[dylanr22]

Hi Guys,

First of all great site! you guys have helped me out A LOT along my build.

Im in the process of putting the topend back together on my 75 CB500t and I have a few questions. I have searched and I cant find anything relating to my question.

Background: I sent my head to my local machinist and he replaced the valve stem guides/cut and lapped the valves and it looks like he skimmed the head ever so slightly.
He then rebuilt it with the valves and torsion bars in ready for me to install the rockers and cams. I am happy with the work, it all looks good.
Also I should say this is my first time rebuilding an engine and I feel confident in my abilities but not cocky.

OK, so I have got the rockers in no worries and I can get the cams in too.
The intake came went in easy and I can easily get the marks to line up BUT the exhaust cam was a pain!
I finally got it in by getting the points side in a little and the using a screwdriver to push the cam down and into the right position for me to lightly tap the speedo side in.
Took me about 3 days of getting frustrated to figure that out but its in nicely now.

Now: My exhaust cam marks weren't lining up perfectly but I noticed that my exhaust valves are open by about 1mm (Australia) due to me caressing the cam in.
I put a ruler across the deck of the head and they don't protrude past but after reading all the posts im worried.

I just used a screw driver to align the marks and now the points side is almost seated but the speedo side had come out more, past the deck. Is this normal??



anyway I'd appreciate any help I can get as im keen to get it running! Thanks!

 

[tbpmusic]

Hi Guys,

First of all great site! you guys have helped me out A LOT along my build.

Im in the process of putting the topend back together on my 75 CB500t and I have a few questions. I have searched and I cant find anything relating to my question.

Background: I sent my head to my local machinist and he replaced the valve stem guides/cut and lapped the valves and it looks like he skimmed the head ever so slightly.
He then rebuilt it with the valves and torsion bars in ready for me to install the rockers and cams. I am happy with the work, it all looks good.
Also I should say this is my first time rebuilding an engine and I feel confident in my abilities but not cocky.

OK, so I have got the rockers in no worries and I can get the cams in too.
The intake came went in easy and I can easily get the marks to line up BUT the exhaust cam was a pain!
I finally got it in by getting the points side in a little and the using a screwdriver to push the cam down and into the right position for me to lightly tap the speedo side in.
Took me about 3 days of getting frustrated to figure that out but its in nicely now.

Now: My exhaust cam marks weren't lining up perfectly but I noticed that my exhaust valves are open by about 1mm (Australia) due to me caressing the cam in.
I put a ruler across the deck of the head and they don't protrude past but after reading all the posts im worried.

I just used a screw driver to align the marks and now the points side is almost seated but the speedo side had come out more, past the deck. Is this normal??



anyway I'd appreciate any help I can get as im keen to get it running! Thanks!

If you have to use a hammer to get the cam "bearings" on, that's a problem.
If you rotate the cams to their loosest points you should be able to easily slide those bearings into place.
Once they're tightened down worry about lining the marks up.
If you can't manage that, there's a chance that your valve were cut too "deep" - a good possibilty that you won't be able to get an adequate tappet clearance later on in the process.
This PDF goes into detail......... View attachment camtime.pdf

 

[Lefty]

This should be a "sticky"^^^^^^^^^^^^

 

[dylanr22]

Thankyou TBPMUSIC! It makes much more sense now.

Sorry I did find that PDF early in my searching but it wasn't until I read it again after dealing with the head a lot more that it made complete sense.
after reading it I realise your meant to put the exhaust cam in with the mark facing backwards then rotate it around with a screwdriver.
Silly me! I was trying to get it in with the mark facing the front.

Lets see how i go now, will attempt top end rebuild this afternoon after work.

Thanks and Yes Lefty that should be a sticky!

 

[ancientdad]

I've always gone by the thought that if you have to force something, it's probably the wrong way (well, at least with Honda engines)