Head refurbishment & mild porting "how-to" - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 96 Old 12-10-2019, 03:00 PM Thread Starter
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Head refurbishment & mild porting "how-to"

I thought maybe I could contribute some useful information regarding refreshing a head. I've had (I think) 6 heads apart, Gen 1 & Gen 2, have seen some pretty bad valve & valve seat wear, on engines that didn't have particularly high mileage on 'em. You can get a pretty good idea of how much valve & valve seat wear an engine has, by the shims required to get valve lash in spec. Each shim increment of adjustment, equates to approximately .002" the valve has recessed (worn) deeper into the head. Worn valves & valve seats affects compression (performance). So often I see guys addressing high oil consumption, replace the piston & rings, but don't refresh the head, only doing 1/2 the job IMO - most mid to high mileage engines could benefit from de-carboning, and at least lapping the valves to restore compression. The Eagle Mike head refurbishment program, at $190 USD, is a bargain IMO.

This is a head from an '01 Gen 1 that I took in trade (set a friend up with a 685 I built), and I think it had around 50,000 miles/80,000 kms (was a bad oil burner). This is, unfortunately, usually the condition I find heads in when I disassemble 'em.



The max width, as per the factory manual, for the valve contact patch on the valve seat, is 1.2mm, both intake and exhaust. The intakes are at max, and exhaust over 2mm. The valve seats are badly pitted, especially exhaust. This head requires valve seat regrinding, and two new exhaust valves.



Here's a few tools of the trade. I'll illustrate/document the process as I progress (if there's interest).

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post #2 of 96 Old 12-10-2019, 04:32 PM
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Sounds good!

As I've mentioned, I'm currently going to be putting together my 685. The bike is a 2001 that doesn't burn any appreciable oil between changes and it has about 30,000 kms (19,000 miles) on it. I didn't follow my own advice and am installing the BB kit on a bike that ran just fine before! My plan was to do a solvent test to ensure the valves were sealing and that they and the seats are in good shape and then just doing a general de-carboning.
I'll follow you thread with interest.


Dave
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post #3 of 96 Old 12-10-2019, 06:35 PM
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Will you be doing standard size valves?

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post #4 of 96 Old 12-10-2019, 07:31 PM Thread Starter
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Quote:
Originally Posted by Tom Schmitz View Post
Will you be doing standard size valves?
Yes, I think so. I'll probably go with the Schnitz aftermarket valves on the exhaust. Regarding going 1mm oversize on the valves, where can you get that done nowadays? I notice the M-Tech KLR650 web page ( http://www.mtechmotorcycles.com/perf...5-705-kits.htm ) no longer works - have they closed?

I'm going to preface this "how-to" by saying, know your limits with respect to your personal capabilities. I personally think most people can accomplish amazing things, but these tasks (and that's how I view them) done improperly can ruin your head... the tolerances between the valve shim buckets & bores, and the valves & valve guides are very tight. If you nick (damage) a valve seat, that will require (expensive) re-grinding... not a DIY job.

You'll notice in previous pics, the combustion chamber was already de-carboned... with valves left in. I use a small screwdriver, on which I've taken like 400 grit sandpaper and radiused the edges slightly to reduce the possibility of gouging the soft aluminum. I use sandpaper, and 3M Scotchbrite pads to finish up. Don't remove any metal - enlarging the combustion chamber reduces compression ratio.

With the combustion chamber cleaned up, time to pop the valves out. The shim & buckets should come out easily - if not, you've likely got scratching in the bucket bores (carefully dress that out with 800 grit). With the buckets removed, use an automotive valve spring compressor tool ( https://www.princessauto.com/en/deta...or/A-p8003725e ) to compress the spring, and remove the locking collets. Be careful to keep each end of the tool centered - don't let the steel compressor end touch the (easily damaged) aluminum bucket bores!







Once you've popped the valves out, next step is to block off all areas you need to protect from crud - de-carboning and porting makes a mess, and you don't want that getting in the oil passages, valve guides, etc. I roll up pieces of paper towel, and wad it in the spots needing blocking off:



Don't forget to plug the oil line orifice, and remove the rubber intake boot. I install the valve cover back on, to keep debris outta there:



Ready for de-carboning... tomorrow. Ugly job that it is.
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post #5 of 96 Old 12-10-2019, 08:18 PM
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I've found that the Thailand plant rarely cut the Most Important 60 degree angle on the exhaust valve seats to properly narrow the exhaust valve seat, seating surface for good sealing and long life.

