Brand new SBT rotary valve cover pitted ?

[makaveli07]

Hey everyone,

i bought a brand new rotary valve cover from SBT, had to go that route as its the only place i can get a refinished one. It arrived in the mail but it looks pitted… should i be concerned ?

 

[mikidymac]

It should be fine but I would call them and complain. Apparently SBT isn’t very concerned with quality cores.

 

[makaveli07]

It should be fine but I would call them and complain. Apparently SBT isn’t very concerned with quality cores.

Yeah i mean mine wasn’t in very bad shape but i figured id get one in good spec since I’m doing a full rebuild so its kind of disappointing not to mention they messed up my address and caused a delay of 5 days and said they would call me to refund shipping (113$ USD) to canada and they didn’t

 

[mikidymac]

Needless to say I’m not a big fan of SBT due to this kind of quality. Or lack of.

 

[makaveli07]

Needless to say I’m not a big fan of SBT due to this kind of quality. Or lack of.

This is why im rebuilding my own motor, didn’t trust buying one from them. Sent the cylinders and rave valves put to Group K and the crank shaft and counter balance to Competitive crankshafts. The crankshaft and counter balance came back they look amazing, waiting on Group K shouldn’t be too long before they come back and ill be ready to assemble

 

[makaveli07]

That rotary valve cover really gets on my nerves, but it is what it is… if its safe to run… ill just run it

 

[makaveli07]

Im probably over thinking this and just too pick but im concerned about shit like this … spend all this money and time rebuilding the engine… im afraid this something might send some metal fragments into the engine. Probably overthinking it tho as it seems pretty solid by hand but I'm not sure how much load this is under, and i wanna make sure its safe before i destory all the hard work and money put in (il very picky i know )

 

[Mekanix]

I personally would not use it.
It will work. Thats for sure. Just try and make sure every edge is smoothed out a little first.
But I wonder is if those holes would cause cavitation at all. I sometimes see rotary valves that look pitted from corrosion but the patern looks more like a prop that has gone through some cavitation for a while.
Also all oem covers I've seen have vertical lines in them. I always though this was to hold oil and minimize surface contact as well as help with minimizing cross port transfer by creating turbulence.

 

[KyleW2]

My opinion is if you are that worried about it, I’d call and complain. You’ll always have doubt about it. If it’s going to make you worry about riding the ski every time you start it up, it’s not worth it.

 

[etemplet]

Hey everyone,

i bought a brand new rotary valve cover from SBT, had to go that route as its the only place i can get a refinished one. It arrived in the mail but it looks pitted… should i be concerned ?

Run it. No problems at all. Don't give it a second thought. That's not SBT's fault it is imperfections in the casting. That part is not all the critical anyway. I've had engines run very well at 40% more clearance than recommended. I'd pass a 1/2 round file aroun the permiter of the ports to give them a little bevel. Othere than that... ride it like ya stole it.

I machine these at home when needed. I think some people would be suprised at what they would find in their running skis after inspection. If you think yours is perfectly flat....Hmmmm... they get pretty bad before they cause problems starting. I guarantee you the more you look to the problems you'll find. Best to be a little nearsighted. The engine often doesn't care.

NOTE: After further consideration concerning this part... this made be a "Made in China" part. That crap casting wreaks of the kind of cheap work that comes out of there. Unless of course SBT welded up and machined the cover which to me would be cost prohibitive. I'd send them a picture... NOT a complaint and ask them about this.

 

[etemplet]

Just for consideration's sake, how would the engine respond to this cover if I left the surface "as is" and installed it? Lets just say... it would take an additional (.005") to clean that up. What is critical? What are you trying to seal with this assembly?

 

[AKnarrowback]

Just for consideration's sake, how would the engine respond to this cover if I left the surface "as is" and installed it? Lets just say... it would take an additional (.005") to clean that up. What is critical? What are you trying to seal with this assembly?

My limited experience with out of tolerance rv covers.

All of the 92 SPs, single carb 580, that I set up had rv covers with too much clearance by a couple thousandths. On the first 10ish I set up that season, I'd say 8 failed the test ride. They started fine, ran fine but if you shut the hot motor down it would not restart until things cooled off. Hard starting when warm.

On my 94 XP I was fighting terrible low end performance, hole shot and low throttle settings. Carbs were good, I got rid of the stock impeller that was way to high on the pitch and still had sluggish response down low. I measured my RV cover clearance and it showed about .004" to .005" out if spec on the wide side but did not show up as a hard starter when warm,only a poor performer. I had a local shop mill it back to stock, not too tight or loose, and the machine came alive with only that one change.

I have heard a characteristic of too little RV cover clearance can be engine overheating, but I have no experience with that.

I do know that the guts racing Rotax sleds would machine to the min stock or a couple thousandths less to get a little more snap from the motor off the line.

 

[etemplet]

Interesting. I've seen some pretty busted up shiznit starting and running. I think clearance spec is .010-.014". I've had no problem with .018 but I'm not racing. The cover in the picture... the ski was running and I took some metal off that thing. LOL

 

[makaveli07]

So SBT, made right by their mistakes. They sent me a label to ship back my pitted rv cover all the way from Canada, and sent me a new one they was here the next day from when i shipped mine (cross shipped), new RV looks much better than the other one, they had their warranty manager check the RV with the engineer before sending it out, and they agreed to refund shipping for the delay, for what its worth they stood behind their mistake, sure it took some back and forth convincing but they ultimately made it right! And thats all i care about.

 

[mikidymac]

That is great news and thanks for reporting back on the good SBT service.