Drag project

[tayyo789]

I've been quiet about this one, but I figured its time to share my latest build with you guys. We wanted to build a drag bike for the sand drags here in Oregon. Since the DS650 has the best building block of a motor for a big single, and we already had a lot of the parts, we stuck with it. We also used an extra 400ex frame for a base chassis, for parts availability and weight savings, and started chopping, cutting, welding, and grinding.

We rushed through it trying to get it running to test out our newly built motor (bored and stroked to 800cc's). So a lot of things are getting improved upon this winter, and at the time of the pictures were just rigged together for the time being. Right now its function over appeal, so its not pretty or nice yet, just a starting place. So now, let the (hopefully constructive) criticism begin.

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[tayyo789]

Unfortunately we didn't get to run it and get times when we took it out. The thing was running like crap the day of the races, and we spent all day tuning only to find out we had an electrical problem that was draining the battery and causing the ignition system to not fire consistently. Hence the wiring mess in the pictures.

I know drag racing's not a hot topic here but I figured you guys would enjoy something different to look at than another crf or yz build ;)

[mx Eli]

CAn you explain why the ds motor is a better base then say another xr650 or raptor 700? (maybe even kfx 700)

[tayyo789]

Its close between the Raptor and the DS, but I feel like the biggest reason is that the DS can rev like a 450, while other big singles are more tractor-like. I can rev the DS up to around 7000 and dump the clutch and it won't bog out, even with these tires, and it makes more power the higher in the rpm range you go. Besides that, they are the most reliable with serious mods. Obviously nothing is reliable when you get over 80 horsepower, but the DS can handle it longer than the rest. DS motor's can handle nitrous a lot better than a Raptor as well. The xr650r just doesn't have enough of an aftermarket, and the ports can't be hogged out like the other two to get all the air a big motor would need.

If you go on drag forums, you'll notice all the DS guys are kings of the straight line. On a hill, the Raptor could catch back up with the extra torque.

[mx Eli]

Hmm I see, sorry another drag newbie question? I know there turbo kits out there for the raptors, how do those do on the strip/hill shooting or does anybody run them? just some stupid questions I'v always been curious about

[tayyo789]

There are a lot of turbos out there, but they really aren't practical for what I'm doing. I built this for flat 300' sand strips, and am eventually going to convert it to a hillshooter.
Turbo's just take too long to spool up. They're great if you're going a quarter mile, or something longer, but in 300 feet, the first 60 are the most important, and the turbo guys don't really take off until about halfway down the track. Plus when they shift, it basically starts the whole process over because they need to get their RPM's back up. It's basically the same problem the 4 cylinder guys have on a short track like that, there's just not enough space to take advantage of it. There are a few DS's that I've seen with turbos that run great because they can keep those RPM's higher than say a Raptor would be able to, but they also aren't very cost effective, when nitrous gives you a more predictable boost every time.
I would love to have a turbo on this when it becomes a hillshooter, but I really don't see it being realistic. Plus it would be an absolute nightmare to tune with dual carbs, and I although I think this motor can handle the extra boost fairly reliably, I don't want to risk this new bottom end so soon. Lots of $$$$ in there :ermm:

[tayyo789]

And to answer your question from earlier about a kfx700, the biggest problem is the shaft drive. I've seen some chain conversions, but it's just not worth it to me. And the way they're set up, I would have to move my gas tank and install a fuel pump, etc...
And the extra weight of the motor would also kill me. It would be nice to have a CVT, to make bracket racing a whole lot easier, but all in all, the DS was my best bet.
I was really focused on weight when building it, and there are still a lot of things I can do to shave weight, mainly in the axle assembly, but this was just my starting point. I haven't weighed it yet, but I'm 95% certain its under 300 pounds. I can pick it up with one hand under the axle carrier very easily.

[fastrnrik]

That's a cool bike. I like stuff that's unique and different. What kind of times are you hoping for? How does it (or will it once you get it dialed in) compare to the normal drag strip big bore drag Banshee's? I would imagine an 800cc 4 stroke is a beast out of the hole LOL.

