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lap or no lap

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Discussion Starter #1
About half way through the 685 build, valves are out and clean, head soda blasted clean - waiting on vinton seals ... So while Sherman and I were hanging out, I took a moment to read up on lapping valves in this particular machine. The advice is all over the place from never to light to yes on klr dot net. I have always lightly lapped valves when given the change - kind of a matter-of-course - on a rebuild ...

What does sage wisdom say here ... I'll get a pic of the seat and valve soonest ... but for the theory, let's proceed please.:nerd:
 

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A good lap dance, err I mean Valve lap job is a good thing. Do you know what is even better for your KLR cylinder head?

Narrowing the valves seat to near Minimum Specs! It increases the psi of seating spring pressure.

I'll about bet your valves have 2+ mm of contact surface. Maybe as much as 3 mm?

Specs call for .8 - 1.2 mm. That is .032 - .048 inch.

The work hardened surfaces will retain adjustment far longer, because of less seepage from both lapping & narrowing.
 
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To do a quick clean-up of the valve face and seat? Sure!

As a substitute for a valve job, when things are marginal and that is what is really called for? NOT!
 

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Discussion Starter #5
sounds great!

A good lap dance, err I mean Valve lap job is a good thing. Do you know what is even better for your KLR cylinder head?

Narrowing the valves seat to near Minimum Specs! It increases the psi of seating spring pressure.

I'll about bet your valves have 2+ mm of contact surface. Maybe as much as 3 mm?

Specs call for .8 - 1.2 mm. That is .032 - .048 inch.

The work hardened surfaces will retain adjustment far longer, because of less seepage from both lapping & narrowing.
ok ... I like the idea and know a small seat is better. 1.6 on the intake and 1.4 on the exhaust ... ya got one of them-there fancy videos on how to make a smaller dance seat to give the best valve-job?

Thanks for keeping it real
 

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Discussion Starter #7
Just found this video ...
... No active milling or lapping but pretty good overall flow ... Maybe I'll just lapp them a little and go on with the day :-D
 

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Discussion Starter #8
Another thought - are the stock valves SS or titanium? - hard to find and answer. I feel like I am swimming in the deep end of the pool now . HA!
 

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Stock KLR650 valves are not SS nor titanium. Just good old fashioned Hi-carbon steel.

I dis-agree with the video seat width. But I do understand your lack of proper cutters & their price tag.
 

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Discussion Starter #10
A magnet won't stick to the exhaust valves (does to the intake) and they don't look like stainless ...
 

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Those are stock valves (the "E" gives that away). They should be magnetic, indicating a carbon steel.


They could be stainless, as most stainless is magnetic; the only class of stainless that is non-magnetic is austenitic stainless. However, the most common stainless valve material happens to be austenitic.

A magnet not sticking to a valve, then, is an indication that the valve is stainless. But a magnet sticks to the stock valves shown above!
 

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Sherman, I never had reason to stick a magnet on the stock KLR valves that I've removed. So I could be incorrect.

When their faces look like your seat surfaces I replace them. Re-facing the valves calls for even more trimming of the stems, so I don't re-face.

To be 100% honest I didn't like the looks of the surface of the 45 degree seats or their widths.

You should check on Eagle Mike web site for cylinder head re-furbishing, very good price. Are you in the lower 48 states?
 

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Discussion Starter #14
Tom - Thanks for the quick note back and the metal lesson - I love that stuff! So stock stainless and they can be lapped? Definitely not magnetic. would the titanium be magnetic - guessing not - and if not, how to tell the difference i.e. did they use titanium valves stock not market with and "E"? How many sets of valves have you gone through to hit your 80k miles?

PD - In Virginia - agree that they are getting worn - probably at 18 - 20k (back to the spedo). Money is getting tight for this iteration though - Lots of mods this go around (320 rotor, ss brake lines, klr jet kit, 685 kit and bore from EM - Will they, in your opinion (IYO), last a season? My preference is to do everything but reality is bumping up against the order... wider seats with a fresh lapping might have to be there until the next valve adjustment - I have an extra head gasket - Answering why a $2500 bike needs $700 (plus the valve job) would be hard to explain.

