Jump to content
Sign in to follow this  

05 rmz450 1/2 throttle studder after rebuild

Recommended Posts

I have an 05 rmz450 that the cases were cracked. The bike ran great other than this. I replaced the cases and did a complete rebuild. The throttle cables were fraying so I also replaced them. That was the only thing I did with the carb. 3 weeks later I now everythign finished but Now what im getting is a 1/2 throttle studder/cutting out feeling, but it is only there when i hold steady around a sweeping corner or cruising down a straight at steady throttle. I have it jetted richer because its below 30 degrees on the ice. At that point I had a 45 pilot jet, 170 main, fuel screw at 1 1/2 turns out. So from there I lowered the needle (raised the clip) and it ran much better but the problem still is present. I want to lower the needle one more notch but i took a look at the plug and it is definitely more white than it should be.

I am very confused with this and I am not sure what esle to do. The bike runs like it is rich at half throttle but the plug is showing very lean. I am hesitant to lower the needle one more because of this. What could I possibly be missing? The bike starts in one kick and run amazing everywhere else besides cruising steady 1/2 throttle. I have double checked cam timing, cleaned the carb and made sure all electrical connections are good.

Edited by ben782

Share this post


Link to post
Share on other sites

After playing around with the jetting, figuring I have nothing to lose, I now have the correct plug color: light chocolate color. But the bike still runs like it did before. I now have 165 main jet, 45 pilot jet, 1 1/4 turn fuel screw and needle is one clip richer than stock. Today it is about 40 degrees.

Share this post


Link to post
Share on other sites

I've got an 05 and 06, and they both run best when jetted very close to 07 stock (42 PJ 170 MJ NCYR needle clip #3, fuel screw 2 turns out). In colder weather a 45 pilot helps with cold starting. If you're running the needle on clip #5, that sounds rich enough to cause your 1/2 throttle stutter - try #4 then #3 and see which produces the best midrange power and responsiveness.

Share this post


Link to post
Share on other sites

Thanks I will definitely give that a shot. Would you worry about plug color if I got it to run good in that rpm range. When I was getting closer the plug seemed to be getting pretty white?

Eddie - are you refering to just replacing it with a new oem needle jet? I dont think they come in different ranges thats why im asking. I obviously know the jet needles come in different ranges.

Thanks again!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

  • Similar Content

    • By SNORE125
      Anyone else have 130 main and 38 pilot jets already in the carb I took the wifes ttr 230 carb apart to add the bigger jets and this bike from 05 that I bought new already had them in it? I was reading that they came with a 125 main and a 36 pilot.
    • By Charles Joseph Miron
      Hello all.  Need a helping hand here..  
      I bought an older TT225 and am not about to spend almost $600 on a new carburetor for it. So I'm hoping someone can help me out with an idea of what (other than original carburetor) style, type and brand I should go with..  I'm also having a bit of trouble finding info on this bike.  It's a 1986 Yamaha TT225.  
      Thank you in advanced
      Charles
    • By Br0ck
      Hey guys, I went on vacation all summer and let my bike sit (2002 CR250). When I got back I ripped it apart and cleaned carburetor and put it back together and it started fine and ran alright, but idled really high. I adjusted the idle screw and realized it was a ridiculous amount of turns out. I can't remember exactly how many but id say 6+ turns out. My killswitch was a POS and didn't work anymore so I replaced it with an oem replacement. My last ride I crashed the bike pretty bad and I was off the bike for 2 weeks. I can't get the bike to start ever since I got installed the new killswitch. I think I wired it right I just replaced one wire at a time and it looked pretty straight forward. I verified it by testing spark while holding it in I was getting no spark but with it in running position it would spark. 
      Anyway I am just looking for some base settings for the Mikuni TMX to get my bike running again, my carburetor has a 35 Pilot and 380 Main jet which appear to be stock. I am located in Edmonton, AB, Canada which is about 2500ft and usually ride between 10-25 celcius.
      Thanks for any replies. 
    • By Goon Rides
      Hey guys... so I have a problem... I took the bike at Cal City, broke it in, and while I was doing so, the bike was bogging in first gear (Yes, first gear). Also it doesn't idle at all. I have to keep blipping it otherwise it'll stall. So I adjusted the screw circled in image 1. Well I was listening to the sound of the of the bike, yet the rpm's weren't increasing, and it was still stalling. So then, I unscrewed the screw in image 2, well I found out that it was fully twisted to the right. So then, I twisted it to the left, still nothing; it was still stalling... where's the idle screw? I am sure that the screw in image 1 is for the air/fuel mixture screw, and the screw in image 2 is the idle screw, just broken? I don't know, any and every help would be appreciated.


    • By Zach7018
      So Ive decided its time to pull apart my favorite machine and freshen it up, and I'm looking to make some improvements in the process. I already have a 3x3 mod and a JD jet kit done and it seemed to have changed the world. The stock bike just plain sucked and now its a lot better. I never expect 450 race bike power here but I know there is a little more and I'm wondering if the juice is worth the squeeze. I already plan to add a header and exhaust, an FCR39 carb and stage 1 hotcams. After some research it really seems like those places are where the gains actually come from, so would it be worth it to throw a 434 big bore kit at this bike or just stick with what I already mentioned and a new stock bore top end??? Also my rides are often solo and pretty isolated,how much of a reliability headache can I expect with these mods? 
×