMW and it has held like steel for at least 4 years.
Does not look that pretty, but it fixes holes in mufflers very well I think.
PS< I got my 97 Kat in Sept to bring back to life and they are loud even with the stock muffler on.

[blaaaaarg]

at this point we have concluded the bike to have a bent valve(s). It is something internal. Any how to's on redoing the top-end anywhere? it would be the top end right... never done internal work.

[arsenic]

I doubt it has bent valves, a 1990 600 is screw type valves, adjust them all to .005 in.

[blaaaaarg]

nothing official yet, theres just definately not a header leak at this point. Something is clanging inside the engine and the immediate guess from 3 or 4 people is valve problems. i'll update once i figure out what the hell im doing.

[woobie]

Download a service manual and pop open the engine, shouldn't take more than an hour or so and you'll know for sure once you open it up.