3x3 mods for a stock suzuki drz400
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Every DRZ400 is sold new with restrictions to meet noise and environmental requirements in each country. The DRZ400E is the least restricted, but can't be registered for road use in some areas as a result, especially California. The DRZ400S and DRZ400SM are both more restricted and can be registered virtually anywhere.
What are the 3x3 mods?
Let's start with the airbox and carburetor. The DRZ400SM and DRZ400SM use the Mikuni BSR36 constant velocity carburetor. The DRZ400E uses the flatslide Keihin carburetor which is a much better option, but is expensive. If you are after cheap mods, the one below will work fine with the Mikuni.
The Mikuni carburetor is tuned to run extremely lean in order to meet tough environmental standards. Opening up your airbox and rejetting will be the cheapest best modification to give your DRZ400 more power. Take the seat off your DRZ400, then remove the snorkel on your airbox. Enlarge the air intake to 3 inches by 3 inches (hence the '3x3 mod' name!) and resecure your black ignition box with zip ties. This mod can't be done alone; you also need to rejet the carburetor.
There are aftermarket jetting kits available, and forums like Thumpertalk have plenty of riders discussing the pros and cons of these. You can simply make your Mikuni run richer which will give you more horsepower, but the many aftermarket jetting kits will work better and cost very little for more power.
If you are doing your mods cheaply, you just need to change the stock jets.
T he DRZ400SM and DRZ400S come out of the factory with a:
- 142.5 main jet
- 22.5 pilot fuel jet.
Change these to a 150 main jet and 27.5 pilot.
DRZ400 Exhaust pipe & CAMs
It's heavy but the standard exhaust is very quiet and not as restrictive as some factory systems. The DRZ400E comes with a removeable end cap. For the DRZ400S and DRZ400SM, you can use a circular saw on the end cap to get a nicer note, not much more noise, and a bit more power with the above 3x3 mods. We are strong believers in not annoying the shit out of everyone and would suggest living with the standard pipe you ride in public. You can lash out on Yoshimura pipes and many others but you can't getting that much more power for the money you are spending. You might want to just put the money into a KTM! Believe it or not, performance pipes usually don't give you much extra horsepower - we've seen the dyno charts on the DRZ. The huge increases some riders predict are actually more psychological than anything - if it sounds loud it must be faster, right?!
The DRZ400E has more aggressive cams and these might be worth considering if you are doing work on the head of a DRZ400S or DRZ400SM, or get a grind on your standard ones. Remember though, the DRZ has two piece valves and aggressive cams can place undue stress on these, so it might not be worth the slight power increase for possible damage to your DRZ head.
The DRZ400E also has a higher compression ratio (11.3:1) so can should replace the base gasket of the DRZ400S or SM (12.2:1) if you are doing major engine work. Remember though, you won't be using low octane fuel any more if you up the compression!
big bore kits for the drz400?
You can take the DRZ400 out to 440cc with a big bore kit, or even around 500cc with a stroke kit too. These will give the DRZ more power when done properly, but again is it worth the money? It is usually just better putting that extra money into a bike designed properly from the ground up for performance.
As a case in point, we've ridden a DRZ400SM with a few thousand dollers in mods; it was bored out to 440cc, a racing carburetor, full Yoshimura system, 3x3 mods, valve grinds, 3x3 mods, and finished with a dyno tune to make it all work together. Yes, it was faster, but we were surprised that it wasn't much faster than a DRZ400E with just the 3x3 mods and nothing else! On top of that, a WRF450 motard still pulled away on the straights with ease. All that extra money could have bought any number of performance bikes that would still be faster - and there are still the suspension and weight issues on the DRZ400S or SM which need even more money to correct.
We love our DRZ400 bikes but would simply urge anyone wanting heaps of performance to consider the easy way. But if you like a challenge and a customised bike, just throw money at your DRZ and have fun.
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