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Weird issue
- Thread starter Mekanix
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Hmm, The only reason I assumed it was raves opening is because If I adjust the raves in I can move the kick in to 5000 and if I set them flush I can move the kick to 4500. But yeah its a different animal once the main jets start taking over. IF its just the main's opening and taking over at 4500 then that mean's I've always had an issue with low end and now its much worse.
Can you actually feel the raves opening if that's the case ?
Once its on the main jet and in the upper ranges from 5000 on, everything is really smooth, responsive and I can control the rpm's by the 100's with throttle movement. Its very smooth and controllable in that range.
I tried lowering the rave opening to 4500 to help the transition and now I can smoothly transition from 4000 to 5000 without it hickuping and bucking. but its still hitting and missing until 4500 an then it just goes
Can you actually feel the raves opening if that's the case ?
Once its on the main jet and in the upper ranges from 5000 on, everything is really smooth, responsive and I can control the rpm's by the 100's with throttle movement. Its very smooth and controllable in that range.
I tried lowering the rave opening to 4500 to help the transition and now I can smoothly transition from 4000 to 5000 without it hickuping and bucking. but its still hitting and missing until 4500 an then it just goes
I was about to ask how do you get the oval shaped holes in the cap's vs just drilling a round hole.
I was going to install a few switches and LED's just to know for sure when they opened and maybe mount them near the info center or have something like a light bar that show's how much they are opening.
What RPM do you see yours opening ?
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Sportster-2001-951C-Stock
Well-Known Member
Switches an leds sounds like a winner to me, the curious me has been wanting that too. Most important mod for the to-do list is the fogging oiler.
Yeah I was thinking about that. Why not use a windshield washer pump and install a few fittings in the carb throat. Just have a remote windshield washer tank with a little bit of oil in it. Something from a small car would work great. Or any container would work. Just make sure the fittings in the carb body are restricted a bit. Those pumps can push allot. OR just use a reisistor inline that gives the right amount of flow you like. Then Just fill the tank with fogging oil right from the can and its ready to go whenever you need it.
I would actually use this every time I ride because I fog after every run with a 10 second shot in each plug hole and then start it up for 5 seconds just to fog the can as well.
In a seadoo its a bit tight for space but easy enough to do with a universal pump that you can just mount under any reservoir or inline. but on a boat I would just install the whole washer assembly tank and all because of all the room on the front wall. Maybe even a winterizing tank with antifreeze
Could make a it a one button does all
I would actually use this every time I ride because I fog after every run with a 10 second shot in each plug hole and then start it up for 5 seconds just to fog the can as well.
In a seadoo its a bit tight for space but easy enough to do with a universal pump that you can just mount under any reservoir or inline. but on a boat I would just install the whole washer assembly tank and all because of all the room on the front wall. Maybe even a winterizing tank with antifreeze
Could make a it a one button does all
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Sportster-2001-951C-Stock
Well-Known Member
I kinds like that idea, oil is considerably more viscus so I doubt there will be too much but if so an orifice can be inserted in the line.
I think I'm going to investigate this and see how the ww pump does, being electric I could install a switch on the helm or anywhere. Fog out the other boats at will too, just like James Bond, lol.....
I think I'm going to investigate this and see how the ww pump does, being electric I could install a switch on the helm or anywhere. Fog out the other boats at will too, just like James Bond, lol.....
lol, Used to do it in race car's that were fuel cut rev limited 
just a squirt and away you go way past red line...
Had the GSX out today. No change with the small pilots. Plugs are still wet and not cardboard. Even throttle response feel's slow compared to when I had the pop off set really high and it was leaning out.
I tried removing one plug wire and running on one cylinder. Still misses. Swapped to the other cylinder. Still misses. Swaped plug cap's, Still misses. Gets a bit better as engine warm's up.
Is smoother at 3200 a d 4500+ but 4000 is still hit and miss.
I'm leaning towards the ignitor pickup. I might be just bad at that particular resonance or RPM and I'm giving more throttle and its not letting it rev so its feeling like its rich and loaded up??
Or the CDI is dying slowly. I might try my other computer again on the water to see what hapen's.
Could be a bad ground inside the stator housing. Measures fine at rest but while reving it could be bad.
Still at a loss.
just a squirt and away you go way past red line...Had the GSX out today. No change with the small pilots. Plugs are still wet and not cardboard. Even throttle response feel's slow compared to when I had the pop off set really high and it was leaning out.
I tried removing one plug wire and running on one cylinder. Still misses. Swapped to the other cylinder. Still misses. Swaped plug cap's, Still misses. Gets a bit better as engine warm's up.
Is smoother at 3200 a d 4500+ but 4000 is still hit and miss.
I'm leaning towards the ignitor pickup. I might be just bad at that particular resonance or RPM and I'm giving more throttle and its not letting it rev so its feeling like its rich and loaded up??
