Bolt on Fly W heels Only

I rode mr XR400 this weekend in the tight single track and I love it so much more than my YZ426. So I am going to put a BOLT-ON fly wheel weight on my YZ so the dam thing doesn't stall so much during trail riding.

Who on the list ACTUALLY owns a BOLT-ON style fly wheel? What I want to know is:

Who built it?

How easy is it to install/remove?


Net effect on stalling in rocky single track?

Please don't post if your buddy heard of a guy who knew a guy who had a 37 oz'r welded on and it made him beat Ty Davis like it was nothing. Not that this list EVER does that! :)

Roostn in Denver

Hey Roostin,

I have a bolt on Flywheel Weight (12oz.). It's made by Terrycable. It makes a huge difference. My 426 is my only bike, so I use it for trail and MX. It was fairly easy to install. You do need to drill and tap the flywheel itself. The problem is that once it's on you really dont want to take it off because the fact that you drilled it makes the flywheel even lighter than stock. It is very easy to chang though. Terrycable sells a set (10oz-12oz.-14oz.) so you can tune to track/trail conditions. The flywheel weight does help prevent stalling as well as giving the bike a little more low end grunt, but the fact of the matter is on tight single track and most trails for that matter, the YZ will never be like an XR400. The XR400 has been designed for that purpose. Now a WR426! That's a different story!! Hope this helps! I check this forum about a million times a day, so if you have any questions on the weight let me know.


Ditto on the Terrycable FW kit. It's a pretty straight forward install. If I remember, it was around $150. The extra weights (10oz., 14oz.) are around $30 a piece. I may be stating the obvious, but depending on how much time you have on your bike you may want to buy new gaskets and a new woodruff key (pt# 90280-03017-00) for the install. Hope this helps.


like a kid again!

00 YZ426F

01 TT-R125L (my son's)

91 CR125

83 YZ490

74 Hodaka Super Combat(gone but not forgotten!)


After posting my message I found the info I missed on my first search of the archives. I ordered a Steahly 14oz replacement flywheel. It seems like the way to go so you can easily switch between the two (14oz and stock).

I will buy some replacement keys as well, thanks for the part number.

Roostn in Denver


I have a '99YZ400 and I ride nearly 100% tight trails and race enduros. I purchased a 12oz. weight from for $42.00 and love it. Ignore the price on the Web it is only $42.00. Here is my old post:

Just finished mounting 12oz. weight from Stroker ($42.00 + shipping) on '99 YZ. I bolted it on (bolts provided) so I could have the option of quick removal or change. You can send your flywheel to Stroker or A-loop (I think) to be welded on (about $40.00). The Stroker weight is slightly oversized, it fits over the back of the rotor. Therefore, much time is needed to assure centering of the weight on the rotor. I used shims to position on center then C-clamped together. You will need to drill through the rotor, I would recommend a press if available. You must center your pilot hole in rotor to match predrilled threaded holes of weight. I used some plastic drywall anchors and inserted them into the weight holes to use as a guide for drilling. Once pilot hole are done unclamp and complete drilling to size. I sequentially went up in drill size until bolt would fit (17/64 I think). You must also counter-sink holes as the machine head bolts go in from the outside of rotor and screw into weight. If left sticking out they would hit inside of mag cover. Lots of patients here. The bolts do not have to be flush but 2mm is about as high out as you can go. A roto-tool works well here. I suppose you could also take a little material from the inside of the mag cover, it is only tight a the indent for the shifter. I did need to fine tune my rotor holes with a roto-tool to align weight on center. Even with a press drill bits will walk. High-temp lock-tite or equivalent is an absolute must here for the bolts for the weight. I also used lock-tite on flywheel bolt. I think any good machinist could do the job for you or a welder for that matter. You will need a flywheel puller and a rotor holding tool as well as all the usual stuff (torque wrench etc.) Could probably get away without holding tool. I am not sure but I think 12oz. may be the limit for bolt-on. Size of weight would depend on the type of riding you do. I happen to ride a lot of tight technical stuff and rock / rooted hills. The weight keeps the bike chugging through this stuff and reduces stalling. The weight does flatten out the hit a bit, but there is more than enough left for me. Good luck, feel free to post of e-mail with questions.

Not sure, but I believe the 426 has a taller

1st gear than the 400. I also went with 13/49 gearing and have all but eliminated stalling. May want to consider gearing change. I have owned numerous XR's (still do) and although the YZ will not lugg (not meant to) like the XR at low RPM there is no comparison for overall performance, even in the woods. I found I have to adjust riding style for the YZ, more aggressive and slightly more clutch, but end result is worth it. I am much faster and less fatigued on the YZ.

Good Luck, Keith.

Sorry about long post.

mayge, The Terrycable kit IS one of the more expensive kits available. There are more economical kits. The Terrycable comes with an aluminum spacer for the case, longer bolts, gasket and also requires mod to the shift lever on the heaviest (14oz) weight.

This is supposedly the same kit that Ty Davis uses and changes weights to tailor the bike to each race. I don't see why an experienced machinist couldn't come up with a one-off kit themselves. It's not that complicated. Just need to be concerned with proper balance of the rotor and any clearance problems that may occur.


like a kid again!

00 YZ426F

01 TT-R125L (my son's)

91 CR125

83 YZ490

74 Hodaka Super Combat(gone but not forgotten!)

[This message has been edited by dirtdad (edited 03-28-2001).]


Good explanation of the procedure. I also bought the flywheel from Stroker (10 oz.). If I might add a few points to perhaps save some time.

1.Harbor Freight has a set of transfer center punches that I used to find center. They are only like $8 for a set and help with the accuracy.

2. I drilled the holes to 9/32 to get proper clearance. I think if one could use a mill with a divider you could get accurate enough to go with the 17/64 clearance. Tough to do on a drill press.

3. You can buy a proper countersink bit at most hardware stores. This will give a more professional finish to the job.

4.With the larger clearance on the holes you should not need to grind but make sure that the shims are in place when you tighten the bolts to make sure that the unit is centered. Remove the shims after tightening the bolts.

These things work great. I like the fact that since it is bolt on I can change to different weights as needed.



99'YZ-400 (Mine)

00' TT-R 125 (Hers)

91' KX-125 (Son #1)

93' CR-80 (Son #2)

99' PW-80 (Son #3)

[This message has been edited by enmerdeur (edited 03-28-2001).]

Any machinist by trade attempted to make a duplicate? Just wondering, I saw $150 and I don't think I want to make that investment, the wife might shoot me!!

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