Why didn't Yamaha copy Honda?

ShawnMC...I have to disagree with you about the 'Road Racer GP' bikes...and I have to disagree about the separate chambers for oil and for tranny fluid fight going on here. First, the GP bike statement. IF you are referring to the 125, 250 and 500cc (and this year’s ‘open’ 5-cylinder GP) bikes, they run comparatively similar engines to a ‘normal’ 2-stroke dirtbike engine..except they have more cylinders, obviously. They are running a single chamber filled with motor oil and either a wet clutch or a dry clutch. Most run a wet clutch setup, but there are a couple of teams that are running a dry clutch setup..but it is hardly “All of them”. Where the ‘dry clutch’ craze got started was with Carl Fogarty and the illustrious Ducati 996, 996R and 996SP/SPS race bikes. The V-twin 1-liter Ducati’s were making so much torque that the oils of the day (we’re talking late 80’s to early 90’s here… :) were having a hard time bridging the span between oil viscosity for the tranny and ‘top end’ and grip for the clutch. So they went to a dry clutch so they could dedicate all of the oil’s properties to giving the engine longer life (the rear cylinder of a V-twin takes allot of heat abuse…one way to help it out is to oil the hell out of it).

As far as the dual-oil-chambered engines discussion…Yes, there are benefits to having a certain type of oil lubricating your top end and your crank bearings…and having another type lubricating your clutch. But with engines the size that we need them (they HAVE to fit on the bike) the benefits of being able to choose specific oils to address each area’s needs are VASTLY overshadowed by the fact that using smaller amounts of oil in each of the areas reduces the lifespan of the entire engine. I feel it is better to have one larger cavity filled with an oil that fills multiple jobs well, than to have two cavities that are filled with liquids that each do one job extremely well, but limit the life of the parts that the liquids were meant to protect. Even with ‘proper’ maintenance intervals (how many of us know what the SERVICE MANUAL says about how often to change our oil?) two chambers limits the life of the engine-side and the tranny-side.

'The Hopper'


I think you may need to invest in some research. Your post is somewhat inaccurate and very misleading.

Ditto. Dry clutches have been used in road racing for years (much before the bikes you mentioned were around), and there are now 4 stroke GP bikes from many teams. More research required...

I change my oil every race, or every ride over 1 hour in duration. I'm no engineer. The oil leaving the bike is barely a dark honey color.

This I do for my 250F, just like I did for my 400F. The 400 I rode hard for 3 years with no detectable wear, from me, anyhow.

Maybe I'm nutty, but I think Yamaha did an admirable job of creating not only a high performance every-man's race engine, but one that's long lasting as well. Oil is cheap. Motors are not. :)

[ June 25, 2002: Message edited by: cyclenut51 ]

This thread has focused on the merits of seperate oils but practically ignored the fact that a wet-sump has a much higher risk of interrupting the oil flow into the pump. This is why virtually all race cars use dry-sumps; they don't want high G-forces to result in the oil uncovering the sump pick-up. A well-designed dry-sump tank is tall/narrow (like the YZ frame) and eliminates the possibility of uncovering the oil pick-up.

I agree that much can be done with baffles/trays/trap doors to make a wet-sump work when G-forces (or wheelies) start sloshing the oil. But, race car guys don't think that's good enough and their vehicles don't fly through the air! (Imagine what your oil is doing while that dirt is floating up in your goggles/its floating away from the sump pickup!! This is the reason aerobatic airplanes also use dry-sumps). Nor do race cars often tip-over on their sides with their throttle grip stuck in the dirt and the engine revving to the moon--a condition that has to produce oil starvation on a wet-sump.

Consider that the extremely small amount of "Engine-Side" oil that is used in the Honda/Cannondale approach has to make it even more difficult to keep the sump pick-up "wet" than in a race car with 6-8 quarts of oil.

Another problem with low oil capacity is foaming. Oil tends to entrain air and foam as it is whipped by the high speed crank/rod/piston. Race cars combat this problem by using large dry sump tanks (10-15 quarts) that give the oil a short duty-cycle in the engine/long rest in the tank. This provides the time for the air to escape before the oil reenters the engine. This the opposite of what we have with the current wet-sump MXers, that have less than a quart allocated to engine lubrication.

Now on the other side of the coin, MX motors use roller-bearing crank and rod bearings and are much more tolerant of oil starvation then a plain-bearing car engine. However, the cam bearings in the head are plain-bearings (like cars) and would seem to need continuous oil flow for best life. Maybe, in the end, MXers don't really need the ultra reliable oil flow allowed by dry-sumps, but it has to be a positive--just as using special engine oils is a positive.

Personally, I feel more comfortable with a dry-sump: it provides the very tangible benefits of a reliable delivery of oil that has been removed from the engine long-enough to dissapate foam/bubbles. This seems more valuable to me then the esoteric argument that the magic "moly" additives in an "engine-only" oil will make the engine live longer.

My 2cents,



Well, Cannondale seperated the fluids. And Yamaha didn't copy Honda because The equivelant Hondas produce nearly 20 HP less than the Yamaha. (Which prolly has nothing to do with the fluids) The Yamaha is an excellent design, as well as the Honda. Both have their goods and bads, but for me, the Yamaha holds more good.

