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My Two Stroke Doesn’t Rev Out!

My Two Stroke Doesn’t Rev Out!


so the 125 is not running too hot let’s
pull it in the shop and figure out what’s up with it alright first off I’m
gonna run through the most common and simplest issues that lead to a bike not
wanting to rev out so first off I have to get it out of the way make sure
you’ve got enough fuel in the tank and on a two-stroke check your mixture ratio
if you’re running it too rich that could cause it to not want to rev out I run my
mixture at 32 to 1 next up especially on a two-stroke replace your spark plug and
then the dirty or over oiled air filter will restrict air flow and cause it to
cut out at high rpm a couple more simple things to check over that could cause
the bike to not want to have out would be a plugged up petcock valve here on
the gas tank so I’ll pull it apart make sure it’s all clear and then up on top
here on the cap if the vent is plugged up that could restrict air flow or feel
flow and cause the same issue and then it’s pretty common on two strokes a
cracked or chipped Reed that could do it too so you have to pull off the
carburetor slide out the roof cage and inspect each Reed so if you’re gonna be
pulling the carburetor off the bike I would definitely recommend splitting it
apart and doing some cleaning a plugged up main jet would definitely cause some
issues and a few other things that look over as well would be plugged up vents
or vent hoses a Mis adjusted fuel screw or if the carburetor needs to be
rejected really bad that’ll cause it to not want to rev out – another thing to
consider around the carburetor an intake area would be air leaks so look around
the joint between the air boot and air box fitting between the air boot and
carburetor also between the carburetor and intake manifold and around the reed
cage as well so if you spray starting fluid around all those connections and
joints with the engine running and the idle goes up slightly that means you
have an air leak somewhere oh and one more thing to check out on the
carburetor make sure the choke is operating properly a choke that a sticky
could definitely be a cool Britt one more simple thing to check out
before we get into the serious stuff a plugged up exhaust system is definitely
a possibility too the most likely scenario would be a
silencer that has packing that’s just soaked in oil so worth pull not apart to
check out and this scenario isn’t very likely but it’s worth mentioning so if
the I’d your bike’s sitting for a while there could be a nest or bird inside the
expansion chamber I’ve seen it happen before so definitely worth checking then
do and if you’ve been through all that and you still haven’t solved the issue
yet I would start digging into the electrical components so if you have an
ohmmeter and a service manual you’ll be able to
test the stator which is underneath the flower cover here and the ignition coil
which is usually tucked up inside the frame on most bikes
unfortunately the CDI box is something that cannot be tested and then if your
bike has an exhaust valve like this one does I would check into that next a miss
adjusted sticky or dirty exhaust valve will definitely be the cause of some
issues the last two things we’re gonna check out are somewhat in-depth you’ll
have to turn into the motor a bit so a worn top end meaning low compression is
something to look for and that would be worn out piston worn rings or a damaged
cylinder and then a leaking crank seal would be the last thing I would dig into
on the left side here you’ll have to remove the flywheel cover the flywheel
and stator and then you’ll be able to get a glimpse at that crank seal and
then over on the right side this is a little more in-depth you’ll have to pull
off let’s see here water pump cover both the outer and inner clutch covers
possibly a few gears inside and then you should be able to check out that crank
seal so the majority this info was directed towards the two-stroke but you
could apply most of it to a four-stroke as well and then if you have a
fuel-injected four-stroke there’s a whole host of other things you could
check over that could include fuel pump fuel filter throttle body injector
condenser regulator see what else yeah there’s a whole host a whole lot of
other things you could look over so I think I’ve ran through pretty much every
possible center and now I’m gonna figure out what’s up
with this bike hopefully I don’t have to tear and do it too much so the first
thing I’m gonna look at is the fuel and make sure there’s actually gas in the
tank pretty obvious deal yep tank is full and I know I just mixed that fuel
at 32 to 1 so that is not the issue the next thing I’m gonna check out would
be the spark plug just gonna go ahead and replace this one so the spark plug looks fairly normal it
doesn’t look like it’s majorly fouled out or anything I mean there’s nothing
on it but I don’t see a reason why that would be the issue I’m just gonna go
ahead and replace it anyways by the way you can pick up these two
Stoke stickers over at prime MX com all right I’m gonna fire it up and see if
the spark plug did the trick well it was that simple she’s all good
to go now it’s funny it’s actually happened to me before on this one 25 and
several other bikes as well so spark plugs are just like any other
part they wear out to kind of a bummer though I wanted to tear more into this
bike and give you guys some great content but for my sake good thing it
was an easy fix alrighty guys that is gonna wrap up the
video if you’d like to support the channel and add some flavor to your
bikes or your truck pick up some stickers over at prime MX com
thanks for watching everyone

100 comments on “My Two Stroke Doesn’t Rev Out!

