Topic: Help with first compression test 78 750k

[turin39789]

I'm doing it wrong.  Or my tools broken.


I took my problem bike around the block so she could burn my fingers when I took the spark plugs out.  Got all 4 out, stuck the compression tester(bought a year ago at a yard sale with a cracked boot, the kind with the rubber connection that you hold in) in the holes until and cranked. wiggled it around until it moved a bit and #1 and #4 were both reading ~50psi.    Doesn't look like the tester will wriggle in to #2 and #3, but these results were enough to come in and ask for help.  I initially wasn't holding throttle open but remembered and it seemed to make no difference.

Am I doing something wrong?  Is the tool bad?  Could the bike really be riding(with a low top speed and probably bad seal) with those kind of readings?

Now I have to clean house until I know what to do  when I go back outside.

[martino1972]

if the tool would be correct and it is 50 psi,the bike wont be running......
you need more then 90 psi to get a reasonable running engine..
whats the story on the bike,you just bought it,or had it for years and now she act's up???
did you check the valve clearance to see if there is any clearance?
does she run on 4 cylinders??? (do all the exhaust pipes get hot?)...

all in all we need more info..

[turin39789]

I thought that was too low, gonna pick up a newer tester this week sometime.

Bought the bike as the perfect ready to go brakes already upgraded finally gonna go faster than my 550 dream machine.  PO had ridden her a lot and was moving, says he put her up for the season and was now moving.  Seemed to run fine on my  short neighborhood test drive and then 2 days into ownership developed an oil leak between(i think) #1 and #2 about 1-2 fins down from the top, tops out at about 60-65mph.  Doing a CT just as a general look, assuming I'll need to do an engine pull and replace a gasket at least.

http://forums.sohc4.net/index.php?topic=37477.msg386775#msg386775