How much to shave 951 RAVE Valves?

[AZ Sea Doo XP]

How much to shave 951 RAVE Valves? I went .50 over. How much should be removed? Thanks!

 

[AZ Sea Doo XP]

Anyone, anyone?

 

[jhjesse]

Shave 0.25 off as that is half the diameter.

 

[racerxxx]

Shave 0.25 off as that is half the diameter.

I think that is a little too much. But shouldn't hurt performance any.


Below is what is for a 787, but you talking clearance. OEM only goes to the first over so you don't have to cut the rave valves.



So for a piston that is Standard bore there is .5mm or .020" clearance.

So for a piston that is .25mm over size that is an OEM first over which will cut your clearance by .005" (.020" to .015")

No need to clearance the valve for the ABOVE 2 scenarios



So a piston that is .5mm over you need to shave the rave by .005" to get back to the minimum of .015", if you wanted to get back to stock clearance you would go .010" to get you back to the .020" clearance.

So a piston that is .75mm over you would need to shave the rave by .010" to get back to the minimum of .015", if you wanted to get back to the stock clearance you would go .015" to get you back to the .020" clearance.

So a piston that is 1.0mm over that is piston to rave no clearance you need to shave the rave by .015" to get to the minimum clearance or go .020" to get back to the original .020" clearance from the factory

So a piston that is 1.5mm over you are negative .005", so you need to clearance the valve .020" to get to the minimum of .015" or go .025" to get to the original .020 clearance from the factory.

 

[jhjesse]

So 0.25mm is 0.005" too much. I believe that is approximately a skinny frog hair. :lol:

 

[AZ Sea Doo XP]

I really want to do this right, so I need some help! Do I look for a skinny frog, the remove a hair? Or do I look for a frog that has skinny hair? I have looked all morning and cant find either. this could be a problem! :lol:

 

[AZ Sea Doo XP]

I had .020 taken off.

 

[jhjesse]

So look, your engine will run good with 0.20 removed and never have a problem. Sorry if I caused any confusion.
If my cylinders are punched over 0.25mm, I don't do anything to the rave as it is still within spec.
If my cylinders are bored 0.50 up to 1.00mm, the amount I shave off the rave is exactly half of the amount removed from the bore diameter. It accomplishes two things. Maintains the exact same rave clearance as from the factory and takes allowance guess work out of the equation.
Again that is what I do. Always follow the admin racerxxx advice as he is...well the admin.

 

[AZ Sea Doo XP]

no confusion! thanks for the info!

 

[racerxxx]

So look, your engine will run good with 0.20 removed and never have a problem. Sorry if I caused any confusion.
If my cylinders are punched over 0.25mm, I don't do anything to the rave as it is still within spec.
If my cylinders are bored 0.50 up to 1.00mm, the amount I shave off the rave is exactly half of the amount removed from the bore diameter. It accomplishes two things. Maintains the exact same rave clearance as from the factory and takes allowance guess work out of the equation.
Again that is what I do. Always follow the admin racerxxx advice as he is...well the admin.

Admin is just a name, it does not mean I know everything. I also claim to not know everything, you learn every day.

 

[AZ Sea Doo XP]

do you know what the going rate is for a machine shop to do the shaving?

 

[racerxxx]

No idea, I would do it myself. Full bore does it.

 

[AZ Sea Doo XP]

how do you do it and how do you make sure you are removing the correct amount?

 

[tkarvelis]

I think I read somewhere that guys take a sharpie and put a mark along the edge of the valve. Then take a piece of sandpaper wrapped on the piston and sand a bit off. It does not take much.

 

[jhjesse]

You can send your cylinders to full bore and they will bore and size Pistons to match. Everything will be included for the price.
SES will do about the same service.
SBT has a cylinder exchange program where you exchange your cylinders as a core for a top end kit.
There is another place called Group K. I think they are in California. I here they do good work.

You can also use a local machine shop. If you go this route take your cylinders to them first and have them measure to determine how much can be machined for min cleanup. Then order your pistons and take them to your shop along with the specifications found in your manual i.e. Ring gap, taper, piston clearance, tir, etc.
Have them machine to your specs and cut the raves while they are machining your cylinders. I am getting a set of cylinders done right now for 50$ a hole.

 

[racerxxx]

The above(one past jhjessee)is a good method. I stop at the first over on my cylinders so I won't have to cut raves. I only run OEM parts in my engines.

 

[AZ Sea Doo XP]

This is the RAVE valve after I got charged $75 (for both, which I am told, is a LOT), for a .0020 shaving. . I know it is hard to tell if it is correct, but it looks like a LOT of material was removed. Any suggestions on how to tell?