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View Full Version : How to Dyno a Dirtbike (Cannondale 3 wheeler)



thedeatons
08-07-2008, 10:59 AM
Hey guys, it's been a while, but I thought I would post this as it is relative to the trike world. See my post below from a Cannondale forum:

Well, I finally got my E440 to the dyno last night with Cdsracer. Lots of fun.

The engine:
432cc
Original ASSO piston with 3 hours on it (from original owner)
New ASSO piston rings
Original ASSO cylinder with 3 hours on it
Metal Pump Gears
Aluminum Impeller
Evans Coolant
Megacycle 12 hole intake cam
Hardness checked/approved (by Timbo) Italian 12 hole exhaust cam
Cams degreed to 106.5(Intake)/106.5(Exhaust)
Original timing chain (3 clicks out)
Conical cylinder head outlet filter
Magnets throughout
Aluminum Cam Cover
Latest Generation Timbo ported head with new valves/seals/
Valve lash adjusted to factory spec
Non-Detergent Break-In oil (Napa brand)
5 heat cycles of ~20 minutes each at increasing throttle openings each cycle (heavy modulation throughout the break in runs)

Other info:
New WPS brand chain
13/44 gearing
Carlisle semi slicks for the dyno run

The story:
We showed up at the dyno to find a KTM 525 quad on the dyno. His only mods were a modded stock exhaust (removed spark arrestor), opened the perforated holes in the airbox, and rejetted the main on the carb. The 525's best run (actually a 510cc engine) was 49hp.

Threw my bike on the dyno with a quad rear end (see pics below) and used the same tire/wheel combo as the KTM. First run the AFR was all over the place (we were using a map from my friend's quad with the same setup as a baseline map), but it ran 46hp. Cdsracer started adjusting the flow rate to find which AFR resulted in the most peak hp, then tweaked the fueling map (at 100% throttle opening because that is what our runs were taken at) to achieve the engine's most liked AFR across the rev range. After that was done we played with timing. Thsi got us 47hp.

Early on we realized that the stock canister has a spark arrestor at the end of it, so we decided to remove it. We quickly removed the hex screws from the endcap and cut the spark arrestor cone off with a cut off wheel. A twist of the go-fast grip resulted in a 1hp increase, now we were at 48 hp. We then checked the pipe with a flashlight and found ANOTHER SPARK ARRESTOR at the front end of the can! Crazy power robbing freaks. That end was riveted on so I could not remove it, but it's coming out for sure. That should be another 1hp, equalling my friend Janell's engine setup of 49hp.

Very happy with these numbers and the way the bike pulls down the street. Street gearing is 16/45 and whne you hit the gas in first from a stop it carries the front wheel about 1 ft off the ground to the limiter, then pops it back up in second. That is sitting in the middle of the seat and not even attempting to wheeile. Oh yeah, that was before the 2 extra hp the dyno got us.

The dyno session rocked. All in all we did 13 runs with the dirtbike, then it was past midnight on a Tuesday, so we called it quits. Power was starting to sign off at ~9700 rpm, so I am going to set the rev limiter to 10k for a little over-rev capability. Plans are to also change the Accel/Decel TS to 200, for minimum abruptness when I hit the throttle/chop the throttle and take some timing out of the bottom end. This should result in a very manageable, streetable bike, not twitchy at all.

The dynamically balanced crank runs SO smooth. No vibrations at all in the handlebars or the pegs that I have noticed. They balanced it to 9k, and I will rarely be running it beyond that, which is perfect.

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Additional mods (forgot to list these)

Dimpled valves (Timbo special)
Cyclone Intake
NO dirtbike airbox
No Toil 250R filter
Bored Throttle Body (courtesy of Timbo)
Heavily modified throttle plate (courtesy of myself)
Moto Axle (set @ +4" (widest) setting)

We tried removing the seat after the final dialed in run, the top end went a hair leaner on the AFR (~.5:1 leaner), meaning we could have added fuel to get a little more power.

I had thought of cutting a trianguler section out of the front of the seat so the filter can breathe better, but decided that .5-1hp wasn't worth the fabrication/~$300 in upholstery work.

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Pics below.

VenomRS4
08-07-2008, 03:34 PM
That is bad ass! What are your plans for it? Are you going to make it look like a stereotypical 3 wheeler or are you leaving it as is?

Tri-Z 250
08-07-2008, 03:48 PM
I have to wonder how far off is the quad subframe? Heck swap out the seat and sub with a new set of 250r based triples your pretty muck in there

thedeatons
08-07-2008, 04:48 PM
HAHA..... Good point, I forgot to mention this is my E440 dirtbike, street legal. I needed the quad rear end to dyno it properly, so I swapped them. No plans to leave it as a trike, as I need to commute on it as a dirtbike.

The Cannondale dirtbike frames are nearly the skinniest dirtbike frames in production, therefore fitting the ATV subframe would be kinda goofy without a lot of fab work.

This thing can easily be built for less than $2500. The only other thing needed would be wider triple clamps and a trike front wheel. Just use the dirtbike seat and yer done. Lots of travel, with right at 50hp, in a less than 300lb package. (The stock Cannondale E440 dirtbike weighed 349lbs, so I added ~40lbs for the quad swingarm, axle, hubs, wheels).

mikeftlaud
08-07-2008, 05:54 PM
Why all the work for the trike rear end?? Why not just dyno it on a motorcycle dyno?? Those rear tires are probably good for eating up a couple horsepower

thedeatons
08-07-2008, 10:36 PM
3-4hp actually.

#1, my local dyno guy that let's us map them ourselves only has a car dyno. He tests exhaust pipes for major quad manufacturers (DASA) and air intake kits for quads also. So, I know the dyno works well.

#2, I wanted to make sure the engine made the same hp as my friend Janell's did, which has the same setup. It was a comparison, same dyno, same tires, same quad rear end, same engine setup = same hp output (actually 1hp down because of the 2nd spark arrestor)

Most dyno shops only want to do the work themselves. They have no idea how to use Cannondale's mapping software. Some barely know what lean means. This is a good dyno, with a great operator, who let's us do whatever we want for however long we want.... All for $100.

mikeftlaud
08-08-2008, 02:54 AM
Oh Now it makes sense, you got an insider deal;) Looks cool like that anyway.

thedeatons
08-13-2008, 10:41 PM
Here is my offer..... If anyone wants a 50hp trike that weighs less than 300lb, or even better a 55-65hp trike, get in touch with me.

You buy the Cannondale dirtbike (let me help you pick it out) and quad swingarm/axle, and I will build it. If the engine needs rebuilding I will do the work.

I would love to see one of these rockin' the dunes, but I have other things going on.

I will be more than happy to teach you everything I know about Cannondales. Really great when you get the "reliability list" done to the engine....