Jetting advice

[Just_a_trail_rider]

I have an 05 wr450. 170 main jet, stock pilot jet (45?) and use the blue needle in the 4th position.

I'm no carb expert but it seems to run pretty darn well with the fmf factory 4 pipe. No problems in the past year.

But that factory 4 might be the loudest and most obnoxious pipe ever.

I just put the 96db quiet insert into it and repacked the muffler with the quiet packing. Its a LOT quieter now. But it doesn't run as good IMO.

It starts up ok, but stalls very easily in first at low speed. Also, it seems to have a slight sputter or miss at higher rpms. It does sound a bit fat, but again,I don't exactly have a trained ear for these things.

Common sense tells me that I should go with smaller jets since it is now more choked up. Should I go back to the stock settings and start the process over again? BTW... what are the stock mj, pj and needle settings?

[old man dan]

Your 170 main sounds rich, especially in summer heat. The pilot sounds lean though. Where do you have your fuel screw? Try a 48 pilot and 168 or even 165 main. Do the changes one at a time though. You can change main and pilot jets through the drain on the bottom of the carb, it only takes a few minutes.

[Just_a_trail_rider]

Thanks for the suggestion. I will try different jets to see what happens. I will go down to 168 first and then 165.

I guess I will just have to get out an ride it to see how it does.

Is there a way to really dial in the jetting while the bike is in my garage?

[Turismo]

I would go straight to 165 main and drop needle a clip.

[Dan_Lorenze]

My bike likes the 168/170 main and the 48 pilot. Don't touch the needle, it's fine where it is, right in Z middle..

[OneToGo]

You gonna get somehting different from all.

The high end sputter indicates slightly RICH.

I would recommend 168 MJ if temps are above 75-80f, that should sort out the top end FIRST.

Also, I would just up the pilot (at the same time) to a #48 and turn the fuel screw in 1/2 turn to compensate.

Go for a ride and readjust the fuel screw to sort out the lower throttle settings.

If the bike runs a little rich in the mid or just off idle (1/8 to 1/4) throttle then I would look at the needle (LAST THING). For my bike the BLUE JD was way too rich in any temps >20c (68f) (I have a FMF Q2). The red needle is a better all-round option IMO. RED #5 or #4 may be worth a shot.

?

[old man dan]

How did things work out. What did you end with and are you happy.

[Just_a_trail_rider]

I am working on this today. But first, I have to straighten out my suspension issues. I put in new springs front and rear and I am learning all about "sag". I will let you know.

[Rip Wheeler]

Thanks for the suggestion. I will try different jets to see what happens. I will go down to 168 first and then 165.

I guess I will just have to get out an ride it to see how it does.

Is there a way to really dial in the jetting while the bike is in my garage?

I did the blue needle #3, and the 170 main, little fat, good power, but no range. Dropped it to a 168, better, so I ended up dropping it again ot the 165, runs great, range is improved. I havent dont anything to the pilot, but will move it to the 48. I will swap over to the red needle also. I havent had much time on it this year, so its been tough to dial it in. Too many irons in the fire.

[Irregular Pulse]

so can you do most jetting without actaully tearing any parts off the bike. Never worked on any kind of engine before and jetting is sounding a lot elss complicated than I used to think just from reading these forums, how much dissasembly of teh bike is actaully required to re-jet a bike?

[Turismo]

so can you do most jetting without actaully tearing any parts off the bike. Never worked on any kind of engine before and jetting is sounding a lot elss complicated than I used to think just from reading these forums, how much dissasembly of teh bike is actaully required to re-jet a bike?

Just take the tank and seat off (6 bolts), then you can take the airboot off the carby and pull the carby off the head.

This will allow you to turn the carby to the side to get to the needle.

You can go one step further and pull off the throttle cable to completely remove carby.

[Just_a_trail_rider]

I've taken mine off and its not too bad. Once you do it a couple of times, it gets easier.

I was first rather timid about disconnecting the airbox from the carb. I though I was going to hurt it. But, loosen the clamp, use a little wd40 and pull the boot off of the back of the carb.

Then just bend it and move it out of the way. Its rubber and will soften up for the next time. But, don't destroy it, just move it out of the way.

After that, loosen the front clamp (mainifold?) and pull the carb back and off. Then you can move it to a position where you can work on it.