metalliatic
New Member
if i boost compression by shaving the head will that make my top end rpms higher or lower. im wanting to increase my top speed and this is the only thing i havent tried yet. wha tdo you think?
higher compression head
- Thread starter metalliatic
- Start date
mountain80
Member
Compression increases torque not rpms.
compression increases the torque, but it can have an effect on the top speed if the engine struggles or hits a wall as it is... if it's not a slant head, just opt out for the slant head.. ither the CE head from pirate cycles or just the run of the mill china slant head.. they will both gain compression
metalliatic
New Member
i know it will make more torque, so it will take off easyer. but will it make my top speed higher? once the engine tops out at a highets rpms it can, i cant go any faster, right? im running a stock slant head now and i has thinking of milling off a little off the bottom.
Prasinos
Member
Basically, if a 2stroke bike is made for high end power, it usually has less of a squish band and less compression. Torque normally has high compression and tighter squish band. This is because the limiting factor for power is heat dissipation. If you want your engine just to rev way higher, take off the jug and put 2 base gaskets on and remove the head gasket. This will make it so that your ports stay open for a longer duration allowing your engine more time to take in air/fuel and get rid of exhaust. This will lower your torque but put your torque peak higher in your rev range.
Creative Engineering
New Member
metalliatic,
If you have the equipment and your casting is thick enough, (some aren't):
Mill .080" off of the deck. Make a lathe fixture and machine a squish area that is 1 degree positive off tanget to the crown of the piston. Width of squish surface= .25"-28".
Removing a little material will do nothing! Milling the deck without also creating the squish area will make it run worse!
The cylinder heads that I make offer a noticeable difference in bottom end torque and on average an increase of 1,200 rpm.
Jim
metalliatic
New Member
am i correct that the higher the rpm then the higher the top speed? the faster the engine turns the faster my rear wheel will turn? im running a shift kit so the rear sproket is not a problem.
metalliatic
New Member
The cylinder heads that I make offer a noticeable difference in bottom end torque and on average an increase of 1,200 rpm.
Jim[/QUOTE]
so it is possible to gain rpms by adding compression? you sell your heads on pirate cycles right?
Jim[/QUOTE]
so it is possible to gain rpms by adding compression? you sell your heads on pirate cycles right?
Technocyclist
Motorized Bicycle Senior Technologist
make mods on your exhaust also helps, if you can't get a tuned pipe... 
Pablo
Master Bike Builder & Forum Sponsor
This isn't true.
1) Removing enough material to make the head surface flat will make all the difference in the world.
2) Removing a little material (define little as what? .010"?? .020"?) can give a decent bump in low end grunt and with the correct gearing give the OP a little better top end for a tiny amount of effort.
stuartracing
New Member
Who sells the high comp. billet head????
Pirate Cycles.. but Manic Mechanic makes them
stuartracing
New Member
Does the billet head work on both types of motors(bushing or cage bearing motors)...I notice one has a higher dome and piston pin is different.....One must have a taller/shorter cyl. or shorter/longer rod or something.....
Paul....
Paul....
stuartracing
New Member
Cool.....
I have one of the pistons with the more prominent dome but the wrist pin is in a different position than the bushing type piston is.....Don`t know if the rod is a different length or the cyl. is a different height.....
Thanks,
Paul.....
Masterm222
New Member
Just got one of the billet heads. A piece of art! Now I am wondering if I shouldn't order the piston and rings from Pirate Cycles also. All my motors have been the same except the one el-cheapo that I sold to another guy. Can anyone post pictures comparing the dome of the piston so I can tell if I need to replace mine or not? Better yet would be a measurement of the hight of the dome. I will measure mine tomorrow when I put on my new head.
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Creative Engineering
New Member
Thanks...
I intended on sending Justin an install guide in .DOC format that he could print and ship with the cylinder heads...He sold most of them the day they arrived, and I hadn't finished the instructions.
Check out post #4 on this thread.
http://motorbicycling.com/f3/high-compression-head-17741.html
Jim
Masterm222
New Member
No, I thank you! I read your reply after the fact. I swapped my chinese slant head out for my new head during my lunch hour. Tested it out a little on the two mile ride home. Still good power low to mid but then this thing just takes off revs and pulls like it never did! Definately some of the best money I have spent on this bike. Keep building them because as soon as people start talking about them everyone will want one!
stuartracing
New Member
Is`nt it cool the way it wakes up the motor like that??? It just wants to pull to the moon if you let it....??? I haven`t been able to use ALL my throttle YET......