  1. Cameron, I am 41 with 3 kids and about 5 bikes (2 and 4 strokes) at any given time. Please provide more trouble shooting content. You are a great teacher. You teach how to think through the problem logically. And your videography compliments your basic instructios for a simpleton like myself and I assume many others. This will expand your subscriptions. May I also suggest a video on 4 stroke valve adjustment? Thank you for your content!

  2. when u take stuff apart u should vid on how u put it back together that would really help me know what to do and how to do it thx.

  3. Ok, so I know nothing about dirt bike fixing or anything like that but I love your teardown videos and was wondering if you could make a disassembly and reassembly of the same bike so I could get a general idea on how to fix my 2 stroke. I know you probably won't see this so if anyone could link a video of a disassembly and reassembly of the whole bike I would really appreciate it. I couldnt find any. I might just really suck at finding things on it. Thank you.

  4. Hey cameron my water pump weep hole is always dripping coolant so it runs out and becomes unridable any idea if something is wrong?

  5. lol, could you imagine that bird inside the expansion chamber when you trying to start the bike again!

  6. Hi !

    Your mixture is too rich !
    This is why your sparkplug looks like a niga's ass.
    I use my EXC 300 at 60 to 1 and is don't have problems with this mixture.
    Frensis from Hungary

  7. don run at 32:1 very few oils these days recomend 32:1 check you oil manufacture's mixing recomendation! motul 800 recomends 50:1 motocross and 60:1 trail for their oil! so always good to check!

  8. Thanks to know my bike was doing this but I kinda knew it was the spark plug but not for sure then I remember your video and now I know!

  9. The heat range looks kinda cold on the spark plug you pulled (and yes it was fouled). Hope you went with a hotter replacement plug or at least start carrying spares with you.

  10. To big of main jet, getting to Mutch fuel,sounds it to me,or plug, I would check that before you tare motor apart,good luck!

  11. Spark plug could fouled out due to the 32:1. Personally I try and run anywhere from 40:1 to 36:1 on my yz125. Yea probably the spark plug was old but it looked damp, not a shade above coco Brown. Yes spark plugs go bad and I'm not saying it didn't, just your a tad on the oil rich side

  12. When a two stroke doesn’t rev out it is because something is causing it to be fat. So the plugged peacock and vet hose would not apply here. Crank seals would also make it lean. Being lean would make it high idle.

  13. Almost all 2 strokes I have had did eat spark plugs like candy… 4 strokes runs with same for years, might have something to do with all the oil?

  14. If you foul plugs a lot your mixing your ratio too rich for your riding style if you’re not consistently on the pipe making the motor hot enough to burn the oil you’re going to foul plugs. I run 32:1 on mine and never foul plugs. Gotta keep that motor hot to burn that extra oil.

  15. i'd say carburator needs some adjustment :/ my 50cc had thease problems, altoough that was when driving… but then i watched the full video and now i feel retarded

  16. I thought my CDI box was dead when I throttled it it didn't seem to have a limit to the RPMs. hold the throttle wide open you should hear the RPMs drop due to the CDI you are good to go i was scard it kind of skachy right now

  17. Fuel stabilizers pretty awesome I know for a fact there was junk in the carburetor and it cleaned it all out like new. Check for loose valves and I do mean lose valves. The carburetor valve screws we're literally going to go inside the engine tighten everything down

  18. Your videos are the most informative videos on YouTube. I'm learning a lot about 2strokes, as I grew up riding 4 strokes. Keep up the good work brother!

  19. I have a 03 Yamaha yz250 and it won’t rev out, I’ve changed the exhaust/ silencer, changed my carb, changed the reeds and cage, and it still won’t rev out, I found out that if you shut off the fuel then it’ll start running right, so would anyone know why it’s getting to much fuel, and also I have stock jets in it

  20. I'm having a sort of similar issue with my 50cc moped. When I have driving for a while in a steady rpm, and I wan't to downshift with rev matching before a corner, the bike only revs for like half a second while I have the throttle wide open. When I keep the throttle open, it stutters and eventually shoots right to redline.

