787 rotory valve cover

[Black67tb]

I did the squish test on my rotory valve cover. .019" clearance. So on this 787 engine the spec is .012" clearance. I have .007" excess. My question is: If l send my cover in for exchange, how am l guaranteed l will recieve a replacement .007 smaller? Or are all remanufactured covers just machined to factory specs. Are they all the same dimension? I would like someone to explain how this all works. Does the case surface wear as well?
Thanks

 

[vogs77]

Black67, sorry I dont have your answer but a question for you. Are you trying to correct and issue you are having with your ski or just rebuilding the engine. I am going to be checking this on my 787 as soon as the weather permits to try to address a hard hot start issue.

 

[Black67tb]

Just rebuilding the engine. Didn't have any hard starting or heat problems.Thought l should check this cover also.

 

[etemplet]

(.019") likely won't affect your starting very much. I've had them at .017") and worked fine. I measured a bunch of them. Now I machine them above (.015") I machine my own rotary valve covers and yes, pretty much standard dimensions. I did 3 rotary valve covers last month. A little bit of a pain but.... not bad. In the picture below you can see how the valve plate wore. So.... if you put your soldier too close to the ports you'll get a reading with more clearance. Also notice the smooth area in part in the first picture.... that is what you need a barrier to keep the mixture from getting from one side to the other.





This one wore a different way and as you can see the mixture can cross over from one port to the next.




This one is almost complete. It doesn't end there as the same amount of material that is removed from the rotary valve surface must be removed from the landing where the cover bolts up AND... the same amount needs to be removed from the O-Ring groove.

 

[etemplet]

Anybody got a price on machining one of these covers?? I'm sure I'd laugh given the amount of time it takes me to machine one. I am curious though. You can find good covers on Ebay but watch the gougers... they have quadrupled the price on many items. I found this one for $50 which to me is cool even without the rotary valve.

Sea Doo 787 800 GTX GSX XP carb carbed intake manifold rotary valve cover Seadoo | eBay

 

[mikidymac]

Anybody got a price on machining one of these covers?? I'm sure I'd laugh given the amount of time it takes me to machine one. I am curious though. You can find good covers on Ebay but watch the gougers... they have quadrupled the price on many items. I found this one for $50 which to me is cool even without the rotary valve.

Sea Doo 787 800 GTX GSX XP carb carbed intake manifold rotary valve cover Seadoo | eBay

$120 exchange price from SBT.

 

[etemplet]

Before the insanity in pricing parts were way cheaper. LOL
Problem with SBT is their shipping cost and you're return shipping which jacks the price way up. That might end up costing $160.

 

[etemplet]

What are you guys using to check the clearances? I bought some .032" solder. I place the solder at 11 O'Clock and 5 O'Clock about in the center. A lot of times you can look at the cover and see that it is not worn much or at all.

I've had one that was actually having problems starting and the valve was so damaged it was unbelievable. The owner tried starting the ski when it was full of water.. The valve itself was bowed.

 

[Black67tb]

I have used .062"

 

[etemplet]

I have used .062"

I find that 1/16" is a lot to compress and wonder if the reading may be on the shallow side as in a "false reading" due to the amount of mass that is being compressed (figuring you are smashin .62" down to .15"). That aluminum plate will bow in the middle because the bolts are so far out. I used to cut the .(062") in half which was a pain in the butt. LOL I'd use platic-gauge but I didn't find any for the sizes we are measuring. The process isn't that critical but Ilke to know exactly what I'm dealing with. I'm a macihinist by trade so to me details are very important. I'm much more confident using (.032") YMMV. Good Luck !