06 KX450F Stalling & Hard to Restart

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06 KX450F Stalling & Hard to Restart

Post by 4Strokes » Fri Jun 03, 2016 7:06 pm

Topic: 06 KX450F quick shot, stalling and hard to restart
Author: motocros125
Posted: 05/24/2010 8:12:01 PM

i have an 06 kx450f and i do a lot of trail riding i had a problem this past weekend with it stalling and then it would take forever to start it even with the hot start. One of the quick shots from boyesen has something to do with the hot start has anybody used this and does it help maybe someone has used one of the others let me know how they work.

Reply by b_king on 05/26/2010 6:08:12 PM
I have a Quickshot 2 on my KLX450R. It has nothing to do with the hot start. The purpose of the hot start is to allow fresh, cooler, air in to the carb to ease starting when hot because these new style 4 strokes run so hot they lean themselves out. The purpose of the Quickshot is to ease throttle bursts and eliminate the bog to which so many bikes suffer. Basically when you crack the throttle very quickly the accelerator pump shoots a spurt of raw fuel, in to the venturi of the carb, allowing that quick opening of the carb slide to not lean out the mixture with the sudden increase of air and lack of fuel because it can't respond fast enough via attamization. What you're experience is the bike is getting even hotter than it would normally on a track because trails are slower and tighter. You need to ensure you're hot start cable is adjusted correctly and operates the valve on the end of the cable properly. Otherwise you might have a jetting issue where is is too rich on the pilot circuit. At that point, you can try adjusted the fuel screw to lean out the mixture so when it's hot it's not overly rich. To do this you have to turn the screw in, reducing the amount of fuel. Turning it out(counter clockwise) will increase the amount of fuel. The fuel screw is a fine turning tool for the pilot circuit, controlled primarily by the pilot jet. Good luck! Robb

Reply by motocros125 on 05/27/2010 12:02:52 AM
[This] says hot start assist what does this mean. and the adjustable leek jet will this help keep my bike from stalling? if not who makes a flywheel weight for my bike i have not been able to find one and my only other option is a steel clutch basket. my buddy owns his a bike shop and he adjusted the carb but he's never used anything like the quickshot but he suggested getting the steel clutch basket. i guess i could try to trade it for a klx but there's too much done to mine to get a stock bike.

Reply by b_king on 05/28/2010 10:29:11 PM
If you read what I wrote it explains the different functions of the hot start vs. the Quickshot accelerator pump housing. The link you supplied is the newest version which is simply adjustable. The older versions(Original Quickshot and Quickshot 2) were adjusted by simply changing the jet size either bigger or smaller. But the original benefit of the quickshot was a larger fuel volume in the fuel squirt. Not how much per say, just longer duration as there was more in it. They both sort of affect each other obviously to an extent, but there is a difference. If you are suffering from BOGGING issues when cracking the throttle quickly in gear while riding, then yes, the quickshot could be your solution. Many people swear by it. If you are looking for something to help with taming down the power and making the bike easier to ride in the lower rev range, like lugging gears and short shifting to use torque, and help with stalling in tight woods with a lot of clutch work then a flywheel weight could be the answer, either that or get one of those fancy new auto clutches.

In terms of increasing your flywheel weight, Steahly Offroad makes a weight for the KX. The steel clutch basket will make a little difference, but it's not the right way to do the job because it's not directly on your crankshaft, it on the input shaft to the transmission which is driving by the crank, thus it won't be as much a difference for the money you'll pay for the basket.

Reply by motocros125 on 06/03/2010 10:56:52 AM
i don't want to tame down the power i like it the way it is. It doesn't bog when the throttle is cracked open most of the time when i do it i'm going down a hill and when i'm almost to the bottom it will die. i haven't really messed with the bike much and all the stuff on it was their when i got it i guess i need to check the jetting to make sure he rejetted it after the exhaust. do you know what size jet it should have with a full pro circuit exhaust. i thought the being hard to start might be the valves needing adjustment but when i cleaned the carb out we looked through the intake at the valve and it looks brand new the cylinder is a different color than the head also so i'm figuring the whole top end is new. i called boyesen and they said when using the quickshot 3 with the hot start assist you purge the system by pulling hot start full throttle kick it twice then start it like it's cold.

Reply by b_king on 06/05/2010 08:50:04 AM
Well first off just looking down the intake at the intake valves doesn't really tell you anything about their condition because you can't see the clearance(that has to be measured) you can't see the condition of the seat or the face. If there was any reversion then you'd be able to see it but it sounds like not. You'll have to figure out stock jetting from a dealer, and general exhaust systems require little or no jetting change much to many people's opinions. You can also contact Pro Circuit directly and ask jetting advice. Purging the system is exactly what I wrote in my first reply. It allows fresh cool air to enter. The cylinder might be a different color because it was cleaned, or it's new, or it's a replacement larger bore. The stalling could be a float height issue when you get to the bottom of a hill there isn't enough fuel in the float bowl to continue and it stalls out.

Reply by motocros125 on 09/14/2010 11:46:03 PM
changed the jetting and solved the issue the guy i got it from had it jetted to run race gas probably why he trashed the last top end. Now it can be started by hand and is a beast in the woods. first hare scramble coming up pretty soon.

Reply by b_king on 09/16/2010 04:13:57 AM
Glad to hear you got it figured out. Typically race gas will not trash a top end sooner than pump as most race gas is leaded and cleaner purer fuel than the ethanol pump garage they're selling us. The big thing is the lead in the race fuel. The lead acts as a cushion for the valve on the seat which greatly lengthens valve life, that is as long as they're regularly checked and adjusted.

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