- If I were going to replace them, what would I go with SS, steel , or titanium? Tom, PD, Buler, anyone IYO?
- IYO can I get a season out of them without damaging anything - oil problem should be gone and new piston / rings should fix most of the compression problem ... What is the risk of just lapping

- Goal is dependable for the season and longevity over the coming years - so yes - there will be a valve job in the future - I might even buy cutters to learn how ... but unless critical - it might have to wait. Got an Idea on a price?

Thoughts and guidance welcome!
 

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Based on the pictures you provided; it's well past time for a valve job. Lapping them at this point will only make the current situation worse. Depending on how much of a margin is left on the valve after it has been ground sufficiently to get a clean face, you may need new valves as well. I'd not invest in titanium valves for a KLR. The light weight is probably not an advantage that'd be worth the cost on these engines.
 

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Sherman, Lap your existing valves and ride it 5,000 miles. Re-check clearances, adjust if needed. Then re-check / re-adjust every 10,000 miles. If you run out of available shim sizes, then it is time for a cylinder head re-build.

Once the head is back on the engine, I would Not plan on re-building the cylinder head until truly needed.

Have you checked your air box? And your coolant reservoir?
Melted Reservoir, Dogs! (Airbox, too)

ps, I had to do a complete top end rebuild at 33,590 miles because of an Exhaust joint Gasket failure!
 

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Aside from lapping valves to get by for a while, I don't do my own head work.

I recently refreshed the top end and had the head refurbished at a shop. The cost of tools is prohibitive (and I have no aversion to buying tools). That particular head was ported and had big valves installed in it, stainless, a long time ago. I kept with that configuration.

I guess head work is something I don't want to play with, as I'd spend more in tools than what it costs to have someone that knows what they're doing have at it.

Another head that I have, should I decide to have it done, will remain stock. The only reason to go with special-wonderful valves is to increase the curtain area (performance) but that entails a lot of work. I'd stick with stock unless you are going to do the sort of things that would take advantage of larger valves.

Titanium would be non-magnetic, but the stock valves are not titanium. I'd guaran-damn-tee that. If they are stainless they are a martensitic stainless; I think that you may be mistaking a weak magnetic attraction for no magnetic attraction. Martensitic stainless, though less common in valves, is used and has a weaker magnetic attraction than a high-carbon steel. Martensitic stainless doesn't perform as well with high heat as austenitic does; that's why it is less common.

The exhaust valves pictured above with the magnet stuck to them are stock and that exhaust valve has been used since 1987. Kawasaki hasn't changed valves over the past 30ish years. They did change them in 2011, but I don't know what the change was.

If price is any indication of material, then the price supports the exhaust valves being something other than high-carbon. Perhaps they are some class of stainless. They are twice the price of an intake valve.
 

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Discussion Starter #18
Thanks Bluehighways and PD!

BlueHighways - no no lap and just reassemble? Money is scarce and just need a season and had 150 PSI compression with bad rings ... - or was it valve leakage ... Learning more every post

PD - I love your confidence and this is a fun game of discovery. I am not an engineer by trade. I am a Marine grunt experienced with making due with what I have until a proper fix can be realized ~ as long as it doesn't create more problems - I'll have to look at the dogs - on my list of To-dos after going through your site. Awesome stuff there!


guess this begs another question - Will it hurt the head to just lapp what I have or can that be reworked with a valve job and new valves next winter?
 

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That is Tom Schmitz's 'Souperdoo' site. I refer people to it every chance I get.

Lap your existing valves and seats and ride it 50,000 miles or more. No need to re-do it until it runs out of shim sizes.

ps, I don't even know how to post a pic. I'd really become a post-a-holic!
 
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Discussion Starter #20
I just learned in the last string just drag and drop the picture's file in the "drag and Drop File Upload" area right below the text box where you post! I am on a mac so I take a screen shot of the open picture to get it to the correct size for the thumbnail, just like I did for this reply


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