Who Still Races the 426 ?

CRF450's don't have slipper clutches?

ok...the new bikes do not have a slipper clutch. They have less compression braking due to the exhaust cam set up they have. Install a decompresssion cam in your 426 and you will know what I am taking about.

BTW ....there is a very informative thread stickied at the top of this forum about the decompression cam mod and how it affects the 400-426 bikes...... :D If the hotcam does not give you this then maybe it's timed wrong.....

Can you elaborate on the differences (if any) between the Yamaha cam and Hotcams relative to design and (decompression) timing?

CRF's don't have slipper clutches. As far as the Hotcam being different from the OEM cam...in the way the decompression mechanism works...none. In other words...if working properly, the 426 is no different that the CRF...unless there are other forces at work (ie..pipes, flywheel weights etc)

Are you saying that the exhaust cam on newer bikes relieves compression during deceleration and not during acceleration?

The reason for the 426, is that yamaha decided to bump up the cc's from 400. The AMA allowed it, yamaha raced it(Tim Ferry being the pilot). Then all of a sudden Honda is working on their 4 stroke, Honda decides that the correct cc's for the 250 2 smoke class should be 450cc. There for twisting the arm of the AMA, the AMA say's yes the 250 2smoke class is now 450cc. Something to that affect. In a quick answer and in my opinion that's what happend. Honda has some pretty good influence in the motorcycle industry. Any way just thought i'd throw in my 2 cents worth of this post.

Well I have a kit to help lighten up 400's and 426's. It's a dry sump kit from Dr. D that's still in the package. It was made to lighten up the top of the bike to lower the center of gravity by not using the oil tank in the frame. Pretty much turning it into a 2 stroke motor with all the oil in the crank case. You lose 1 of the almost 2 quarts of oil you use. It's a great kit for track applications, for those of us that change oil every other track day. I converted my 426 into a full trail bike and never put it on because Dr. D doesn't recomend it for trails or desert, just tracks. It's a cool idea but it won't fit on my 250f that is my new track only bike. If anyone really wants it let me know. I paid $140 for it but I already figured it a loss and it has been collecting dust in my parts box, make me an offer.

But getting back to the real question 426 to 450's, It really depends on you. We can only have what we can afford and I would recomend the 426 to anyone. Yeah there is a weight difference and a little power difference, but not enough to make me sell my 426 and go buy a 450. If you have the money sitting around than put it into your 426 with suspension and the cam mod. When you start out riding your bike and start riding like Chad Reed then it might be time to step up to a 450. And when that happens they are going to be giving them to you for free. The 426 is still a great bike and isn't out dated enough to get rid of. Bottom line is money. Every year a new bike comes and it always designed to be better that the year before. So by a pro riders standered the new bike is alway supposed to be better. But like McGrath his favorite bike was the old 250 with the standard frame, not the "NEW" aluminum frame because it didn't flex. So like I said it depends on you, What can you afford and what are you comfortable on? If you are out riding what you can afford than you need to save up. A new bike isn't going to turn you in to a Chad Reed. The only upgrade that will do that is you and more time on the track. It is incredable how reliable the 426 is and I love mine. So ride hard and ride often, Dan

Are you saying that the exhaust cam on newer bikes relieves compression during deceleration and not during acceleration?
It is really when the valves are opening or are allowed to stay open that is affecting engine braking. Different grinds and degree settings will change a lot of factors.

Got mine in January this year and I race it. I love it. I've said enough about it on other threads.

It is really when the valves are opening or are allowed to stay open that is affecting engine braking. Different grinds and degree settings will change a lot of factors.

True. Another thing (I've learned from the Hotcam mod) that can be said is that while auto decompression cams don't necessarily reduce engine braking, they do help prevent stalling due to the fact that they come into play as the engine is about to stall out, reducing the tendency to actually die. Another cool by-product. :banghead:

I seen Satch's Ole #9 in person and what a tricked-out bike it was

So cool i had to start making my own

first the OEM yamaha cam mod...huge difference

then the YZ450 make-over...and now the only way i'd part with bike would be a new fuel injected model when they come

but to be honest i'd have to still keep it

I just got back from ridin my 2000 426 for 7 days straight. all i can say is that it is an awsome machine :banghead: . mine is still on its original chain, sprockets, tyres etc. still started 1st kick every time. taking it in this week to get the cam chain and valves checked for peace of mind as i did some real fast 5th gear stuff on the last day. other than that. i trust this thing more than my old WR400 !!!

the only thing i dont like is that :banghead: clutch and those 2-piece valves, they worry me big time :lol:

Hey Yamakaze, Are you sure it wasnt a Yam or a Suz someone put red plastics on? Come on, beating a Honda? Well every dog has his day!

