dumb mod / tuning questions...

[aramis]

Ok, I'm getting antsy to start working on the skis as spring is around the corner here...can anyone help me understand what, if any, carb tuning I'd expect to have to do if I:

- bore the b-pipe / manifold diameter out to the "stock" diameter (46mm I think it should be? mine is smaller than "normal", it is a really old one).

- go from stock reeds to vforce 3's

- install the R&D angled reed spacer

Its a '98 RN with stock dual 38's, Pro-tec Rec head (180psi), MSD cdi, ltd chamber. Tuning is what I'd consider perfect right now. Prop is a 5mm-cut C-75 magnum swirl, 13/17 IIRC.

Also, is there any compelling reason to swap out the Pro-tec rec head for an ADA girdled head w/ 35cc domes? Should be the same compression, and I don't think I need to be as concerned about cylinder cracking as the 61x guys, but for some reason I wanna do it...

 

[Freakrider]

Cost of a new/used cylinder and topend if you crack it ? you are a 61X guy !! call Matt at ADA ask him about the $50.00 off for a blem head shell....can not tell the difference minor finishing flaws.....work fine...ADA head on and off quick with grease no silicone to clean up...u can do easy cyl wall inspections....

 

[aramis]

I'll admit I've never been sure about it, but always assumed I had a 62t due to the year and dual carb setup. How can I tell? I remember looking last fall, and not seeing any marking on the cylinders at all. I can dig out the stock head if that will tell me. Sorry for being clueless on this one... Thanks for the info on the ADA deal!

 

[Boris]

You have 62T cases but a 61X cylinder.
That's what they came with from Yamaha.

 

[Freakrider]

96 and up are 61x cyl on 62t case...some guys have cracked three or more cyls...

 

[aramis]

thanks for setting me straight...I realize now that i had misread some info in the Group K tech docs, and that's where my confusion came from. Went back just now and re-read it after your comments and it makes sense now. Adding the girdled head to the list!

 

[Freakrider]

tip: make sure you put anti seize on the studs and do not use loctite on the six acorn nuts because it will turn your studs right back out upon removal... and use grease only on o-rings to hold in place for install...

 

[aramis]

Thanks for the help. Any comments on my other pending mods? I'm hoping that since I've already got the b-pipe (and jetting, etc that goes along with that) that the VF3's and intake spacer won't cause me to have to re-jet...?

Also, I know that my b-pipe manifold and head pipe has the "undersized" diameter in it, and I want to correct that. How does that affect my carb tuning? I'm thinking that I might end up being lean, if the exhaust can "pull" more on the intake charge.

Thanks, and sorry for the dumb questions!