Message for kaybearjr

Hi kaybear....

I have a 79 honda cb750 L (same as a K but 10yr anniversary), and I
acquired this from my neighbor in late summer... he had the carbs off, the
exhaust, tank seat...there were some problems with it which i have fixed....
ie front calipers and master cylinder, speedo cable, no spark to coils, but
here is my problem....
The bike is hard to start... and when it does, it seem like it is
misfiring. I have spark to all cylinders, the carbs i put on I bought from
someone that said he took them off a running bike (same carbs as the ones i
have with bike). I have checked the timing. I did this without a light....
I made sure the high point of the cam was even with the electronic breaker
on and looked at the timing mark. I did this with both breakers and timing
was right on mark. I have been told to rebuild the carbs and put them back
on, but I believe it to be more of a sticky or stuck valve. One other thing
is the oil light stays on all the time.... I have checked that oil is
getting to the top of the engine, and it is.....what could that be?? a
clogged screen or filter?? I put a new oil filter on when I did the oil,
but I didn't replace the other filter or screen under the motor ( I think
thats where its located).
So, I guess my question is, how can I check to see if I have a stuck
valve without having to tear the enigne apart very much?? Can I take the
exhaust pipes off and check thru the exhaust ports to make sure they are
operational? Each cylinder gets hot when it runs rough.... the number one
cylinder is the hottest. Can I run a compression check without having the
bike running?
Or... should I rebuild the carbs first and then check the engine? Its
expensive to rebuild the carbs, and I have to assume the carbs are ok since
the guy told me they came off a running bike....

any advise you can give me would be much appreciated.... thanks in advance..

Fwed

 

thanks kaybear......

I am thinking (in simple terms here) maybe i have the firing order
incorrect.... is it 1-4-2-3, or 1-4-3-2???

thanks..

Fwed

 

this firing order would be for a 1979 honda cb 750 L

Fwed

 

Ok... so I do have it right... I have left coil left side going to
cylinder 1..... left coil right side giong to cylinder 4....right side coil,
left side going to cylinder 2, and right side coil, right side going to
cylinder 3.

It still sounds like its a timing problem.... the timing marks line up
fine...although I realy don't think the camshaft is misaligned, it might be,
but not likely.....maybe there is a leak or something... i think its time to
do a compression check....

Fwed

 

Kaybearjr....

This is a dual overhead cam engine, and it can be worked on without
having to take the motor out of the frame. A friend of mine has a
compression tester he is letting me borrow.... i will have it in a few hours
and post results a little later....I will also check to see if there is a
centrifugal advance unit too....

As for the oil pressure light staying on... the bulb itself looks like it is
burnt out (its dark on the inside) and it also looks like the filament is
funky... I had to charge up the battery first, but am gonna start by
replacing the bulb to make sure its not just a bulb that likes to stay on...

Fwed

 

The oil pressure switch was replaced (with a used one) and am getting the
same problem.... so I really don't think its the switch as it wasn't a
problem in the other bike..

I am about to do the compression test as I just got the gauge.... Ill
let you know in a half hour what the results are...

Fwed

 

Ok... the results are in.... lol

cylinder 1 = 130, cylinder 2 = 75, cylinder 3 = 120, cylinder 4 =
120...

looks like cylinder 2 is the reason things are running a bit rough.... am I
wrong in thinking its time for a top end job?

Fwed

 

Valves or rings... Prolly valves (I'd guess)