[theinsanegizmo13]

I have a 2006 Yamaha Majesty with 15K on it. Wife and I together weigh 400 lb and we have been traveling All Over Georgia with it. Clutch went out, so I replaced the throttle body diaphragm, clutch, belt, weights/sliders. Went from 25-30 mph, to 30-45 mph (up to 55 going down long hill). I did ignorantly mess with the OBD system after cleaning the throttle body with a toothbrush, water, and degreaser, which made the check engine light come on, didn't realize it just needed to dry out. Every time I turn the key on, the clock has been reset back to one, the two trip odometers have been reset back to zero, but the primary odometer still reads correctly and is still adding miles. All I have to do is turn it off and on and it's all reset again.
Did I accidentally put it in limp mode, am I missing something, how do I make my baby peppy again? I'm SO heartbroken and I need advice from someone who is more experienced with this specific bike than I am. I've had this bike for 20 months before this happened. Loved being able to take road trips with it. I saved up for 2 years to get this bike, not this one specifically but one like this, and I lucked up on this one for $2.5K, and I can't afford to put it in the shop, which is why I've been doing the work myself. I've been turning wrenches on four wheel vehicles for 35 years, but this is the first Japanese scooter I've ever worked on. I have plenty experience with small displacement Chinese scooters. I miss my peppy pretty baby. Someone, with more Majesty experience than I, please help.

 

[minimac]

I sent you some info. Check your "conversations" in your account info.

 

[Itinifni97]

Howdy,
I have an 05 YP400, my wife combine for similar weight. I have no problem reaching and cruising and maintaining over 90 mph (indicated).
Please clarify a few things, are you saying you're topping out at 45 mph now? Also, you mention you replaced the clutch, belt and I think you're saying changed out the weights for sliders, is that correct?

A few questions:

• Why did you also replace the diaphragm?
• Did you install weights or sliders and what weight did you use?
• What RPM is the engine reaching under wide open throttle, either under acceleration or when topped out?

 

[theinsanegizmo13]

Howdy,
I have an 05 YP400, my wife combine for similar weight. I have no problem reaching and cruising and maintaining over 90 mph (indicated).
Please clarify a few things, are you saying you're topping out at 45 mph now? Also, you mention you replaced the clutch, belt and I think you're saying changed out the weights for sliders, is that correct?

A few questions:

• Why did you also replace the diaphragm?
• Did you install weights or sliders and what weight did you use?
• What RPM is the engine reaching under wide open throttle, either under acceleration or when topped out?

I changed out the weights and the sliders. I just used the same ones that came with it from the factory. Partzilla didn't really specify what weight they are, only that they were the same weight as what came with it new. It doesn't rev up over 4000 RPMs. I changed the diaphragm because it was ripped. Had holes in it, you could see clean through it.
Before all this happened, it had no problem cruising down the highway. On our way back from Savannah to Atlanta, I had it throttled up all the way because it was dark and getting cold and wanted to hurry up and get home. There was a guy that pulled in behind us at a gas station, he had been traveling behind us on 75 north. He made the comment that if he hadn't been behind us doing 110 mph here of never believed it was a scooter. I never really had any issues out of this until the clutch went. I wonder if I did not put it into some sort of test mode on accident, using the Diagnostics instrumentation computer that is accessible through the digital readout that is between the tachometer and the speedometer.

 

[Itinifni97]

Ok, so factory parts were used, am I correct you also got the piston valve (diaphragm) from Partzilla?

I would re-check all work done at the throttle body. If your variator was not changing ratios properly I would expect either the engine would be at very high rpm and low speed (the same if your belt was slipping) or the bike would be very slow to accelerate from a stop.

• Is the throttle plate opening fully, cables properly routed?
• Piston valve and spring installed properly, no binding or vacuum leaks?
• All hoses connected and secure?
• Throttle position sensor and Intake Air Pressure Sensor both connected, TPS adjusted properly?

I've been an ASE Master Technician over 40 years, never heard of anyone using water and degreaser to clean a throttle plate. I don't think there's an air flow meter on the YP so I don't think there's any harm in that but I would recommend using carb cleaner in the future.

You're electrical issue may be unrelated to the drivability issue, I'd check for retained power at the meter.

Is the MIL still illuminated? If so what code do you get?
I don't think there's a fail-safe mode but you could try pulling the negative cable off the battery and leave it for about 10 minutes to clear any memory from the ECU.

