4 stroking

Jellyfish420

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Jul 5, 2017
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Ok I know most cases is caused by running to rich... But my bike did good. Would 4 stroke for maybe mile them once warmed up would run perfect up to 40mph/8750rpm. Last week it started 4 stoking for a good 4-5miles before it would actually run right... Yesterday and today it won't stop at all... Top speed of about 25mph now. I don't know where to start. The main jet can't just all of a sudden be to big now... Or can it? Someone please give me some advise on what I should be checking please
 

crassius

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Sep 30, 2012
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over the first 200 to 300 miles the motor will change as it runs in - I never bother serious tuning until then as long as it runs well enough
 

Jellyfish420

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Jul 5, 2017
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It's got about 700 mile. It's not running well at all. And it's eating up gas faster than it used to as well...
Not a loose main jet
 

Greg58

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May 1, 2011
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I always start with the basic things, check your plug for build up. A dirty plug can cause it to not run right, check the compression, some times one piston ring breaks. Check all the connections on the ignition system.
 
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crassius

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clean it well, then ride it a while and look for oil residue around your gaskets
 

Jellyfish420

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Haven't had a chance to really look at it... But I used to be able to get to my girls house and back twice with gas left to make it around a little.... The other day I filled it up made it to her house and ran out of gas almost back home. When it is constantly 4 stroking would that cause it to use like twice the gas it normally does?
 

crassius

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lots of things use extra gas - riding WOT, leaking fuel lines, leaking carb, any leaking gasket that robs power, clogged muffler, dragging brake pad, low tires, rubbing chain, slipping clutch

which of those is going on with your bike?
 

Greg58

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It shouldn't take but a few minutes to check a few things, it may keep you from being stranded a long way from home. Loosing compression at the head gasket would definably cause a lose of power, simply take the head off, look at the gasket, look for scratches in the cylinder and look at the plug condition. Then reinstall the head and torque it down evenly. 12 to 15 foot pounds will be good.
 

Jellyfish420

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Jul 5, 2017
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lots of things use extra gas - riding WOT, leaking fuel lines, leaking carb, any leaking gasket that robs power, clogged muffler, dragging brake pad, low tires, rubbing chain, slipping clutch

which of those is going on with your bike?
Nothing leaking. Tires, brakes, and clutch are fine. Mufflers not clogged. Haven't been riding any more wot than I I had before.
Didn't get a chance to pull the head off last night. But I did notice riding last night just going by sound..... Flat ground sounds like straight 4 stroke... Down hill it 4 strokes with a sputter but going up hill it 4 strokes with intermittent 2 stroking... From what I've read that sounds like a rich condition?
 

crassius

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Sep 30, 2012
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yes, it does, but weird for it to go rich if it wasn't before

clogged air filter or changed float level or maybe ignition missing a beat every so often
 

Jellyfish420

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Jul 5, 2017
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yes, it does, but weird for it to go rich if it wasn't before

clogged air filter or changed float level or maybe ignition missing a beat every so often
Changed float level huh? That would do it? Couple weeks ago something went wrong.. Wouldn't run like no gas... But there was gas coming out the back so I pulled carb apart and the jet was laying in the bottom of the bowl. Maybe I accidentally changed it. Where should the float level be?
 
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Jellyfish420

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holding carb upside down sight across float, main jet should be just barely peeking thru hole in middle of float
Thank you so much crassius! Runs so much better!
Still seems like it has a little miss to it... But I bet that might be the plug as rich as I have been running it. Going to pick a couple more up tomorrow.
My friend that's pretty knowledgeable with dirt bikes told me to try running the next hotter plug too. Currently I'm running a ngk b7hs.... You think stepping up to the b6hs would do anything for me?
 

Greg58

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May 1, 2011
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The b6hs is probably the most used plug, on these little engines the plug and plug gap can make a big difference. I've heard of people using anywhere between 24 to 32 thousands, I would try several till you get the best results. 26 to 28 has worked well with mine.