What makes the DRZ (sm) so special?

[FasYankee]

I posted this over on SMJ, and was referred here.....at any rate, my query is what specifically about the DRZ SM makes it so bullet-proof as opposed to other supermoto single engines, either purpose built, or converted dirtbikes? Some responded the higher oil capacity, which I can see as a contributing factor, while others responded "engineered better", which, well, doesn't really pinpoint what I'm looking for. Is the crank journal oiled better?, larger con-rod? Longer stroke? There must be something specific......

I currently have a converted '00 WR400 which I chose b/c of the steel valves and wider ratio tranny. I really enjoy the bike, but am concerned about blowing it up. I had considered replacing it for a DRZ, soley on the reliability reason, but then got to wondering what specifically was the reason they're considered so superior.

[CBus660R]

The DRZ engine was designed from the get go to be a reliable high performance trail engine, not a max HP motocross specific engine. Basically, the internal parts will be a little heavier and more robust, and while I haven't checked the specs, I bet it does have a longer stroke and smaller bore, along with a little lower compression too. With MX bikes, every last ounce that can be saved and every last detail to get max RPM are taken advantage of, but this does lead to less durability and higher maintenance.

[YZEtc]

I owned a 2009 DR-Z400SM for just over a year and about 6,300 miles.

Great bike and I had a lot of fun with it. ?

CBus660R is correct about the DR-Z engine being designed to be reliable for many miles without an overhaul.

The trade-off is that, stock and off the showroom floor, they're basically dogs.

In other words, don't expect a stock DR-Z400SM to run like a WR-400F does.

The DR-Z can be hopped-up to run like the WR fairly easily, though, and there are plenty of parts sold for the DR-Z so that you can make it run as strongly as you like and you can modify it all the way up to time bomb teritory if you want to.

It just takes money.?

My DR-Z had what are considered the typical mods to make them run strongly:

*Big hole cut into the airbox top (called the 3X3 mod for the 3" square hole)

*FCR39 carburetor

*HotCams, both intake and exhaust

*94mm big bore kit (called a 434, 435, or 440cc kit, depending on the ad)

*FMF header and Q2 muffler (although this exhaust is too plugged-up according to most people for maximum power)

The results were fantastic and the engine was night-and-day better in performance.

If you install the parts correctly, the engine will still be reliable, and I had no trouble for the 4,000 miles I rode the bike like this.

You could mod it even further, but the next steps involve a longer crankshaft stroke, more radical cams, upgraded valve train parts, and complete engine disassembly.

Yes: $$$$

There are reportedly 60hp-at-the-rear-wheel DR-Zs running around, but, I believe that's pretty deep into time bomb territory, or at least where I wouldn't expect it to go countless miles before an overhaul is needed.

I recommend you go to the DR-Z400 forum and start reading and asking questions because there are some regulars there who know their stuff, particularly Eddie Sisneros, the acknowledged DR-Z master. ?

[FasYankee]

What I'd really like to do is to take the reliability aspect of the DRZ (the specific reasons) and incorporate them into my WR. I really enjoy the WR, I'm a huge Yamaha fan (R1/WR/YSR currently, last bunch of bikes have been Yam's with the odd Suz/Hon/Kaw thrown in as samples) and I'd rather build on what I have.

That being said, I thought of welding/balancing the crank, maybe lightening it in the process, chamfer the oiling passages for better flow, new (read beefier) con-rod, lightening/balancing the flywheel, forged piston, and somehow adding an in-line oil cooler, or an additional resevoir tank(other than the frame). I think the cooler would help 2 fold, adding capacity, and obviously cooling duty.

Valve checks/adjustments I'm not too concerned about, they're easy, and the 5 valve heads on all my streetbikes have consistenly stayed within tolerances for the most part. (I had a '94FZR1k that had well over 45k miles, valves always within spec).

Any other suggestions that you guys can think of as far as bullet-proofing my WR? I don't beat my rides up, but I'm not easy on them either.

