Topic: .

[CB750Fury]

   .... ...

[PeWe]

Spend some extra on the valves. It cost some to just lift head (Head gasket), cut seats etc.

Read this thread. I had new super flow exhaust valves used  about 54-60 minutes, left the head at my local tuner for cutting the seats and replace IN valves. He found that the super flow valves had too slim stems, but my old steel guides were all OK. He installed new Kibblewhite exhaust valves.
http://forums.sohc4.net/index.php?topic=135107.0

Check with Dynoman and APE.

[Nic]

If you polish the nitrite coating off them they are ok. Stems too thin? Not in my experience.

[Bailgang]

I only put about 6k miles on my 77 F2 after installing the cycleX super flow valves and kibblewhite guides early last year so I don't think I can give a long term opinion but so far the engine continues to run great. Keep in mind my original valve guides were junk and the tops of all the original valves were severely indented so anything was an improvement. I was aware of the thread PeWe mentioned but by that time I had already purchased the valves and I wasn't about to just let them set on the shelf so I rolled the dice and installed them with the nitride coating intact.

[Retro Rocket]

If you polish the nitrite coating off them they are ok. Stems too thin? Not in my experience.

Why polish the coating off Nic..?

[Nic]

If you polish the nitrite coating off them they are ok. Stems too thin? Not in my experience.

Why polish the coating off Nic..?

Good question Mick, it's a longish story but to cut it short a little. Someone asked if they had used the superflow valves, I was an early responder and said I thought they did the job, then along comes Mark HondaMan and tells a horror story of how he had a head that had them and the coating had come off and ruined the guides and he had to have the seats re-cut quite deep and then surface ground the head to compensate for the lost compression.
So now panic sets in, at least in my mind as I had just got my engine going with the superflow valves, now seeing as I had to pull my engine down for tranny reasons after 2500Ks I decide to replace the superflow-ers. It was quite a lengthy thread. When I pulled the valves out I found no dramas at all. Mark said he polished off the coating and the valves were good.
Whether he had valves from a bad batch, who can tell. I'm doing a rebuild for a forum member at the moment and to save some bucks we agreed that I would polish off the coating and use my old super flow valves, they came up a treat and I don't anticipate any dramas. More important IMO is to get the proper clearances with the new guides.

[Retro Rocket]

Interesting, I was of the impression that nitrite coatings actually penetrate the part being coated, while only minute, that was my understanding...

[Nic]

Interesting, I was of the impression that nitrite coatings actually penetrate the part being coated, while only minute, that was my understanding...

Yes well if you can find the thread, Mark's story put the wind up me. When I put the valves in the drill press and used 600 the inlet valves went silver in no time, the exhausts took a bit longer. This didn't seem to alter the stem diameter so the coating is thin. I was able to keep the inlet guides and my machinist used some fancy racing insert he put in the exhaust guides which were too far gone.

[Retro Rocket]

Interesting, I was of the impression that nitrite coatings actually penetrate the part being coated, while only minute, that was my understanding...

Yes well if you can find the thread, Mark's story put the wind up me. When I put the valves in the drill press and used 600 the inlet valves went silver in no time, the exhausts took a bit longer. This didn't seem to alter the stem diameter so the coating is thin. I was able to keep the inlet guides and my machinist used some fancy racing insert he put in the exhaust guides which were too far gone.

Hmmm, just thinking about it, i am wondering what exactly the coating was, I was referring to Titanium nitrite which is very common gold finish on fork tubes, extremely good friction coating, i can't remember what the black coating is that Ohlins also use, but its supposed to be better again.... Wonder exactly what that coating on those valves are.....?

[Nic]

Back in the original thread Mark said he emailed CycleX but they weren't talkin

[calj737]

I'd bet dollars to donuts Mike Rieck has the inside on it all.

[Nic]

This is what he said in the thread linked above.
Before everybody gets their underwear tangled I would suggest finding out exactly what kind of "coating" is used on CycleX valves. The pics I saw on the other thread do not look abnormal including carbon pitting. I do not know who did the valve job but the valve face contact area looks very wide too....it should start at .060.
 There are a few other things to know too. #1 bronze guides do not last like cast iron.....period. I have seen them oval in under 5,000 miles and that is with guides from the 3 companies that supply them. That is also with Kibblewhite valves, 6.5 and 5mm stems.
#2 Forget about installed height and go with actual spring pressure on the seat and at max lift. Kibblewhite springs are set up to stiff IMO.
#3 CB750's have a steep valve angle and create a lot of side load....combine that with a cam that supplies .060 to .080 more lift and you are going to see a lot more wear especially with heavier valves and higher revs. You don't have these problems in modern bikes with vary shallow valve angles. You do have big problems with Harley heads and bronze guides because the reasons I listed are even worse (very heavy valves, .500 - .600 lift cams & huge valve angle). I know several shops that will not install bronze guides in a Harley head for those reasons.
 Kibblewhite valves have some type of DLC applied and yes...the treatment does wear at the areas of highest load. I have seen it many times. I have also seen their hard chrome gall up a little to. The old stainless Manley's and RC's weren't any better.
 So....before the bandwagon sets off I'd find out a bit more and consider the points I just made. If you want minimal valvetrain wear get iron guides (or some of the old RC steel guides though the length was way to short), use weak springs and a stock cam. I'd also highly recommend zinc additive too.
 I don't go for internet bashing in general...if I don't like a product I won't use it. If the CycleX valves were displaying variations in stem diameters, valve margins and head diameters that is one thing....that is real and measurable. There is too much speculation here IMO.

