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Is my cylinder head and cam trash?
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I've seen much worse. There are companies out there that do cam journal repair for less than the price of a new head.
Or, if your not too picky, you could try to knock down some of the high spots on the journal and cap with some emory cloth, then polish it smooth. Go slow and don't go crazy with it, or it could end up having too much slop in the cam... at which point, you will need to send it off for professional repair.
The high spots are either where the aluminum partly melted from oil starvation, or debris got in there and scarred it up.
Interesting, thank you.
If a shop repaired it, would that involve removing material, or somehow adding some back? Guessing I may also need a new exhaust cam, at least? It has marking as you can see, but I can't feel it like I can on the cap.
I'm bummed to have to deal with this and spend more money, but it is fascinating to learn more about these engines.
Usually they deck (remove material) from the cam cap, and or the head (the flat mating parts) to make the cam bores smaller, then they line bore them both again to specs. The cam looks pretty good to me, but you would need to take a caliper to it to see if any metal wore off. Aluminum is softer than steel and has a lower melting point, so as long as there is no aluminum build up on it, the cam is probably good. You could always give the shop the cam also, and they could tell you for sure. Good luck... when its fixed, it should give you some real world experience on why oil and filters on these bikes should be changed at regular intervals. And also the importance of the oil pump and all those tiny little oil passages going up to the head and into the cams to keep them lubricated.
use some fine valve lapping compound on the cam & journal and lap it in i have seen this work many times over the years
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ive seen them much worse than this running just fine. I would lightly sand this with a very fine sand paper, then use some lapping compound. Im sure youll never have an issue
Millennium-technologies does repairs on cam journals. If you wanna have then fix em I can get you a quote and extend a discount to you through my shop for them. Let me know if I can help.
Good stuff, thank you. I think this ultimately will be a great learning experience, which is actually part of the reason I'm getting back into moto after 10 years.
In the top cam cap picture, do you see screw in the top right that looks a little chewed? Not sure what that does but it appears damaged.
Right in, thank you. I think that's gonna be the plan.
There are some burrs on a couple of the corners where (I'm guessing) melted material may have deposited? As I mentioned above that screw in the top right of the cap picture is damaged...
What's the worst that happens if I don't do a perfect job cleaning it up? My intention with this bike is to have fun ripping corners and keep my wheels on the ground, not like I'm racing sx.
Thanks man, really appreciate it. Think I'm gonna see how well I can clean it up myself but if that goes poorly I'll definitely consider this 👍
EDIT: After looking at the fiche again, it looks like that bolt keeps the finger follower pin in place in the head. If you look down the hole inside the head, you should see a small cutout in the finger follower shaft. The end of that bolt goes down inside there and keeps the finger follower pin in place when the cam cap is on. If you take that bolt out of the cam cap, you should be able to slide it down inside that hole without any hangups.
The Honda part number looks to be 90025-K95-A20 if you wanted to order a new one. RMATV price is $2.92. Honda's only description is 'Special Flange bolt (6x26)'
Ah yes ok, thought it might be something like that based on my quick look with a buddy yesterday. Appreciate you having a look and helping me out!
Don't forget to inspect the pump and lines ... figure out why the cams ran dry in the first place. Possibly due to a problem with the mechanism and a blockage in the lines.
The sequence on a KTM (I'm not as famillar with the Honda) is top down so after the head runs dry, the piston seizes to the cylinder. So definitely lift the cylinder if you haven't yet.
Ok thanks. I did pull cylinder (replacing piston) but don't necessarily know what to look for in regard to oil flow yet. I'll look into it.
Another thing is my intake valves have basically zero clearance. Need to look into that too.
It probably would have been fine like that for several more hours of engine run time. What does everyone else think about that? How many hours before this would have shat the bed?
Man, I'm starting to think this thing is shot again. The intake valves have zero clearance (can hardly spin the cam) and are currently shimmed with 1.4mm shims. Ugh
I think you can get shims as small as 1.2, but yeah it sounds like at the very least the valves are worn, and possibly the valve seats as well. You would need a valve spring compressor to remove the valves to get a better look at them.
Let me know if you might be interested, I believe I still have a head that is in perfect usable condition, its ported with Web cams. It was taken off because my rider changed engine packages. I have to verify it is complete with valves when I find it.
I may very well be interested in that. Let me know!
Pit Row
I do have the head if you are interested, it is complete with valves, springs ect. It does not have any of the rockers or shafts or anything but has the cam cap and I also have a set of web cams that can be sold with it or without. Let me know, it wouldn't allow me to send you a private message
I'd get a cylinder head if it's got that many problems. Not worth the ongoing headache
Not to thread jack or anything but to piggy back off the header of this thread does anyone know if this could be fixed
Call up Engine Dynamics. They can fix it
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