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Stock fuel screw installation

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Hey, I put a jet kit and an aftermarket fuel screw in my 09 crf450x but it tmadee it really boggy and I'm afraid if I don't have tthe fuell screw set right I will end up blowing the motoor. So I am goingg to put my stock stufff bback in. My question is, when I install the stock ffuuel screw, to put it back to stock setting, do I just screw it all the way in or do I only screw it in only a certain amount off turns

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A fuel screw will not make it 'boggey', a fuel screw is for idle only. Assuming you set it for a perfect idle when hot, that is all there is too it.

A bog does not suddenly develop. What else did you change?

Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.

Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly). Once warmed, slow the idle to the lowest possible speed.

*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***

Turn the screw in until the idle becomes rough or the bike stalls.

if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.

If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.

Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.

If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.

If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.

If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,800 rpm, but go by the spec in your manual.

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Thanks for the reply, I also changedd tthe main jet to a 165 and the needle jet to the red one on the 4th clip. I tried to adjust the fuel screw before but had no luck. I rode the bike for about 20 mins and I loosened the screw unttil the idle was rough and then turned it in 1 and 1/4 and then adjusted the idle to a decent speed. And then I tried adjusting it and no matter how many turns I made it still bogged.

I am planning on selling the bike to buy a. Vehicle anyways so it would be just as easy for me to put the stock stuff back in the bike and sell the jet kit and stuffff with it. Thanks again

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Again, the fuel screw is for idle only. It has ZERO to do with any bog.

You made a lot of changes and did not explain scientfically why you did what you did. Nor did you apparently folow the method I carefully outlined to properly set teh fue;l screw and idle speed. You cannot 'wing it' and expect good results.

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Thanks for the reply, I also changedd tthe main jet to a 165 and the needle jet to the red one on the 4th clip. I tried to adjust the fuel screw before but had no luck. I rode the bike for about 20 mins and I loosened the screw unttil the idle was rough and then turned it in 1 and 1/4 and then adjusted the idle to a decent speed. And then I tried adjusting it and no matter how many turns I made it still bogged.

I am planning on selling the bike to buy a. Vehicle anyways so it would be just as easy for me to put the stock stuff back in the bike and sell the jet kit and stuffff with it. Thanks again

Fuel screw is for IDLE ONLY

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Thanks for the replies. Even tho you guys gave good tips and a good guide to go by, im still going to put the stock stuff back in, because i dont have the time or interest to try and dial it in, as im going to be selling it anyways. With the stock fuel screw, do i screw it all the way in to get it back to the way i took it out at stock sttings, or do i turn it so many turns. thanks

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fuel screw couldn't be adjusted or messed up enough to make the motor blow, if it doesn't seem to be working correctly make sure the oring, spring and washer are stacked on it correctly (or not missing). same with the stock screw, adj is made screwed in all the way to lightly seated and the number of turns are counted screwing back out.

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Actually I might end up keeeping my bike till the spring, so how do I get rid of the bog. Someone said before I need a 50 leak jet. Is this correct. I don't undeerstand why I need to do anything else, becausee I've seen other people on here with the same elevation and temp and stuff and their bikes ran perfect and they did the same jetting. I did not cut my airboox tho, would this be the reason I am getting the bog? Thanks

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Actually I might end up keeeping my bike till the spring, so how do I get rid of the bog. Someone said before I need a 50 leak jet. Is this correct. I don't undeerstand why I need to do anything else, becausee I've seen other people on here with the same elevation and temp and stuff and their bikes ran perfect and they did the same jetting. I did not cut my airboox tho, would this be the reason I am getting the bog? Thanks

Thousands of posts on this exact subject in the 450X forum.

Follow the stickys at the top of the forum.

Not everyone rides in a way that they would notice the bog. If the bike is plugged up, the bog is not noticeable.

50 leak jet and a Merge racing apump linkage spring are the parts you need.

Then if it still bogs, you need to adjust the linkage.

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