Topic: 1975 CB750 Points and Timing Adjustment

[John G]

Following the book on setting the valve lifters doesn't work because I installed a grind 41 cam which obviously changed the cam lobes enough that I had to rotate the engine for each lifter until the lobe was pointing down to set it. That I figured out. Now if look at the two pictures I've attached you'll notice the notch is pointed on the cam and then with the no. 1 & 4 T and F don't correspond with setting the timing according to the book. Anyone know how I set the timing and points?

[John G]

Would an electronic ignition be easier to install?

[robvangulik]

You should have started with setting the crankshaft on the 1-4 T mark, before timing the camshaft.

[John G]

I put No 1 cylinder at TDC. Is that what you mean?

[bryanj]

If no1 piston is at tdc the T 1-4 mark should be in line with the static mark, as to cam timing the people who ground it should provide instructions!

[John G]

I had the no 1 cylinder at TDC and the T lined up as described in the Honda manual. Only problem was I had to rotate the cam to be able to set the tappet. There was no instructions with the cam. I received the cam with the bike when I bought it but there were no timing instructions with it.

[bryanj]

Most aftermarket cams still time up with the original marks as per diagram then you set the valve clearance, which is frequently different to standard

[John G]

Thanks bryanj. I always panic first. Hahaha I still might install an electronic ignition. Time will tell.

[newday777]

A bit of information on the 41 webcam in case you need it.


http://www.webcamshafts.com/pages_vehicles/motorcycle/honda_install_data/tc_000641_002489.html

https://www.tapatalk.com/groups/hondachopper/webcam-41-or-stock-cam-t56222.html

[madmtnmotors]

You will see no difference in the timing advancer T/F pointers whether points or electronic ignition are used. It looks to me more like your cam chain and sprocket are off by one tooth.

[John G]

Thanks Madmtnmotors. I will have a llok at the chain to see if that's my problem. A bit of a head scratcher.

[BenelliSEI]

+1. That cam needs to go one tooth counter clockwise (when crank set to TDC). Slack off all the adjusters to make it easier.

[MauiK3]

I think I'm dyslexic. When 1-4 are at TDC wouldn't the cam need to come back one tooth, counter clockwise?

[BenelliSEI]

I think I'm dyslexic. When 1-4 are at TDC wouldn't the cam need to come back one tooth, counter clockwise?

No issues for you..... you are correct and I was asleep! Will correct. J.

[madmtnmotors]

Cam/crank alignment should be checked prior to installing the rockers. If the cam/crank alignment is too far off and you are using a high lift/long duration cam you could have encountered valve to piston contact. Of course if turning by hand you would have felt it, but if you try to crank past it (even by hand) you could bend a valve.

[John G]

That did it. The chain was a tooth out. Everything now lines up as it should. Thanks everyone.

[Tracksnblades1]

Cam/crank alignment should be checked prior to installing the rockers. If the cam/crank alignment is too far off and you are using a high lift/long duration cam you could have encountered valve to piston contact. Of course if turning by hand you would have felt it, but if you try to crank past it (even by hand) you could bend a valve.

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