Head Job

[RebelRouser]

As Long As Your Heads Are Off You Can Rotate The Motor All Day Long To Clean Your Pistons And Cylnders, Just Make Sure You Put It Back To Top Dead Center, Then Rotate It 90 Degres Either Way Before You Reinstall The Heads

[cjflyer]

Hello and thanks for the great documentation here! I have procured a gl1000 with broken timing belts. After head removal I discovered 3 bent exhaust valves, pistons are ok. My question is: Did you replace the Cam oil seals with new and if so, were the new seals included in the engine gasket kit? If not, do you have a part number or where I can find it. Thanks.
Chad

[RebelRouser]

Yes I Replaced Them, No They Are Not Included, And Here Are The Numbers 3 Cam Oil Seals # 91209-371-003, And You Can Get Them From crescentmooncycles.com Part Number 15 086

[Hoosier Daddy]

One more time in case you thought no one read this anymore...
Thanks for taking the time during the build to take pics to help new guys like me, as well as posting this thread! Much appreciated.

[kritch]

Ok the only way I have ever seen valves remachined was on a vavle grinder and I have seen that suction cup deally before but, Is there any way we can get some details around the "lapping" of the valves using the tool and the compound?

I suppose that it involves the compound on the seats and the valves and putting the valves back in the guides and using the tool to turn them but, Im not sure. Can you give a couple of lines about that?

While we are at it, I think you mentioned guides being bad. Can you say how you determined that and the method for replacing the guides?

And one last thing. Can you give us a quick guide to how you cleaned the surfaces and pistons+bores?
thanks,
Mitch

[DJ]

I never did trust lapping.

When valves get hot, and they get much hotter with a faster temperature change rate than the head or block or valve seats, they get bigger.
They swell more and faster than the seat.
When valves get bigger, they contact the seat with a different diam circle than where they contacted the seat when you lapped them.

The surface you thought you cleaned up while COLD is not likely to be the same surface that contacts the seat when running.
Besides, you are cutting a groove into the already-grooved surface when you really want it flat and straight.

I have also read somewher that the Honda valves had a coating that you do not want to grind through, so NEW valves are the preferred method.
Does anyone have more info on that? I would like to know more.

Because of rocker arm leverage, valve guides wear in a mostly oval pattern. The oval that is rubbed into the valve guide opening at the rocker end of the guide is also most likely to be worn in the opposite direction as the oval opening worn near the other end because of the valve being "pushed" to lean in one direction.
More wear near the rocker end, and less wear as you go closer to the valve-head direction.
The best way to check is not necessarily by wiggling the valve head as most people do, tho that does tell you info. Often, there is more wear to be detected if you wiggle the valve stem at the rocker-end of the valve guide because that is where the rocker pushes and drags the valve stem sideways a tiny bit when it tries to open the valve from a slight angle.

A dial indicator is the best tool to use.

On cars, the way I prefer to recondition guides is to bore them out a bit and use a brass sleeve which is then lightly reamed to a perfectly round shape and sized to the new valve.
Keep in mind that used valves will also have worn spots along the stem that can give them extra wiggle room even if you use new guides new guides, at certain parts of the lifting cycles.

A worn valve in a new guide can encourage fast wear.
A new valve in a worn guide has a somewhat better outcome, but still not as good as starting fresh.

[Whiskerfish]

I have seen some heads that experience really good improvements with a decent lap job and some that saw no improvement at all. Typically if you have been running fouled carbs and the head intake ports are black that means you have a leak past your intake valve and a good lapping can often fix that. I had one low jug on my first 78 when I got it and it gained over 20 psi after lapped. I have the little tool with the suction cups but I seldom use that. I insert the valve into the seat and at the end of the stem I hook up a battery operated drill. Using plenty of compound I run it forward and reverse varying the pressure against the seat. Low rpm and make sure you do not put any lateral loading on the stem with the drill. I have never had a problem doing this but this is probably a high risk method so if you screw it up don't blame me

The valves have a Stellite coating. Some info here in this thread
http://www.ngwclub.com/forum/viewtopic. ... t=stellite

[tehtide]

One quick question... in the service manual it calls for coating the cylinder block and head surfaces with a liquid sealer. What is acceptable to be used here?

Also... what kind of lubricant do I need, if any, to put on the cam shafts, etc... when they get reinstalled?

BTW... thanks for this wonderful guide.

[Whiskerfish]

hmm. I always do mine dry.

As for the lube engine oil will be fine. All you are trying to do is provide a few seconds of protection till the pump gets oil flow up there on initial startup.

[Victour]

Just a couple add ones here . The Exhaust valves are the only ones with stellite coating.. I had mine ground because I read somewhere that it is ok to do so.. Lapping the valves will also remove some of the coating.. So I will let you know in about 20 thousand miles if my valves are burned up.. the Main thing is to make sure you Adjust them again later to make sure they are still at .004 thousands... They will burn quick if too tight...

I ordered the Complete engine Gasket Set.. $135.. It does not say a word about seals. so I had to go to Advance Auto parts to get the camshaft seals Beck/Arnley # 052-2755@ $3.99 Ea.
Thanks to the Shop Talk page.. $6.35 Napa price.. $11.00 Honda

I never put a engine together without Lube.. I use Assembly Lube from Permates also from AO

Automotive type engines I used a stp&oil mix 75/25 Never use Stp in a bike with a Wet Clutch... Don't believe me ask a old friend of mine..

[MPTXGL1000]

Thanks for the time spent posting this picture tutorial, it is lots of help as I attempt to freshen up the top end on my '75.

[the chef]

One quick question... in the service manual it calls for coating the cylinder block and head surfaces with a liquid sealer. What is acceptable to be used here?

Also... what kind of lubricant do I need, if any, to put on the cam shafts, etc... when they get reinstalled?

BTW... thanks for this wonderful guide.

I was told that no kind of sealer was needed between the head and block ,,,, I just scrapped the surfaces down real good and clean and bolted it back up with only the new head gasket in between the two. runs very fine.

Upon re-assembly
Just oil up the parts with regular clean 10w 40 .

[Victour]

I used the copper coat spray on the Head and cylinder top.. always works for me.. from Advanced or Auto Zone.

[vmeyer]

I have to ask. Who is Frenchy? Just so I know where to get affordable parts from when I have to do the job.

[sunnbobb]

Frenchy is the owner of cresent moon cycles and a sponsor of this site. A link to his store can be found on the front page of the website.