rotary valve?

[skipperchuck]

D solie, iam sure you can help,paid a good tech to swap out a SBT 787,all is good, but have not run it,cause he said there might be a prob with rotary valve.keep in mind fired it up twice reves fine,but the nature to stranding me was rotary valve fail..I understand that the rotary valve is important,can engine run fine without it?.Anyhow why is the shaft gear on said valve made of weak *** brass?Also there is no way in hell to jimmie rig a rotary valve from what i have read? thanks 20 year+ rider not a tech

[dsolie]

Re: rotary valve?

No, the motor will not run without the rotary valve. The RV is like an injector, open at times, closed at times. Each time it is open, it allowed the pre-determined (by the carbs) amount of fuel and air into the crankcase, which is then taken to the top, compressed and ignited. When it is closed, it keeps the lower case compression in the crankcase so it can be pushed to the top of the cyl to be ignited. Having no RV would just force that fuel-air back out of the carbs when the piston is traveling down (path of least resistance)

The RV gear is made from brass because it is a weaker metal. When you have two forces that attack each other, the weakest one looses. SD, and rightfully so, decided that if and when the RV get's snagged, or a motor top end fails, it's cheaper and easier to replace the RV & gear than the entire crank / possibly the crankcase.

Why does your tech think there is something wrong with the valve?

[skipperchuck]

Re: rotary valve?

thanks dsolie your know these rotax like a book,if i remember ,tech said something like you should also replace R/V cause it mite have caught a loose part/ something in it.he suggjested a new cover and R/V. like i said it fires up,fine but have not even rode it to break it in/load on the motor.is the RV cut and dry? meaning you can make it run out of the water, no load, as far as my motor is now?i dont now how to say it other than when I jammed him up on His opinion on the RV ,it was like you should be ok??.I know Iam going to replace anyhow .. TYVM

[skipperchuck]

Re: rotary valve?

BTW like i said dont know squat about RV and fanagualing them, but the tech's tone on the rv talk,left me thinking to ask the pros here.. again..TYVM

[dsolie]

Re: rotary valve?

RV's are pretty cut and dry, but they can behave differently on land as they do in the water. If the RV snagged on something, you would KNOW it and the tech should have said you NEED a new cover, period and not you might want a new one.

If it starts, idles and revs well, I say go for a gentle lake test.... If you floridan's hit 70 degrees and it's too cold to ride for ya (haha), then pull the RV and cover and take a look yourself. Take some pics and post them up on here. The main thing to look for is deep grooves and burrs (sharp edges from an impact)

[skipperchuck]

Re: rotary valve?

thank you your very helpfull,i love that ski its light,and pretty good hp. i was mainely worried cause i tend to venture out alone, were there is not alot of company.any how good ideal will open it up and look around,But it is never to cold to ride out!!!if its frozen hockey time,have not seen that down here yet lol.....good day skipper out