YFZ Central banner
1 - 13 of 13 Posts

·
Registered
Joined
·
528 Posts
Discussion Starter · #1 ·
Hey, what all is involved with putting in a high comp piston? Is it just the piston, rings and seals that makes it high comp? Can I do all of it by myself? I feel that I can (I have the mechanical ability) if I don't have to send out any part of the motor. I just thought it might be a good next mod. If I can do it by myself. Any input would be great. What brand and size? 13 or 14. Also, would I have to jet richer? For those of you who have done it, what is your jetting now compared to before? Thanks, Mike
 

·
Registered
Joined
·
1,685 Posts
pahrump has a 13:1 and he says he wishes he went with the sparks 14:1. i do not know the rest PM him
 

·
Registered
Joined
·
19 Posts
I just went from a 13:1 to a 14:1 this week (standard bore). You can do everything yourself, as long as you have the proper tools. (torque wrench, feeler gauges, (2)new gaskets, etc..) I strongly recommend getting a service manual (with all the torque specs). I run straight C-12 (108 octane). I'm still playing with the jetting, but for right now I'm using a GYT-R jet kit, pilot 42, main 165, 4th clip, 2 turns on fuel mixture screw. I'm at 3000 feet elevation. To respond to some of your questions, I would recommend the 14 instead of the 13; you can do it yourself (be sure to be confident and mechanically inclined) without sending stuff off; my jetting hasn't changed much, but I'm still playing with it. Recommend to call Curtis Sparks, those guys were very helpful and treated me as their favorite customer.
 

·
Registered
Joined
·
50 Posts
I also changed from a 13:1 to a 14:1 and I would recommend the 14:1. I also have the cam mod, sparks pipe, sparks air filter kit, and FTZ porting. I run a 182 main, 45 pilot, and 5th clip on GYTR needle. Raising the compression should not require significant jet changes.
 

·
Registered
Joined
·
575 Posts
I wouldnt unless you do a stroker kit which gives the piston a longer stroke,then you have to worry about it coming up too far and hitting the valves.
 

·
Registered
Joined
·
542 Posts
Originally posted by 2000racing@Feb 23 2004, 10:00 AM
I wouldnt unless you do a stroker kit which gives the piston a longer stroke,then you have to worry about it coming up too far and hitting the valves.
:what
 

·
Registered
Joined
·
542 Posts
Originally posted by 2qk4u@Feb 23 2004, 09:48 AM
do you not got to worry about piston to valve clearance?
No, because the higher compression pistons have deeper reliefs cut into the top of them so the valves will clear. :rock
 

·
Registered
Joined
·
542 Posts
Originally posted by 2000racing@Feb 22 2004, 11:55 AM
Doesnt running higher octane fuel chande the jetting a little bit?
Yes, from what I have heard, you should go up one step on your main to avoid running to lean with race gas. This is assuming you have it jetted correctly in the first place. ;)
 

·
Registered
Joined
·
19 Posts
UPDATE- I changed my jetting to 170 main.
 
G

·
Originally posted by midnighttalker@Mar 6 2004, 01:28 PM
i have a Q. ?? do u have to use race gas when u use a higher compression pistons ??
Yep.

C-12=108 ($6.00 a gallon around here or 38 bucks for a 5 gallon drum)
13:1= 100-112 octane :re
14:1= 108-112 octane :re
Thats the only reason i wouldnt do that mod :rock :sonic
 
1 - 13 of 13 Posts
Top