brian lewis087
Active Member
951 motor new top end and carb kit done .. it will stall out from idle to wto. can feather it and she wil fly
ty inadvance
ty inadvance
2000 rx
- Thread starter brian lewis087
- Start date
- Status
This kinda crap is not encouraging me to work on the 98XPL. What are your carb settings, high and low speed.? Took my ski out and had big time issues getting it to accelerate off idle. When I got back home and pulled the carbs, I had the low speed on the PTO completely closed.
Brian, I hate that engine with a passion! I have mostly stayed away from it, because though it looks kinda like the 2 stroke 787, it's actually a PITA 130 HP engine.
Your giving some really good info here, but there still leaves several things that could be causing the problem. First off, the 951 is the only Rotax that has "reed" valves instead of the rotary valve. These things are very finicky. If you have one that is slightly bent, or not making a seal, what will that lead too? Loss of vacuum. Everything your describing is related to vacuum. The reason you can get something from feathering is, your not opening your butterfly plates, causing a total loss of vacuum, and the little fuel your getting to the engine, is actually helping you build a little bit at a time.
When you rebuilt your carbs, did you do an air test? Did you check the pop-off pressures? On your mag carb, you have the fuel pump, that connects to your lower crankcase, that creates the reciprocating motion for pumping your fuel. Remember, the fuel pump does not squirt fuel into your engine, it's sucked it by vacuum. That fuel pump is only there to make sure, your fuel lines and carbs are full, and the rest is recirculated back to your tank. The fuel is introduced into the motor by the opening of your throttle plates. When that plate is closed, and your motor is at idle, you have an idle jet that is in front of that butterfly plate. It's what is creating vaccum at idle. As you begin to open it, fuel is "sucked" into the throat of your carb, because that vacuum pulls down on that diaphragm, where your needle valve is, opening it up and allowing fuel to pass into your idle jet. You have the idle jet (non adjustable), the low speed jet (usually adjusted to 1 to 1 and a quarter turn out, then your high speed jet, which really ain't a jet at all. It's actually a by pass around the jet, that's why it's normally closed.
To me, it sounds like you probably got an air leak. When you pulled off your carbs, did you pull off the reed valves? Did they look good, even, no gaps or reeds bent? It doesn't sound like a pop off problem, cause you can feather the gas to get there. If it were me, I think I'd take the carbs off, check the seals at the reed valves, then make sure your sealing surfaces to the carbs are very clean. They also make a spray you might want to try. It's gold in color, and it's almost like a tacking spray. If there are any leaks, it will stop them.
But, it does sound like you have an air leak. If you can get to it, while it's at idle, get some soapy water and try to squirt it at the base of the carbs, at the engine block. You'll likely not see the leak, but if it's bad enough, you'll hear the change in the sound of the engine.
Good luck, hope this was of some help to you!
- Status
