Broken reed stop?

[nola 521dvx]

04 225 HO FHLSRM, rebuilt April 2010 after injector #5 leaned out and melted the piston. In case it's important, motor has the optional 150 degree t'stats and iridium plugs. #5 was bored 20 over and I rebuilt myself with new rod bearings, new injector for that cylinder, and after a few wrinkles (EMM oil inj shorted, fuel pump relay problems) has been running perfect for ~75 hours.

Last weekend after running for 20-30 mins without incident I stopped to idle past a fisherman and promptly lost a cylinder getting back on plane - pulled it apart yesterday to find one of the reed stops in #5 had broken off close to one of the retaining screws, sending a piece of metal about 1 x 5/8 x 1/16" into the cylinder with ugly consequences for the spark plug and piston.

I can understand the reeds themselves getting brittle and breaking but the stop? It's as thick as a dinner fork. Because of metal contamination after the injector failure I disassembled that reed block and cleaned it very thoroughly during the rebuild last year. Given the puny nature of the retaining screws it's hard to believe I stressed the stops putting it back together but it appears that there must have been a defect in the metal that vibration worsened to the point of failure. Has anyone seen this happen before? If I go ahead and rebuild again, should I change all of the reed blocks out or is that paranoia?

Thanks for your sage advice.

[ChampioNman]

As always, anything associated with a failure on the cylinder the components should be replaced. Reeds are suspect as they need to be inspected too. The reed stops May not need to be replaced but if the reed block has been disassembled then the proper thread lock should have been applied to the threads of the seating screws. As a practice I replace all reeds on the effected side of the block depending on the block style.

[nola 521dvx]

Thanks. The reeds are stoll intact, just the stop bust. The correct threadlock was used and none of the screws came loose. Seems that it is basically guesswork as to what to replace, no rhyme or reason past obvious damage. As a scientist by trade that isn't very comforting!

[ChampioNman]

Possible metal fatigue.

[nola 521dvx]

Thanks for your thoughts ChampioNman.
That's my thought too - I could see how vibration at just the "wrong" frequency could cause that, and I don't see how else just one finger would break off. Considering the reeds are now 7 yrs old I think I will bite the bullet and replace all of the reed blocks this time around, hopefully I can get another 3 or 400 trouble free hours of use.
Edit - one other question. The cylinder head has numerous very shallow marks on it from where the metallic debris was colliding with it, no cracks or gouges, no damage to plug hole or injector hole. Is this cause for replacement or can I re-use it?


Modified by nola 521dvx at 11:12 AM 9/20/2011

[ChampioNman]

Go with Chris Carson's reeds on all of them.

[ChrisCarsonMarine]

Andy,your reeds are completed and will ship Monday,chris

[nola 521dvx]

Great - look forward to getting them in the motor! Thanks for the quick and friendly service.