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Discussion Starter #21
I have to agree that the next step should be checking that the valve clearances were done at TDC compression and not TDC exhaust and then making sure that the coils, caps, plugs &c are good.
That's a good point, Bob. When I line up the rotor to TL the rockers wiggle. I'm pretty sure that's where it should be? Is is possible to spin the rotor around again, loosen the valve clearance adjusters and try it again from THAT point?
 

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If by chance you set the valve clearance on the wrong stroke, then turn the crank a full revolution you wiill find that there is too much clearance, so reset and you will be OK. If you set the valve clearance on the correct stroke then turn the crankshaft one revolution you will find the valve clearances tight. Do not reset.
 

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The TL mark indicates that the piston in the left cylinder is at Top Dead Centre (the TR is for the right side). In a 4 stroke cycle engine the piston is at TDC with the valves closed at the end of the compression stroke and at TDC again at the end of the exhaust stroke but this time with the valves open. The valves need to be closed to measure the clearances so if you set the valve clearances at TDC exhaust when the rockers should be pushing the valves open the valves won't open at any time during the cycle.
 

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Discussion Starter #24
The TL mark indicates that the piston in the left cylinder is at Top Dead Centre (the TR is for the right side). In a 4 stroke cycle engine the piston is at TDC with the valves closed at the end of the compression stroke and at TDC again at the end of the compression stroke but this time with the valves open. The valves need to be closed to measure the clearances so if you set the valve clearances at TDC exhaust when the rockers should be pushing the valves open the valves won't open at any time during the cycle.
You've all been helpful and given me alot to think about. I think I need to address the valves maybe. At the moment, on TL, the rockers are loose. IF I loosen all the valve adjusters to maximum clearance and watch the push rods what should I look for at what point on the rotor to know where I am? This is the first time starting from a bare block as ground zero.
 

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Discussion Starter #25
If by chance you set the valve clearance on the wrong stroke, then turn the crank a full revolution you wiill find that there is too much clearance, so reset and you will be OK. If you set the valve clearance on the correct stroke then turn the crankshaft one revolution you will find the valve clearances tight. Do not reset.
Thanks, Reclined. I'm fairly confident I have that right because that's what I have.
 

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Yep. The easiest way to tell if you are at TL compression is to set it at TL and feel how loose they are and then turn it until it is at TL again and compare (the same for TR).
 

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Yep. The easiest way to tell if you are at TL compression is to set it at TL and feel how loose they are and then turn it until it is at TL again and compare (the same for TR).
Or just watch the valves go up and down as you rotate the crank.
 

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Discussion Starter #30
Or just watch the valves go up and down as you rotate the crank.
I'm fairly sure that's how I set it up in the first place, but worth a look. Like I said when I checked the valve timing yesterday the rockers were loose at TL. Wouldn't that indicate that the timing is correct? I'll have to go out and watch what happens as I turn the crank to make absolutely sure that the valves are closed at TL and the exhaust opening on the next turn around?
 

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Discussion Starter #31
Thanks. Fixed.

BTW: If the clearances were set on the wrong stroke the valves won't go up & down.
They do. I'm dreading taking this engine back apart.
 

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...at TDC again at the end of the exhaust stroke but this time with the valves open the exhaust valve just is closing and the inlet valve just opens.

There is no point in a four-stroke engine where both valves are open. ;)

verbrennungsmotor-viertaktmotor-otto-animation.gif
 

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Actually, the intake valves start to open just beforeTDC the exhaust valves finish closing just after. They aren't fully open but they are all open a bit at the same time so at TDC exhaust the rockers should all be pushing on their valves.
 

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There is no point in a four-stroke engine where both valves are open. ;)
Some engines, depending on camshaft design, have valve overlap where both valves are open at the same time. Theory is that the gases rushing out the exhaust port help to draw fuel air mixture in through the intake port.
 
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These engines have a fair amount of overlap.

Most high revving engines do or they can't breathe.

This for a CDI CX

Intake open - 79 degree BTDC

Intake close - 123 degrees ATDC - open 202 degrees.

Exhaust open - 114 degrees BTDC -

Exhaust closed - 85 degrees ATDC - open 199 degrees.

TI is a little different.
 

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The TI 500s have a different cam? I wasn't aware of that. How different is it?
 

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From Haynes Manual
500 EC inlet opens 5 BTDC, closes 30 ABDC, ex opens 30 BBDC, closes 5 ATDC

All other 500 models
inlet opens 6 BTDC, closes 46 ABDC, ex opens 46 BBDC, closes 6 ATDC

All 650 models
inlet opens 7 BTDC, closes 53 ABDC, ex opens 40 BBDC, closes 15 ATDC

Note; all numbers are degrees. Where is the degree symbol on my keyboard????
 
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I may have heard about the Euros having a slightly different cam profile. Never had to worry about that here.
 

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Discussion Starter #40
I doubt it will make any difference but the block I've used is a later model (P0) but EVERYTHING else is from the '78 to 80 years. Just the engine block is later.
 
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