JN Motors HP Ported Cylinder and Piston Kit

Discussion in 'Performance Mods' started by desertsteve60, Feb 2, 2014.

  1. desertsteve60

    desertsteve60 New Member

    Does anyone have any experience with JN Motors HP Ported Cylinder and Piston Kit? Part # JNM 1288.

  2. Fabian

    Fabian Well-Known Member

    I would like to see a hi-res photo of the transfer port modification on the HP Cylinder.
  3. HeadSmess

    HeadSmess Well-Known Member

    i wanna see the top of the piston, cutaways are silly and shouldnt be sold commercially. they are simply for testing new port timings rather than destroying a cylinder. (though on these engines the piston+rings costs the same as the cylinder so that argument is irrelevant)

    they defeat the purpose of the squish band, that is pointless anyway without removing the top 2mm of the cylinder to remove the HUGE chamfer there, and simply weaken the piston crown. great idea if its a high performance engine, huh? make things weaker?

    id like to see the intake port being opened up to about 25mm, but i cant see that happening with any stock cylinder!
  4. AlexNave

    AlexNave New Member



    Attached Files:

  5. jaguar

    jaguar Well-Known Member

    It will be a real screamer with the port durations increased by making the port ramps on the piston. In other words for fun only, not for utilitarian use. And goddess help you if you haven't first balanced the crank. vibration to Mt Olympus!
  6. Fabian

    Fabian Well-Known Member

    What i want to know is why people can't take proper high resolution photos with a camera phone, when modern camera phones have reasonably good image quality.

    The photo quality in the above pics are so bad that you can't see any detail.
  7. AlexNave

    AlexNave New Member

    I have a LG G2.
    There's not a whole lot to look at on the cylinder.
    What would you like to see more of Fabian?
  8. Fabian

    Fabian Well-Known Member

    If you are using a camera phone to take macro photos, get yourself a Joby Grip Tight Mount and attach your phone to a Tripod. Select the macro setting on your phone and take detailed high resolution photos of the porting work.

    I (if not most people) want to see every angle of the porting modifications.
    Believe me, there is a heck of a lot to look at for those who have an understanding of 2-stroke porting modifications.
  9. AlexNave

    AlexNave New Member

    Ok I will give the tripod a try because the OIS on my camera is flawed.
    Can you explain to me what i should be looking for exactly?
    I am still very new to 2-strokes and have much to learn.
    By "not a whole lot to look at" I meant not a lot of area that had been tooled away. It just isn't that much different from the stock ports, but not knowing I might be expecting too much.
    Jaguar is also very correct on the balancing of the crank first.
  10. Fabian

    Fabian Well-Known Member

    Ideally take photos of the transfer ports, from the base of the cylinder looking into the transfer's themselves.
    Take photos of the ports (as best you can) from inside the cylinder, so we can see if the ports heights have been altered and to see what kind of chamfering has been done to the port edges.
    Port width and port taper is also an aspect that would be of interest.

    If you take about 12 photos from every different angle, you should be able to present enough information for those with some level of 2-stroke porting knowledge to work with.

    A single cylinder engine (without balance shafts) can only be balanced to "minimise" vibration at a specific rpm zone, and as an end user you will have to determine which rpm zone is the preferred range that the engine is to be run. This in turn will determine the "balance factor", which will involve the use of maths.

    The easiest way to reduce vibration is to reduce engine rpm. If you reduce normal max rpm, then you will need to increase torque to make up for lost power. Methods (and products) are available to boost the 2-stroke torque curve.
    It's a win-win-win situation because vibration is reduced as well as reduction in noise as well as increased engine life through reduced rpm.
  11. AlexNave

    AlexNave New Member

    Thanks for the advice Fabian. I have experimented with extended intake and exhaust manifolds before and they help a lot in town at low speeds.
    Once i get it open and the proper lighting I will get all the pictures I can for you guys.
    I also just received a new CDI from Jaguar today.
  12. Fabian

    Fabian Well-Known Member

    The Jaguar CDI is an excellent product. No one should leave home without it.

    If your funds extend far enough, you should look into the Rock Solid Engines reed valve intake as a method of increasing low and midrange torque, as well as reducing induction noise.