Topic: Valve job

[Caaveman82]

Anyone on the forum here do valve jobs?

When I took the head off and poured some stuff on it and blew air into them a few of the valves had bubbles coming up, there is a lot of carbon and stuff and I just don't want to mess with it incase it needs to be milled. The places locally are trying to charge over $450. I don't think it should cost that much personally.

Any advice would be super!

[HedNut]

Here's a quick link to a valve lapping run thru:
(I just quickly googled it)

http://www.affordablegokarts.com/valve-lapping.php

For about $9 get a valve lapping tool (a stick with a suction cup on the end) and valve grinding/lapping compound.

And some patience and time... it's an easy job to do....and you'll get rid of those leaks.


Upon conversation with a buddy who refurbishes motors on a regular basis yesterday, he told me  that, if you have access to a hand dril....

Skip the valve lapping tool..... load up the seat with compound.....put the valve in... tighten the drill onto the stem of the valve....and spin it while pulling the valve into it's seat.... TADA.... 1/16th of the time it takes to hand work the seats to a beautiful finish.

On that note here are a few tips:

-Lubricate the stem of your valve inside the guide
-Do not spin the drill to full speed (hopefully it's variable)...you can work them fast/slow etc....
-Every handfull of revolutions push the valve out of it's seat...then pull it back in (it replaces more gritty compound in there)....you'll feel it.
-do it in shot runs....pull out the valve, clean it, and if needed reapply compound and repeat  (just to make sure you don't go too far and take off too much material)  Again....after the first valve or two...you'll have a good feel

I did mine by hand....as I didn't think to use a drill!...but it would've been slick'n'quick...and I definately will be doing that next time I come across a lapping jobby.

Cheers!
Brendan

[MCRider]

I agree with you HedNut. And I uise the drill technique a few embellishments is to use a variable speed reversable drill and low revs. (you mentioned that). Instead of clamping right on the vavle stem, put a 6"+ piece of flexible tubing, rubber, vinyl, etc on the valve stem and chuck that into your drill. Pretty hard to damage anything with that cushion in between.

A few quick in and outs, and you'll have a nice shiny "sealing ring" around the seat of the valve.  Throw that valve lapping suction cup away.

Poormans valve job, and all that many need. 

[Caaveman82]

MC what kind of compound is he refering to?

Also would I need to remove the valve springs?

I am afraid to screw something up...

[MCRider]

MC what kind of compound is he refering to?

Also would I need to remove the valve springs?

I am afraid to screw something up...

valve grinding compound, avaialbe at any auto parts store, in a small toothpaste type tube. Its a gritty paste.

Yes springs come off. valve stem seals too

Ask your machinist how much to "lap" the valves as opposed to a valve job. A valve job invlvs cuttters and higher skill level, maybe an expensive machine.  Could be much cheaper. Still clenaing (often glass beading or wire brush) and disassembly/reassembly is same for both operations.

Lapping will fix most leaky/burned valves.  But maybe you need a valve job?

[Caaveman82]

MC what kind of compound is he refering to?

Also would I need to remove the valve springs?

I am afraid to screw something up...

valve grinding compound, avaialbe at any auto parts store, in a small toothpaste type tube. Its a gritty paste.

Yes springs come off. valve stem seals too

Ask your machinist how much to "lap" the valves as opposed to a valve job. A valve job invlvs cuttters and higher skill level, maybe an expensive machine.  Could be much cheaper. Still clenaing (often glass beading or wire brush) and disassembly/reassembly is same for both operations.

Lapping will fix most leaky/burned valves.  But maybe you need a valve job?

I am no pro at this stuff.

I just checked it how some other guy who's been doing this stuff for a while said to and it had leakage.

It didn't look that bad to me but again, no pro here.

I would love to keep it under 100. That would be super duper.

[ev0lve]

MC what kind of compound is he refering to?

Also would I need to remove the valve springs?

I am afraid to screw something up...

Pretty hard to screw up - as witnessed by my not screwing it up. I used 120/280 grit on mine for no particular reason except it was the first link I came across. These guys know better I'm sure  

Yes, springs out. And the little suction cup dealie sucks. Wish I'd even considered a drill at the time.

[MCRider]

MC what kind of compound is he refering to?

Also would I need to remove the valve springs?

I am afraid to screw something up...

valve grinding compound, avaialbe at any auto parts store, in a small toothpaste type tube. Its a gritty paste.

Yes springs come off. valve stem seals too

Ask your machinist how much to "lap" the valves as opposed to a valve job. A valve job invlvs cuttters and higher skill level, maybe an expensive machine.  Could be much cheaper. Still clenaing (often glass beading or wire brush) and disassembly/reassembly is same for both operations.

Lapping will fix most leaky/burned valves.  But maybe you need a valve job?

I am no pro at this stuff.

I just checked it how some other guy who's been doing this stuff for a while said to and it had leakage.

It didn't look that bad to me but again, no pro here.

I would love to keep it under 100. That would be super duper.

Yes I read that about your testing, that's fine. As long as you don't have to replace anything other than seals you could lap them your self for under $50, maybe under $25. You can usually rent a valve spring compressor from an auto parts store, or buy one. Plenty of tutorials and help on lapping. Not rocket science, but you got to pay attention.

If the ports are dirty, they'll probably stay dirty for that price. But if you've been riding a bike with leaky valves, you'll notice a difference.

I'd take a wire brush on a drill to the combustion chambers while the valves are still in place with springs. Clean vacuum as you go. Keep the gunk from migrating to the valve side of the head. DON'T take the valves out and then wire brush as you'll trash the seats in the head.

[Caaveman82]

Sounds good to me. I'll get on that this weekend then. Thanks for the help.

[HavocTurbo]

Might not be worth it.... but ship it to me with a $50 bill and I'll powdercoat it for you as well as lap the valves.

For what it's worth, you may need new valve seals no matter what, and since the head is off.... might be good insurance.



Just an option.