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offroadxj

WR450F just bought, major issues running!

24 posts in this topic

Hello everyone, I used to be on this forum but just got back into riding recently due to recovery from an injury.

 

I bought an 07 WR450F that I made into a dual sport to ride around town and up to the woods. I'm having major issues with it that I can't get figured out and I'm getting really frustrated with it!

 

A little background, bike seems like it was barely ridden and is very clean. Had an FMF ti powercore slip-on on it but because I was buying it to ride on the street I asked the small motorsports dealer to put back on the factory one (they had it) and rejet back to stock (maybe a big mistake?).

 

I put the street legal kit on (Tusk) which included redoing some of the factory headlight wiring, but other than that doesn't connect to factory wiring at all. 

 

My first ride I started having issues. Started at constant throttle and is best described as cutting out/missing. Then as the bike got hotter, it started doing it across most all rpm range. Always noticeable during smooth acceleration. It is hard to describe how bad this problem is. The bike is really almost unsafe to ride because it is jerking/cutting out so badly. 

 

Things I have tried so far: first I changed the spark plug. No difference. Then I tried unplugging the TPS. Bike was quite a bit better but still very very noticeable issues. Just tried today to put back on the FMF exhaust , and if anything it's worse. 

 

Any help is greatly appreciated. I have quite a bit of money tied up into this bike right now, and can't even ride it! Thanks.

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Hello everyone, I used to be on this forum but just got back into riding recently due to recovery from an injury.

 

I bought an 07 WR450F that I made into a dual sport to ride around town and up to the woods. I'm having major issues with it that I can't get figured out and I'm getting really frustrated with it!

 

A little background, bike seems like it was barely ridden and is very clean. Had an FMF ti powercore slip-on on it but because I was buying it to ride on the street I asked the small motorsports dealer to put back on the factory one (they had it) and rejet back to stock (maybe a big mistake?).

 

I put the street legal kit on (Tusk) which included redoing some of the factory headlight wiring, but other than that doesn't connect to factory wiring at all. 

 

My first ride I started having issues. Started at constant throttle and is best described as cutting out/missing. Then as the bike got hotter, it started doing it across most all rpm range. Always noticeable during smooth acceleration. It is hard to describe how bad this problem is. The bike is really almost unsafe to ride because it is jerking/cutting out so badly. 

 

Things I have tried so far: first I changed the spark plug. No difference. Then I tried unplugging the TPS. Bike was quite a bit better but still very very noticeable issues. Just tried today to put back on the FMF exhaust , and if anything it's worse. 

 

Any help is greatly appreciated. I have quite a bit of money tied up into this bike right now, and can't even ride it! Thanks.

 

 

Do you know what jetting changes were made when they put the stock pipe back on? Did this problem occur prior to the work being done to the bike? Sounds like a possible lean condition.

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Did it sit for awhile? Sounds like it did potentially, in which case the carb is likely in need of a proper cleaning. I just got done helping a buddy of mine this weekend go through the FCR carb on a Honda 450X he just bought that is super clean but definitely sat awhile and ran horribly. Cleaned the carb, replaced the jets (his pilot was almost completely clogged), and modded the accelerator pump and bam - totally new bike. Anyway, this would be suspect #1 for me if it were my bike.

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Thanks for the responses guys. I do not know what he put in as far as jets. I'm also not sure if it did it before. It was a consignment deal and the dealership tells me he knows the seller very well and that it had no running issues before.

I do believe it probably sat for a while, but can't be sure. Tabs were a couple years old so I assume it wasn't rode a whole lot recently. I've heard a couple things about modding accelerator pump, should this be done? What's the best thing to do, parts I can buy? Thanks again for any help.

Edited by offroadxj

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I am thinking of buying the jd jetting kit and from what I'm reading with exhaust I should use a 168 main and 48 pilot? What about red or blue needle, probably on position 4?

Edited by offroadxj

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Tons of info on how to uncork/rejet and even go to yz carb specs for best running condtions.

 

Read the FAQ section at the top of this forum

 

Ballpark jetting with uncorked intake and exhaust

 

165m

45p

R&D remote fuel screw

ncvs neede or blue needle 3rd clip

50 leak jet

ACV valve pin cut, and main air jet changed to 100

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My first ride I started having issues. Started at constant throttle and is best described as cutting out/missing. Then as the bike got hotter, it started doing it across most all rpm range. Always noticeable during smooth acceleration. It is hard to describe how bad this problem is. The bike is really almost unsafe to ride because it is jerking/cutting out so badly. 

