When to replace camshafts and buckets/lifters?

739 Views 6 Replies 3 Participants Last post by SparkyMJ, 10 mo ago

SparkyMJ

Discussion Starter · 10 mo ago

Hey folks, wanted some weigh in.

Working on my project K4 750, and it's got about 40k+ miles. It had pretty worn camshaft lobes, so I replaced the camshafts with used ones that were in better shape than my set. The wear looked like scratches/scuffing on the lobe tips, no chunks missing or anything that crazy, but enough I thought that replacing with used better ones would help it last longer. Haven't run the engine at all yet since replacement, due to other parts being worked on.

Anyhow, I've never opened up a bike engine that had lifters/buckets with any tangible wear. Sometimes they have visible wear patterns, but absolutely nothing you could feel with a fingernail, pick, or anything. The camshafts on this bike in particular as I mentioned had some pitting on the tips of certain lobes.

I guess the pitting on the lobe tips didn't cause tangible wear on the lifter/buckets. The pitting was very mild, but enough to me that I would like to try and not run those. The lifters looked absolutely flat, uniform, and good, with one exception, and it had a circular wear pattern on the head of the bucket, but again nothing I could feel in any capacity.

Question is, if you never run a stock motor out of oil or abusing the engine or anything like that, when or how would camshafts and lifters wear enough to warrant actual replacement?

Are lifters harder materials, and hopefully would result in only camshaft lobe wear, and not both? What level of wear is unacceptable for lifters?

What do you guys think?
Thanks in advance.
-Mike

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SparkyMJ

Discussion Starter · #3 · 10 mo ago

Good to know. Lines up with my personal experience as well. My other bike has 55k miles or so, and the top end looks superb. Better than this 750 in fact. I was pretty religious with my oil changes.

But now that the bike has some amount of top end wear, would it speed up further wear even if I do the oil changes and maintenance as prescribed? Like, when should I stop using those top end parts if they have accelerated wear? Manual just says stuff along the lines of "any wear is too much wear, remove and replace"

Thanks for the input.
-Mike

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SparkyMJ

Discussion Starter · #5 · 10 mo ago

Yeah that is true. Probably ride it, and visually monitor those components from time to time.

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SparkyMJ

Discussion Starter · #7 · 10 mo ago

Yeah I think that is a good conjecture about the causes of this. My other bike with much more miles shows way less age, and I rode it nearly every day.

I actually did bring those camshafts into a shop to have the tips ground down at a perfect right angle. They unfortunately didn't have the tooling to make that work, but indeed I understand the concept. I was willing to live with losing a few thousandths of valve lift to have the peace of mind, but it was just cheaper to find used camshafts in better shape than pay hundreds of dollars to fix my ratty ones.

But yeah I think I just need a monthly ride on all the bikes to keep stuff like this from happening or worsening. Probably the real cause on machines with almost two decades of age on them...

-Mike

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