I posted earlier about a 73 Maverick 250 with 22,000 miles that had been sitting for years. I got the fuel issued cured but believe it has a broken intake valve. I am doing the work myself except for the head work. Anyone know the head bolt torque and sequence specs? It has a rocker arm shaft so should those bolts be torque?. Anything I should have the machine shop do when I take it? They said they would check for warpage. Any suggestions I need when I reassemble it?
is it broken or just stuck? I've had stuck valves that I just tapped with a mallet and it was good to go.
Yeah.. assume the worst but hope for the best. I'd inspect valve tip lengths and run compression test before tearing it apart.
What are the indications of a stuck valve? It has a steady miss, no backfiring or engine noise, rough acceleration,
Those symptoms match up with a sparkplug that isn't firing. Check for a spark at each plug wire and do a compression test like groberts101 suggested. Inspect each plug. MD
If you had a broken valve?.. trust me here.. you'd know something was very very wrong. You'd hear it rattling around and that cylinder would be puffing through the carb every crank revolution. To physically see a bent or stuck valve should be easy enough. If everything checks out there then look at ignition too. Ignition is much easier to check than pulling parts off is. Start there first.
A stuck intake valve would probably be blowing compression back through the carb... That's at least if open which is generally the case, if it's stuck shut then the push rod will be bent... As already stated run a compression test befor going crazy... No need to pull it apart for what may be a simple problem... Also more often than not broken valve = junk engine... Valve pieces bust piston and usually block cylinder wall...
with it running pull a plug wire from a plug. if the idle doesn't chang, put the wire back on. go to the next plug and do the same thing. when you get to the one that when you pull the wire off and nothing changes...that's the cylinder that has the problem. swap that plug with one of the ones that was firing, that will tell you if it's a bad plug.
