Topic: Failed collet

[Trevor from Warragul]

Has anyone ever had a collet (valve keeper) do this?!  Snapped in half!  I thought the bike was making a slightly different top end noise & this is what I found.  This is the 4th collet failure I've had on my 350/4.  The first 3 wore away the ridge that fits in the valve groove (resulting in 2 dropped valves) - this was diagnosed by a mechanic as crappy case-hardening.  I got the collets case-hardened & two of the exhaust valves collets then proceeded to wear away (elongate) the valve grooves.  I then replaced those collets with the standard Honda ones only to have this happen.  Sheesh, this bike is starting to piss me off!  I replaced the broken collet (without removing the cylinder head - I'll tell you how if you ask).  I then removed the sump - I couldn't find the missing piece but there was a lot of fine crushed metal of the same colour (yep, you're gonna tell me it's bits of bearing, gears, pistons, cams, etc, but the top end looks remarkably clear of damage).  I cleaned out the sump & oil strainer, put in new oil, & the bike runs fine.  What next?!

[MRieck]

 You running stock springs in that? I've seen keepers pop out before secondary to overrevving and/or not enough pressure.

[Trevor from Warragul]

Completely stock...  and I don't rev it that hard!  The good thing is, the bike is teaching me an awful lot about rebuilding motors!  When it came time to rebuild my Kawasaki H1A I thought "That'll be a piece of piss!" (Australian for "very easy").

[crazypj]

what you describe is common when he colletts don't quite fit the valves. Did you check they grip valve stem, have same angle as spring top seat and are of correct radius?
Also, do like Harley says, have the gaps fore and aft when you install valves,( inline with rocker arms) they are less likely to jump out even if severely overrevved
Oops, another trade secret out of the bag
PJ

[kettlesd]

Yes, sounds like over-revving and/or the keepers have not been installed so that the ridges fit precisely in the valve-stem grooves. Theres no way you should be burning through them like that.

[Jerry Rxman Griffin aka MuthaF'er]

Completely stock...  and I don't rev it that hard!  The good thing is, the bike is teaching me an awful lot about rebuilding motors!  When it came time to rebuild my Kawasaki H1A I thought "That'll be a piece of piss!" (Australian for "very easy").

Completely stock yeah, but did you buy it new?! If not you'll never know for sure what might have been done to it in the past 30 years such as different valves or keepers that don't match the valves. This is not necessarily indicative of your bike but something that can happen to any of us.

Now, if Kooler King Terry has had his hands on it down under, well............................

[Trevor from Warragul]

NOS from David Silver Spares - even came in the genuine Honda plastic bags.  I think I got a bad batch...

[Jerry Rxman Griffin aka MuthaF'er]

Yeah but are those valves stock? What I meant by "did you buy it new" was the bike. If the engine had been opened up prior to your purchasing it perhaps valves had been changed with an after market brand and the seats/grooves for the keepers are slightly different. Perhaps the retainers could be part of the issue if they aren't a perfect match. Are the valves slopping around in the guides creating an issue? Just different scenarios to throw out there. I hope it was a bad batch and you get your problem solved easily.     

[Trevor from Warragul]

Everything was NOS, from the cam followers through to valves, springs (inner & outer), etc.  EVERYTHING!  As for overrevving, I have not taken the bike past 6000 RPM since installing new rings.  I truly believe I got a dud set of collets... 

[Jonesy]

Not sure if it helps you out at all, but one trick I was taught was after the keepers are in place and the springs are released, lay a rag over the top of the valve spring and lightly tap on the top of the valve stem a few times with a small hammer. This helps to fully seat the keepers in the spring retainer, and if something isn't in properly and the keepers pop off, the rag keeps them from flying across the shop (or into your eye).

[dusterdude]

Not sure if it helps you out at all, but one trick I was taught was after the keepers are in place and the springs are released, lay a rag over the top of the valve spring and lightly tap on the top of the valve stem a few times with a small hammer. This helps to fully seat the keepers in the spring retainer, and if something isn't in properly and the keepers pop off, the rag keeps them from flying across the shop (or into your eye).

very true.