I am looking to make some mild improvements to my 04 DS. This quad will be mostly ridden on fast (3-4th gear) trails and sand dunes (silver lake, little sahara, st. anthonies) along with some tight technical trails occasionally. Since this is going to be my reliable trail bike, I want to stay on pump gas...do you think I could get away with 12:1 or will I have to stay with 11:1? What cams do you guys suggest for my riding style. I top out around 300 pounds so I need to keep the torque.

Right now my mods are HMF slipon, TM45 with ported intake, RWR CDI, RWR 60% clutch springs. I LOVE the way it runs right now but just looking for a little more oomph on Devils Dune.

Thanks,
Josh

 

Howdy Josh, good to see ya around!
I too am making some improvements for this year's Idaho trip, gotta get new shocks cause mine are shot!

My opinions on the motor are as follows, you menioned reliability so that is what I focused on,

On the subject of reliability on piston compression - I do not think reliability is an issue at all no matter what compression, all the way to 14:1, as long as it is put together right from the beginning and the correct fuel is used. The only real factor is what octane fuel you are willing to screw with. IMO I would not go higher than 11.5:1 on pump 93 at sea level, and 90 at utah and idaho at 5K'. From 12:1 up you're gonna have to mix, and IMO its easier to just run pure 110 than mix, so for that matter might as well go 14:1.
I ran 11.5:1 for 4 years cause I didn't wanna step to race gas, but now that I went up to the 14:1 and runnin race gas, I wish I would have from the start. Running the 14:1 out west at altitude makes the bike feel exactly like it does at home runing 11.5:1, this I speak from experience using wheelie ability as the gauge since we don't have dunes here like they do in Idaho. Likewise, running 11.5:1 at 5K was about like running stock motor at home, again just judging by feel.

But for cams, reliability is a factor, or rather frequency of maintenance is a factor. The more agressive the cam, the more often you will have to replace valve springs. There is no builder or supplier that I personally have been able to get straight answers on how often the springs should be replaced when using their cams. some of them say that if the right springs are used and set up right for the cam then they can last idefinitely. But I and many many others both on the forums and off have suffered from broken valve springs that were totally correct for the application. I can only speculate that builders and suppliers are looking more at a drag standpoint than a long term multi thousand mile hundreds of hours standpoint. I will put more time on a motor on one single trip to St. A's than a drag bike will see in an entire season.

I run the RWR axtel grind, aka a1/a2, commonly refered to as being in a similair class as the HPR3's. Somewhere after 300 hours I broke both outer intake valve springs, and this is the common spring I've been hearing of braking the most, since the intake lift is typically higher than the exhaust in many cam grind configurations. So I am on a strict regiment now to replace springs every 200 hours at the most. If you do not wanna mess with this kind of maintenance, a less agressive sport style cam is the only way to go, but it will give minimal gains in comparison.

Call up and talk to THEBOM, RWR, and HPR, and see what they all say, and make an informed decision based on the entire collective.

 

I agree with Hightower. I also am a big fan of the A1 A2 cams. I am also a big guy and Ive noticed how nice the A1 A2 pull from bottom to top. I would suggest talking to Jeff Ross (THEBOM) about these cams.

Another suggestion I have would be to go with the 520 chain kit and spinning down your hubs to eliminate alot of rotating mass. Its a cheap way to go faster.

Good Luck
[img]i/expressions/face-icon-small-smile.gif[/img]

 

I agree a lightened flywheel will also wake up your build.

 

Yep, planning on a 520 conversion with lightened hubs for sure.

Question... do you need the shim under conversion with the Axtel cams?

 

Also Hightower, how is the light front end with the stock swingarm? Is it hard to keep down climbing the hills in St. A?

 

A little more oomph on Devils Dune. Thats easy! NITROUS!!!!!!!!!![img]i/expressions/face-icon-small-happy.gif[/img][img]i/expressions/face-icon-small-cool.gif[/img]

 

i have a hpr 14 to 1 piston with about 1.5 hours on it, all you need are some new rings and c-clips......

 

Josh I have the old style swingarm, the steel one, its 1.5" longer than the new cast aluminum model. with it I have no problems at all, it is perfect for out there. at home, for drag starts, its way too short. but I mostly trail ride at home, and its perfect for that. so I suffer when dragging at SL bigtime, in exchange for being spot on everywhere else.

you would probably notice the same - you can use your wieght to keep her down when you need to, and have no problems out west, but drags at home will have you reaching for the sky or feathering the clutch like crazy to keep it down and never winning because of it. actually you would probably notice it more with your shorter swinger, being your weight isn't much more than mine.

I had my hubs lightened locally for $50, any local shop can do it.
I have not gotten the 520 chain, yet anyway. I am reading that the new ti-moly sprockets are holding up great, this is what I have been waiting for. the 530 only advantage over 520 is it is 50% wider, making sprocket life much longer, and I go thru front sprockets now like crazy. if the new fronts are lasting on 520 setups, then I may do it eventually.


a used piston is not a bad way to go for money savings, but yes indeed do new rings, and have your bore honed for ring break-in regardless of it being new or used.

 

Well I wanna do the 14:1 but do I want to lug race gas with me to the mountains of pa and clear across the country is the question. Where did you buy your 110 in Idaho?