Gp1300r throttle issue, not linear

[Unni]

07 1300r. Bought the ski in pieces with a blown engine. Rebuilt it, running decent except for that the throttle is like an on/off switch. I can either go 0-20mph or 60mph and there is no in between. Once i hit a certain point in the throttle, like 15-20%, it just takes off like someone flipped a switch. There is absolutely no in-between whatsoever. Its not bogging, physical feel of the throttle is fine, not sticking or anything.
Thinking two things, tps obviously is the first. But, when i got the ski someone had taken the proximity sensor/throttle off sensor off the rail instead of unplugging it and leaving it attached. I can't find any information on this sensor at all. How do i set it correctly? What exactly does it do? Any input on this would be great. Thanks
Also what is the 3rd thing on the throttle body rack? I assume it's something to do with the off throttle steering?

[Unni]

Purchased the yds system. Tps voltage is perfectly linear. No dead spots or anything. The only abnormality is that the magnetic throttle-off switch shows off all the time. Never registers that the throttle is closed. Could this be the issue? It doesn’t seem like it would but who knows..

[raiderteen]

How familiar are you with 2 strokes? Cause it almost sounds like you are just not used to the 2 stroke power band. On the 1100/1200 NPV motors anything between ~3500-5000 RPM is useless as it will constantly be wanting to jump up to 5000 rpm to be in the power band. Just how 2 strokes are. On my Yamaha LS2000 boat (twin 1200 NPV) it won't stay on plane if I let them get below the power band. I cruise just above 5000 rpm to stay in that band but not wind it out and suck fuel faster than it already does.

[Unni]

How familiar are you with 2 strokes? Cause it almost sounds like you are just not used to the 2 stroke power band. On the 1100/1200 NPV motors anything between ~3500-5000 RPM is useless as it will constantly be wanting to jump up to 5000 rpm to be in the power band. Just how 2 strokes are. On my Yamaha LS2000 boat (twin 1200 NPV) it won't stay on plane if I let them get below the power band. I cruise just above 5000 rpm to stay in that band but not wind it out and suck fuel faster than it already does.

Very. Ridden dirt bikes for years, had a few 2 stroke seadoos as well. This is very abnormal feeling. My friend has a 1300r that's perfectly linear and smooth.

[rhys.500]

Hey Unni. What was your problem in the end? I have same issue, motor bogging down hard and then suddenly takes off to full throttle, but no in between whatsoever... You could possibly save me a mountain of time!??
Cheers, Rhys

[steve45]

This is a very common problem when towing a skier behind a twin-engine Yamaha 2-stroke boat. It's very difficult to get the engines running about the same speed when running 25 MPH +/-. What most people end up doing is running one engine at 2500 and the other at 4500, or whatever speeds work to get the boat speed that the skier wants.

[rhys.500]

Except i am not towing anything. there is something legit going on there it is splutering like fuck, am wondering if could be the throttle position sensor? Although there is no code.. Was thinking maybe adjusment, if there is any.... If not then maybe fuel pump no good or gauze clogged up? Or is it possible it could be power valve adjusment? Whatever it is it is simple. because once it decides to go it goes. But is choking like hell down low.

[ttbone72]

Unless someone has changed the cylinders 07's don't have Power Valves and the Ecm would have to be changed to control the cable operated PV's are you sure it has PV's

[steve45]

What model are you working on, Rhys?

[rhys.500]

Sorry mate it is the gp1300r 2003 model...

[rhys.500]

I just thought someone world wide is bound to have had the same issue i am having. but i am guessing it could be 1 of a number of things that could be causing the problem.

[rhys.500]

Does the throttle position sensor have adjustment on it at all? Or is it fixed? If does have adjustment then what is the factory setting. Everything is factory, except i have a d plate and chip in my motor

[ttbone72]

Sorry I didn't pay attention that you're not the OP;
the power valves could be gummed up, when was the last time they had been taken apart and cleaned, have you check that they are actually cycling

[rhys.500]

PV were gunked up after i noticed that one of the cables wasnt seated correctly and they couldnt cycle. I cleaned them best i could and put back together. Do you think they could just still be trying to get rid of crap build up? Are they always this problematic? should i just pin them open permanently and forget about the PVs altogether? Or does the motor just want run at WOT for a while to clear the build up completely? I am just a wee bit worried running at WOT for too long as has just been rebuilt and dont want her to Chernobyl right off the bat....

[rhys.500]

At least if i bypass PVs and the engine then goes fine then i guess i will then know what the problem was...
I am running a cheaper 2-stroke oil thru it too which is prolly not helping anything.