Originally posted by wolfmangk:

And Yamaha didn't copy Honda because The equivelant Hondas produce nearly 20 HP less than the Yamaha.


I disagree grasshopper.

Also, I never said that Yamaha built an inferior product, so all you guys gettin lathered up can sit down and drink your beer.

Would it fair to say that most of the debris in the Yamaha motor, and dont tell me there isnt any because I clean it out of my filter every time, comes from the trans? Of couse it is. This alone is reason enough to separate the chambers. As far as oil foaming, that generally happens in high pressure conditions required by plain bearing engines. Most of the roller motors run on like 15-20 psi. You simply dont need any more. Excess pressure causes nothing but heat. Now, the top end being a plain bearing on the cams is an issue that I dont know how they handle. I know the required pressure there isnt imense as the load is coming from the valve springs as opposed the driving force of the piston. So I dont think that requires a ton of pressure either. More like 15-20, like the bottom end.

The KTM's went all the way with a centrifuge in thier motors to sling air out of the oil, and two filters, but the Austrians are like that.

More oil is always better but, at the cost of weight and storage on a motocross bike its a trade off.

If the engine oil isnt being polluted by the trans & clutch, the life of the engine oil should rise, no?

Also, if you could put a better trans oil in, that wouldnt be very good for the "engine" wouldnt that last longer also?

Result :) on paper)Both oils last longer and do a better job of what they are doing.

And dont be fooled by anybody, just because the Yamaha engineers didnt split the chambers doesnt mean the engineers wouldnt if they bean counters would let them. Engines arent hard on oils, transmissions are. Thats why I would separate them. Dont discount the help a "really slick" oil helps a fourstroke engine. Especially on the cam shaft,and even more so when you dont have a roller lifter. OK now, I have mounted my asbestos armour and helmet, you may now flame me!

I just gotta keep jumping in. I think most of us guys change our oil more than is necessary to begin with. Why would we need our oil to last longer if we change it so frequently anyway? If the manual said you don't need to change your oil for 20,000 miles, we'd still change it after 50.

Does the CRF450 have aluminum plates in the clutch? If so, I would say that the instantaneous contamination that occurs from them would be a good reason to separate the oils though.

The main purpose of the oils is to eliminate metal to metal contact of all the rotating/rubbing parts and to provide a cushion. So as long as you have that ever important clean film of oil in between these parts the motor should theoretically live forever because there has never been any contact.

Just look at how many neglected XR600s there are out there just baking their combined oil away year after year. They just keep running.

I may sound like a broken record (that doesn't make sense, a broken record wouldn't even play) but it just doesn't matter they both will last forever.

OK, wait, you might be right. I think with proper oil changes a YZ450F will last 7 years, 6 months, 13 days, 4 hours and 10 minutes.

A CRF450 will last 7 years, 6 months, 13 days, 4 hours and 11 minutes.

Too bad the Yamaha didn't have separate oils, it would have lasted soooo much longer.

Finally, Yamaha made it that way because they thought it was a better way of doing it. If they really thought that separating them was the way to go then they would of done it. Just as KTM thinks that seats should be 75 Rockwell hardness and front fenders are supposed resemble male body parts. Kawasaki thinks they must use black primer under their green paint. Suzuki thought they needed to change to a brighter yellow. Honda thinks they must use Dunlop 490/695 tires. They have their reasons. Yes, many times cost is a factor but I wouldn't say so on this.

DQ Blizzard anyone?


I agree that trans contamination is a valid concern. However, considering that the world fleet of high performance street bikes are virtually all single oil designs--and do just fine--I'm not going to lose sleep over a few lose clutch particles; that's what the oil filter is for. I remain more concerned about the intermittent oiling that is bound to occur when the wet-sump pick-up is uncovered during whoops, jumps, and a simple low-side cornering mistake.

Regarding special engine oils: I like the super-slick stuff and have been running Honda Pro 4-Stroke WITH MOLY (the stuff in the GOLD bottle that your not supposed to let near your clutch) for two years (45 rides) and have never had a problem. My '01 426 clutch doesn't slip, grab, or make noise and I've never replaced any clutch parts. I do use the clutch for nearly every tight turn to avoid stalling, but I'm not a guy that slips the clutch alot with the power-on--there's no need. Anyway, I think the hype about the moly oil is overblown. Consider that Honda has been selling the MOLY oil for years even though they were building only single-oil engines. If it can be used with a wet-clutch why were they selling it?

They've only had the dual oil CR450 since last fall which is the first time they made a big deal about using MOLY oil only in the engine side.



If there is less wear using separate oils then it wouldn't be much and is more of a side effect anyway. I don't think honda did it for less wear. I think the reason for separate oils is simply that it gives you more options and MAYBE more racing performance if you dont like the way your clutch is hooking up or you want to try some wacky engine oil additive or something like that. If you are a racer or trail rider you have more clutch options and more oil options. With one oil you are stuck with what works ok for all.



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