Engine Trouble Possibly carb issue but not sure

Discussion in '2-Stroke Engines' started by dotcom, Jan 8, 2016.

  1. dotcom

    dotcom Member

    I would like some feedback about why it boggs alot and the idle screw is all the way in and still at a fairly low idle and want to cut off if I dont stay reving but when I rev it during idle, it sounds great without any hesitation or bogging like features but when I try to take off, it struggles badly and boggs and wont exceed about 12mph. It was working fine before and I checked and replaced all gaskets and made sure there are no air leaks but it appears its something with the carb. I made sure the needle is in properly all the way down and even tried 2 gaskets near the float bowl since it did appear to be spitting gas near the air filter and around the new gas line that I just installed. I have been using #66 jet with great results for quite some time now. I have tried raising and lowering the eclip needle setting but that only changes things alittle so it's back to where its been on the 2nd from top notch. I removed the air filter for the first time just for experimenting purposes and that does shows a slight difference but not what I was looking for . I took the carb apart to clean it before the first fire up on the new frame and it has been difficult to diagnose. The seals seem to be fine too since when I rev during idle it sounds perfect.
     

  2. crassius

    crassius Well-Known Member

    I'd go back to one gasket, then check the float level. It sounds like you have an NT that is running rich. With carb upside down, sight across the float to see just a tiny bit of the main sticking thru - 1/2 the jet sticking thru is richer, not sticking thru is leaner.

    I'd also try the top notch to see how that runs, if too lean it's easy to put it back.
     
  3. dotcom

    dotcom Member

    sight across the float to see just a tiny bit of the main sticking thru.

    Can you be more specific and technical with what this above means?
     
  4. crassius

    crassius Well-Known Member

    can't get out to the shop right now, but measurement from the gasket to top of float should be 21mm (or 27 as I can't recall without looking it up, but it should be obvious when you look which it should be)
     
  5. dotcom

    dotcom Member

    Its at top and still acting too rich. Any suggestions?
     
  6. dotcom

    dotcom Member

    Still boggs when I try to take off and all the way through higher speeds
     
  7. dotcom

    dotcom Member

    Have to keep choke almost all the way up while riding and cant put choke all the way down or boggs out
     
  8. crassius

    crassius Well-Known Member

    that certainly is lean rather than rich - hard to get that lean without something stuck in the fuel inlet path or a major air leak somewhere at the intake path
     
  9. dotcom

    dotcom Member

    I will try another nt carb when I get home tomorrow and we'll see then
     
  10. crassius

    crassius Well-Known Member

    at the shop now - float setting is from the gasket seat (with gasket removed) to top of float equals 21mm
     
  11. dotcom

    dotcom Member

    seems like its the way you described but I still plan to test with different carb. I assume if the same thing happens with a different carb, there is another problem. I really don't feel or see any air leaks though and I cleaned the carb and blew through the jet to make sure it was clear. We'll see after testing with another carb and I will report it here.
     
  12. crassius

    crassius Well-Known Member

    I use a spray bottle to mist water in the area to find air leaks.
     
  13. HeadSmess

    HeadSmess Well-Known Member

    and here we are with nomenclature difficulties... "bogging out"

    some seem to think its when its too lean.

    some seem to think the term applies better when its too rich.

    i prefer

    "it dies when given full throttle" for too lean.
    " it runs but doesnt really rev" for too rich

    if you need to tweak the choke whilst riding...it is lean. very lean.

    what causes this? forget airleaks, they are only a concern at idle.

    a blocked jet is likely.

    a blocked fuel line/filter calls second place.

    a blocked vent on the petrol tank takes third place.

    you can eliminate the last two issues by seeing how fast/consistently it will flow from the (disconnected from carb) fuel line into a handy glass or similar vessel.


    and lastly, very rarely...the clip comes of the needle and its no longer being lifted by the slide. idle is fine but it stalls as soon as the throttles opened.
     
  14. dotcom

    dotcom Member

    It was not the carb because I used another stock carb exactly like it and the same symptoms occured so I went on to check the crank seals and I thought one looked like it might needed to have been replaced so since i had an extra, I changed it but that appeared not it be it either. So now I think I will check my fuel flow from petcock and increase it if needed and see if that was it. I dont think it can be a blocked jet since I cleaned it and even tried with a working carb so it must be the fuel flow from petcock like headSmess suggests but I will check and report back.
     
  15. HeadSmess

    HeadSmess Well-Known Member

    i forgot to mention base gasket between case and cylinder...thats an air leak that will affect everything. the evidence of a leak is fairly obvious though. a very rare one is the case gasket itself, where the two halves bolt together.
    make sure headnuts are tight... worth popping the head off to check the gasket.

    personally i use teflon tape rather than the lousy aluminium things they normally fit for a gasket. bit of fiddling and you figure out how to use it.

    but it is sounding like fuel line issues here...
     
  16. dotcom

    dotcom Member

    Ive removed the gas line and checked the fuel flow from out of the petcock and seemed possible but unlikely to me but I also removed the petcock and cleaned it and put it back. Now I guess I will move on to the next possible culprit, the base gasket.
     
  17. crassius

    crassius Well-Known Member

    when checking fuel flow, I always pull the drain screw at bottom of bowl to see whole system at work
     
  18. dotcom

    dotcom Member

    I keep get new issues from leaking gas to an air leak near head somewhere but I have spent all day trying to fix it since this morning and just got these two new issues of leaking gas (AGAIN!) and air leak near head. I put my old gasket at the base and when I tried it out just now, I got a new leak at the top near head so I will continue it probably tomorrow
     
  19. crassius

    crassius Well-Known Member

    stick with it, you'll get better at it - once you've had some experience with these, you'll wonder why it seemed so hard earlier
     
  20. jaguar

    jaguar Well-Known Member

    FYI the head from the factory is warped and needs to be planed flat. Use sandpaper on glass.
    Make your own gasket from gasket material from the auto parts store. aluminum sucks
     
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