[YZEtc]

Three things come to mind:

1) Check the oil level often, like a couple times a day if you're running it hard.

2) Change the oil often.

3) Service the air filter often.

[CBus660R]

Any other suggestions that you guys can think of as far as bullet-proofing my WR? I don't beat my rides up, but I'm not easy on them either.

Honestly, if you keep it off the rev limiter, you'll be OK. Maybe slap a big bore in there with stock cams to move peak power down the rev range a bit and boost torque a little. Probably the most important thing is to have a good cush drive hub. I'm assuming you already have that with the SM wheels.

[FasYankee]

Honestly, if you keep it off the rev limiter, you'll be OK. Maybe slap a big bore in there with stock cams to move peak power down the rev range a bit and boost torque a little. Probably the most important thing is to have a good cush drive hub. I'm assuming you already have that with the SM wheels.

nope, no cush drive on the sm wheels, DNA wheels.?

I see where you're going with the big bore.....less revs/more torque.....what about raising the compression?

[osiris07lv]

I posted this over on SMJ, and was referred here.....at any rate, my query is what specifically about the DRZ SM makes it so bullet-proof as opposed to other supermoto single engines, either purpose built, or converted dirtbikes? Some responded the higher oil capacity, which I can see as a contributing factor, while others responded "engineered better", which, well, doesn't really pinpoint what I'm looking for. Is the crank journal oiled better?, larger con-rod? Longer stroke? There must be something specific......

I currently have a converted '00 WR400 which I chose b/c of the steel valves and wider ratio tranny. I really enjoy the bike, but am concerned about blowing it up. I had considered replacing it for a DRZ, soley on the reliability reason, but then got to wondering what specifically was the reason they're considered so superior.

you said it your self>>>>>> "I had considered replacing it for a DRZ, soley on the reliability reason"<<<<<

[blt]

how many ring piston on the WR?

[CBus660R]

nope, no cush drive on the sm wheels, DNA wheels.?

I see where you're going with the big bore.....less revs/more torque.....what about raising the compression?

More compression would lead to higher temps, but how much? As long as you're still on pump gas, shouldn't be that big of an issue. The cush drive is more for your tranny. A thumper with the power pulse every 720 degrees followed by a coasting for 2 revolutions puts a big shock on the tranny, much more so than you see with multi cylinder engines where the shocks are smaller and spread out.

[Svery]

My understanding is the engine is just a bit more solid, but therefore heavier than the likes of a KTM etc....

[flamotard]

What makes a drz so special? It makes you grin from ear to ear every time you get on it.???

[Goebz]

What I'd really like to do is to take the reliability aspect of the DRZ (the specific reasons) and incorporate them into my WR. I really enjoy the WR, I'm a huge Yamaha fan (R1/WR/YSR currently, last bunch of bikes have been Yam's with the odd Suz/Hon/Kaw thrown in as samples) and I'd rather build on what I have.

That being said, I thought of welding/balancing the crank, maybe lightening it in the process, chamfer the oiling passages for better flow, new (read beefier) con-rod, lightening/balancing the flywheel, forged piston, and somehow adding an in-line oil cooler, or an additional resevoir tank(other than the frame). I think the cooler would help 2 fold, adding capacity, and obviously cooling duty.

Valve checks/adjustments I'm not too concerned about, they're easy, and the 5 valve heads on all my streetbikes have consistenly stayed within tolerances for the most part. (I had a '94FZR1k that had well over 45k miles, valves always within spec).

Any other suggestions that you guys can think of as far as bullet-proofing my WR? I don't beat my rides up, but I'm not easy on them either.

Find a flat tracker that runs your engine. These guys know all kinds of tricks the mxers will never spend the time ot learn. They operate on showe string budgets, keep the same equipment for years and get the most miles and ponies out of it.

I have seen guys graft a 500 cc JAWA Speedway motor into aFramer and the thing kills everything in its class.