Trying to understand engine mods. Help plz.

Ormanjw

New Member
Nov 17, 2012
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Hastings, mi
Ok so ive looked into the porting and I think im going to send out the jug in the near future to be done. What is it called when you have the head way more bowl shaped? Also after having these things done what about a +3 crank? Does it make a dif? Do u have to majorly tweaj your timing? Can u do all this put it back together kick it and itll run? I know timing generaly is very tricky (for me at least) and I dont want this to not run. Any help would be greatly appreciated im very new at the mods and all that.
 
you'll be fine to do all that at once, in fact it is recommended to do the + crank with the porting so the port timing, squish and compression can be adjusted for that exact crank/piston
timing is usually advanced 3-4 degrees and helps low end torque as does the + crank.
some refer to the head modification as hemishpherical.

a performace pipe and bigger carb/intake usually compliment these mods

whats your budget ?
 
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If you optimize the head shape there becomes less and less advantage to moving the ignition timing more forward and more risk that you will run the engine too hot and start detonation.
 
The head mod is called re-chambering, not to be confused with "shaving". As far as engine mods, have a goal in mind and discuss your goal with your chosen builder. An honest builder with tell you what it takes to get where you want to be and steer you clear of things that won't work with your plan. Then agree on a price, discuss his warranty and turn around time.
 
My budget is very limited. Ill prob just have to save up for and talk to the builder to find the total cost. That was another thing I was worried about was overheating issues. I suppose if I start w a pupe then do all the engine mods at once ill be alright? After you do a +3 crank do you have to do the adjustable stator? Thanks for all the quick replies.
 
I prefer to build engines around stock ignition timing optimizing the other parameters instead of advancing ignition timing. With limited other modifications, the ignition timing modification is a cheap and easy way to get some more bottom end power.

Once you get serious about an engine build (starting with a serious reasonable power goal or some part of the puzzle is a GREAT start) you generally want to steer clear of the "cheap and easy" stuff as it has a tendency to give a short term gain and long term loss. :(
 
Ok great. I dont want to get into moving timing around alot. Id like more low to mid range power because I ride 80+ acres of woods generally w my boy sitten in front of me. Im rarely wide open unless its through the first few gears so all this is helping greatly.
 
Ok great. I dont want to get into moving timing around alot. Id like more low to mid range power because I ride 80+ acres of woods generally w my boy sitten in front of me. Im rarely wide open unless its through the first few gears so all this is helping greatly.

The beauty of the head rechambering is that it can GREATLY improve bottom end torque. The stock head design is..... lazy... to put it nicely. Not changing the port timing any at all, just increasing the compression ratio and repairing a few of the "problems" with the stock head will help that bottom end a bunch.

Honeslty, it's a great modification for basically every engine. As long as the goals are relayed to the person who is doing the head design, you'll get some serious bang for the buck out of a head rechamber.
 
Having the +3 IMO compliments that low end, some say if you have too large a carb you loose that, I can say from my experience , didn't really noticed going from 30mm to 35mm air striker any less low end on my sons +3 ported motor, I attribute that to the stroked crank. On this +3 build I've only tried 33pwk and the 35 A/S with no difference. I have always had my head modified and shaved for the +3 so no spacer plate required(less area to develop a leak). And the porting was matched to the stroked crank, Both these motors rip. I can tell ya each pipe will move that low end around a bit! My power pros (right bend) was nice but lacked a bit of the torque I liked in the trails. The toomey, has soo much more torque than the right bend, My opinion best trail pipe I had ridden so far! And the nice easy flange and o-ring setup is leak proof so far! I have also ceramic coated it, Not sure if it has added anything but looks!:D
 
What dif does vitos blaster dual petal reeds make if any?

just a little better throttle respnce. no power gains. what kind of motor are you wanting to build here? a low end grunter for mx or a topend screamer for high speed trail riding or dune riding? or something inbetween for normal trail riding? that will tell us exactly what you want your supporting mods to be and what kind of portwork you will need. timing on a blaster isn't really based on spark timing. it is more based on port timing, how long the ports in the cylinder are open durring the stroke of the piston,the angle or the ports, and the shape of the combustion chamber are where you get most of your power gains. my motor is pretty well modified and I run stock timing

if you get into serious drag racing timing becomes more of a tool but not much on a mx or trail machine