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Hot cam Design fault

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Just finished fitting an Athena 440 kit, and while stripping the head i noticed this:

DSCN0894.jpg

The riveted pin that the auto de-compressor uses has worn a groove in the head. The rivets not loose but if you compare the hot cam and the Suzuki genuine exhaust cam, you can see how much the pin sticks out and why it catches. (Hot cam on the left, Suzuki on the right

DSCN0891.jpg

The Hot cams have been fitted for about 6 months 2500 miles and seem to work OK, but i have re fitted the Suzuki cams for now. Has anybody else had this problem, should i put the hot cams back in as the cam has worn its own clearance channel. :bonk:

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I am very surprised that it was not noticeably binding when it was originally fitted :naughty:

And this is the first mention I have seen of this particular problem.

But that said I would now just relieve the head in that area, so it cannot happen again, and carry on with it.

Any damage that the swarf from this contact may have done, is done now, just give the filter and frame trap a good clean.

Neil. :bonk::D:bonk:

PS:Make sure that pin is not able to move in and out.

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What does the thrust surface in the head and on cam look like? It took a pounding for a little while. What is the current lateral end play?

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The difference in the cams is obvious. Looks like Suzuki shaped it to avoid this happening. I would have thought that Hot cams would check the fit in an actual head when they built it. Two thoughts come to mind. First, is there an end play issue? Second, Have you checked with Hot Cams? This kind of thing could lead to improvements in the design.

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Hmmmm. I just got a Hotcam exhaust cam and was planning on installing it in the next few days. I'm wondering if it would be OK to take a sanding disc to it to smooth it out a little better. Mine is just slightly sticking out about 1mm. Here is another pic for comparison...:bonk:

331006.jpg

331011.jpg

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I'd let HotCams address this. Sanding down 1mm of material, however insignificant it may seem, would unbalance the cams. Could be something, could be nothing. Are you willing to gamble your engine?

That's just me.

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I'd let HotCams address this. Sanding down 1mm of material, however insignificant it may seem, would unbalance the cams. Could be something, could be nothing. Are you willing to gamble your engine?

That's just me.

Well at this point it seems the bigger gamble is to install it as is and let it wear a groove in the head!!!

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I'd suggest that sanding the rivet head is a bad idea, and not for balance reasons, but because the head of the rivet will be weakened, and possilby break off, getting stuck somewhere in the whirly bits.

I would assemble the top end, and turn the cam by hand, examining the area in question before getting on the phone with HotCams. I'd only call them if A) you're absolutely positive that everything was installed correctly, and :bonk: if there is actually interference.

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since it has a thrust guide, could'nt you just install the cam, and measure the distance between the pin and the head? I have same cam in my motor. Just adjusted valves and it checked out fine.

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since it has a thrust guide, could'nt you just install the cam, and measure the distance between the pin and the head? I have same cam in my motor. Just adjusted valves and it checked out fine.

Will do. I figured sanding the head off was a bad idea, just throwing it out there. If it's touching at all I'm taking it out and not using it. Another note is that the auto decomp mechanism seems to rattle a little bit on the cam since the keyway is a little larger than the dowel pin that holds it on...

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Just measured how far the pin sticks out, 1.5mm. I think i'll contact Hotcam and see what they say. Don't really want to make more filings cleaning it up. But to any body thinking to fit a Hotcam exhaust cam check the clearance of the pin, it's probably a quality control issue if no one has noticed this before. Just my luck, it's not been my week with one thing and another. I'll post the reply from Hotcam.

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Thmuper, looking the the pictures posted so far it looks to me as if your rivet has not been peened over as far as the other example :naughty:

Perhaps another pic will show this area better.

Neil. :bonk::D:bonk:

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Thmuper, looking the the pictures posted so far it looks to me as if your rivet has not been peened over as far as the other example :naughty:

Perhaps another pic will show this area better.

Neil. :bonk::D:bonk:

Couple more pictures of the rivet, looks and feels secure enough just sticks out too far.

DSCN0906.jpg

DSCN0904.jpg

See what you think.

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Judging by the pics yours is sticking out quite a bit more than mine. I wonder if it worked itself loose or came that way...

I hope the oil filter and screen caught all the shavings and it did not cause any damage to your motor. Good luck with it...

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Couple more pictures of the rivet, looks and feels secure enough just sticks out too far.

DSCN0906.jpg

DSCN0904.jpg

See what you think.

Do you have an exact measurement from the tip of the rivet to the center of the thrust guide? Measure both the stock and the hot cam. Just curious if there might be another possibility.

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Another note is that the auto decomp mechanism seems to rattle a little bit on the cam since the keyway is a little larger than the dowel pin that holds it on...

I noticed the same thing on mine. I'm at about 4k hard miles and it looked fine.

The CRF250X I did a cam on, seemed to have the decompressioner rotating pin very loose in the hole. Thought it was a wierd fitment too. KB

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dude,there is no way that turned smoothly upon install.

I was thinking the exact same thing,dint it get hung up durin install? Or is that something that got progressively worse?

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dude,there is no way that turned smoothly upon install.

Can't believe I'd have not noticed it catching when i fitted it, turned it over several times by hand so i can only suppose it's moved some how. still looks like a quality issue to me. Worth checking if your about to fit one.

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