Dirtbike Performance Centre

Motocross and Enduro Engine and Suspension Tuning

Dynobike has been building and tuning high-performance fourstroke machinery for many years. Allow us to apply our expertise to your thumper - whether it be a weekend bushbasher or a serious MX bike, we can make it better. Often, much better! Check out our Workshop Services

We also have numerous products which will enhance your motocrosser or enduro bike including a comprehensive range of Wiseco Pistons

For information on how much more performance you may expect, and how much it will cost, read this short article on a WR/YZF250 Hotup
Article on WR450 Engine Rebuild
Another article on a WR450 Hotup

DRZ400 440cc big valve conversion

DRZ400 high_comp_440cc.jpg

DRZ400 high compression 440cc


DRZ400 ported head

DRZ450SM de-restricted

Well this is quite a straight forward job, however the carburetor on these bikes are very difficult to get at and you need to pull it right out to change the main jets so make sure you have plenty of time and tools for the job if you attempt it yourself.
Apart from that it's all self explanatory if you look at the pics. Once you have pulled out the intake snorkel mark out the top of the box roughly 75mm square and cut it out with a hacksaw blade. remove the two lower sub frame bolts so it can be tilted out of the way while you get the carb. we finished up with a 150 main jet, needle in position 3 and pilot air screw set at three and half turns out. This is only guide so don't assume it will be right, make sure you check the air fuel mixtures.
As you can see from the graph the result's well worth all the effort. "feel the difference"

What's it cost* 

Jet kit - $145.00 optional (we didn't use one is this example)
Labour to cut out the box and dyno tune $450.00 

The owner writes:

Nice work Dave, Bike feels all round snappier/stronger. Seems to breath a little better.
Thanks again.

DRZ450SM carb
DRZ450SM airbox

DR650 power upgrade

This is what makes my job so good Take a really gutless stock DR650, remove the exhaust and fit a Staintune big bore exhaust system, remove the air box restricter and drill some extra holes so it can breath. Then a little jetting work on the dyno and voila! A rocketship!. 
How can you not get excited about that.


DR650 Airbox drilled


DR650 bigbore header


DR650 graph - great results!

Husky 510 EngineRebuild

No, it didn't blow up - this guy had the good sense to rebuild it before that happened. So here you go this is hows its done:

Engine out, head and barrel off, quick measure to make such the barrel's ok. 

Pull the clutch assembly and flywheel off - you will need a special flywheel puller for that. Then split the cases, pull the crankshaft out, press it all apart and fit the new rod kit. Press the crank back together to the correct web width which we measured before we started and then true it all up to within .05 mm, and re-assemble everything in the reverse order. 

Easy as that!

The owner did mention that the engine is now a little smoother so maybe it was on the way out. 


Husqvarna 510 Engine Rebuild


Husqvarna 510 Engine Rebuild


Husqvarna 510 Engine Rebuild


Honda CRF450 2008

Already had a healthy power curve, to clean up the bottom end and middle range we fitted a JD jet kit for strong throttle response and mid range, so you can be more aggressive with it. Often when this area is improved it has a flow on effect to the whole package as seen in the power curve.
God I love this job!.

Honda CRF450 Jet Kit

Just like the road bikes, these things tend to run lean when you change the muffler. We fitted a JD jet kit as per all the instructions.

You just cannot argue with the results - bottom end stumble is all gone the bike's a lot more fun and easier to ride.

"feel the difference"

Honda CRF450 in the Workshop

Honda CRF450 in the Workshop

Honda CRF450 Dyno Graph

Honda CRF450 Dyno Graph

Race Reports

Danny Bray Race Report: Victorian Thumpercross March 2005
Danny Bray Race Report: Arena X Round 1 April 2005
Danny Bray Race Report: Gippsland Centre Round 3 July 2005
Danny Bray Race Report: Monza Park - Ballarat 18th June 2005

Vic Titles 2005 Round 3 results.xls


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