  21. My quad revs to high back wheels gose like mad clean the carburettor and got a brand new spark plug cables fine so what else could it be

  22. hi my name are kim lindholm from sweden i have a suzuki rmz 250 year 15 then only start up whit choke.were can a do to fix so a can start up wite out choke on warm motor

  23. what mix ratio do u use for your CR?????it looks super clean and no spooge at all…..Greetings from Greece!!!wish u health and fast recovery

  24. Really liked your 4-stroke (Yamaha) video on jetting…..I think that you left a bit out here. Might still be a little rich…..I will bow to your knowledge on jetting. On 4-stroke the idle mixture screw controls fuel….so going out richens/in leans…..on two-stroke it controls the air….going in richens/out leans. I know you know but some of your viewers might not. You are a super good teacher….others can really learn from you. How goes the health? Praying for you. Tom

  25. Sometimes that insulator inside the plug will crack and it will look ok but will be sparking up inside the plug and not down at the electrode tip. I think it happens if the plug is screaming hot and then gets a dab of oil or fuel on it and the porcelain cant handle the thermal difference.

  26. I went for a ride today. My bike was running good. The bike did not want to idle so always had to rev it. Then after a while i was playing with the air skrew. It did not do anything. So i left it and went to go and ride again the bike just died so i went home and checked the plug. Its full of oil and when i clean it and start it again its just a lots off smoke coming out of the exhaust and then dies then the plug is full off oil again? Any help with that issue please.

  27. Love your video I got my first 2 stroke bike and I got it cheep put new top end on it and it will run good but when I go to buy it in gear it Boggs but the carb is clean and everything it sound good in neutral but in gear it bogs and goes and bogs and goes

  28. What if my 125 idles fine but bogs when under power I have to really work the clutch (more than I should have to) to get it into powerband

  29. "Oh it doesnt look too fouled out or anything" yeah it's not fouled it's just blacker than a burnt marshmellow

  30. I've had terrible luck with ngk plugs fouling in a 125 no matter how it was rode, tried a champion equivalent and haven't had an issue sense

  31. I have a rm85l and i put to much oil on the air filter i cleaned it and also cleaned out the air box but bike is still bogging. I also replaced the spark plug and cleaned carb can anyone help?

  32. That spark plug looked like hell… bike running way rich and the entire electrode end of the plug was totally black.

  33. Hi cam I’ve go a question for ya I have a 2007 cr85 and if you give it full throttle it Boggs out and dies like it’s not getting enough fuel, and it’s also got new VForce3 reeds. it had a 40 pilot jet and 140 main I bumped the main to 150 and the pilot to 45 and it still Boggs…🤔 do you have any idea what that would be?

  34. I saw an ad for a yz125 that doesn't rev out (1000$), do yall think it's worth it? I just emailed the guy about the model year

  35. My kx60 does this, I’ve changed the spark plug, air filter, cleaned the carb, exhaust cleaned, what could it be

  36. My Bike Will Not kickstart but will drift start but is running like its on life support, what do I do? We just replaced the top gasket kit and checked the carburetor. HELP ME PLEASE It’s a 1996 Rm125

  37. I have a similar case with my Kawasaki HD3 125

    It isn't rich or lean
    It definitely isn't running with too much oil being mixed because it has sufficient smoke coming out the exhaust

    Turns out the spark plug is just fouled up… cleaning it did the job

    But I replaced it with a new one after a week or so

  38. Question. Watching some scrambles and the way they bog there 2 strokes is unreal. How can they bog them around and not file plugs?

  39. why look for anything at all? once u hear that sound u know it has something too do with the spark plug, always check the spark plug first.

  40. hows it going I love your channel also I have a question you might be able to awnser to so I busted the throttle tube on my 2000 cr125 and I put new one on haven't really worked on dirtbikes before and now everytime I start the bike it screams and revs to redline I adjusted the cable on the carb and up top to allow the most possible play and the engine still screams when you twist the throttle. it snaps back and doesn't seam like its hung up on anything also I was twisting the throttle with the bike not running just to test the play im thinking I might have flooded the carb.let me know if you have any ideas on what might be the cause thank

  41. Hi cameron .. I have a honda cr 125 from 2007 but I have problems with the carburetion .. You could tell me please the jet of the maximum and the jet of the minimum and the notch of the pin I have a 28-68 pin … Thanks carburatore mikuni

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