'99 YZ420 weight reduction plans

OK, posted a few days ago about selling my '99 because of the weight. I am now thinking that an agressive weight reduction campagne may be in order.

I like the bike / motor / suspension, all dialed in to my abilities / style. It's all payed for long ago. ( I hate debt, only pay mortgage ) I would'nt really benefit that much from a newer model, weight being equal.

Here are my plans : Dry sump, neutral switch removal, removal of small brakets / gaurds like fin, caliper, fork chap guides, decompressor cable ( 450 cam mod ), some milling away of glide plate, carbon fiber airbox, SDG seat, light tubes / tires. I have a full E-series with header already on.

I am running the tubular steel subframe, wonder if the alu. version is much lighter?

Would appretiate any input.

A yellow Hurricane kit with a black tank may cap off my project to give a new bike feel / look.

Am I overlooking anything? :cry:



You really are not going to lose that much weights there. Maybe 5lbs at the most.

I would start with an Aluminum or Ti subframe. TIs are discontinued, so search ebay or the classifieds. Same with many CF parts for the 400-426 bikes. You can find CF chain sliders on ebay from a guy named "MXHouse". If you can find a CF glide plate, top motor mounts and water pump guard you will save some weight.

So 00-02 subframe is what you want.

Then get some aluminum body mount bolts. you can usually get a pack made for a Banshee for $25 for the rad. shrouds, side panel and number plate. Also for the 04 450, all the radiator washers, bushings, sleeves and bolts are all aluminum. That is weight up top!

The cam mod is a good one. Remove the decomp system there. Get aluminum bars if you dont have them already.

You may want to look into a 00-01 frame since the geometry is improved over the 98-99 bikes.

Also running half a tank of gas helps. That is a lot of weight up high on the bike.

Run something like the Light Speed for guards with CR routing. Dont know if you lose any weight, but the CR routing with SS line helps. Leave the guides on the forks and just cut off the tabs. Otherwise the guards will rub into the metal on the forks. Not good.

The dry sump I have heard is discontinued. The cons really outweigh the benefits of that. But the neutral block off is good.

You can see if aluminum clutch plates are available to replace your steel units. I run them and one steel plate weights more than the box and complete set of aluminum plates (they are cryo treated).

Beyond that, the cost gets huge and many parts are not available anymore. Things like Ti headers and Ti/CF exhaust, Magnesium hubs, triple clamps, Ti bolts (still available for engine and sprocket), Ti footpegs (from 04+ bikes), newer forks (each year they drill out more parts to make them lighter weight). The list goes on, but the $$$ goes way up. Each year Yamaha in the motor drilled out more parts to make things lighter on the bike. The Technical seminar books list all the mods by year with weight reduction on each part.

You could also convert to the 03+ subframe, tank, airbox and plastics to get the newer Ergos and smaller gas tank.

Thanks Matt, you are right about dry / wet sump. After having posted I searched and realizied that it was a very bad idea. I like keeping cost down, this is a hobby only.

I will most likely do only the above mods you mentioned, I will have to forget about the '03 plastics however.



I have the aluminum subframe to replace a bent steel on my bike and It's somewhat lighter but not dramatically. These are good bikes and mods make them even better. Any reduction of unsprung weight wheels/hubs/sprockets/guide and so on will be more noticable than unsprung weight. Bars, pegs, brackets, anything carbon will help. Athough the biggest problem is these bike's higher center of gravity and really the only way to help this is the 03' plastics have better ergos. The 03 cam mod is a great mod.

Good Luck.

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