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Discussion Starter #1
Hey guys new here and am shopping for a bike for a sumo conversion but need some help. I've narrowed down my search to a either a wr450f or wr426f but am having some concerns. The 450 seems much easier to find wheels for... Does motostrano make wheel conversions for the 426? Or are they the same perhaps? I'm afraid the hubs are different... Also any recomendations from anyone riding either of these bikes? I don't mind a kick start vs. electric. I'm looking for something light, with reliability. between the 2 which one has a better motor (for street)? Also once uncorked will both bikes be comparable powerwise? And if I go with a 450 is the 07+ the way to go, or will I be just as happy with the steel frame chasis? Sorry for all the questions, but I was having a hard time finding specific answers through the search. Thanks fellas.

-Ming
 

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07' or newer WR450F is the way to go. Reliability (450-426) is equal. Yamaha makes a pretty good motor. My 06' YZ450F is still the original motor and I probably have close to 200 hours on it. Stick with the WR though...Wide Ratio transmission
 

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finding wheels for the yamahas are no big deal. I just put some wheels that came off of a 2008 450 on my 2000 yz426 and all i needed was new front wheel spacers. Just food for thought, you can pick a yz426 up for cheap which means more money for go fast goodies and gear.
 

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Discussion Starter #4
07' or newer WR450F is the way to go. Reliability (450-426) is equal. Yamaha makes a pretty good motor. My 06' YZ450F is still the original motor and I probably have close to 200 hours on it. Stick with the WR though...Wide Ratio transmission
Anything different besides the aluminum frame from the 05 to 07+? Specs online show the 05 is the same weight as the 07+ (the 06 weighs more though... :headscrat) If reliability is the same what are things to worry about/look for on a used on? trany issues with the wr426? hours/miles? etc. I know the 426 will be a decade old vs. the 450 (looking @ an 05 or 07+). And I'm def doing a WR. :thumbup:

finding wheels for the yamahas are no big deal. I just put some wheels that came off of a 2008 450 on my 2000 yz426 and all i needed was new front wheel spacers. Just food for thought, you can pick a yz426 up for cheap which means more money for go fast goodies and gear.
Thanks! I just saw a bunch of wheels available for the 426. the warp 9 wheels just didn't work for some reason... all other brands seem to have the right spacers/hubs for the 426. Also knowing that a 426 is a decade old, is there any major things I nned to look for when purchasing? Or are there any major rebuilds that need to be done? (head work, valves, trany, clutch, etc.)
 

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One thing to consider on the 426. I ride mine almost daily. The one and only gremlin that seems to not go away is the TPS on the carb causes a hiccup on occasion. There is really no ryhme or reason to it. Apparently all/most of the 426 sumos do it. No big deal, but it can get annoying. Most of the time you can unplug the TPS and the bike runs great without hurting anything. I have also heard of people not being able to get rid of the hesitation by unplugging the TPS, so...
 

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Discussion Starter #6
One thing to consider on the 426. I ride mine almost daily. The one and only gremlin that seems to not go away is the TPS on the carb causes a hiccup on occasion. so...
Thanks for the heads up! By hiccup do you mean a dead/flat spot or a surge in power? Is this something that happens at a certain RPM? Or under steady or hard acceleration? Is there anyway it can be tested on a test ride?
 

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Thanks for the heads up! By hiccup do you mean a dead/flat spot or a surge in power? Is this something that happens at a certain RPM? Or under steady or hard acceleration? Is there anyway it can be tested on a test ride?
Dead/flat spot in power. The best way to test is to ride it at a relatively constant throttle just like cruising at a certain RPM or speed down the street.
 

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Discussion Starter #8
Dead/flat spot in power. The best way to test is to ride it at a relatively constant throttle just like cruising at a certain RPM or speed down the street.
Thanks for the clarification. :thumbup: Last question about the dead spot. Is it something to with timing/jetting/etc? (possible fix with yz cams, different carb/needle, etc)? And most importantly is it a dead spot for a split second then goes away, or is it something that can happen unexpectated at any time? I'd hate to be riding a whoolie and have the bike dead spot on me to the point where it'd slam me down, or even worse loop me from trying to grab more throttle...
 

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Thanks for the clarification. :thumbup: Last question about the dead spot. Is it something to with timing/jetting/etc? (possible fix with yz cams, different carb/needle, etc)? And most importantly is it a dead spot for a split second then goes away, or is it something that can happen unexpectated at any time? I'd hate to be riding a whoolie and have the bike dead spot on me to the point where it'd slam me down, or even worse loop me from trying to grab more throttle...
It's just a split second, but it is kind of random. From what I understand it is a mapping issue. I also think that it might be cured with a newer FCR carb...I think. I wheelie the hell outta my 426 and haven't had any issues. I have it jetted pretty well and adjusted the tps and got most of the hiccup out of it. There is a few threads about it on thumper talk if you want to read more on it. Weather also seems to play a role in it. I just leave mine unplugged now and its fine.
 

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Discussion Starter #10
thanks again for the info bro :thumbup:
 

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My YZ sputters\hesitates\hiccups constantly at a steady RPM. I think it is the jetting as cooler weather helps my bike run better. I also think humidity plays a factor. I ride every day so I see all sorts of different weather.

As soon as I crack the throttle she is ON...I think if the mapping were off I would notice while accelerating...
 

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Discussion Starter #14
rode a 426 today (w/ fmf pipe). gonna test out another 426 (stock) and a 450 stock) tomorrow. I know I'll find out tomorrow for sure, but how much noticable difference is there in power between the two? the 426 didn't feel much quicker than a drz but the front tire came off the ground much easier that's for sure. Will the 450 have more scoot that the 426 or are they pretty close?
 

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Discussion Starter #15
2005 wr450!

Got the 450! Time to start the build :thumbup:

 

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Discussion Starter #17
Take care of that exhaust situation first. Looks like that one hasn't been de-restricted. Nice bike though, you're gonna love it.
Thanks man! I can't keep the front end down! lol. It actually has been opened up. It was drilled out and re-packed, the little tip you see is the end of a new baffle put in. Also the grey wire has been snipped and the throttle stop has been fixed. It has also been jetted to match the exhaust mod. I'm excited to start the sumo transformation. Just need to know what gearing I should start out with... :hmmm:
 

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Discussion Starter #18
ordered wheels today! :bannana:
May have to start a build thread. :D
 
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