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Discussion Starter #1 (Edited)
Here to tell my story but first I have a few question. I have ordered a new cylinder head for my 300f. Does anyone know if it will come with valve guides preinstalled? The parts department told me it did but based on the cost of the guides alone combined with what the head itself costs I am a little concerned he may have been guessing and incorrectly at that. Second question is regarding the service manual in which it states that we need to ream the valve guides, does anyone know if this is actually required when using the original valves? I am going under the assumption that we are not able to reuse the old guides/seats.



Here is the story though. Per the title I am just under 12k miles/19k km. I was out riding on the freeway and I was at around 8-9k RPM in 6th gear. I let off the throttle for a moment to pass and when I got back on the throttle there was a substantial lack of power. I managed to get the bike home (less than a mile as I was on my way home anyway) and by the time I pulled in the bike would barely idle and had a bad noise coming from the valve train.

I will attach the pictures but the short of it is that somehow it appears that I lost oil pressure to the head and the intake cam journals melted. Can anyone think of what could have done this besides a loss of oil pressure? I had completed an oil change a few days prior to this and I have changed it every summer since I bought it. I also ride throughout winter.

I have been working on every type of engine in existence for decades, although this is a bit deeper than I typically dive into them, so I am certain that the oil change was done correctly but I still did pull the filter carefully to make sure it was installed correctly. The only thing different with this oil change is that I used a Fram oil filter instead of a genuine Honda one as I normally do. Regardless I am definitely sticking with Honda filters from now on.

Based on the angle of the motor and the fact that the intake cam ate it and the exhaust cam still looks pristine I am thinking that perhaps only the part of the head that sits higher in the frame lost oil flow. I will be taking off the side cover to check for metal in the screen and oil pump before I continue.

The good news is that although the service manual told me that the engine needs to be removed from the frame to take the head off I can confirm that it will come out while still in the frame as long as you double nut the exhaust studs off. Thanks for any info though. Enjoy the carnage. Picture of the piston just in case anyone wants to know what 12k miles of carbon buildup looks like.
 

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The head should come with guides ready for the valves no reaming required-it's a hard lesson to learn but Fram filters suck many documented cases of failures-check the rear of the filter and see if the rubber seal is there and if so is it a good fit-you lost oil pressure slowly so the seal letting oil excape would be my guess-some people have been known to put the filter in backwards if that was the case one or two miles would have been it zero oil pressure-it's one of those things you think your doing good by changing the oil and filter and this happens
 

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Had a shop discover similar wear to the intake side of my head (not quite as much wear as yours) during recall work. Chalked up to high heat or low oil.

When it came time to order replacement parts, despite the F and R purporting to be identical internally, there were two heads in the system at the Honda dealer I went to, and the 'F' head/cam were significantly cheaper. Sure I have a receipt somewhere if you want to compare costs..
 

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Discussion Starter #4 (Edited)
Thanks for that info. That will help a lot. At least parts are fairly cheap. This level of damage to my Colorado would have cost thousands. As it stands I should have everything I need and only $148 in parts. The head was around 85, cam was 35, and head gasket was 18 or so, and about 10 bucks for crush washers for the head nuts.
 
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