Troubles with 90 SP
- Thread starter Josh
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Are you the original owner? Is this a used boat? Do you have any history on it?
Some places to start if you are unsure about any of this:
- Become a premium member to download the shop manual!
- Check cylinder compression
- Plenty of fuel?....how do you know?
- check external fuel filter
- condition of fuel lines
- remove and clear out fuel selector valve (compressed air helps)
- jets to the carbs - are they clogged? You can deliver a lot of fuel that isn't spraying right.
Report back on what you have done or found. We can help walk through it.
Some places to start if you are unsure about any of this:
- Become a premium member to download the shop manual!
- Check cylinder compression
- Plenty of fuel?....how do you know?
- check external fuel filter
- condition of fuel lines
- remove and clear out fuel selector valve (compressed air helps)
- jets to the carbs - are they clogged? You can deliver a lot of fuel that isn't spraying right.
Report back on what you have done or found. We can help walk through it.
non running 90 SP's
I am not the original owner.The skis were supposed to have been rebuilt last winter.I have had the skis to a mechanic and he said they were getting plenty of fuel and plenty of spark.He even put a hand primer ball on one of the skis, but it still will not start.The skis have 130 lbs. compression.The mechanic thinks the rotary valve is out of time but hes not sure.The manual says to set the rotary valve timing at 130 deg. but I read somewhere that it should be at 115.Im not sure what I need to do from here!!!
I am not the original owner.The skis were supposed to have been rebuilt last winter.I have had the skis to a mechanic and he said they were getting plenty of fuel and plenty of spark.He even put a hand primer ball on one of the skis, but it still will not start.The skis have 130 lbs. compression.The mechanic thinks the rotary valve is out of time but hes not sure.The manual says to set the rotary valve timing at 130 deg. but I read somewhere that it should be at 115.Im not sure what I need to do from here!!!
Rotary Valve
I researched this and typed a full comment and for some reason, I got shut down on my internet connection.
I'm 99.9% sure it's your rotary valve and later this evening, I'll re-type my findings on why I think it's your rotary valve....
I'll be in again around 8:00p.m. central time.............
O.K.....the rotary valve. I do think the rotary valve could be your problem. My information is from the 1994 SP because I don't have anything on the 1990, but I still think the info is good for reference.
You've got spark and fuel but no ignition. This could be caused by the clearance between the rotary valve and cover. If the the rotary valve clearance is over the required .35mm clearance, then the engine will be extremely hard to start, if it starts at all. On the other hand, if it's below the .35 mm of clearance, the engine will run, but run hot. There are also other things in the rotary valve that can cause you problems such as the backlash and the deflection. For the 1994 SP model, the rotary valve type was 147 degree wheel and the XP was a 159 degree wheel. They both are interchangable mechanically, but won't operate properly if installed on the wrong engine (which on our premium members section, you can see these rotary wheels in actual size to understand the difference). The purpose of the rotary valve is to control the opening and closing of the inlet ports in sequence for cylinder fueling and ignition.
You were partially correct on the timing. The 1994 SP is set to be open at 130 degrees BTDC (before top dead center) + or - 5 degrees and the closing at 65 degrees ATDC (after top dead center) + or - 5 degrees.
So if you got spark on the plugs and it's obvious they show signs of fueling, I'd bet heavily on the rotary valve either being out of clearance or out of timing.
This information is based on the 1994 SP and I believe that it's entirely possible the 1990 shares the same engine and set-up.
I am not a certified OEM mechanic but have worked on small engines, automobile and outboard engines practically my entire life. I say that because I don't want you to take my advice as that of an OEM certified mechanic. It's entirely based on research and my understanding of the Rotax engine and may or may not be completely accurate to your problem.
Please let us know what you do and what you find out. I'll be curious to know if you find a solution and what you did to find it.
I researched this and typed a full comment and for some reason, I got shut down on my internet connection.
I'm 99.9% sure it's your rotary valve and later this evening, I'll re-type my findings on why I think it's your rotary valve....
I'll be in again around 8:00p.m. central time.............
O.K.....the rotary valve. I do think the rotary valve could be your problem. My information is from the 1994 SP because I don't have anything on the 1990, but I still think the info is good for reference.
You've got spark and fuel but no ignition. This could be caused by the clearance between the rotary valve and cover. If the the rotary valve clearance is over the required .35mm clearance, then the engine will be extremely hard to start, if it starts at all. On the other hand, if it's below the .35 mm of clearance, the engine will run, but run hot. There are also other things in the rotary valve that can cause you problems such as the backlash and the deflection. For the 1994 SP model, the rotary valve type was 147 degree wheel and the XP was a 159 degree wheel. They both are interchangable mechanically, but won't operate properly if installed on the wrong engine (which on our premium members section, you can see these rotary wheels in actual size to understand the difference). The purpose of the rotary valve is to control the opening and closing of the inlet ports in sequence for cylinder fueling and ignition.
You were partially correct on the timing. The 1994 SP is set to be open at 130 degrees BTDC (before top dead center) + or - 5 degrees and the closing at 65 degrees ATDC (after top dead center) + or - 5 degrees.
So if you got spark on the plugs and it's obvious they show signs of fueling, I'd bet heavily on the rotary valve either being out of clearance or out of timing.
This information is based on the 1994 SP and I believe that it's entirely possible the 1990 shares the same engine and set-up.
I am not a certified OEM mechanic but have worked on small engines, automobile and outboard engines practically my entire life. I say that because I don't want you to take my advice as that of an OEM certified mechanic. It's entirely based on research and my understanding of the Rotax engine and may or may not be completely accurate to your problem.
