720 Rotary valve cover indentations vs smooth?

[andy.262]

My rotary valve cover is shot, deep grooves in it. Looking to get a good used one from eBay, and I'm noticing that many of them have these indentations on the surface that my current one does not have. What is the purpose of these indentations, and are they interchangeable with/without them? Is one better than the other in some way?

I'm seeing that the one with the indentation is stamped 810-527, while the smooth is stamped 810-522 (like my current, damaged one) but they both come from a 720 engine which makes me want to believe they are interchangeable.

 

[etemplet]

Did you lay a straight edge across the surface of your cover just to see what it looks like? Did you do the checks to determine how much clearance you have currently?

I'm not sure if those slots help a lot as they were discontinued. I wouldn't concern myself if there were present or not.

 

[andy.262]

This is from my GTI that the previous owner allowed those cageless needle bearings to fall into the crankcase. Both the rotary surface on the case and the rotary cover have actual chunks taken out of them near the ports and extremely deep groves. I'm getting a good used crankcase and a good used rotary valve cover, so can't really measure anything since I don't have either half yet. This question is just to make sure I don't accidentally purchase a rotary cover that I can't use for whatever reason.

 

[Darrol13]

My rotary valve cover is shot, deep grooves in it. Looking to get a good used one from eBay, and I'm noticing that many of them have these indentations on the surface that my current one does not have. What is the purpose of these indentations, and are they interchangeable with/without them? Is one better than the other in some way?

I'm seeing that the one with the indentation is stamped 810-527, while the smooth is stamped 810-522 (like my current, damaged one) but they both come from a 720 engine which makes me want to believe they are interchangeable.

View attachment 66769 View attachment 66770

After listening to people debate how to fix this problem I went ahead and used jb weld it worked perfectly my jetski runs like a dream

 

[Darrol13]

Just file indentations then sand flat making sure its flat

 

[Darrol13]

This was the gouge from port to port before I filled the jb

 

[WhiskeyD]

This was the gouge from port to port before I filled the jb

We'll see how long that last

 

[burtshaver2021]

I was thinking the same thing

 

[burtshaver2021]

But have to give the OP points for ingenuity and effort. Let us know how it turns out long term

 

[andy.262]

Updating for anyone viewing this in the future. The original 2 parts I posted, the cover WITH the indentation (810-527) and the one WITHOUT (810-522) are NOT in fact interchangeable. from what I can tell, the 527 part is for a dual carb intake, vs the 522 part which is for a single carb intake (which is the setup I have in my GTI).

You can see the bolt pattern and o-ring shape are completely different on the 2 parts and you will not be able to bolt your single carb intake to a 527 part, you must get a 522 part. Even though they are both from a 720 engine. Learn from my mistake and save you some time and money.

In hindsight, they are obviously different part numbers, so like, duh, of course they aren't the same part. Oh well, lesson learned. I guess I now have an extra rotary cover for a dual carb 720 for if I ever acquire a ski with a bad one.