Wet Sump Conversion


I agree. Hope I didn't imply something else.

But of course there is a ratio of how much oil is required in order to keep the oil within operating range, for a given engine and lubrication design.

The other issue is that oil can't be too cool or it causes complications as well.

So I think an YZF engine with and without the conversion is going to have near similar oil operating temps. However, the converted bike may come up quicker.

I don't recall an oil thermostat that regulated the frame circulation....right?


Now I see some things here that arent well thought out.


Lets say 20 min. of run time creates a contamination level of, say, 5 in a volume of oil of 1700cc. If you reduce the volume by 50%, the same run time will produce the same contamination, but you only have 50% of the oil to contaminate. So you basically double the contamination of the oil in a said period.

Power to Weight ratios:

Yes making a motorcycle lighter will theoretically make the bike "feel" more powerful and easier to handle (especially one that weighs 255#s). But doing said mod doesn't increase horsepower. It decreases mass. Less mass, greater horsepower to weight ratio. Not greater horsepower.

Oil cooling:

The speed that these motorcycles travel, averaging

say 45 around a motocross course, the oil cooling from the oil being in the frame is going to be nil. The fact that the volume is greater prior to the mod might help to some degree, but your still only talking about 1700cc total.

Separating the engine oil from the transmission is probably the most inmportant thing thats happend to 4 stroke motocycles in a long time. You dont want clutch debris in the valve train, especially at 10+ thousand RPM. Not to mention the ability to run friction modifiers in the crankcase / valvetrain portion of the engine.

This whole thread is a bit academic really.


Not well thought out? Come on…sure it is.

Don't you think it really depends on how quickly things get ugly with the oil, and then how much longer you run that ugly oil?

If the oil gets funky say within 30 mins of riding, and the wet-sump guy replaces it every 45 minutes of riding, he really hasn't done much harm.

But if the same amount of contamination occurs but is spread out over more oil, BUT is ridden for several hours, you can bet this would result in more damage.

Damage is such a hard word, but you know what I mean.


As for that horsepower thing, I agree with ya. But there are many forms in how one can talk about horsepower or the use of it. Say for example, a lighter rear wheel does not make more horsepower, but it uses the available horsepower more effectively, and therefore the bike goes faster.

Will my bike be faster with 3 less pounds? Of course it will. Is it enough to notice? Don't think so. But I would notice even one less pound in rotating mass.


Ego ya know whats really funny, Im a mortgage broker and things are slow as hell.

So my last post is what you get when an IQ of 140 plus thats addicted to horsepower and motorcycles gets on a rant.

If I was racing, Id have to be thinking twice about dry sumping my overweight motorcycle, and seriously considering a much lighter red one.

Personally, I couldnt ride a 20lb lighter YZ any faster than I ride the big blue pig I got now! :)

Whos got a 140 IQ Hey if he wasnt drinking cold Ice Water It might be160 maybe 175 +.

Anyway I have a buddie with an IQ that I am not sure can be rated, The dude has 3 PhD's speaks 7 languages, has a photo graphic memory and is a chief scientist at IBM under R&D for new technology.

Anyway they guy has not a lick of sence, all that intelligence and dumb as a 6 lb bag o nails. Somethings just dont need to be anal-ized :)

WooooEeeeee Shawn MC

Showing some brain functionality :D

This was why I posted this to get some seriuos discussion on this mod.

I see it in a plain ol Black and White Way

For the money you spend to save 3 pounds with no appearant advantage over the competition or Plain Trail riding, You can Shave 10 pounds off by getting of that Dead Butt, beer bellied Azz and stop eating that fast food crap.

:D No offence but thats the way I see it. Geez buy the Atkins Diet book for 11.95 and in 14 days loose 20lbs. Now there is a weight to power ratio :)

It all seams a bit anal to me

[ April 17, 2002: Message edited by: EgoAhole ]


I started my diet this morning......

We'll see how long I can stay on it..... :)

DaveJ I think you misunderstood what I was trying to say about contamination, which would be my fault for not being more clear in my analysis.

Less oil bad. More oil good. Problem oil is heavy. Must make trade off.

Change oil like madman with wet sump@850-900cc.

Change oil like sloth with dry sump@1650-1700cc.

True oil cheap. True 3lbs worth of weight from titainium not.

Rotating mass bad. Best weight loss available, very expensive.

Gym memebership cheap. Buy vitamins and lifting weights, looking at scantily clad coeds during: good.

All things in life are trade offs.

Interesting guys. I like what DaveJ has to say. I haven't done the mod yet but 90% of the reason I'd do it is to make the oil changes easier. I change it about every 2 hrs use as it is right now so it wouldn't make much difference to me. I also think that even with the reduced quantity, there will be no reduction in reliability. I believe you'd really have to run the snot out of it for hours of continuous use before the oil would even start to be contaminated enough to cause problems. These motors are bullet proof. It's not like they are air-cooled XR350s. I never hear of anyone wearing out camshafts,rod bearings, crank bearings,etc. Sure, there have been cases of things physically breaking, but we never hear of lubrication related failures. It must mean that they are well lubricated.

Why don't we do a test. Run a wet sump for an hour with 900cc of oil and a dry sump for say 4 hours with 1800cc of oil and send them in for analysis.

My 2 cents has been spent........

Guys, IMO I think that if you're a hard-core racer that spends alot of time racing or riding at the track (regardless of results) 3 pounds is a big difference. Let's face it the four stroke bikes are heavier that the 2 strokes. 3 less pounds to throw around the track all day is alot.

But then again if this profile fits you that means you already have your name on the waiting list for the new YZF450, I think it's safe to say that most of the rumors will become true with the new bikes and they probably will the new CRF case design. If you can't wait, $160.00 is actually pretty cheap compared to what I've spent on my bike for other mods. These days It's hard to find a pair of pants and a jersey for that money.

Also, I have heard time and time again if you want to lighten up your bike go on a diet. Yes, I see that being a good idea to a certain extent but let's all be honest here. It takes alot more strenth to muscle a heavier bike around track. And me personally have lost weight only to find that I wasnt as strong as I was when I was 25 pounds heavier.

Man, I really hope the new Yamaha's are lighter, I've ridden the CRF and can't stand the way it handles, but man it's light!!!!

DL :)

OK. This whole topic is relative. For anyone getting a paycheck to race, this is probably a great mod. For 99.9999% of the population, spend your dough on lessons/tires/chain/sprockets/gas/oil/insurance/diet!/safety gear/practice fees. I am as guilty as anyone for spending too much money on the bike and too little time riding it. It is REAL easy to look at the mags and catalog and spend! spend! spend! Yeah, that will make you a better rider!!

Now, be truthfull. Have you gone to the races and seen some unknown rider show up on a kx125 and LAP everyone in the OPEN/PRO/MONEY class. I am sure it was because his bike was 3 pounds lighter than stock!

Just my 'pinion


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