Cant get WOT rpms up!

[srvfan]

Not trying to sound stupid here, but have you checked the airbox for mouse nest and the exhaust ?

 

[Sno-Xr]

Not trying to sound stupid here, but have you checked the airbox for mouse nest and the exhaust ?

I havent, but thinking Id run into more issues by now if that was the case. But worth looking into. Thanks for the input

 

[Thunder Products]

I havent, but thinking Id run into more issues by now if that was the case. But worth looking into. Thanks for the input

Dave, we might have a solution to ALL Viper owners who have hard starting and won't rev correctly.

Stay tuned as this seems to be an issue we found and once discovered, the sled hits the rev limiter.

@Sno-Xr give me a call today 906 484 1650

 

[74Nitro]

Did you check the timing indicator that sometimes moves. It's on the stubshaft.

 

[Sno-Xr]

Dave, we might have a solution to ALL Viper owners who have hard starting and won't rev correctly.

Stay tuned as this seems to be an issue we found and once discovered, the sled hits the rev limiter.

@Sno-Xr give me a call today 906 484 1650

Sorry, just got this message. I will get with you soon, thanks

 

[super1c]

Dave, we might have a solution to ALL Viper owners who have hard starting and won't rev correctly.

Stay tuned as this seems to be an issue we found and once discovered, the sled hits the rev limiter.

@Sno-Xr give me a call today 906 484 1650

any update on this?

 

[yamadoo]

Dave, we might have a solution to ALL Viper owners who have hard starting and won't rev correctly.

Stay tuned as this seems to be an issue we found and once discovered, the sled hits the rev limiter.

@Sno-Xr give me a call today 906 484 1650

Terry you TEASE......good to hear from you and look forward to your findings as I have hot start issues despite most recent flash

 

[Sno-Xr]

any update on this?

Unfortunately no, I just caught Terry's post today. The 70° weather today isnt helping my motivation on finishing my other sled, so the RPM issue has taken a backseat.

 

[Thunder Products]

It's the timing indicator on the snub shaft. As @74Nitro mentioned.

The sled has been giving this guy so many issues with starting hard or not starting, he went and bought another sled. His Viper would not rev at all...no matter how much weight he took out. Was slow as you can imagine.

This is what was tried and replaced.

Different ECU from Yamaha....did the same thing
Different ECU with EVO stage 4 flash. Started all the time, even hot....but wasn't going to let the Stage 4 EVO ECU in the sled. So back to square one.
Different throttle bodies and injectors
Fuel, plugs, checked leakdown....still would start hard or not at all.

Last thing was the gear on the snub shaft....
That was it. Starting good now and running even better. Hit the rev limiter instantly when out for a test ride.

Now all good!

 

[Sno-Xr]

It's the timing indicator on the snub shaft. As @74Nitro mentioned.

The sled has been giving this guy so many issues with starting hard or not starting, he went and bought another sled. His Viper would not rev at all...no matter how much weight he took out. Was slow as you can imagine.

This is what was tried and replaced.

Different ECU from Yamaha....did the same thing
Different ECU with EVO stage 4 flash. Started all the time, even hot....but wasn't going to let the Stage 4 EVO ECU in the sled. So back to square one.
Different throttle bodies and injectors
Fuel, plugs, checked leakdown....still would start hard or not at all.

Last thing was the gear on the snub shaft....
That was it. Starting good now and running even better. Hit the rev limiter instantly when out for a test ride.

Now all good!

Thanks!
Thats awesome that it got figured out. Is there an outer tell tale? Or does the stub need to be removed? What exactly do I look for?

 

[cannondale27]

Stub shaft needs to be removed and there is a mark.

 

[cannondale27]

Here
https://ty4stroke.com/search/2233987/?q=Stubshaft&o=relevance&c[node]=102

 

[Sno-Xr]

Here
https://ty4stroke.com/search/2233987/?q=Stubshaft&o=relevance&c[node]=102

Holy crap.....40 pages!! Lol Thanks Steve

 

[Sno-Xr]

Unfortunately it doesnt look like the stub shaft is my issue, that is, if the alignment mark is supposed to be centered on the the valley of the inner splines??

 

[cannondale27]

Unfortunately it doesnt look like the stub shaft is my issue, that is, if the alignment mark is supposed to be centered on the the valley of the inner splines??View attachment 160629

Pretty sure that’s correct. Dang.