Tim Ferry's 426

I was going through my Jan 3rd Cyclenews(again) and was looking at Tim's 426 when I noticed it had been converted to a wet sump motor and if you look closly you can see there is no filler tube on the frame tube in front of the tank. Hummmmmmmm I wonder if this will be a future change, anyone know or heard anything about this ?


From my understanding, this was done as another weight saving measure. It carries just enough oil to do the job and it gets changed extremely often.

I believe that Henry's and Button's thumpers were also set up this way.

so are the baby thumpers of Fonseca and Ramsey. YoT claims it is a 2-3lb savings and they dump the oil after every race.

I've heard MXA and Dirtrider commment on the wet sump set up before. They stress that it not only shortens the life of the motor, but is only used with the factory racers and top pro's since they have a large discretionary expense account for rebuilding and replacing motors. Yes, they save 2-3lbs, but there is a high price to pay for that in extreme wear.

For the masses though, they have to make the four strokes last several seasons, not just several races.

My two sense.....


I think Yamaha has run wet sump YZFs since day one. I don’t know to what extent they are allowed to modify the frame but all the extra material that makes up the reservoir could add up to lots of weight.

Aren’t ‘Bergs and KTM thumpers wet sump from the factory?

Does anyone know how they've plumbed the breather into the head pipe on Ferry's motor?

Do they use reversion reeds or some other method to control the exhaust pulse?

Maybe the tube I've seen isn't even the breather.



Yes it's true!! All the factory YZF's run wet sumps. It cuts down on weight. Would you believe they also have plastic gears!

Yup, it's true too. Plus Mr Ferry's YZF tips the scales at an envious 227lbs.



227 for a 426?!

sign me up!!!!!

i don't care if that is dry (prefer wet).

now that would be SWEEEEEET!

The plastic gears in Ferry's bike are 4th and 5th only on his Supercross bike. They're actually there just to take up the space and save weight over the "real" gears. The theory is that he doesn't need the last two gears on a supercross track!

In addition, I think they block off the shift drum so they cannot shift into the plastic gears. Obviously that would be a big problem.

I thought they used the plastic gears in case the rider inadvertently shifted into fifth (I’d never heard of them removing fourth as well). Modifying the drum, if that’s legal, makes more sense.

Also, it seems that losing a quart of oil and a few oil lines isn’t gonna help much. I’m thinking they must modify the frame, taking some metal out of the reservoir area. I’m not sure if it is AMA legal to modify the frame, but they DID remove the fill spout, maybe that isn’t technically considered part of the frame…

Or maybe they fill the reservoir with Helium :)

Yamaha has to use a plastic 5th gear to abide by AMA rules. Yes, they save weight, since he doesn't use 5th while racing. I know this is true for the outdoors, but you may be right about 4th and 5th for his Supercross bike. Ferry's bike must have the same number of gears as the production YZF's. Gears 1-4 are real gears, not plastic. Weight savings on the factory bikes comes from many different areas. Ti bolts, magnesium and carbon fiber everything, wet sump motor, and probably some top secret stuff. We'd all love to have a YZF that's 20lbs lighter, but if you got beat by a stocker, man wouldn't that suck? I know of many racers that put every trick part available on their YZF's, but they still seem to get mid pack finishes. What's with that? Keep it real. Spend the money on lessons. My two sense.


Hi Guys,

I just thought I'd clear up any confusion about Timmy's bike. First, there are no plastic gears in his transmission. Having plastic gears would create a problem due to high heat. They would simply melt. His bike does have 5 steel gears per shaft. His bike is a 4 speed though.

Second, his bike is wet sumped. This is primarily to save weight, and to lower the center of gravity. The frame is modified within the AMA rules and is perfectly legal.

The engine oil is changed every hour of use. The engine temp goes up slightly because the hot engine oil is being stored in the cases rather than up in a remote tank. The wet sump does not pose a engine wear problem as some have suggested, however the oil must be changed regularly.

The correct weight of Ferry's machine ranges from 224-227 depending on the bike setup, i.e. sx vs. mx.

Finaly, the breather on the right side of the cyl. head uses negative pressure from the exhaust to vent the crankcase. The small tank incorporated condenses oil vapor and returns it to the crankcase via a small return line.

I hope this post dispells any myths that may be floating around. If you have any questions or comments feel free to post them and I will try to answer quickly.



Yamaha Factory Race Team

(mechanic for Timmy Ferry)

Brian, could you elaborate on the 5 gears yet 4 speeds?

Thanks for the description of the breather system. Can you describe the internals? Does it use a check valve? Does the negative pressure from the exhaust coincide with the positive crankcase pressure during the intake and ignition strokes?

Originally posted by BK:

His bike does have 5 steel gears per shaft. His bike is a 4 speed though.

Finaly, the breather on the right side of the cyl. head uses negative pressure from the exhaust to vent the crankcase. The small tank incorporated condenses oil vapor and returns it to the crankcase via a small return line.

Yes, please go into a litte more depth about the negative exhaust pressure assisting the crankcase venting. Is there a check valve integrated into this design?

Well...now don't I feel like a dumb sh*t!!!

In my defense though, I wasn't making the comment about the plastic gears up. I had read an article on the factory YZ (although I think now it was Button's SX bike and just assumed it similar to Ferry's) and it was mentioned. Of course now I can't find the article to reference, but I believe it was MXA. I guess my mistake was believing everything I read! Thanks for clearing all the questions up Brian. I'll just sit here and quietly read the posts...

Well, I guess all the talk of plastic gears and excessive engine wear are myths....Thanks for clearing that up Brian. I think I'll just sit here with Dirtdad and read quietly too.......


I'm sorry if I offended you guys. I should be more careful with my posts. I would really love to elaborate on my previous post but unfortunately I can't due to contractual reasons. I hope you all understand. I am not trying to be an arrogant a**hole. I will keep answering questions as time permits.

Thanks all.



BK, I don't think any of us were offended by you dispelling the rumors on Tim Ferry's bike. In my defense though concerning the plastic gears. I had read that several times in more than one of the popular mags.

As a matter of fact, I just read it once again in the April 2001 issue of Dirt Bike!

On page 69 they feature Tim's bike and at the end of the first paragraph state, "Yes, the fifth-gear pair are plastic, and the shift-cam has fifth blocked off for supercross"! I wonder where they're getting this info!? Anyway, thanks for clearing that up. Maybe you could give us your opinion on the use of race gas and oil usage. Those are very controversial subjects here.


like a kid again!

00 YZ426F

01 TT-R125L (my son's)

91 CR125

83 YZ490

74 Hodaka Super Combat(gone but not forgotten!)

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