2007 WR450 stutters at low rpm?

[nickt916]

I bought this bike not long ago it had a grat wire mod, intake mod and YZ throttle and then jetted supposedly for those mods. I installed a YZ header and a YZ muffler that i shortened to a 08 shorty YZ muffler. It stutters at lower rpms, but when i open up the throttle then it has no problems delivering the power.

I dont know much about jetting and just wondering if this is jetting related or do i have fuel delivery issues at lower rpms? any suggestions on jetting if this is the case? thx

[nickt916]

i just looked at whats written on the carb and it says

1.5

48

170

anyone know the top of the head what stock is?

[tweav]

anyone know the top of the head what stock is?

What are you talking about ?

as far as your shutter goes it sound like the normal low rpm shutter you get from these bikes . If you take your bike to a dyno ,and put in on a wide band O2 sensor you can get your jetting spot on and alot of the shutter will go away . when I put my bike on the dyno it said it was too fat straight acrossed the board except it went way lean when I cracked on it . so I put in a smaller mj and pj and got a rd powerbowl to fix my non working accel pump

[KennyMc]

i just looked at whats written on the carb and it says

1.5

48

170

anyone know the top of the head what stock is?

If you are talking about jetting, stock is 162 Main and 45 Pilot

[motoscotty]

Nick,the 170 may be a little fat but with winter just around the corner cooler temps. will help a little.I would suggest a 165 or 168.I have an 08 with the same mods and the 170 was a little fat went to a 168 got the pump working right and it is spot on crisp and no bog.The 148 sounds correct,do you know what needle is in it?

[nickt916]

Nick,the 170 may be a little fat but with winter just around the corner cooler temps. will help a little.I would suggest a 165 or 168.I have an 08 with the same mods and the 170 was a little fat went to a 168 got the pump working right and it is spot on crisp and no bog.The 148 sounds correct,do you know what needle is in it?

well i dont ride when its colder than 50-60 degress, im not sure how to check what my needle whats in it, how can i check? those are the only numbers i see on the carb, 1.5, 48, 170,

i think when i bought, it had intake mod and gray wire mod and YZ throttle, with stock WR muffler+pipe and it ran good around the street at low and high RPMs. However, when i put on the YZ header and then short YZ muffler it started running stutterer at lower RPMs, but fine at higher RPMs. im not sure which way i should go with the screws and needles, but maybe i should try the 165, 168 and see how it does?

[flyer05]

try a 50 pj.

[drtbk4ever]

im not sure how to check what my needle whats in it, how can i check? those are the only numbers i see on the carb, 1.5, 48, 170,

I think it is time you got intimate with your bike. I see you have a lot of posts on Thumpertalk, so you are not a newbie. Although the questions you ask are what we would expect from a first time poster.

Get yourself a manual and pull jets out of the carb. Just because it is written on the carb doesn't mean that is what is still in there.

Do a search on here and find the jetting tutorial. Do a search for stutter. All those threads will help you explain what is going on and will help you to understand your carb a little better.

[nickt916]

I think it is time you got intimate with your bike. I see you have a lot of posts on Thumpertalk, so you are not a newbie. Although the questions you ask are what we would expect from a first time poster.

Get yourself a manual and pull jets out of the carb. Just because it is written on the carb doesn't mean that is what is still in there.

Do a search on here and find the jetting tutorial. Do a search for stutter. All those threads will help you explain what is going on and will help you to understand your carb a little better.

i never had luck with carbs and jetting, thats one thing that just doesnt work with me lol, i tried searching in the jetting Q&A section with people who posted their bikes with mods and jetting, but?

[SJMC_DON]

Search TPS

[nickt916]

Search TPS

whats this is?

[KennyMc]

whats this is?

TPS = Throttle Position Sensor. Type in TPS in the search function in this forum and read the threads. Others have experienced the same type of thing.

[drtbk4ever]

Here is the thread on how to access the jets on your bike.

https://www.thumpertalk.com/forum/showthread.php?t=308687&highlight=jetting+tutorial

[nickt916]

I forgot that my smog equipment is off

Intake snorkel cover is off

Gray wire is cut

YZ throttle

with those mods this is the jetting 1.5, 48, 170,

it ran great with those settings, however right after the YZ Header and YZ muffler it stutters a bit at lower RPM but once it opens up it runs great.

Can someone please help me go buy the right jet kit, im very busy the next couple days and must buy and install correct jets by saturday, dont have enough time this week to do enough research on my own to buy the correct jets ? please help?