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WR426 to YZ Timing

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in WR400F/426F/450F

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Guest Guest

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Does anyone know what must be done on the 2001 WR426 to change it to YZ timing? I own a WR400 and changed it to YZ timing. When I picked up my WR426 this week I asked the shop mechanic if it was done the same way (rotate the exhaust cam one tooth clockwise. All he could say was "since this bike is so new we're not really sure if its is done the same way or not." Anyway, looking for some help with this one.

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Guest Guest

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Last night I found some information on the DirtRider magazine web page from "Mr. Know-it-All." According to him the timing on the 2001 WR426 was not retarded as in years past and comes stock with the same timing as the YZ. So far I'm only finding mixed messages. At this point I'll wait a while longer for a clear consensus to appear before digging into it and messing with the timing.

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Last night I found some information on the DirtRider magazine web page from "Mr. Know-it-All." According to him the timing on the 2001 WR426 was not retarded as in years past and comes stock with the same timing as the YZ. So far I'm only finding mixed messages. At this point I'll wait a while longer for a clear consensus to appear before digging into it and messing with the timing.

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Apprentice

Dan

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Heard a rumor that ignition curve on WR is different than YZ in all cases and cam timing changes actually screw up the power output. Maybe this is why there are so many guys having trouble jetting and such. I have nearly stock jetting, stock needle in So Cal desert (1500-5000 ft elev.) and have zero problems. Maybe I am just very lucky.

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Grand Master

Taffy

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that isn't the problem. both YZ's & WR's are in trouble. even though people have tested & asked questions we don't know of any difference. but i know we'd be glad of any evidence. good luck.

Taffy

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Guest Guest

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I currently own a 2001 WR426 (just got it last week) and still have my '99 WR400. Both of these bikes are uncorked and race ready. However, my 400 is also set to YZ timing. My unofficial, unscientific test tells me the WR426 does not come stock with the same timing as the YZ. When I ride them back to back, the 400 power hits much harder. You can loop it pretty easy in 1st or 2nd gear just by hitting the throttle hard. The 426 is clearly more powerful but the power does not hit nearly as hard as my 400. The 426 feels more like my 400 did with the original WR timing (only stronger in power).

I know this flys in the face of "Mr. Know-it-all" from Dirt Bike magazine, but that is what the seat of my pants tells me. I guess in time we will all know for sure.

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I currently own a 2001 WR426 (just got it last week) and still have my '99 WR400. Both of these bikes are uncorked and race ready. However, my 400 is also set to YZ timing. My unofficial, unscientific test tells me the WR426 does not come stock with the same timing as the YZ. When I ride them back to back, the 400 power hits much harder. You can loop it pretty easy in 1st or 2nd gear just by hitting the throttle hard. The 426 is clearly more powerful but the power does not hit nearly as hard as my 400. The 426 feels more like my 400 did with the original WR timing (only stronger in power).

I know this flys in the face of "Mr. Know-it-all" from Dirt Bike magazine, but that is what the seat of my pants tells me. I guess in time we will all know for sure.

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Experienced

mcarp

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If you're looking advice for a 74 maico or 77 Husky, Mr Know it it all "Knows". 2001 Yamaha? Hardly. This guy is the biggest joke I have seen in print! The magazines aren't that much better. They don't want to bite the hand that feeds them test bikes, dinners, and cocktails, ya know, so they don't recommend wildly different settings than stock for fear of scaring folks away from the bike. There are a lot of folks (most of my riding friends included) that are scared to death of carbs. Even simple 2-stroke or CV carbs.

Hmmm, I had to replace ALL the jets (pilot, main, air), the needle, play with the fuel screw, etc. The float height seems to be OK.

Even stock the pilot, main, and fuel screw needed changed/adjusted.

The new WR's are timed the same as the old, don't the Mr. Fart's A Lot tell you otherwise. True the ignition curves are different for YZ and WR's, but plenty of folks (including myself) have successfully jetted the WR w/ YZ timing with extremely pleasing results (no plug fouling, easy starts, ripping performance)

Here's my $.02. Ride with the WR timing for a time while you learn the bike. Turn that fuel screw out a little to smooth the engine out. Perhaps go with a 45 pilot if you're headpipe is glowing or it's backfiring on deacceleration. I need a 48 myself, but yo're better off making one incremental change at a time.

Good Luck! BTW, all us 400 owners are insanely jealous!

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Guest Guest

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Presumably he knew he was wrong before he said anything wrong....so, what's the use?

The service manager at the shop I bought my bike from gave me a big spiel about people changing their WRs to YZ timing when I went in to get the throttle stop they had removed. I didn't talk to him long, so didn't get elaborations on the specifics concerning just what is so bad about it. He did say that many owners had brought their bikes in after the change with problems, wondering why they would not run right, and that the two engines were very different. If "entirely different motor" means different ignition mapping, I suppose I can see his point, but the description would seem to indicate more differences than ignition mapping and timing to me... He also said that most of these peoples problems started when they listened to "some nut on the internet"....heh.

Has anyone on here actually tried the timing change on a 2001 WR? I'm curious to hear about the results. Haven't had enough chances to ride my bike stock, to even think about changes yet...

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Grand Master

Taffy

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scouringpad

as i understand it, yes we need a generator, we need a wider gearbox, we didn't need or get the beefed up clutch. the differences between the bikes are kept to a minimum.

as for the ignition dave van brocklin has tried them back-to-back & felt no difference. nobody has said "yes it's a fact, there is a difference". i've been right through the cam timing fastidiously.

the cam timing is IMHO a fudge for both models. i believe that the ignition can't afford to vary much.

no mate, too many people are too happy with their WZ's to say that we've made a mistake. i only had a problem with starting AFTER i'd changed from YZ to a halfway-house between the two.

poor starting; it's not the carb or it would happen to DR's & Katoom's. it's not the generator bacause it affects both the YZ & the WR. people have had it happen out of the crate.

go for it.

Taffy

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Dave_VanBrocklin

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I agree with Taffy, everybody I know with a WR has it timed to YZ specs,absolutely no problems.You have got nothing to lose by changing the timing, besides, if you don't like it you can change it back.Read the posts on how it's done,It really isn't that difficult to do, and it doesn't take alot of time either,just pay attention to details.Good Luck and keep us informed.

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