If you don't have it already the PDF manual is available online.

Good luck

 

[theinsanegizmo13]

Ok, so factory parts were used, am I correct you also got the piston valve (diaphragm) from Partzilla?

I would re-check all work done at the throttle body. If your variator was not changing ratios properly I would expect either the engine would be at very high rpm and low speed (the same if your belt was slipping) or the bike would be very slow to accelerate from a stop.

• Is the throttle plate opening fully, cables properly routed?
• Piston valve and spring installed properly, no binding or vacuum leaks?
• All hoses connected and secure?
• Throttle position sensor and Intake Air Pressure Sensor both connected, TPS adjusted properly?

I've been an ASE Master Technician over 40 years, never heard of anyone using water and degreaser to clean a throttle plate. I don't think there's an air flow meter on the YP so I don't think there's any harm in that but I would recommend using carb cleaner in the future.

You're electrical issue may be unrelated to the drivability issue, I'd check for retained power at the meter.

Is the MIL still illuminated? If so what code do you get?
I don't think there's a fail-safe mode but you could try pulling the negative cable off the battery and leave it for about 10 minutes to clear any memory from the ECU.

If you don't have it already the PDF manual is available online.

Good luck

I've been working on engines and machines and mechanical stuff since I was 13, mostly cars and Chinese scooters. That's 37 years I've been turning wrenches. The things that you mentioned, I have done. That was my first go to, that I seated the diaphragm wrong. So I took it back apart and double checked it. To get to one of the screws on the throttle body cap, I pulled the throttle body outward. I used a toothbrush, and degreaser, and I clean the entire throttle body and intake and everything around it. It wasn't really greasy, which is why I diluted the Degreaser with water. And then I cleaned it all with blue Dawn diluted in water to clean it a second time so it didn't have residual residue from the Degreaser on it. When I got done it was throwing three codes at me. Throttle out of position, throttle body out of position, and it was something else electrical, I can't remember exactly what it was now. This is the first Japanese bike I've ever worked on. I've worked on a shit ton of Japanese cars, so I've used that knowledge and applied it here. What little of that was actually applicable. I wonder if it could be so simple as needing a new battery. If that's it, I'm going to be kicking myself in the butt. LOL

 

[theinsanegizmo13]

Howdy,
I have an 05 YP400, my wife combine for similar weight. I have no problem reaching and cruising and maintaining over 90 mph (indicated).
Please clarify a few things, are you saying you're topping out at 45 mph now? Also, you mention you replaced the clutch, belt and I think you're saying changed out the weights for sliders, is that correct?

A few questions:

• Why did you also replace the diaphragm?
• Did you install weights or sliders and what weight did you use?
• What RPM is the engine reaching under wide open throttle, either under acceleration or when topped out?

I also want to say thank you very much for your advice, it is greatly appreciated and greatly valued.

 

[theinsanegizmo13]

Ok, so factory parts were used, am I correct you also got the piston valve (diaphragm) from Partzilla?

I would re-check all work done at the throttle body. If your variator was not changing ratios properly I would expect either the engine would be at very high rpm and low speed (the same if your belt was slipping) or the bike would be very slow to accelerate from a stop.

• Is the throttle plate opening fully, cables properly routed?
• Piston valve and spring installed properly, no binding or vacuum leaks?
• All hoses connected and secure?
• Throttle position sensor and Intake Air Pressure Sensor both connected, TPS adjusted properly?

I've been an ASE Master Technician over 40 years, never heard of anyone using water and degreaser to clean a throttle plate.

I was cruising down Northside Drive this afternoon. I got to thinking about things that had happened previously and it's almost like the throttle cable isn't pulling the throttle all the way open. I made it a point to pay attention to the tachometer yesterday. Taking off, it's revving up to 2K RPM, and then lowering down to one while I'm getting going uphill. It's like there's just no torque. I wonder if I have a stretched out throttle cable, but if that's the case why didn't it do it before the clutch started going out? It actually got up to almost 4K RPM at 45 or 50 mph. I already started reading the manual you sent me. I wish it had specifics on what each number in the OBD that's accessible in the center screen.

 

[Itinifni97]

I have to reiterate my suggestions above, it sounds like your throttle is not fully opening. I highly doubt the throttle cable could stretch that far without breaking. If this issue was not present before you worked on the throttle assembly then that's the place to start.
Page 7-4 of the manual has all the information on the on-board diagnostic codes and flow charts for each one.

Good luck.