Author Topic: First valve job. (Read 3049 times)

D-Ral · « **on:** April 16, 2015, 04:54:30 AM »

I've pulled apart my head to inspect the valves. Everything is plastered with carbon and nasties. 3 out of 4 intake valves didn't slide extremely easy out of the guides. I got them out without a lot of effort, but they didn't exactly slide out easily like the exhaust valves. The top of the heads don't look mushroomed, but the bottom lip of the heads are worn and flipping out a little. It's def just the heads that are catching in the guides.

Is it ok just to replace the valves that are damaged? It doesn't look like I damaged the guides by pulling the valves out, is there anything I should look for besides measuring the play between valve and guide?

I was hoping to just replace the seals and lap the faces, but things never turn out the way I'd like. Ha ha.

70CB750 · « **Reply #1 on:** April 16, 2015, 05:03:06 AM »

What bike?

D-Ral · « **Reply #2 on:** April 16, 2015, 05:04:13 AM »

Sorry. 750K4

70CB750 · « **Reply #3 on:** April 16, 2015, 05:08:00 AM »

I think you got it. Measure the play, lap faces and you are good to go.

Now if it was 78SuperSport ....

D-Ral · « **Reply #4 on:** April 16, 2015, 05:09:56 AM »

Thanks, brother, I appreciate the help.

70CB750 · « **Reply #5 on:** April 16, 2015, 06:30:03 AM »

One more thought. Look at the tappet adjusters, if they need replacement, here the front row are new and the back are old tappet adjusters:

evanphi · « **Reply #6 on:** April 16, 2015, 07:07:43 AM »

Quote from: 70CB750 on April 16, 2015, 06:30:03 AM

One more thought. Look at the tappet adjusters, if they need replacement, here the front row are new and the back are old tappet adjusters:

Good shooting!

70CB750 · « **Reply #7 on:** April 16, 2015, 07:08:27 AM »

I am a show off

D-Ral · « **Reply #8 on:** April 16, 2015, 07:08:31 AM »

Ah yes. Okie dokes. I'll check those as well.

So, about that carbon all in the cylinders around the valve faces... What's an appropriate method for cleaning? Solvent and green scrubby? Or can I hit it with a wire wheel?

70CB750 · « **Reply #9 on:** April 16, 2015, 07:11:17 AM »

Bead blasting, on my head it was 25 dollars I think. Wire wheel is too aggresive.

I used 3M scratch pad to clean piston tops, dealing with aluminum, you dont want to use anything harder than the metal you are cleaning.

Edit: oops. yes wire wheel will work on valves

evanphi · « **Reply #10 on:** April 16, 2015, 07:19:45 AM »

Quote from: 70CB750 on April 16, 2015, 07:11:17 AM

Bead blasting, on my head it was 25 dollars I think. Wire wheel is too aggresive.

I used 3M scratch pad to clean piston tops, dealing with aluminum, you dont want to use anything harder than the metal you are cleaning.

Edit: oops. yes wire wheel will work on valves

I used a dish-washing scrub brush with stiff plastic bristles, and various assortments of engine/carb cleaner, and acetone for mine.

You should get HondaMan's book. He has an excellent chapter on valve work! Also make sure that when everything is said and done, you perform a leak test on the valves. Turn the head upside down once assembled, and fill the combustion chambers with WD-40 or other light oil (make sure spark plugs are in too!)... if one loses all the fluid, you still have some work to do!

D-Ral · « **Reply #11 on:** April 16, 2015, 07:48:45 AM »

Ha ha. I actually have his book. I have this problem (?) of asking many people the same question to make sure I get the same answers

D-Ral · « **Reply #12 on:** April 16, 2015, 08:02:25 AM »

I guess my language was a little off, back there. When I said around the valve faces, I meant around the valve seats.

evanphi · « **Reply #13 on:** April 16, 2015, 10:09:52 AM »

Quote from: D-Ral on April 16, 2015, 08:02:25 AM

I guess my language was a little off, back there. When I said around the valve faces, I meant around the valve seats.

Yes still use solvent and mild scrubber. No wire wheel.

flybox1 · « **Reply #14 on:** April 16, 2015, 10:18:39 AM »

Quote from: evanphi on April 16, 2015, 10:09:52 AM

Quote from: D-Ral on April 16, 2015, 08:02:25 AM
I guess my language was a little off, back there. When I said around the valve faces, I meant around the valve seats.

Yes still use solvent and mild scrubber. No wire wheel.

+1
scotchbrite pad and acetone

evanphi · « **Reply #15 on:** April 16, 2015, 03:11:58 PM »

Quote from: flybox1 on April 16, 2015, 10:18:39 AM

Quote from: evanphi on April 16, 2015, 10:09:52 AM
Quote from: D-Ral on April 16, 2015, 08:02:25 AM
I guess my language was a little off, back there. When I said around the valve faces, I meant around the valve seats.

Yes still use solvent and mild scrubber. No wire wheel.
+1
scotchbrite pad and acetone

And proper PPE for your hands and eyes. Work in a well-ventilated area... or else you'll be pretty loopy for the rest of the day. Ask me how I know.

DaveBarbier · « **Reply #16 on:** April 16, 2015, 05:39:22 PM »

To clean up my valves I put masking tape around the tip of the stem and chucked them in a drill. Then held a green or red scotchbrite pad against the valve face and ran the drill. Cleans up really nicely.

---
1978 Honda CB550K

DaveBarbier · « **Reply #17 on:** April 16, 2015, 05:45:38 PM »

Great video. Note that he says he has a BRASS wire wheel. Not steel.

---
1978 Honda CB550K

D-Ral · « **Reply #18 on:** April 17, 2015, 03:55:59 AM »

Wow. Great video. Thank you!

DaveBarbier · « **Reply #19 on:** April 17, 2015, 04:43:41 AM »

Quote from: D-Ral on April 17, 2015, 03:55:59 AM

Wow. Great video. Thank you!

No problem. He doesn't work on bikes ever, but this guy takes Eclipses and Hyundai Elantras and makes them sleepers. Something like 11 or 12 second cars.

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1978 Honda CB550K

70CB750 · « **Reply #20 on:** April 17, 2015, 06:45:23 AM »

Sure. I will find that old target and you can look at it from 1000 yards all day long if you want..

Dunk · « **Reply #21 on:** April 18, 2015, 01:09:20 PM »

Quote from: DaveBarbier on April 16, 2015, 05:45:38 PM

Note that he says he has a BRASS wire wheel. Not steel.

Yes, I use a brass wire wheel in a die grinder to clean carbon off valves and also around ports and such.

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Author Topic: First valve job. (Read 3049 times)