Honda Twins banner

1 - 20 of 38 Posts

·
Registered
Joined
·
60 Posts
Discussion Starter #1
Hello,
Since my compression seems to be low (80 psi both sides), I thought I would adjust the valves according to the Clymer manual. So I pulled the valve cover off but can't figure out how the manual is telling me to adjust the valves. The picture is terrible. I can't seem to find the adjuster bolt/screw they are referring to.
Can someone point out where the adjuster is? Where do I place the feeler gauge?


I went ahead and pulled the head off to see what I could see. Everything looks good on the inside. Just a little bit of carbon build up. Piston walls are smooth. no scoring.
 

·
Premium Member
Joined
·
10,203 Posts
First you will need a PROPER factory service manual. PM sent.

You will be needing a new head gasket to put it back together, just as well replace the cover gasket as well.
 

·
Registered
Joined
·
60 Posts
Discussion Starter #4
How do I do a leak test with the head off? I have done a leak down test on a car but the head has to be on.
 

·
Registered
Joined
·
2,981 Posts
He means to invert the head and pour liquid in the combustion chamber to see if it runs out of the ports.
 

·
Registered
Joined
·
1,469 Posts
Fill the chambers with alcohol , wood not grain, and let it sit for a few minuets and see if it leaks out. this will tell you if the valves are sealing or not. 80 psi compression is a little low.

Bill
 

·
Registered
Joined
·
493 Posts
^^^^ha ha ha^^^^I was gonna ask if Jack was better than Jim. Or maybe Crown.

Be purdy expensive.....!!!!
 

·
Registered
Joined
·
60 Posts
Discussion Starter #9
Ok got it. I did figure out how to adjust the valves by the way. I couldn’t figure it out because I had already removed the rocker arms. Duh
 

·
Registered
Joined
·
60 Posts
Discussion Starter #10
Just for fun why not do a leak test on the valves since you have the cylinder head off?
I am happy to report absolutely no leaking from the intake or exhaust valves.
 
  • Like
Reactions: Bill H

·
Registered
Joined
·
60 Posts
Discussion Starter #12
Update:
Finally got the bike all back together. I don't have a lot of free time.
I completely disassembled and cleaned the carbs while everything else was apart. They were surprisingly clean but there is leaking around the air cutoff valves so I think I need to resolve that. Also did my best to sync them.
I can start the bike but it won't idle. It is also popping out of the exhaust so I must have a air leak somewhere.
With the engine sort of warm, I am getting 115 psi on both cylinders now so that's a little better.
Would leaking air valves prevent it from idling though?
 

·
Premium Member
Joined
·
24,208 Posts
Yes, leaking air cut valves will cause idle issues as well as lean run conditions.
115 psi compression is way too low, 185 +/- 14 is spec and @135 is about as low as you can go and expect it to run sort of ok.
Are you checking compression with both plugs removed, throttle wide open, choke off and cranked until the gauge stops rising? Usually 10 revolutions will top off the gauge.
 

·
Registered
Joined
·
60 Posts
Discussion Starter #14
Yes for all of the above except I didn’t know about WOT. And I wonder how accurate my tester is. Mine has a rubber stopper I hold in the hole. The screw in adapters I have are designed for a car.
 

·
Registered
Joined
·
2,981 Posts
You might figure out a way to prop the vacuum slides up when you check it to make sure it gets enough air through the carbs to get a reading.
 

·
Registered
Joined
·
60 Posts
Discussion Starter #17
How about removing the carbs? I need to pull them off anyway.
 

·
Sensei
Joined
·
27,160 Posts
No carbs are fine for the compression test......
 

·
Registered
Joined
·
60 Posts
Discussion Starter #19
Just another update before I pull the carbs off (I seriously do not have a lot of free time).
Someone wanted to hear it run so I attempted to start it with some starter fluid.
It would not fire at all. I checked the spark and could not see any with the spark plug out, held against the metal. So then I put a spark plug tester on it and could barely see a light. I'm not getting much spark but I replaced the coil recently. So what part do I check next?
 

·
Premium Member
Joined
·
24,208 Posts
The spark on this model is faint when you see it, bright sunlight makes it impossible to see. Also in order to get spark on one plug the other side has to be installed and connected.
Since you've replaced the coil already I'd check the resistances of it unless you did the GM coil mod. There's a couple of suppliers selling too high of resistance coils for this model. Less the 1 ohm primary resistance is critical, latest spec is .55 ohm
 
1 - 20 of 38 Posts
Top