Or the CDI is dying slowly. I might try my other computer again on the water to see what hapen's.
Could be a bad ground inside the stator housing. Measures fine at rest but while reving it could be bad.
Still at a loss.
Sportster-2001-951C-Stock
Well-Known Member
Hmm, it's possible an ignition issue I guess. Still think it's rich carbs, I'm stubborn, LOL. 
Sportster-2001-951C-Stock
Well-Known Member
More spring pressure more water you should have in pipe, no? Maybe I got confused when I had mine off playing with it. Pintle moves up to reduce cone pipe water right? And pressure in WB pushes the diaphragm up?
I musta got it backward....
I musta got it backward....
Hmm, it's possible an ignition issue I guess. Still think it's rich carbs, I'm stubborn, LOL.
Yeah I'm not sure either way. the only reason I'm thinking electrical now is because If I pull one plug off I still get the miss in the other cylinder and if I pull that one the miss is still on the other one. So that makes me think the issue is affecting both cylinders at the same time and both carbs being too rich could be the issue but less likely than ignition causing it.
I have a spare mpem and ignition pickup but not much for carb parts to work with.
Sportster-2001-951C-Stock
Well-Known Member
CDI can be a tricky animal so it's not impossible there's some strange malfunction, could even be advance curve related maybe.
Well I did some research and looks like the CDI only advances after 4000 so from 3 to 4000 the timing is constant and starts advancing after that. So I'm getting the issue just before its advancing.
Thinking maybe ground in the stator housing or the stator or the cdi itself. The mpem gets a signal from the cdi and I'm not sure if its the mpem that controls the curve or the cdi does. But its the MPEM that has the adjustment So I'm guessing it does the rev limiting and advance control.
Oh and the water regulator I had to think about that. I think its always dumping into the waterbox and pipe but as pressure rises in the box it moves the pintle up and cut's off how much goes to the pipe and just bleeds it off to the box instead.
Thinking maybe ground in the stator housing or the stator or the cdi itself. The mpem gets a signal from the cdi and I'm not sure if its the mpem that controls the curve or the cdi does. But its the MPEM that has the adjustment So I'm guessing it does the rev limiting and advance control.
Oh and the water regulator I had to think about that. I think its always dumping into the waterbox and pipe but as pressure rises in the box it moves the pintle up and cut's off how much goes to the pipe and just bleeds it off to the box instead.
Sportster-2001-951C-Stock
Well-Known Member
That's how I thought the regulator worked from when I had mine apart. Seems like if the pintle moved up there would be less water injected to the pipe. But you found the opposite was the reality, less spring pressure kept the pipe cooler, right?
Not that I want to know for my own purposes (I'll figure it out for myself when that day comes), but don't want to mislead anyone. Just b/c I think I know how it works doesn't make it true.
Right, you have to keep engine speed under 4000 while checking timing, that's what I remember. Not sure if MPEM controls that but I think it does. All I know is some CDI's have the advance curve built in dunno about Seadoo. The CDI is inside the MPEM on the 951 setup (Yuk!).
Not that I want to know for my own purposes (I'll figure it out for myself when that day comes
), but don't want to mislead anyone. Just b/c I think I know how it works doesn't make it true.Right, you have to keep engine speed under 4000 while checking timing, that's what I remember. Not sure if MPEM controls that but I think it does. All I know is some CDI's have the advance curve built in dunno about Seadoo. The CDI is inside the MPEM on the 951 setup (Yuk!).
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Dove into it tonight just to swap out some parts.
Changed the pickup, stator and re-assembled it. Still has that tell tale miss at 4000, I can even tell while its on the trailer.
Took the grey box apart again and checked all grounds and voltage between grounds just to be sure.
Then I took the CDI unit out and went through the resistance checks in the manual. Well, it failed that miserably! Several of the resistance values were way off. Like Mega ohms off the spec.
Decided the swap in my spare computer and replace the Mpem, holder relay, cdi with an all in one unit from the GTX. Surprisingly all wiring matched up and I only had to change two wires from one harness to the other.
It started. Everything seems to work. Just a mater of setting the ignition timing and trying it out.
Can these CDI's half fail?
Changed the pickup, stator and re-assembled it. Still has that tell tale miss at 4000, I can even tell while its on the trailer.
Took the grey box apart again and checked all grounds and voltage between grounds just to be sure.
Then I took the CDI unit out and went through the resistance checks in the manual. Well, it failed that miserably! Several of the resistance values were way off. Like Mega ohms off the spec.
Decided the swap in my spare computer and replace the Mpem, holder relay, cdi with an all in one unit from the GTX. Surprisingly all wiring matched up and I only had to change two wires from one harness to the other.
It started. Everything seems to work. Just a mater of setting the ignition timing and trying it out.
Can these CDI's half fail?
Sportster-2001-951C-Stock
Well-Known Member
Yes, I've had CDI's do similar things like that before. Mostly no start weak spark though, I think the capacitors go bad? Haven't heard of that much on the Seadoos though.