 

Something similar, but not exactly the same, happened to me after I overheated my wr years ago. 

 

One thing to consider is that electrical/electronic components are sensitive to excessive heat.    If your bike behaves differently as it gets hotter, then you should start first with changing the ignition / spark plug coil.   Thats what my problem was.     

 

After that, then you may need another controller.

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^^ YES, the stator is very fragile, and does not last forever, especially if the bike has been running hot/lean for years

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I had a Kant Take Much (KTM) for a few years.  It was VERY sensitive to the fuel line routing from the tank to the carb.  It seemed that it would heat the fuel, cause vapors/bubbles in the line, which would cause it to hesitate horribly.  You might just check that the line doesn't/can't airlock from the tank to the carb.

 

Good luck, Sir!

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Thanks for all the help guys. I will look into electrical as well. Interesting though that now after the pipe was put back on it seems worse. Doesn't need to get nearly as hot, basically started doing it right away.

I had a Kant Take Much (KTM) for a few years.  It was VERY sensitive to the fuel line routing from the tank to the carb.  It seemed that it would heat the fuel, cause vapors/bubbles in the line, which would cause it to hesitate horribly.  You might just check that the line doesn't/can't airlock from the tank to the carb.

 

Good luck, Sir!

It is a little weird that right after I got done installing the street legal kit, the bike did not want to start and then I started noticing issues after (although it was really my first longer ride after). Point being, I had the tank loose, but not off, and was moving it back and forth probably twisting on the hose some. The hose does look fine and I've had the tank off a couple times since, is there anything that can be checked to see if this is happening? If there is air what could be causing that?

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Thanks for all the help guys. I will look into electrical as well. Interesting though that now after the pipe was put back on it seems worse. Doesn't need to get nearly as hot, basically started doing it right away.

It is a little weird that right after I got done installing the street legal kit, the bike did not want to start and then I started noticing issues after (although it was really my first longer ride after). Point being, I had the tank loose, but not off, and was moving it back and forth probably twisting on the hose some. The hose does look fine and I've had the tank off a couple times since, is there anything that can be checked to see if this is happening? If there is air what could be causing that?

 

You are looking in the wrong place

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I had a clear fuel line on my bike so I could see bubbles forming.  It would run fine initially, but as soon as it warmed up, it was a surging/bucking monster because of the fuel line vapor lock.

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I had a clear fuel line on my bike so I could see bubbles forming.  It would run fine initially, but as soon as it warmed up, it was a surging/bucking monster because of the fuel line vapor lock.

 

For a clear line to get hot enough to create vapor lock, IT WOULD MELT.

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Nope. 

 

It was my experience, my problem that I solved, and it caused horrible surging until I rerouted the fuel line so that the bubbles could escape up into the tank.  It was one of the reasons why I got rid of the dang thing.  That Kant Take Much made me fix the carb over and over again, fixing one problem after another.  Chase one leak, fix another.  Rinse, lather, and repeat.

 

Back to topic, I'm trying to give offroadxj something else to look at to solve his problem.  Since I'm not there, the shotgun approach is adequate for me.

 

Offroadxj, did you figure it out yet?

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I worked on a 2006 WR450 that had the dual sport kit installed on it with similar issues as yours and after spending many hours on trying to figure out the problem I found they didn't route the stator wires properly and the rotor assembly wore through a wire and caused a short. Even though the bike still ran it sputtered and jerked. It does sound like an electrical problem.

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I worked on a 2006 WR450 that had the dual sport kit installed on it with similar issues as yours and after spending many hours on trying to figure out the problem I found they didn't route the stator wires properly and the rotor assembly wore through a wire and caused a short. Even though the bike still ran it sputtered and jerked. It does sound like an electrical problem.

What do you mean didn't route the stator wires correctly? Nothing tapped into the factory wires at all. I ran everything along side the factory harness. The only things that changed was the factory taillight which I unplugged and taped off and the headlight harness as mentioned above.

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Put a higher output stator in it and a 15a fuse. You will be good

Which stator should I use? Links/brands? Thanks.

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