Lean Condition????

[tacundra]

My '05 450r seemed to be missing in the upper rpm range(not hitting rev limiter)....this is during hard acceleration, like drag racing. When I get to 2/3 throttle or more, the engine begins to miss and sputter. Choke is not on.

My 450 is completely stock

I took the spark arrester out to see what kind of difference it would make...the low end seemed to have more grunt. However, this only aggravated the top end missing....while wondering, i also took off the air box lid to see reaction....the 450 would barely go after this change....

So, Is this simply a lean condition? Or should I be worried about other issues?

Thanks for any help!
Jimmy...:confused:

[Motoman440]

Dump some fuel on that baby!!! Way to lean!!! Stock main jet is 125. If you remove the airbox lid and open up your pipe you would need to move to a minimum of 185 for the main jet.

[Jersey450R]

the stock jet is a 118, not a 125.

[Motoman440]

Originally posted by Jersey450R
the stock jet is a 118, not a 125.

Your right. Sorry about that. I went to a 125 with a full pipe but a closed airbox lid.

[2manycrashes]

Originally posted by tacundra
My '05 450r seemed to be missing in the upper rpm range(not hitting rev limiter)....this is during hard acceleration, like drag racing. When I get to 2/3 throttle or more, the engine begins to miss and sputter. Choke is not on.

My 450 is completely stock

I took the spark arrester out to see what kind of difference it would make...the low end seemed to have more grunt. However, this only aggravated the top end missing....while wondering, i also took off the air box lid to see reaction....the 450 would barely go after this change....

So, Is this simply a lean condition? Or should I be worried about other issues?

Thanks for any help!
Jimmy...:confused:

Jimmy,

I never had my quad totally stock, but it sounds a little like you are just having some difficulty power wise getting to the rev limiter in 5th. Maybe there is someone here that is still stock that can help.

Either way, keep in mind when you start changing one thing it will require modification of other components as well.

You might try this link as it has some helpful tips on improving your R on a budget.

http://www.trx450r.org/forum/index.php?showtopic=1672

Good Luck

[WhiteZee]

Originally posted by tacundra
My '05 450r seemed to be missing in the upper rpm range(not hitting rev limiter)
what jetting are you using? most people who over jet will get a stutter and feel like your hitthing the rev limiter before you really are.

[tacundra]

Appreciate the input!

NO jetting etc has been changed on the quad.
The only thing I did was remove the spark arrester and then removed the airbox lid....each of these changes made the R
stutter even more on top.

I figured it probably was a lean condition, but i did not expect that much of a performance change.

When i did the same thing to my 400ex, i only had to change the jetting up about 2 sizes.

But you guys say i should bump all the way up to a 185 from a 118?! OK, sounds reasonable if this is what the HRC kit uses also.

I think i will go with the "cheap" setup that was posted on TRX450R.ORG.....

thanks.

[WhiteZee]

lol, i didnt know you had the air box lid off.

[Thump_It]

Yeah you definately want to rejet after taking the lid off. The bike is now consuming much more air. Don't run your bike until you have it rejetted.

No airbox lid+No rejetting=Future motor PROBLEMS

[450Rkid]

when you take the air box lid off it allows more air to be sucked into the motor causing it to run lean

too much air = lean
too much gas = rich
if you run it lean for too long it will either seize or blow up

[mattonln]

well, I went to a K&N w/outerwear and no airbox lid and have the HRC endcap. I went up on the needle 1 and the jetting at 145... anything over was way rich!!! get the FMF jet kit, its really easy to use and has detailed instructions.... btw, you are running way lean..... 450's run just a tad lean stock off of pump gas....

[Martin Blair]

Originally posted by mattonln
well, I went to a K&N w/outerwear and no airbox lid and have the HRC endcap. I went up on the needle 1 and the jetting at 145... anything over was way lean!!! get the FMF jet kit, its really easy to use and has detailed instructions.... btw, you are running way lean..... 450's run just a tad lean stock off of pump gas....

anthing over is lean? bigger the number bigger the jet, it would get richer as it goes up, If I where you I would run a 170 at least with that. Leave the needle alone it is fine at stock position. I have yoshi full system and hrc lid with uni a 180-185 seems to work well. I will stay at 185 when I get a cam.

[mattonln]

whoops! fixed... meant to say rich.... thanks for the hawk eyes!:D