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engine isue ...

Dana01
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Post by Dana01 » Tue Jan 25, 2011 6:25 pm

... most definitely on the go
Dana

1966/7 CB-77 Red of course
1976 CB-550F (project over-budget and under-funded)
1985 GS-450S (Land Speed Racer)

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Snakeoil
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Post by Snakeoil » Tue Jan 25, 2011 6:26 pm

Maybe there is a typo in my Honda spec book, but the CB72/77 compression is shown at 150 psi or 10.5 KG/cm2.

If platine means points, then they are set right. But when you change the gap you also change the timing.

If your book has the wrong compression spec, it might have the wrong ign timing spec, too.

Points gap - .03 to .04 inch
Ign timing - "F" 5 deg BTDC @ 1200 RPM.
Full adv - 45-48 deg BTDC starting at 3800 RPM

Good luck,
Rob

56_oval
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Post by 56_oval » Tue Jan 25, 2011 10:28 pm

Snakeoil wrote:Maybe there is a typo in my Honda spec book, but the CB72/77 compression is shown at 150 psi or 10.5 KG/cm2.

If platine means points, then they are set right. But when you change the gap you also change the timing.

If your book has the wrong compression spec, it might have the wrong ign timing spec, too.

Points gap - .03 to .04 inch
Ign timing - "F" 5 deg BTDC @ 1200 RPM.
Full adv - 45-48 deg BTDC starting at 3800 RPM

Good luck,
Rob
That's why I am thinking timing too advanced. If the points are changed by only .05 and you have a problem? Then I would think the timing is already too advanced. Once again, just a guess without actually looking at it.

LOUD MOUSE
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Post by LOUD MOUSE » Tue Jan 25, 2011 10:33 pm

0.3 to 0.4 mm
0.012 to 0.016 in. for the points. ................lm


Snakeoil wrote:Maybe there is a typo in my Honda spec book, but the CB72/77 compression is shown at 150 psi or 10.5 KG/cm2.

If platine means points, then they are set right. But when you change the gap you also change the timing.

If your book has the wrong compression spec, it might have the wrong ign timing spec, too.

Points gap - .03 to .04 inch
Ign timing - "F" 5 deg BTDC @ 1200 RPM.
Full adv - 45-48 deg BTDC starting at 3800 RPM

Good luck,
Rob

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Snakeoil
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Post by Snakeoil » Wed Jan 26, 2011 10:40 am

Snakeoil wrote:If your book has the wrong compression spec, it might have the wrong ign timing spec, too.
Points gap - .03 to .04 inch
Ign timing - "F" 5 deg BTDC @ 1200 RPM.
Full adv - 45-48 deg BTDC starting at 3800 RPM
My apologies. In my post, I totally screwed up the points gap. LM provided the correct gap which is 0.3mm -0.4mm or 0.012 inch - 0.016 inch.

Again, very sorry. I apparently cannot read nor type. I should stick to crayons.

regards,
Rob

LOUD MOUSE
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Post by LOUD MOUSE » Wed Jan 26, 2011 11:03 am

Watch out for those CLEAR colored crayons!. . :-) .............lm

Snakeoil wrote:
Snakeoil wrote:If your book has the wrong compression spec, it might have the wrong ign timing spec, too.
Points gap - .03 to .04 inch
Ign timing - "F" 5 deg BTDC @ 1200 RPM.
Full adv - 45-48 deg BTDC starting at 3800 RPM
My apologies. In my post, I totally screwed up the points gap. LM provided the correct gap which is 0.3mm -0.4mm or 0.012 inch - 0.016 inch.

Again, very sorry. I apparently cannot read nor type. I should stick to crayons.

regards,
Rob

michael-nadav
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Location: Israel , Tell-Aviv

Post by michael-nadav » Wed Jan 26, 2011 12:21 pm

Thanks for the tips , i"ll try to change the timing in the next coming days .
One more thing , how much kgm should i use for the tightness of the top of the engine screws ??
in my book its say 2.1 kgm for the c72 but nothing about the cb77 ....

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