third broken rave valve 787

[Danosll]

okay so ive broken 3 rave valves on the same cyl. in the past year(both oem and SBT). 2 at shaft 1 blade in half. have changed valve housings and soft parts. but the problem is in the actual guillotine bore itself. . stock bore piston +rings and cylinder are in great shape View attachment 32054 compression is 150+..i thought about having it welded, too hard to reach and too thin. thought maybe high temp jb weld or devcon. now i leaning on a replacement cyl and if possible pressing good sleeve out of my bad cyl and pressing it into a good used cyl. that way i can salvage my piston, possibly even my rings. anybody have any suggestions . im open to any ideas

 

[Dr Honda]

I've seen them shatter... but not just bend like that.


Personally... I would use a small TIG head, and weld a bead into the guide. And then file it clean. I understand about it being a tight fit... but that's how it always is when welding on engine parts.

 

[Danosll]

im goning to have a welding shop i deal with look at it monday. i dont think they will be able to get to it. what about pressing my good cylinder into a used barrel. that way i can use my piston and rings and be back on the water this weekend. like i said my compression is good.150 piston and cyl are real nice

 

[Dr Honda]

I doubt you can get the sleeve out without destroying it. Even if you do... when it goes into the new jug... it will deform a little... and it will need re-machined.

These engines aren't like some of the large diesel's I've seen, where the sleeve is truly the "Cyl".

 

[racerxxx]

Are you still using the original rave housings? If so, I can just about guarantee they're sloppy and worn out. Also, what does the area where the guillotine rests against the cylinder look like? Is there a depression? It should be flat and smooth. The further worn that surface is the close the guillotine is to the piston.

 

[Danosll]

I doubt you can get the sleeve out without destroying it. Even if you do... when it goes into the new jug... it will deform a little... and it will need re-machined.

These engines aren't like some of the large diesel's I've seen, where the sleeve is truly the "Cyl".

even if i cut off the old cyl. put the sleeve in freezer overnight ,replacement cyl in toaster oven , then press in?

 

[Danosll]

Are you still using the original rave housings? If so, I can just about guarantee they're sloppy and worn out. Also, what does the area where the guillotine rests against the cylinder look like? Is there a depression? It should be flat and smooth. The further worn that surface is the close the guillotine is to the piston.

housings were changed end of last season and i have broken 2 valves with new housing see how the valve is worn out toward guillotine View attachment IMG_20150801_175744.jpg and the bore is worn looking out from inside cyl

 

[racerxxx]

How about where the valve rests against the cylinder? Is that beat up or smooth?

 

[Danosll]

How about where the valve rests against the cylinder? Is that beat up or smooth?

in the pics I posted you can see looking out from cyl how badly worn the cyl is

 

[Danosll]

 

[racerxxx]

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[Danosll]

View attachment IMG_20150802_135413.jpg but where the problem is .its at the other end of the guillotine bore where it is badly worn . thats why hard to photograph and i believe impossible to weld.

 

[racerxxx]

Yeah, your rave area is beat to piss. That will allow the guillotine to protrude further into the bore. The guillotine only has 0.5mm of clearance to the piston in a stock bore cylinder. I'll say if that depression is much greater than that that could be where your problems could be stemming from. I see the slots are worn severely too. I'll guess you have a ton of hours on this engine. I know it doesn't look like the piston has hit the valve, but they just don't bend on their own.


Here is you cylinder

 

[Danosll]

i dont believe it has high hours motor was never opened standard bore great compression other rave is good. i believe the previous owner didnt know there was a broken valve. View attachment 32064 View attachment 32065

 

[racerxxx]

Low hour, just not shown any love. Does the other cylinder have that marking?

 

[Danosll]

no other side is good . tomorrow ill try to find a good cylinder locally .

 

[racerxxx]

Probably the best bet. If you can find one with a clean standard bore just run a ball hone thru it and I'd put new rings on it. Between the cylinders on the gasket there is a series of holes, that's the thickness of the gasket you'll need.

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[Danosll]

thanks racer. i just now read in my manual how to determine thickness of base gasket.so i know mine is .4mm. thanks again

 

[racerxxx]

no sweat cheif, glad to help

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