slant head. its like running with the baffle out, only quieter!

Discussion in '2-Stroke Engines' started by linnix13, Aug 28, 2009.

  1. linnix13

    linnix13 Banned

    i recently have been having mounting issues(i fixed that with some grade 8 steel) and it was missing alot(new cdi wiring fixed that) then my clutch was screwing up badly, i fixed it with a small nut inside the slide between the pin and the ball bearing, then i finally got to put the slant head high compression on my bike, it runs sweet! the tone is a bit lower and it sounds slightly louder but it rockets up the hills! and it also gives me 100% less vibration in the high end, it will go faster too! it usually vibrated like crazy in the highs and i had to back off at 40 or so, but now it cruises on up to 50, and it will now pull 40 up a hill where it would do 25 before, its the best 20 bucks you can spend!
    oh and i just turned 4000 on the odometer today,
     

  2. Hawaii_Ed

    Hawaii_Ed Member

    I blew the plug hole out on my first one, went back to a regular head while I waited for the replacement, and MAN what a loss! I was so happy to get the slant back on.
     
  3. Al.Fisherman

    Al.Fisherman Active Member

    head

    Ed...did you ever think of installing a Helicoil in the plug hole? Where did you get the slant HP head, something I might look into to haul my 210# load.
     
    Last edited: Aug 28, 2009
  4. Hawaii_Ed

    Hawaii_Ed Member

    I did Alabama, but it was still pretty new, and zoom shipped me a free replacement. I also picked up one more to toss in my kit bag since I do some long range stuff and hate being stuck. I still have the stripped one though.
     
  5. Al.Fisherman

    Al.Fisherman Active Member

    Was this before or after you went to 1 copper head gasket and boosted the compression ratio? I'll have to GooGLE Zoom and check them out.
     
  6. Hawaii_Ed

    Hawaii_Ed Member

    This was my second build, and I knew I wanted a slant head, so I ordered a whole new kit from zoom bicycles. Good guys BTW. I put it together and ran it stock about one day. Then I noticed it had two head gaskets. I immediately took one out and ran it that way, and then put the sick bike parts thin gasket on a week later. I also installed a NGK plug. After 6 weeks of hard riding, the plug blew out of the hole. I enlarged the stud holes on my old regular head to fit the engine and ran it on some long rides like that until my new replacement head came. The slant head boosts compression of course, and the thin gasket boosts it more, so it is a bit harder to start, buts runs really well.
     
  7. arceeguy

    arceeguy Active Member

    Maybe that's why I like my current lot of 50cc engines, they have the slant head - and pull very nicely. Not as big of a difference to a 66cc "regular" head engine as one would imagine. Maybe I need to try a slant head on a 66cc engine to really get cookin'!
     
  8. linnix13

    linnix13 Banned

    yeah i got my kit from zoombicycles, 4000+kms and she still runs like a tank(a really old crappy German one)
     
  9. Foximus

    Foximus Member

    A non slant head will result in better and smoother power when setup with a proper squish clearance and combustion chamber.
     
  10. Hawaii_Ed

    Hawaii_Ed Member

    Well Ok then! What is the magic squish clearance number, and how do I dial in the combustion chamber? :detective:
     
  11. Foximus

    Foximus Member

    I would say a minimum squish of around 0.7mm and as for the combustion chamber I'm not sure what will be a good volume, but idealy a tight chamber that centralizes over the center of the piston.
     
  12. Fabian

    Fabian Well-Known Member

    Now here is someone who is making some sense out of the "slant head vs "conventional head"

    Quote "Foximus
    A non slant head will result in better and smoother power when setup with a proper squish clearance and combustion chamber.

    I know just a little bit about engines but can someone please explain why a non centralised sparkplug location (what every engine designer is trying to avoid, since time began) would bennefit combustion pressure, apart from the casting protrusion increasing compression ever so slightly, if at all.

    Fabian
     
  13. arceeguy

    arceeguy Active Member

    I'm thinkng that the angle plug heads produce more power not because of plug placement, but because the chamber volume is smaller - increasing compression a little. I should cc a standard head vs. a angle plug head to see what the difference is........
     
  14. Foximus

    Foximus Member

    Well heres the thing... As I have actually never seen one of these slant heads that you guys desire so much, I'm just speaking from experience... So theres a chance I spoke to soon.

    Most small CC, mass produced cheap motors with a slant head dont use squish bands, but a dome head. Centralized combustion chambers almost always tend to use a squish band design. It just works better. Slant domes have resonance issues. BUT... On these aircooled engines a compromise between the two is a more expensive slant head WITH a offset squish. As the exhaust side of a cylinder ALWAYS runs hotter than the intake side, the slant head allows the motor to run at a more even temperature, and overall runs a tad cooler, allowing you to bump compression, have denser crankcase pressures, and on average have higher power output.


    Sooooo.... in short theres your answer. IF the slant head has a squish, then its a good head, if its just a dome head like most are, then its just a junk head with higher compression.
     
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