Bad bogging

Discussion in 'Engine' started by Conner Jones, Jan 1, 2020.

  1. Conner Jones

    Conner Jones Member

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    I just rebuilt the top end on my blaster. It was running good. I have about 4 or 5 hours on it. Then all of the sudden in the middle of a ride, it started bogging real bad if you went past half throttle, to the point where it would actually shut off. The parking brake and tors is already eliminated. I checked the reeds and they were good. I did a leak down test when i rebuilt the motor and no leaks. Compression test shows 130 psi. I cleaned the carb out completely and all jets and settings are stock. I dont know what to do. It smokes slightly more than normal so maybe something changed to cause it to run rich while I was riding.
     
    Last edited: Jan 1, 2020
  2. Larry's Shee

    Larry's Shee Active Member

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    Do another leak down test. Did you check float level when you had carb apart? Air cleaner clean?
     
  3. Conner Jones

    Conner Jones Member

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    I did a leak down test and it held 6 psi for 5 min. I checked float level and it was 21mm. The air cleaner was clean. I took off the cylinder, and upon further inspection, the screws holding the reeds on were about to come out, so maybe that caused the reeds to not work correctly. I also noticed that there was a small amount of blowby past the first ring right at the ring gap. It didnt get past the second ring. Is this normal? I am going to reassemble everything tommorow and see if tightening the reed screws fixes the issue.
     
  4. Larry's Shee

    Larry's Shee Active Member

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    Clean reed screws and cage. Use loktite on screws. Wait 24hrs. for it to set before starting.
    A little blow by isn’t unusual
     
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  5. DKavcak

    DKavcak Member

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    I had this happen to me on a trail with my YZ250. I was very new to two-strokes then (as in a year ago) and I had ZERO idea what was going on. I had the whole damn bike ripped apart on the side of the trail trying to figure out what the hell happened. I removed the reed box after checking out my jets and air filter. I noticed ALL of my screws holding the reeds in were loose as well as there was some cracking on the reed petals; mind you, this was a 27-year old bike that never saw much love.
    Larry can correct me if I'm wrong, but you should use BLUE Loc-Tite on the bolts.
     
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  6. Larry's Shee

    Larry's Shee Active Member

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    Blue is fine. The color is actually size dependant, not much force on small screws/bolts. I use it on medium bolts that might not be critical or stressed. I was given about a quart of red yrs ago, so it gets used on most everything. A friend “borrowed” it from the marines :p
     
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  7. Larry's Shee

    Larry's Shee Active Member

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    BTW, Green is like welding it together, super high strength for very large bolts 3/4 (19mm) +
     
  8. Slydog

    Slydog Member

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    X2 on the locktite.your lucky srews are still there.
     
  9. DKavcak

    DKavcak Member

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    Having friends in the service definitely helps you out. My buddy Nick sent me a 50lbs box of metric bolts (all organized) back when he was a Gun Sargent in the Marines. Good 'ol Buckshot Rogers.
     
  10. Conner Jones

    Conner Jones Member

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    I tightened down the reeds and used blue loctite and the bogging is gone. Now that it is running well and i can be a little agressive with it, I am noticing that after holding it wide open and then letting of the throttle slightly to around half throttle or so, I hear 2 or 3 slap noises as the rpms are dropping. In not sure if this is what detonation sounds like or if its something else. It shouldnt be piston slap because I had the cylinder bored and honed and chamfered by a machine shop and they measured and told me to get a piston for 67.50 bore, which i did. The compression is 130, and it passes leak down test with only about .25 psi lost after 5 min.
     
  11. Slydog

    Slydog Member

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    That's weird.whats plug look like.loose bolt somewhere?
     
  12. Larry's Shee

    Larry's Shee Active Member

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    Deto is only under heavy load/acceleration

    Block it up under engine. Check swing arm begs. Mark chain and rotate wheels so chain makes one full lap. You might have a sticky link
     
  13. Conner Jones

    Conner Jones Member

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    What are swing arm begs? And also what am I looking for when i mark the chain and spin the wheels so it makes a lap? Will the chain pop or something?
     
  14. DKavcak

    DKavcak Member

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    Larry means the swingarm bearings.

    But you got the main idea about the chain. If you go through water a lot, like I do, you lose a lot of lubrication in the chain. That being said, occasionally you'll get links that bind (they typically will make a clicking/popping sound). The other purpose is to see if you're slapping off your chain guides if it's too loose.

    I also had a weird bogging issue from half to full throttle on mine. I actually just cleaned out my main jet because it had such a tiny imperfection in the jet that when the quad was cold, it pulled hard, but when hot, it would bog and it would backfire on occasion.
     
  15. Conner Jones

    Conner Jones Member

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    I think im going to start a new thread because this one is still titled bogging, even though thats not what were discussing anymore. But i just tried it in neutral and it still makes loud slap / pop noise 3 or 4 times when at high rpms and then decreasing a little. So its something with the engine
     
  16. Slydog

    Slydog Member

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    Is your exhaust secured tight? Orings?2 springs?no leaks? Pipe not rattling?
     
    Last edited: Jan 14, 2020
  17. DKavcak

    DKavcak Member

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    I'm not a fan of exhaust springs with our setup. That's why I'm keeping my stock exhaust, and also because DCNR only allows up to a certain decibel range, which most exhausts exceed.

    Speaking of which, I need to make a flange and weld it to my buddy's exhaust since we both love plowing into waterholes.
     
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  18. Slydog

    Slydog Member

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    Had mine saftey wiired for a while
     
  19. DKavcak

    DKavcak Member

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    Ew. No. Gross.
     
  20. Larry's Shee

    Larry's Shee Active Member

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    Unless you’re making an up pipe for water holes, a well sealed pipe with stock silencer, which fits most aftermarket pipes, is worth considering, IMHO
    OR a downward facing elbow, plus make sure the packing is good
     

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