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Suff

08' WR450 Grey Wire - No difference ?

15 posts in this topic

I just bought a very lightly used 08' WR450. It had a JD jet kit and TT AIS removal kit already installed. The throttle stop is cut to the correct length, the air box baffle is removed, the exhaust baffle is removed, and the grey wire was cut. The bike runs very smoothly (jetting is very good) but it did not seem very strong compared to the last two WR250's I had. I jumped on the dyno this weekend to check it out. 36 hp. I tried a few pipe options without much change (less than 1 hp). Out of curouisty I did back to back dyno runs this afternoon with the grey wire reconnected and then cut again. No difference whatsoever in the peak power, power curve, or air/fuel. Any ideas before I start checking out the motor?

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I noticed my grey wire. From my seat of the pants it doesn’t have an effect until 8k RPM.

I have a long steep hill climb. The WR would just stop pulling 2nd gear 8k. Disconnect the grey wire and it just keeps accelerating on past 8k. Maybe you have the wrong grey wire disconnected?

What pipes did you try? The stock header is a clog but the silencer is the worst, even with a GYTR tip..

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I guess your sure your jetting is right . when I first ran my 07 wr450 on the dyno I saw the air / fuel was all over the place . my accel pump did not work and all my jets were wrong . you know there is also a chance the your cams are not timed right. the bad news is the valve cover will not come off with the motor in the frame.

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Grey wire was the midde wire on one of the two 6 wire connections behind the left side rear plate. Same one I have done on the last two WR's I have had. I tried the stock pipe with the larger baffle in and out. I also tried a YZ muffler we had at the shop. The YZ added a little in the mid and about .5 hp on top.

The jetting is real good. Holding right at 13 to 1 on the main jet according to the sniffer.

This thing really has me confused. It starts and runs great. The jetting from top to bottom is as good as any dirt bike I have done in the last few years. The compression seems very good. The bike has a smooth curve up to around 7500 rpm's where it peaks at 36 and heads back down. I will post the dyno sheet tomorrow when I am in the office with a scanner.

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is it possible that the grey wire was grounded to something? are there any other electrical modifications to the bike?

is it possible that the throttle stop was not cut down enough?

or maybe the bike has one of those slow turn throtle tubes:p .

I found this dyno run of a stock 05. the only mod is the throtle screrw.

http://www.southbayriders.com/forums/showpost.php?p=160647&postcount=8

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No other mods have been made. I have cut the wire in two different locations and taped it up completly.

I looked down the carb with the airbox off over the weekend. The slide was completly up @ full throttle. I pulled the screw tonight to double check.

23 mm total length.

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the bad news is the valve cover will not come off with the motor in the frame.

tweav - I've had the valve cover off and checked my valves once w/o any problems. I can't recall how difficult it was but that cover definitely came off with the engine in the frame. I did have the upper engine mounts off.

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tweav - I've had the valve cover off and checked my valves once w/o any problems. I can't recall how difficult it was but that cover definitely came off with the engine in the frame. I did have the upper engine mounts off.

agree. they do come out and I also had to remove the top motor mount. I've done it on three different 08 WRs. there is a trick to it. you have to pull the cover out the left side( ie same side as the kick start). its lame becasue you drag the half moon gaskets over the cam. but its the only way.

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tweav - I've had the valve cover off and checked my valves once w/o any problems. I can't recall how difficult it was but that cover definitely came off with the engine in the frame. I did have the upper engine mounts off.

Yeah it's not real fun but I got to the point I could do it without even removing the hotstart cable... trick is removing the cover first with gasket stuck to the head and in reverse order upon install... it's almost impossible and hard on your gasket if you follow the instructions in the manual telling you to remove the cover and the gasket as one:prof:

I never really rode my bike with the grey wire att'd, all my other WR's were canadian so no grey wire and I have never had my current bike on a dyno so I could not tell you what to expect in terms of hp gains or power curve but I am curious to hear the outcome...

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Maybe it will come out but it was very tight in my bike , So I just pulled out the engine . I was changing the piston anyhow.

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36 hp is that it? I thought these bikes make alot more. My drz makes around 33 i think and the wr feels like a totally different type of bike, thought it was at least in the 40, o4 450 with yosh carbon slipon and jetted right

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tweav - I've had the valve cover off and checked my valves once w/o any problems. I can't recall how difficult it was but that cover definitely came off with the engine in the frame. I did have the upper engine mounts off.

he kinda scared me when i read that....i was like the carb is bad enough but the valve cover too...haha

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I'm beginnng to get a little skeptical about the whole grey wire mod thing. I've seen so many conflicting thoughts and pronouncements that it really makes me wonder if there is an effect by disconnecting/connecting the grey wire.

Does anyone have any objective evidence? :excuseme:

trailhead2004

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