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Mr_Yz426

Yz 426 upgrades

10 posts in this topic

i want to upgrade my 2001 yz 426 and im not sure if i should get a different sproket set, get a bore kit for it, or something else, any help?

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Ton short on details. Where are you riding it? Are you racing? What do you feel is lacking in the 426? Power? :shocked:

Most bikes need suspension work to bring out speed on the trail or track - the engine is seldom where I'd start looking for speed.

A gearing change will help you, maybe, but it depends on where you're riding. A big grin-inducing hit of power is cool, but it actually might hinder you too. Sometimes a linear controlled roll on of torque is much better for your terrain.

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I had an 02 426. Going to 12 /50 on the sprockets seemed to help off road in tight technical stuff. And a steering stabilizer would certainly help because of the high center of gravity. At of all the motors I've owned, that was probably my favorite. No need for mods there and it lasted forever before I needed to rebuild it. I thought the suspension was pretty good for off road too, but probably could be better. Put your hot start up on the bars, that was one of the first things I did.

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CR front brake set up get you'r self a CRF 250 or 450 front brake master cylinder and front brake hose off E-Bay I think I paid $50.00 for both Lighting speed CR type fork protectors $35.00 they are plastic and the bike will stop much better (Dont waste your money on oversized rotor or the CR brake hose routing with the stock YZ master cylinder).

Hot Cams make the bike very easy to start ($250.00 for Both) if you put hot cams in do the timming chain ($25.00 OEM ) at the same time.

Gear the bike for what you ride at.

Adjust the suspension for your riding style I think if the bike is setup right you should not need a steering stabilizer I feel it just hiding a problem I had a KTM everyone told me I had to have one to get he bike to handle WRONG after I figured the bike out it handle better than the other bikes with them.

Swaped out my Carb to the new style YZ450( E-Bay $45.00) I put the stock Pilot jet and main out the stock 426 carb put the needle on the 3 rd slot air screw 1.5 turns out and a remote type fuel adjustment screw (R&D), the stock carb was giving me problems so I up graded it you going to up grade the hot start and need to put the YZ 450. Throttle cables ($20.00) on the same time to make this comb work.

1/4 turn ($65.00) Q2 quick turn throttle tube.

It's not much money but for me made the bike more user friendly and more fun to ride.

Edited by marv02

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I also been thinking redoing the topend one of theses days if I do this I will go big bore and port the head with Kibblewhite Stainless steel Vavles.

If I deside to spilt the cases I put the WR transmission in my YZ I ride desert so the wide ratio transmission will work better for me.

Edited by marv02

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... one of theses days if I do this I will go big bore and port the head with Kibblewhite Stainless steel Vavles.

Why the Kibblewhites?

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When I had my KTM they all said these are he valves to have much better quality than stock ones.

I like to have a set that the pro racer use but I heard they are some big bucks I have a buddy at work could most likley get me a set of the high end stuff he knows pepole I use to know pepole back in the day.

Why the Kibblewhites?

Edited by marv02

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The KW's aren't really a big improvement over the OEM Yamaha valves as they are with other brands of bike, and if money's the reason, the stainless valves from a 2000 model YZ426 are about a third or less the cost of OEM Ti or KW's.

Always use the right springs to match the valves, though. SS is about 80% heavier.

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Didn't know that thanks for the info.

The KW's aren't really a big improvement over the OEM Yamaha valves as they are with other brands of bike, and if money's the reason, the stainless valves from a 2000 model YZ426 are about a third or less the cost of OEM Ti or KW's.

Always use the right springs to match the valves, though. SS is about 80% heavier.

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