mods/replacement parts???

I'm looking for suggestions on replacement parts for the 426. Any opinions on chains/sprockets, pipes/silencer/spark arrestors (I'm leaning toward FMF Power Bomb/

power core IV2 S/A). I'm not a pro-level rider and want to smooth out the bottom and middle as well as ride part of the time in the woods where I need the S/A. As far as the chain goes, I understand the stock item is suspect and will use it til it starts to stretch which I understand will be quick. I'm looking for replacements that I won't have to change out every six months of steady riding. Sidewinder SS Sprocket? Has

anyone done any mods to the airbox (ie: filtered air box vents) or is this a bad idea on this bike? Lastly, anyone familiar with/used Amp Traction Blocks?


This is subjective stuff here so remember this is only my opinion…

I have a PC T4 and I like it, it is well made, fits nicely, installed easily and perked up the midrange pretty good while smoothing things out at the same time plus it comes with a USFS approved S/A insert. But if I had it to do over again I’d probably opt for a White Brother’s, their stuff seemed to make the best dyno numbers in the magazine tests I’ve seen. Of the more popular systems White Bro.s is the more four-stroke oriented company (I suppose Yosh qualifies as well). But they are all too darn expensive. Maybe you should get the S/A insert and save your money for a Scott’s damper. IMO that would be money better spent, plus with a new mounting kit you can swap the damper to any other bike.

The only sprockets I have tried is Renthals and one Sidewinder. The latter is heavy but it lasts forever. I bet you’d go through four or five (or more) aluminum sprockets by the time the SS wore out. I have no good evidence to support it but I believe the SS makes my chains last longer as well since it holds its shape where aluminum ones begin hooking which would seem to put more stress on the chain.

The only chains I can remember using are DID and Regina, both o-rings. O-ring chains are more expensive but I’ll never go back to a normal chain. Somehow a good o-ring chain lasts two or three times longer than a standard chain. The DID I tried seemed to wear out more quickly than the Reginas, plus the master link must be pressed on, unlike the Regina.

I don’t think drilling holes in the airbox will give you any noticeable power gain.

I’d love to try the Amp blocks but I thought they stopped making them. They seemed like a great idea to me. I’d love to know where to get them.

If you are looking to replace the quickly vanishing stock rubber swingarm guard I would recommend the T.M. Designworks Chain Slider. It makes a spooky noise at first but it lasts forever. I don’t have their number handy but Montclair Yamaha carries them (800-743-3926). They also make a kit that includes a complete replacement guide, slider and two chain rollers for around $200, the slider alone is I think about $70. I bent my guide a few times, one time so bad I broke my chain, and figured the solid plastic part would be an improvement. I haven’t been disappointed.

Hope this helps!

Hick, Thanks for the info. In regard to the Amp Traction Blocks, Amp research has apparently re-introduced them. According to DB magazine (Nov99) they're available for YZ's and CR's and priced around $120. You can get more info by calling the Traction Block Hotline at (888) 983-2206. According to the review, they have an amazing affect on suspension/handling. Hope this info helps and thanks again for the response.


Hicks,how did you get the rubber swingarm guide off? After my first ride on my 01 426,I noticed that it's loose between the hex bolts. I tried to tighten the bolts up,but they only turn,and do no tighten up. I guess there is some sort of insert in the swingarm. Any ideas?? Thanks



What do you mean by swingarm guide? The chain guide or the arm guard (slider)?

As far as I can tell the fasteners that hold the arm guard on just thread through a hole in the arm like a sheet metal screw. In fact, I have heard of guys having trouble keeping them around, there isn’t much surface for loctite to adhere to, and resorting to a long bolt and nut that goes all the way through the arm from top to bottom. So far I haven’t lost any but they do need periodic retightening. Stock they have a collar or concave washer that holds the guard in place, once the collar makes contact with the swingarm the fastener (screw or bolt, I forget) can’t be tightened any further. Maybe this is what you are describing.

As for the chain guide, it has lock nuts on the other side of the hex bolts so you need to tighten those while holding the bolt w/ another wrench.

Hope this helps!

Hick, Sorry to say but, seems I gave you some bum info. I called Amp Research today

and found out they just stopped making their

traction blocks for bikes again. They said that they made a short run on them but did not get enough interest so production was stopped. I was very disappointed to find this out as I really wanted to give them a try on my bike. Apparently, the company still makes them for quads. Anyway, sorry

for the bad info previously.

If you manage to strip the threads for the slider, you can use a pop-rivet as a band-aid.

I would get a white bros. pro meg shorty with a tapered header or powerbomb header! They smooth out transition and give it even more meat in the powerband on a 98' YZ420!


I get my kicks on a 2001' YZ426!

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