How level does the engine need to be?

Discussion in 'Frame Mounted Engines' started by Fletch, Oct 7, 2010.

  1. Fletch

    Fletch Member

    I have my engine mounted at almost this exact same angle. I have the Z extended intake though which is longer and puts the carb at a slightly higher angle. I was thinking about adjusting the mounting to make it more level, but if it isn't necessary I'll leave it alone. I have only ran the bike for a couple minutes so far before the chain tensioner went into the wheel.

    Attached Files:

  2. professor

    professor Active Member

    Whole lot of bikes here look like the same angle to me.
  3. Al.Fisherman

    Al.Fisherman Active Member

    Get the carb bowl as level as you can. Anything else is of no concern. Is the rear mount perfectly flush with the seat tube? Pictures below show correct mounting fit on the rear mount.

  4. Fletch

    Fletch Member

    The rear mount is perfectly flush. Unfortunately there's no way I can think of to level the carb without moving the whole engine. I want to get a billet intake down the road which would solve that problem. Hopefully it will work out fin for now.
  5. Al.Fisherman

    Al.Fisherman Active Member

    At this time there is no need to worry about the angle of the carb. I have seen worse and still run fine. I feel that at the angle yours is in that there is more then enough fuel in the bowl so that it isn't being depleted too fast for refill. If when you get running down the road, and more fuel is burned with the increase of RPM's that will be the test.
  6. wheelbender6

    wheelbender6 Well-Known Member

    Since your carb isnot quite level, a needle valve adjustment may compensate for it. Search the site for "needle" and see if you get some posts explaining that adjustment.
  7. Al.Fisherman

    Al.Fisherman Active Member

    I don't think the needle adjustment will have any effect as far as engine angle . What the problem might be is that at a angle the float is not level. The higher the rear of the engine is the more fuel can enter the bowl. The lower, the less fuel can enter. What you might need to do down the road is adjust the float setting.
  8. Fletch

    Fletch Member


    I have the cns "racing carb with all the jets and blue air filter. I took it apart and didn't really see any adjustment on the float. I'll have to double check that if it becomes a problem. Thanks
  9. Al.Fisherman

    Al.Fisherman Active Member

    If a carb has a float then there is a adjustment. At least that is what I've found on every float carb. There is or should be a tab that pushes up on the needle into the seat as the float rises and drops the needle off the seat when the float drops (as in running out of fuel). Adjustment is accomplished by bending the tab.
  10. philski

    philski New Member

    Hi, im sure, as long as the carby is level you can run this 2 stroke engine upside down. The angle does look high in the picture. But when you consider all the angles it goes through in normal use. i cant see it hurting too too much. Fuel surge/starvation perhaps? A set of longer forks would solve it somewhat. Can you lower the front axle a little or drop the back? you may pick up 1/2 a deg at the float level here and there. your float should be 1mm below the top of your main jet when upside down. But, because its tilted it may now be 3-5mm out.

  11. Fletch

    Fletch Member

    Hey Phillip,

    Unfortunately I can't lower the front axle any because the break pads won't reach, and there is also a metal piece that is a circle with a hook basically that hooks into the frame.

    A longer fork is a great idea...I hadn't considered that. Tight budget right now though.

    If you want (don't mind), I have a recent thread with some details about what I'm troubleshooting right now:

    I've already got some good advice, but more opinions/suggestions are always welcome.

  12. HeadSmess

    HeadSmess Well-Known Member

    any old two stroke can run at any old angle, as long as its any old carb is level or designed for running upside down.

    even the old floaters are pretty tolerant of any serious inclination. only real concern is when the idle/main jet is exposed due to too much angling... related to float height. and that liquid stays horizontal.
  13. wbuttry

    wbuttry Member

    shoot my motor is cocked so hi in the back almost 45 degrees and it runs fine and it has good fuel flow the carb is also cocked up as hi as the engine i'll post a pic as soon as i take one tomorrow