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2006 kx 450f bogging

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so when i was riding my kx randomly it started to bog at lower rpm and it would eventualy stall. and i noticed now that its bogging at the lower rpms its backfiring a little bit. when the bike gets hot the bogging gets worse and makes it near impossible to start once it stalls. my valves where adjusted a few months ago and the main jet is bigger then stock, it ran great for awhile now its not running so great. if anybody can help me out that would be great i want to go riding this week end :lol:

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you might be boiling the gas in the tank. if you're doing that, you just need to put some heat tape on your tank.

you also might need your valves done again.

or you may need to tune your carb some more

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thanks for your answer last time i had a local shop do the valves and carb, this is my first four stroke so idk much about them ive rebuild a few two strokes, im not to sure what the valves should be set at for the intake and exhaust. i would like to learn how to do it myself so i could save me some money. and do you think it coulnd be just a bad spark plug?

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It could be just the plug, didn't think of that, pull the plug and see what it looks like.

and your valves should be

intake- .10-.15mm

exhaust- .17-.22mm

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First, you need an owners' manual.

Then, follow the recommended maintenance schedule.

If you have more than 150 hours on the top end, you need to rebuild your head, check your crank play, and put in a new piston and rings.

You can't guess you're way through the problem. Start at the beginning, routine wear maintenance, and go from there.

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Why does your 06 carb have a bigger than stock main jet?

At under 1500 feet and moderate temp and humidity, with the stock (open+loud) muffler, the 06 stock jetting is really good!

Fuel screw = 2 to 2.5 turns out.

Pilot = 42

Needle clip = middle position.

Main = 175.

If you like to "chop" the the throttle a lot at low revs, then try the 55 leak jet. Stock = 75.

It also makes a huge difference if the AP diaphragm is new, AND the AP cam screw adjuster is set so the AP rod moves as soon as the slide lifts! The AP timing can get out of adjustment with lots of use or bad luck. Easy to check by sight and feel: with the bowl and air boot off and a finger on the end of the rod. Turn the throttle slowly, watch the slide lift and feel the rod push down. Adjust the screw inside the right cover. There will be a certain screw position that works best. All this can be done with carb on the bike, but if you don't know the carb well, then I'd suggest you take it off.

Get all the above right, and the engine should cope with at least two full throttle on/offs at very low revs under load. It should start first kick most times. :lol:

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sorry for the late response guys but when i first got the bike it was back firing like crazy so i sent it to a local shop that he shimmed the valves and put the main jet from a 175 main to a 190 he said it ran better this way i guess...it also is very hard to start now with cold weather. i noticed that my hotstart lever looked as it was getting stuck while riding could that cause a fouled spark plug?

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A sticky hotstarter plunger can cause the back firing. That should have been the first thing the shop checked.

A 190 main is just wrong, and it'll kill the power too. Some owners might like to lean down the needle pos and run a 180 or maybe 185 main, but I prefer stock for the best mix of roll on response and wide open power.

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how could i tell if the hot start is stuck? the lever retracts normally when you pull it in. and as far as the main jet it ran fine so far with 10 hours on the valve adjustment and 190 main could that really make it bogg after atleast 10 hours or more of riding time?

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how could i tell if the hot start is stuck? the lever retracts normally when you pull it in. and as far as the main jet it ran fine so far with 10 hours on the valve adjustment and 190 main could that really make it bogg after atleast 10 hours or more of riding time?
To check the plunger is returning fully (not in the lean position) you have to remove the plunger from the carb and clean in there. Just take the fuel tank off. Then get a 14mm spanner and be careful not to over tighten it when putting it back together.

You could easily get away with 10 hrs running fine, and then bog stall it because the jetting could be better.

It takes less than 10 minutes to change a main jet. Leave the bowl on. Get a 17mm spanner and remove the drain plug on the bottom of the carb, then with a 6 or 7mm socket (I cannot remember which) the main jet comes out.

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so i finally got the chance to work on the bike today, on my gas cap i have a small peice of rubber hose with a check valve on top, i read online that these are not a good idea for some reason, i removed it and replaced it with a normal rubber hose. i started it up and rode it around, no more bogging or stalling anymore. so so far so good but i still have a mild back fire on deceleration tho. so this weekend im going to buy some feeler gauges and see if the valves are a little out of spec. if there good im guessing its in the carb?

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so i finally got the chance to work on the bike today, on my gas cap i have a small peice of rubber hose with a check valve on top, i read online that these are not a good idea for some reason, i removed it and replaced it with a normal rubber hose. i started it up and rode it around, no more bogging or stalling anymore. so so far so good but i still have a mild back fire on deceleration tho. so this weekend im going to buy some feeler gauges and see if the valves are a little out of spec. if there good im guessing its in the carb?

Yep. had the same issue, dumped the check valve and swapped gas caps( gas cap was definitely the issue, so pull yours apart and check for blockage. The check valve was just part of the process.) Go 1/4 turn richer on the fuel screw.

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you think 1/4 turn on the fuel screw would fix it even tho the carb has a 190 main?

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