GTX 787 NEW 82.25 top end

[ape1972]

Hello everybody!
I’m sure this question has been asked but...
I just got a new top end on my 96 GTX 787 and had a question regarding the rave valves. I was able to go to a 82.25 MM and wanted to know if I need to trim the rave valves? I’ve read that I didn’t need to but my question is would it be a good idea to trim them anyway?

Thank you in advance,
Adrian

 

[Mekanix]

Best thing is to measure and see how close you are. Keep in mind that used raves and used cylinders might wear in a way that the raves come closer than what it says in the specs. So measure and then rock the valve side to side and see if any portion of it comes closer. Your not trimming much at all. For me I use an old piston with 400 grit sandpaper wrapped around it. And pass the valve over that at the same angle as what it is when its mounted in the cylinder. Only 2-3 passes is enough to get the minimum 25 thou gap I'm looking for.

 

[etemplet]

Agreed Mekanix.... I'd check as well. I'm working on a 787 that I thought I ordered .25mm over but I see I have .5mm. That gives me a little mechanical cushion on clean up anyway but I think. .25 would have worked. I've gone larger and had to break out the file and I agree.... sometimes the valve hammers the cylinder which allows the valve to go a little deeper than when new.

When installing the blade and valve check closely to make sure nothing is dragging and the valve moves freely. The gasket can cause drag and hold the valve open which it will melt the piston quickly... Ask me how I know. LOL Good Luck !!!

 

[Chester]

Hello everybody!
I’m sure this question has been asked but...
I just got a new top end on my 96 GTX 787 and had a question regarding the rave valves. I was able to go to a 82.25 MM and wanted to know if I need to trim the rave valves? I’ve read that I didn’t need to but my question is would it be a good idea to trim them anyway?

Thank you in advance,
Adrian

No need to trim them, you're good to go.

Chester

 

[ape1972]

Thanks for the help guys! I will check the gap

 

[Chester]

Shaving the valves is only required at .5mm oversize and up.

Chester

 

[Matt Braley]

Right and shaving the valve back more then needed can weaken the bottom end power.

 

[etemplet]

Thanks for the help guys! I will check the gap

Check twice... cut once. LOL