Please let us know what you do and what you find out. I'll be curious to know if you find a solution and what you did to find it.
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I have pulled the rotary valve cover off of 1 of the machines and the valve seems to be set at the timing mark on the case.These are the original cases so I would assume that they are right.I still do not have the machine running not sure where to go from here. I did reset the rotary valve to 115 deg. to see if that made a difference but that did not do anything either.I had read somewhere that the rotary valve should be set at 115 deg. so I thought I would try it while I had the cover off!
Rotary valve?
Josh, did you try and turn the shaft of the rotary valve? Just wondering if the shaft, where it connects to the crank, may be broken. Would be very coincindental that both were broken at the same time.
If you got spark and fuel/air, good compression, there is basically nothing left except the timing.
The other thing to consider is if these are the original engines, then there 17 years old. Worn out mechanincal and electrical parts can play a major role too. There are some very close tolerances that the machine needs to adhear to for it to run well. But to have the compression you say you have, spark on the plugs and fuel, I'm stumped!.....you should at least get it to backfire..........
Let me know if you find anything else out.
Josh, did you try and turn the shaft of the rotary valve? Just wondering if the shaft, where it connects to the crank, may be broken. Would be very coincindental that both were broken at the same time.
If you got spark and fuel/air, good compression, there is basically nothing left except the timing.
The other thing to consider is if these are the original engines, then there 17 years old. Worn out mechanincal and electrical parts can play a major role too. There are some very close tolerances that the machine needs to adhear to for it to run well. But to have the compression you say you have, spark on the plugs and fuel, I'm stumped!.....you should at least get it to backfire..........
Let me know if you find anything else out.
I did get the 1 machine running with the timing set at 115 deg.I then went and got some fittings to hook up the garden hose to it.When I first got it to fire up it did shoot alot of what seems to be fuel and oil out the back.I suspect this would be from trying to crank it so much to get it to start but it just not starting but do not know for sure.I assume all the fuel and oil was going into the exhaust and laying in there since it would not fire?When I get it to start it will only run for about 30 seconds and that is with me working the throttle then it dies.I do have a good stream out the back so I know water is running through it!What should I look for and should I just run it premixed and do away with the oil tank, if so what do I have to do just plug off the oil feed line and premix the fuel? What should I mix the fuel ratio at?
Premix?
Josh, I know JoeZ has recommended a ratio of 40 or 50:1 to others. I believe he has more experience in suggesting the procedure of the switch over. I still use oil injection and I've read posts that he's made about going to premix and I think your right. I think you just cap off the oil lines going to the carbs. But I'd advise JoeZ to help you out on that one.
The oil and fuel spitting out the back would be from you constantly trying to crank. If it's runnig for a few minutes before dying out on you, while your working the throttle, does it sound like your getting to much fuel, like its choking out on you? Does the engine seem to struggle to run, like it's seizing up? To much fuel will keep the engine from igniting as will the timing.
Like I said before, an engine this old, could be several things. If it's running, I'd look at the syncro on the carbs. In short, both throttle plates need to start opening at the same time.
Josh, I know JoeZ has recommended a ratio of 40 or 50:1 to others. I believe he has more experience in suggesting the procedure of the switch over. I still use oil injection and I've read posts that he's made about going to premix and I think your right. I think you just cap off the oil lines going to the carbs. But I'd advise JoeZ to help you out on that one.
The oil and fuel spitting out the back would be from you constantly trying to crank. If it's runnig for a few minutes before dying out on you, while your working the throttle, does it sound like your getting to much fuel, like its choking out on you? Does the engine seem to struggle to run, like it's seizing up? To much fuel will keep the engine from igniting as will the timing.
Like I said before, an engine this old, could be several things. If it's running, I'd look at the syncro on the carbs. In short, both throttle plates need to start opening at the same time.
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Actually you are right on. Unless you have RAVE valves, you can cap off the lines and remove the entire system. If you have the valves, then you cap off the lines to the carb, and leave the ones to the valve.
As quoted, 50:1 or 40:1 works.
Especially with the older oil injection systems, a failure can completely cripple an engine and you'd never know it until it was too late. I know not everyone agrees with me, which is fine, but it is my personal opinion that the weakest link in the chain should be removed.
As quoted, 50:1 or 40:1 works.
Especially with the older oil injection systems, a failure can completely cripple an engine and you'd never know it until it was too late. I know not everyone agrees with me, which is fine, but it is my personal opinion that the weakest link in the chain should be removed.
I was curious as to if anyone knows for sure what the rotary valve timing should be set at?When I pulled the cover off of the one machine the rotary valve was lined up with the factory arrow that was on the case the manual and several sites on the web state to set it at 130 deg. I did read somewhere to set it at 115 deg. which is about 12 oclock.I set it at 12 o'clock before I put the cover back on to see what it would do and found it will start but will not idle.I can keep it running with the throttle but I did not let it run very long because I did not have the hose hooked up to it.What will happen to a machine if the rotary valve is not set at the correct timing?I believe the idle problem is possibly the carb but I do not know for sure I am planning on hooking up the hose to it later this week at try to mess with the carb to see if it will idle.I do have alot of fuel coming out the exhaust but could that be from the ski be cranked alot and not starting I mean the fuel does have to go somewhere and if it is not starting I would assume it would goto the exhaust and lay in it until it is blown out?Any suggestions or assistance would be greatly appreciated!
PM josh...
Josh, I just sent you a PM if you'd like to check it out and respond for me
Josh, I just sent you a PM if you'd like to check it out and respond for me
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