Your old WR 400 (sold) buddy, Fred

I bought a '02 426 in April of '04, the previous owner took good care of it and passed on the starting drill, which is quite simple and Ive never had a starting problem with it. I compete in the 40+ plus class mx and some open traction TT's..in fact I won the Summer Series TT +40 class a couple of months ago on my 426 and have a 5 foot tall series winner trophy to prove it...If one would think a 426 would be at a disadvantage, the ultra fast TT's would be it, but I won a lot of races on it, and Ive beaten a lot of guys on 450's in mx too, in my class..sure its heavier than the newer bikes, but it turns just as well and can anyone honestly say that they ride to the full potetential of thier bikes suspension???...I just checked the valve clearance and its dead center of factory specs...of course I change the oil regularly and the oil filter , clean the air filter after every ride and all the other things your supposed to do...The 426 is a great bike...wont win any beauty contests, but it can and mine anyways, will win some more races...

Ive been on a cr 250 for the past 4 years, About 2 months ago I got a deal on a slightly used 01 426..My first " Modern " Thumper...Took a little bit to get used to but am loving it now...Starts No problem , all the time...And has plenty of power to haul my 220 pounds around the moutains of Arizona...Can be a little difficult on tight technical singletrack compared to my 250...But it loves jeep and fire roads and to go fast..I may change the gearing to slow it down a little for the tight stuff...I know when its time to ride, I ride the 426...

If any of you 426 guys are interested my local shop has a complete top end for a 426 that is brand new. I could not believe it when i saw it. They have cams, valves, piston,cylinder, head and gaskets and i am pretty sure they only wanted 1000.00 for everything. If I was on a 426 I would pick this set up. It was at Delta Sports Center in Delta Utah.

The reason for the 426, is that yamaha decided to bump up the cc's from 400. The AMA allowed it, yamaha raced it(Tim Ferry being the pilot). Then all of a sudden Honda is working on their 4 stroke, Honda decides that the correct cc's for the 250 2 smoke class should be 450cc. There for twisting the arm of the AMA, the AMA say's yes the 250 2smoke class is now 450cc. Something to that affect. In a quick answer and in my opinion that's what happend. Honda has some pretty good influence in the motorcycle industry. Any way just thought i'd throw in my 2 cents worth of this post.

Youve gotta go back and look at the rule book a little better. The fourstroke displacement rule was 550cc until they dropped it to 450.

Guy Cooper was riding a 550cc KTM and so did Everts that couple times he rode over here in the one or two Nationals he ran. I think Lance Smail was riding one for a bit too.

The bike Doug Henry was riding the first year was a 426 although they called it a 400 and used a prototype extemption allowed for a single season by the AMA. That thing was sick power wise...it made 62 HP, had some mobile valve/restrictor in the exhaust pipe that would choke it at low RPM for more bottom and then it would open up and let the thing absolutely scream on top.

I had a 00' 426. It was a great bike. That thing has at least 300 hours on it now. They guy I sold it to keeps thinking it needs a top end but he just had a leak down done and its right on the money.

I wouldnt say the reason for buying a 450 would have anything to do with power. Its a handling issue. I sold the 426 after one ride on a 03 CRf simply because it handled immediately bone stock. I had close to a thousand dollars into the enzo suspension on my 426 and I still didnt like it all that much. It was light years better than stock, but it still wasnt as good as the bone stock CRF IMO, at least for me... I let the guy I sold my 426 to ride my CRF...he came back shaking his head...his words.."thats just no fair". :applause:

I just think my CRF is easier to ride than the YZF. Its no faster, but it makes me faster.

The reason for the 426, is that yamaha decided to bump up the cc's from 400. The AMA allowed it, yamaha raced it(Tim Ferry being the pilot). Then all of a sudden Honda is working on their 4 stroke, Honda decides that the correct cc's for the 250 2 smoke class should be 450cc. There for twisting the arm of the AMA, the AMA say's yes the 250 2smoke class is now 450cc.
You're making that up. :applause: The reason was simply that the 400 was as big as they were comfortable with at the time. As they learned more, the engine got bigger. But as Shawn points out, the displacement limit actually went down to 450.
Are you saying that the exhaust cam on newer bikes relieves compression during deceleration and not during acceleration?
Absolutely not, under any circumstance. The auto decompression mechanisms are universally centrifugal in design, meaning they work based on the speed of the camshaft, and have no way of being aware of throttle position or load. Below the specified RPM, it releases a portion of the first part of the compression stroke. Above that, they are completely inactive.

CRF450's have reduced engine braking compared to the big YZF's up to '05 because the wrist pin was offset away from the center of the piston. That makes the rod angle different on the upstroke compared with the downstroke. The overall length of the rod will change engine braking even if the pin remains centered, too. It has nothing to do with either the clutch or the decomp mechanism.

Personally, I think engine braking is one of the coolest elements of riding a four-stroke. I can see why it's difficult for lifer smoker riders to adjust to, but I say, embrace it, use it, love it.

I have a 2000 yz 426, 03 cam mod. It is a great bike...for me. I change the oil every 5 hours or so and always a clean air filter. The bike sat from thankgiving weekend until last week. 6 or 7 weeks. Went to the track. One Kick! :applause::bonk::cry: It was awesome.

I rode my friends yz 450, it was nice, I am a novice at mx and to be honest I dont think It would make much of a difference in my riding. It just keeps on going and going.

just parked mine last year, racing an 05 wr 250 now here in the east. COntemplating what to do with the ol horse, Motard?? Go kart??

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