Does it run differently now?
Does it run differently now?
Its too late and too loud to tell. It started and revd to 4500 or just into the smooth range, Could be just not primed fully yet and running leaner or its working better I'll have to lower the idle to find out. And I think the timing was different in this computer. Mine was 1 degree advanced. This computer is set at -1 I think it was.
Weird that it works and starts just fine but only one specific range is affected.
I'll have to lower the idle to find out. And I think the timing was different in this computer. Mine was 1 degree advanced. This computer is set at -1 I think it was.Weird that it works and starts just fine but only one specific range is affected.
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Sportster-2001-951C-Stock
Well-Known Member
This is too rich down low, not a lean hesitation, right? If it was a lean hesitation first place to start is making sure fuel lines are airtight. Is that fuel pickup the baffle type with draw tubes down low in the tank, cracked baffle gets you airated fuel.
So much for the failed CDI test procedure.
I guess if a crank seal was leaking you'd notice a lean condition or an intermittent lean condition like runaway on trailer and trouble adjusting a steady idle and maybe by now would've roasted something front or back? You did say one cylinder was missing... Thought that was corrected at the carb? Haven't you had the head off as well?
Rich 4-stroking(eventually clears out with more throttle) or lean hesitation(must back off throttle else runs out of fuel, falls flat on it's face and quits), that's the question.
If it's too much fuel then turn it down.
Not sure about the rotary valve.
Aside: Cutting firewood today. Gassed up a chainsaw hadn't used in a couple years, pull and pull, and nothing... Fuel pump check valves were stuck like glue to the valve body, wouldn't pump fuel.
So much for the failed CDI test procedure.
I guess if a crank seal was leaking you'd notice a lean condition or an intermittent lean condition like runaway on trailer and trouble adjusting a steady idle and maybe by now would've roasted something front or back? You did say one cylinder was missing... Thought that was corrected at the carb? Haven't you had the head off as well?
Rich 4-stroking(eventually clears out with more throttle) or lean hesitation(must back off throttle else runs out of fuel, falls flat on it's face and quits), that's the question.
If it's too much fuel then turn it down.
Not sure about the rotary valve.
Aside: Cutting firewood today. Gassed up a chainsaw hadn't used in a couple years, pull and pull, and nothing... Fuel pump check valves were stuck like glue to the valve body, wouldn't pump fuel.
I think the CDI is ok. Fail's the manual's test but works just as well as the one I have in there. But then again the one I have in there might not be good either
Its just weird...
Had the head off to change the o-rings and there was a problem with the carbs that was fixed with rebuilding the mag carb.
Also I had the pop off so high that it was running lean but it was on both.
Since then I've gotten the carbs to be somewhat manageable.
Everything above 1/3 throttle or when on the main jet or raves open, Not sure which it is but its smoothed out after that.
If it was an intermittent crank seal I would have hoped to see some evidence of what to look for.
Pulled the engine out tonight (I'm getting good at this lol)
Going to replace the mag gasket and seal. Also the rotary valve , valve cover, O-ring.
But first I'm going to make some blanking plates to do a leak down test. Hoping something will start hissing and maybe an AHA moment will hit me.
Got an OEM valve this time!
Started reading up on how rotary valves work. I guess at high rpm's its inertia that pull's the new charge in and at lower rpm's its the low pressure that draw's it in.
Maybe there is a problem with the signal. As in the engine want's to pull in a new charge but the valve is allowing a back flush enough to equalize the pressure or cause it to reverse for a second.
Its just weird...
Had the head off to change the o-rings and there was a problem with the carbs that was fixed with rebuilding the mag carb.
Also I had the pop off so high that it was running lean but it was on both.
Since then I've gotten the carbs to be somewhat manageable.
Everything above 1/3 throttle or when on the main jet or raves open, Not sure which it is but its smoothed out after that.
If it was an intermittent crank seal I would have hoped to see some evidence of what to look for.
Pulled the engine out tonight (I'm getting good at this lol)
Going to replace the mag gasket and seal. Also the rotary valve , valve cover, O-ring.
But first I'm going to make some blanking plates to do a leak down test. Hoping something will start hissing and maybe an AHA moment will hit me.
Got an OEM valve this time!
Started reading up on how rotary valves work. I guess at high rpm's its inertia that pull's the new charge in and at lower rpm's its the low pressure that draw's it in.
Maybe there is a problem with the signal. As in the engine want's to pull in a new charge but the valve is allowing a back flush enough to equalize the pressure or cause it to reverse for a second.
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Sportster-2001-951C-Stock
Well-Known Member
Squish of 1.6 vs 2mm doesn't sound so bad considering the compression is so dang high? How about cc'ing the combustion chamber, isn't there a TDC cc spec somewhere?
Or, toss your old head on and give that a whirl?
Or, toss your old head on and give that a whirl?
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