Degreeing the Motor

[cannondale27]

Has anyone done this on either a Viper or Nytro motor? Are they the same?

Guys Yamaha is very conservative and it would not surprise me one bit if they messed with the cam timing. Remember the YFZ's one tooth change just was a huge change in performance. Just wishing it were that easy. Not sure if even possible to do in chassis.

 

[CustomApexMan]

You can NOT get to the cam chain tensioner unless you pull the engine or take the back motor mount bolts out and pry the engine up that's what I did when I put the head shim in.

 

[cannondale27]

Thanks. Looks like a summer project. Info has to be out there though.

 

[cannondale27]

Just want that torque moved 500rpm higher.

 

[MrSled]

LMAO... you make me laugh Steve...LOL

 

[cannondale27]

I know. I dont give up. Still have 2 running Cannondales both raced. This is nothing compared to keeping those things running!

 

[MrSled]

I know. I dont give up. Still have 2 running Cannondales both raced. This is nothing compared to keeping those things running!

Your funny... I would drop an Apex Motor in that Viper Chassis.... I can help you do it this summer

 

[cannondale27]

Or fit a gear reduction on this and leter rev!

 

[TD Max]

With the HP curve still climbing at a pretty respectable rate past 9,000 I think we are fine. The HP gain does have to exceed the rate of decline in clutching efficiency though. Somewhere there will be a point of diminishing return.

 

[bjowett]

I have what you are looking for.

 

[cannondale27]

Awesome! Gear reduction or Deg specs?

 

[Srxspec]

FX Nytro/SR Viper, both the same when checked.
Overlap: 72.00 degrees
Intake Duration: 276.00 degrees
Exhaust Duration: 268.00 degrees
Intake Installed Centerline of 100.00 degrees ATDC.
Exhaust Installed Centerline of 100.00 degrees BTDC.

Fuel injected Vector
Overlap: 70.00 degrees
Intake Duration: 260.00 degrees
Exhaust Duration: 260.00 degrees
Intake Installed Centerline of 95.00 degrees ATDC.
Exhaust Installed Centerline of 95.00 degrees BTDC.

 

[cannondale27]

Those are stock cam specs? Allen have you degreed both engines?

 

[Nytros rule]

Cannondale are you thinking the Engines are different.
I think this all comes down to the Cat ECU being maped differently than the Yamaha.
Cat put an O2 sensor in for? this thing should be more tuneable than the Nytro.
I would think if the O2 sensor was properly supported in the ECU it should be the same as a PCV with auto tune.
We should (in theory) be able to do air box mods, and/or exhaust or anything short of major Engine mods or Turbos and the ECU should adjust accordingly because of that O2 sensor.
But we know that is not the case.

 

[Nytros rule]

What would be interesting to see Nytro and Viper side by side on Dynos and fuel delivery (AFR) and ignition timing maps at each 100 RPM same as Torque and HP.