2000 RX slight hesitation at 3000 rpm

[boatrboy]

I have a new SES rebuild in my ski and am just breaking it in. It runs fantastic except for a minor hesitation at around 3000 rpm if I slowly accelerate. If I hold it wide open from idle it jumps up with no hesitation at all. I have the carbs set to the factory settings and thinking about opening up the low speed screws slightly but wanted to see what the more experienced guys think.

Some reference info:
Rebuilt premium motor
Rebuilt carbs with OEM kits from OSD
New fuel and vent lines
Cleaned raves
New oil lines
I am running with an extra ounce of oil per gallon (in gas tank) per SES instructions.

I am very happy with the performance as she hit 58 when I gave it a short burst. It starts right up and idles great. At that 3000 rpm mark it almost sounds like a mis- but more throttle it does not even bog, it just goes. I maybe be worrying for nothing.

Any input is appreciated!

 

[tkarvelis]

Have you replaced or cleaned the fuel selector? Does it run better on reserve? Have you pulled the choke out a bit at 3k? If it runs better, you are lean, if not, it is rich.

 

[boatrboy]

Have you replaced or cleaned the fuel selector? Does it run better on reserve? Have you pulled the choke out a bit at 3k? If it runs better, you are lean, if not, it is rich.

I have throughouly cleaned it when I replaced the fuel lines. I have not tried reserve yet. I will try the choke trick next time I ride it.

 

[SabrToothSqrl]

Is the engine warm when you do this? It's a big carb 2 stroke, so it's not going to jump like a fuel injected engine does from any RPM.

How do the plugs look?

If this is the first tank (break in, extra oil) I'd wait for at least the 2nd -3rd before you get too stressed about tuning. I chased a top end problem across 3 years to find out it was the jets...

 

[mikidymac]

It could also be the RAVE valves opening, Not sure of the exact rpm this appens though.

 

[boatrboy]

Is the engine warm when you do this? It's a big carb 2 stroke, so it's not going to jump like a fuel injected engine does from any RPM.

How do the plugs look?

If this is the first tank (break in, extra oil) I'd wait for at least the 2nd -3rd before you get too stressed about tuning. I chased a top end problem across 3 years to find out it was the jets...

It seems to happen more cold- but then again, since it runs so well as a whole, I don't remember for sure. This is my second tank so I will chill for a little on this issue. The plugs look perfect to me. I may just try opening up the low speed jet an eighth of a turn to see if that does anything.

Thanks for the feedback

 

[mikidymac]

I know when I am breaking in a new engine I am super worried and hear every little thing. Also since you are being easy on the throttle and varying in up and down I tend to notice it coming "on the pipe" more than normal. Most modern 2 strokes will come to life around 3000-4000 rpm and the RAVE valves add to this. It might just be transitioning into the powerband especially since you indicate it idles and runs perfect.

 

[boatrboy]

Tonight I rode for an hour or so. I may, as you suggest may be worrying for nothing. Here is what I experienced:
-From idle, I crack it wide open and it nearly stands straight up (ok that's exaggerating but close) and I have to hold on for dear life. No hesitation just perfectly smooth acceleration.
-If I slowly accelerate around 3-4000 rpms I noticed what I described earlier as a hesitation, but now I am thinking it is at the point where the ski is about to plane so I may just be feeling some kind off transition as mentioned earlier with the raves or just between low and high speed jets. I did pull the choke a little and no change. Now I did slowly accelerate until I felt this and then cracked it open and it jumped right up with no hesitation.

I am hoping what I am describing to you is more normal than not. I did hit 60 mph today for a few seconds. This thing makes me feel like a kid with a new toy!