Have you experienced the same fault?

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post #6 of 96 Old 12-10-2019, 09:03 PM Thread Starter
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I've found that the Thailand plant rarely cut the Most Important 60 degree angle on the exhaust valve seats to properly narrow the exhaust valve seat, seating surface for good sealing and long life.

Have you experienced the same fault?
Hi PD. Can't say I've noticed that specifically, but I would say I noticed a difference in the shims that Gen 2s come out of the factory with. There appears to be thinner shims than what used to come with Gen 1s - when performing valve adjustments, on lower mileage Gen 1s, I found it not uncommon to find 275 or 280 shims... Gen 2s I'm finding 260, 265 factory installed. This means they are (needlessly?) removing more materiel during grinding & lapping, recessing the valves deeper. Seems a shame, as you'll run out of adjustment shim sizes sooner.

What I see though, is by the time exhaust valves require 225 or 230 shim size, that contact patch is very wide, like 2.5 to 3mm... i.e. re-grind is required before running out of shim sizes. The crazy thing, is they seem to still run OK like that, with badly pitted worn valves and valve seats. The power goes soft tho, as the compression fades. Around here, they use crushed limestone for gravel, and that dust is, I suspect, very abrasive. No air filter is 100% efficient (there's always some particulate getting thru), and I suspect wear rates correspond to what's seen in the way of exposure... and air filter maintenance!

Related... just like on the head I've got here/am working on now, on most of the previous heads that I've had apart, I generally see exhaust seats wearing way faster than intake. I suspect that's carbon bits getting caught between the seat & valve on the way out, causing pitting.

Thoughts? See the same?
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post #7 of 96 Old 12-10-2019, 09:21 PM
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Originally Posted by GreatWhiteNorth View Post
Yes, I think so. I'll probably go with the Schnitz aftermarket valves on the exhaust. Regarding going 1mm oversize on the valves, where can you get that done nowadays?

No where unfortunately. I bought the last three 1mm oversize valves from Schnitz Racing. M-Tech didnít have any in stock and said theyíd order them, but I havenít heard anything back from them. Schnitz Raving is no longer making them. If you find a 1mm oversize intake please let me know.

In the meantime Iím looking at a quad ported head where you use stock and oversize valves.
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post #8 of 96 Old 12-10-2019, 10:11 PM Thread Starter
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Originally Posted by ILove2Ride2Wheels View Post
No where unfortunately. I bought the last three 1mm oversize valves from Schnitz Racing. M-Tech didn’t have any in stock and said they’d order them, but I haven’t heard anything back from them. Schnitz Raving is no longer making them. If you find a 1mm oversize intake please let me know.

In the meantime I’m looking at a quad ported head where you use stock and oversize valves.
That's too bad. For the larger displacement big bore kits, I think those oversize valves would make a difference. I see in the KLR Chris 60 hp EFI project bike, that he used a 1mm oversize valve head - I wonder who did that for him?

One thing about it, if you stick with stock size valves, you can get the valves re-ground at a dealer. I sent one head to E-M for refurbishment, and have had the local Kawi dealer re-cut the valve seats on two or three heads. The lead tech there does a fantastic job grinding & lapping valves, but it costs me dearly to get it done there.

Last edited by GreatWhiteNorth; 12-10-2019 at 10:28 PM. Reason: fix typo
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post #9 of 96 Old 12-10-2019, 10:38 PM
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That's too bad. For the larger displacement big bore kits, I think those oversize valves would make a difference. I see in the KLR Chris 60 hp EFI project bike, that he used a 1mm oversize valve head - I wonder who did that for him?

I believe KLRChris did it himself. I too think the larger valves would be of benefit. My cylinder is in EMís hands now getting the 719cc BBK installed. Iím going to be sending my crankshaft out to Crank Works Inc. to be modified as a stroker. If I can get a quad port head maybe itíll be an even better engine for my needs. I have an ongoing thread on it now.
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post #10 of 96 Old 12-11-2019, 07:59 AM Thread Starter
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Originally Posted by ILove2Ride2Wheels View Post
I believe KLRChris did it himself. I too think the larger valves would be of benefit. My cylinder is in EMís hands now getting the 719cc BBK installed. Iím going to be sending my crankshaft out to Crank Works Inc. to be modified as a stroker. If I can get a quad port head maybe itíll be an even better engine for my needs. I have an ongoing thread on it now.
I'll check out your thread. Maybe give Chris a call - he's very helpful.
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