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Check for head gasket leaks that are easily seen by the naked eye.

After removing the head pour the ports full of acetone and wait/look for leaks around the valves..

Those are seriously low compression numbers though... :( Was your compression check done hot or cold? Throttle wide open???


Others here will have more detailed info for you hopefully.....


GB :mrgreen:
 

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Tom... Were your compression readings taken hot with the throttle wide open?
If NOT, re-do it that way.... If so, it might be top end rebuild time....
The minimum compression spec on a 500T is 160 PSI....You have half that.... It's a wonder it's still running.... You could try filling the jugs with Marvel Mystery Oil and letting it soak awhile, but chances are about equal the PO messed up or the rings are indeed stuck beyond chemical freeing....
There are quite good explainations on group here that will guide you through a re-build should you decide to do it yourself.... Bill (tbpmusic) is an expert on the 450/500's and I'm sure he will chime in.... I'll help all i can.... Steve
 

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Tom.... yes the "auto" experience is correct about the valves/tappet clearances, BUT.... Set them to the factory specs... DON'T just adjust based on instinct.... The standard clearances are EXCESSIVELY small (.0012) and "loose" (which is where I set them) would be .002"....... Because the tappets adjust on excentrics, there are TWO spots where you can "read" the proper clearance, BUT only one is correct.... The little index "hash" (90 degrees off the screwdriver slot on the end of the excentric) MUST be correctly oriented (away from spark plug) or excessive cam/tappet wear will ensue....
 

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Discussion Starter · #6 · (Edited)
Thanks! Yes, I saw several descriptions and pics of the orientation of the 'T' shaped marks on the adjusters. A few weeks ago, I was in there with several feeler gauges (and a friend helping me to wedge them into the gap). That is an incredibly small gap, and with a wimpy thin feeler gauge I found it hard to know whether I was even close. But I'll go at it again.

One question for you: does it matter how many 360 degree turns the eccentric adjusters are in or out, or do they just "spin" without going deeper into the head? (Not to confuse matters: I know that the 'T' is supposed to point, e.g., on the left side exhaust and right side intake, to somewhere between 10 o'clock and 4 o'clock)
 

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Delaware500 said:
....the eccentric adjusters are in or out, or do they just "spin" without going deeper into the head?
tom

That's correct, they're not threaded, they just spin.

Use 0.002", at least the feeler will survive for a while.
They'll usually try to move when you lock down the nut - you'll have to figure out how much and pre-compensate by feel/instinct.
It takes some patience until you get the touch.
 

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Also, don't trust those plug colors after using Seafoam and any other oils or magic chemicals in her.. Only check your plugs like that if they're new ones..

GB :mrgreen:
 

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Discussion Starter · #9 ·
Bill (and others who have been chiming in)

I decided to start from scratch and verify the timing and set the valve clearance. I found one missing bolt on the exhaust side cam cover--other than that, nothing surprising until...

I got about a half a quart of oil on the ground after taking off the alternator cover. It is still dripping slightly now, 10 minutes after I cracked it open! Back in February, Bill responded to a similar post by writing:

"Oil will come out if you take off the alternator cover -that's normal."

But I can't remember that kind of volume the last time I had the cover off. Is this a bad sign?
 

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Delaware500 said:
Is this a bad sign?
No - not seeing any oil at all, now that's a bad sign..........

Remember, when you check the oil level, do NOT check it with the dipstick screwed in. The dipstick should just rest on top of the threads in the crankcase.
 

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Discussion Starter · #11 ·
OK thanks again. I now have the feel for the valve adjustment; I was able to use a .0015 and vary between sticky and non-sticky. Helps to close your eyes.

BTW (I'm getting ready to stick my foot in my mouth): why don't the various manuals just say, for the purpose of finding the correct valve adjustment position of the cam to crank, to line up the LT and T marks (respectively) with the appropriate cylinders WHEN THEIR CAM LOBES ARE FACING OUT. This seems clearer than going through the "compression stroke" and "intake stroke" explanation. Of course, you can't get a feeler gauge between the lobe and the valve when the lobe is pressing into it!

So, I'm still in the middle of my tuning; right-side carb is next. Timing and valve clearance are now good.

tom
 

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tbpmusic said:
Remember, when you check the oil level, do NOT check it with the dipstick screwed in. The dipstick should just rest on top of the threads in the crankcase.
Now this is something I didn't know. Is this the same for all of these Honda twins? (i.e. my '80 CB400).
 
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