We used to have a KFX700 with mild motor work, exhaust, clutching, etc and that thing was fun, but you're right the shaft drive and being stuck with the stock swinger kind of limits getting too crazy with extra hp LOL. I saw some chain drive V Force setups on the Kawi forum that were several thousand a pop. Ouch! LOL

[tayyo789]

Ya the chain conversions for those are tough to try and make it worth it. I know a guy who has one that he bored, stroked, cam, etc, and recently put it on a 20 shot of nitrous. He actually cut his swingarm, and added material to make it longer, and extended the shaft inside. It's still only running low 5's though.
Compared to a drag banshee, I don't know yet. I can say though that our other DS, with a stock chassis, still heavy, not a big bore, and only 11:1 compression could keep up with and beat one that I was racing for fun one day, for at least 300 feet anyways haha.
Our goal for this is at least low 4's. We've still got a little motor work to do and then probably shortening the swingarm to get some weight over those tires before we actually go get it timed. The only seat time on it was around our camp on our last dune trip, trying to test everything and making sure it won't break. I practiced a few launches and it seemed to run very strong, but after about 2 practice launches the battery lost its juice and we spent the rest of the trip trying to figure it out.

[mx Eli]

A turbo coupled with a cvt trans sounds like a good setup, just becuase you could clutch it to run nhigher rpm's and have that turbo spooled the whole time without shifting

[tayyo789]

I've never seen one like that, but its a good concept. Correct me if I'm wrong, but KFX's don't have a clutch lever do they? You would have to set the clutch to disengage at such a high RPM that you wouldn't be able to build much speed before you're tach'd out

[mx Eli]

no they do not have a clutch lever but you could set the cvt to engage at a say 5000ish- then have the cvt sleeves start shifting at say 7000-8000 rpm to have the boost so it would stay in that 7k-8k but the wheel speed is being increased. you could set the clutch to engage and shift at whatever rpm's you want

[tayyo789]

That would be interesting to see someone do. You'd need a pretty gnarly belt to hold up to all that I'd think.
Now that I think about it, I've heard of some snowmobile powered bikes with turbos on them, I'm imagining you could try that on those perhaps? And I think I saw a new Arctic Cat snowmobile that comes with a turbo stock. I'm not really into snowmobiles though so I've probably missed something

[mx Eli]

Yeah arctic cat has the z1 I think its called with a turbo stock, could perhaps use a sled belt, 150hp is commen for a sled so one of there belts could hold up pretty good. more and more people are boosting sleds just becuase with the cvt it keeps the boost on, yet increases the track speed.

I Ice race two people that ride 250r geometry frames with polaris 400 two stroke motors, plastic, cvt, and chain drive.

[250x_kyle]

not saying that it wouldnt be a cool thing to attempt or that the cvt belt wouldnt hold up but theres two issues. 5k is a high rpm range for something turbo powered to engage and something not let loose if it does grab. again i understand that 5k is a guesstimate and im honestly not sure where something this small would begin to build boost at. would deffinately be cool to try if you have the spare change though.

[mx Eli]

Not being a smart *** but there's 350+hp turbo sleds out there, and a belt can hold that power. it might be alittle differant but stock sled will engage about 1500-2000 rpm, with a clutch kit it goes to around 3000-3500 depend on brand and weights, I guess that would be about 1500-2000 more rpm on top of that. as small as these turbo's would be I would guess 5000 is well into the boost area. I'd like to see when the boost hits on a small atv turbo

[HondaPohl]

Its not as Banshee but I Like it. No really that looks like a torque monster. Nice build. Get some vids up!

[tayyo789]

It'll be a while before I can get any vids, I've got to tear it back down and do a little motor work, and redo some stuff on the frame, maybe build a new subframe too. I'm aiming for having it all back and running next summer, but with a much better setup

[250x_kyle]

Originally posted by mx Eli
Not being a smart *** but there's 350+hp turbo sleds out there, and a belt can hold that power. it might be alittle differant but stock sled will engage about 1500-2000 rpm, with a clutch kit it goes to around 3000-3500 depend on brand and weights, I guess that would be about 1500-2000 more rpm on top of that. as small as these turbo's would be I would guess 5000 is well into the boost area. I'd like to see when the boost hits on a small atv turbo

oh i know my dads friend has a turbo sled. im just saying that getting the correct size belt and that if that one time it slipped and then caught something internally (transmission wise) would more then likely go. the transmission setups were not meant to withstand boost. not saying i still wouldnt try it but just another factor. no hard feeling just trying to throw out a few ideas of possible faults with the system :p

[mx Eli]

Originally posted by 250x_kyle
oh i know my dads friend has a turbo sled. im just saying that getting the correct size belt and that if that one time it slipped and then caught something internally (transmission wise) would more then likely go. the transmission setups were not meant to withstand boost. not saying i still wouldnt try it but just another factor. no hard feeling just trying to throw out a few ideas of possible faults with the system :p

Understandable! somthings goin to break!:(

[JOHNDOE83]

Holy S#!t that things a beast!