[70CB750]

Interesting, I was of the impression that nitrite coatings actually penetrate the part being coated, while only minute, that was my understanding...

Yes well if you can find the thread, Mark's story put the wind up me. When I put the valves in the drill press and used 600 the inlet valves went silver in no time, the exhausts took a bit longer. This didn't seem to alter the stem diameter so the coating is thin. I was able to keep the inlet guides and my machinist used some fancy racing insert he put in the exhaust guides which were too far gone.

That was my experience too.  I had CycleX valves on my bench when the scary thread started - so I took one valve and clean the coating off where it matters not - right under the grove, above the section that goes in the guide.  Micrometer showed minuscule difference between coated and uncoated valve.

[Nic]

Why has the thread topic disappeared?

[PeWe]

Thread starter might have changed his mind about pistons and valves.?
This is a forum, all ideas can be interesting for others that plan to do same thing or get the idea to do it. I have got many expensive ideas from this forum.

[Jerry Rxman Griffin aka MuthaF'er]

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[calj737]

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My thoughts exactly.

[MRieck]

All I will say is I have installed dozens of those CycleX valves with no complaints or returns, Honestly I have only had one return and it was because the engine was run lean  and it beat the crap out pf the exhaust guides and valves.  I am not dumb.....I told the owner what I thought happened but he denied the situation.
 OK ......replaced the parts which he paid for and that was that. Obviously it worked out OK as I never heard from him again.
 Bottom line....don't lie to people who know......the seals were loose as $hit and the valves were galled to hell.....it was run very lean.
 I do not remember exactly what Mark was talking about in his thread.....flaking or something ....but it is specious IMO.
 Here is a link to company that makes most of the valves/springs for people in this country....look at their coating.        http://supertechperformance.com/

[calj737]

...I'll have my dozen donuts now, please 

[70CB750]

As far as I remember, Hondaman posted the coating wore off valve stems and they (valve stems) ended up too small diameter for installed guides and he had to replace guides because of that.

[Nic]

Here is Mark's original statement, now Mark is well respected around here n bearing that in mind, I didn't consider what he said to be bull #$%*.


I will never use them again.

I built an F2 head for one of our members, he sent me those valves to use. In less than 300 miles, the "nitride coating" ground off and ruined the brand-new guides, destroyed the seats, and damaged the chambers. It was like pouring sand into the engine, only worse, as it stuck well to the valve faces.

I had to re-replace all the guides, re-cut the seats deeply, then mill the head another 1.2mm to get the compression back. Then I polished all that 'coating' off the valves and found what appears to be stainless valves underneath. I had them re-faced, and put it all back together. It ran fine, then.

Other members here have suffered a similar fate from them.

After reading this, is it too much to ask that a bloke might be worried he'd just put these valves in his engine 
Here is the thread http://forums.sohc4.net/index.php?topic=134463.msg1513246#msg1513246

[Retro Rocket]

Here is Mark's original statement, now Mark is well respected around here n bearing that in mind, I didn't consider what he said to be bull #$%*.


I will never use them again.

I built an F2 head for one of our members, he sent me those valves to use. In less than 300 miles, the "nitride coating" ground off and ruined the brand-new guides, destroyed the seats, and damaged the chambers. It was like pouring sand into the engine, only worse, as it stuck well to the valve faces.

I had to re-replace all the guides, re-cut the seats deeply, then mill the head another 1.2mm to get the compression back. Then I polished all that 'coating' off the valves and found what appears to be stainless valves underneath. I had them re-faced, and put it all back together. It ran fine, then.

Other members here have suffered a similar fate from them.

After reading this, is it too much to ask that a bloke might be worried he'd just put these valves in his engine 
Here is the thread http://forums.sohc4.net/index.php?topic=134463.msg1513246#msg1513246

Nic, Mike Rieck would have fitted far more of these than anyone else of this site ,  his head work is second to none...

[Nic]

Not disputing that at all Mick, just tryin to justify my original concern. IT WAS LIKE POURING SAND INTO THE ENGINE.
With the passage of time Mark's original statement has lost most of it's bite, bad batch? Mark has been pretty quiet on this issue since his original post, I dunno, I'm happy to use them now but I'll still polish off the coating. I'm not trying to drag the carcass around till the head falls off, I'm just trying to justify MY concern when I had just put these valves in MY engine and then read Mark's post, what would you do?

[Retro Rocket]

Not disputing that at all Mick, just tryin to justify my original concern. IT WAS LIKE POURING SAND INTO THE ENGINE.
With the passage of time Mark's original statement has lost most of it's bite, bad batch? Mark has been pretty quiet on this issue since his original post, I dunno, I'm happy to use them now but I'll still polish off the coating. I'm not trying to drag the carcass around till the head falls off, I'm just trying to justify MY concern when I had just put these valves in MY engine and then read Mark's post, what would you do?

I wouldn't even say "bad batch" this seems to be an isolated problem. I would take Mike's word, there are plenty of good products that have had small failings,{numbers} but are still used successfully, these types of coatings are very common, probably every performance part manufacturer at some stage has had a failure of a new part, you see it in motor sport quite often... I also think that If this was a common occurrence you would have heard far more than one case i'm sure, If you are really worried, use different valves or remove the coating as you plan  ...    I do understand your concern..

[CB750F2]

Nic and Retro. I used those valves in my rebuild. The bike has been back on the road for about twelve months with about 1000Km with no problems. The guides are cast iron and did not have to be changed. My intention is to keep riding and hope I don't have any problems. Pat