You know where to get the stuff for your DS to make the yfz look like a blaster. All the time and money you have in it already, why stop now. But if you end up selling off the DS for a yfz I hope you have fun on it. [img]i/expressions/face-icon-small-happy.gif[/img]

 

The YFZ is basically a race engine. It is great for racing but the problem I see is the inability to get more from the engine. It's possible to get double the power of a stock DS out of the Rotax 650 but I doubt you could do the same on the YFZ without some serious money. It's already close to it's full potential or at least much closer than the Rotax.

 

Glimp,

I'm not so sure that totally accurate. The percentage of power increase with available mods fairly close to that of the Bombardier. Both motors can be built to an increase in horsepower of 50% over stock (with the stock bore). Further improvements can be had with a larger bores in both quads. The available components are ...

1) CDI
2) Exhaust
3) Carb
4) Cams
5) Piston (higher compression)
6) Valve Springs
7) Head Porting
8) Oversize piston kits (for larger bore)

These mods are very similar to every other mod out there for the DS. Both sets of components are also similarly priced. The result however is a faster quad - component for component.

Now, saying all that, does not mean I don't like my DS, not at all! There simply is no more room in my garage for another quad. Since I've already built the heck out of my DS, its time for a change.

 

mark, why sell the ds when you could sell the 440ex. the yfz is a very nice bike. it would look great sitting next to the ds in the garage, with the ex on the way out

 

Bigslim,

That is a valid option. However, from a business perspective, I need the 440EX for a demo quad. There is a lot of need to build 400EXs, cuz there are so many around and people are looking for power. I also admit that I enjoy the 440EX a lot more since I've put the mods on. Sometime you'll have to take her out. She beats piped Raptors, 416EXs, some Predators, and the 450R. She's also a very torquey quad, that can turn the 22" 9 Paddle anywhere, anytime. In the trails, the 440EX is by far the funnest quad I have ever been on.

 

Mark-I was impressed when i saw how much faster your 440 is this year than last it seems to have made quite a difference to bump up your compression and run lighter tires.I found out this weekend that my 690 is much more at home drag racing at south jetty hill as opposed to comp and it did much better at the longer south jetty.Have you considered building a raptor similar to mine?A raptor could give you both comfort and when built like mine excellent performance in a drag race.Next time we are at the south jetty you should do some drag racing on the 690 i think you might be surprised at what it is capable of on a longer hill.

 

Hmmmmm. I'll have to give that one some thought. I did like the way yours rode over the dunes. But will my DS friends ever forgive me! LOL

 

Your ds friends may not forgive you but it could be worth it with all the drag racing wins you could pull off.I know that my raptor is not the fastest but it does very well and last weekend after a gearing change i beat every banshee,250r,yfz and dirt bike that i raced at south jetty so i suppose it is doing better all the time and i may purchase some ultralites just for busy weekends to get even more out of it.

 

You might be able to get more out of the YFZ but I cant imagine it being durable. How do you get revs much above 12k rpm and keep it reliable? The exhaust makes a big differance but the other bolt on mods I've seen have made very little differance. Even the pro's mechanics say theyre very close to race tune out of the box.

 

duneittilludie,

I'll take you up on that test ride sometime. I know the 440 did take quite a few heat cycles to finnally break in. It will be intersting to see the progress of your 690.

Glimp,

As far as durability, I can live with 85%-90% durability over stock. Especially with the YFZ. And, as far as increasing RPMs beyond 12k, well, that's only one aspect of building a motor. For the YFZ, thats not the secret to building her in my opinion. I've talked with many race mechanics, parts manufacturers and riders. And I have been close to those that have had thier YFZ motors built. Im not at all concerned. Like I mentioned before, when I dropped the 13:1 into my EX, everyone said she would not hold her gaskets. But, with the right gasket, and a proven track history, there is no problem. There have been enough of the YFZs built now where there is no more mystery, and the bleeding edge of unknown technology is now only cutting edge. No fear.