Extending track

[old man winter]

I know a lot of you have extended your short track nytros so I'm looking for advice . My nephew recently bought an 02 viper that was changed from a 121" to a 144" with 2" lugs. I rode it last week and it seamed to have very poor throttle response. We don't know if any clutching has been done to it but it revs high before the clutch engages and then seems to rev a lot with very poor acceleration. This thing is a dog not any thrill to the ride. We both also own 02 viper 121" and are comparing to that. He's going to get rid of it but I think he should play with clutching first. I would expect the track extention to reduce top end but will it loose that much low to mid powerband loss. Any advice or suggestions would be great. I tried to post this in the two stroke viper forum but I would need to register there before I can post so if I'm out of bounds posting it here I am sorry and delete if necessary.

 

[bradb]

it sounds like it might still have stock gearing in it, i would start there, your probably going to have to change that first going to a 2" lug

 

[nitris223]

I stretched a 2002 SXR 600 to 144" and left the stock gearing in for flatland use. Never really noticed much difference over the short track performance. I had to adjust the spring and rivets in the weights to get the rpm right but it pulled along just fine.

Have you pulled the power valves to have a look at them. Might want to dig into the clutches also. In the tech section there should be some clutch combinations from guys with MTN vipers.

 

[ViperTurboPete]

Check gearing and clutching specs for stock Mountain Viper and compare.