UPGRADES: The Power Post (Work in Progress)

Doing the supermoto post calculations of bore and stroke on that little 350 DSES got my brain boiling. It was not too long ago (alright a couple of years) in a blog entry I referenced this chart and made allusions to how much power I might be able to get out of the mighty 494 cc ATK.

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So rather than sit and dream I did a little research on ways to get the most out of your Rotax. I wish that there was a more organized way to present this information, but since I kind of use this blog more for my own reference back to things I have seen, Ill just have to deal with the way I present it...

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I will start with determining the power that I have. For the most part it has been subjective. The only other bikes I have ridden in the past 5 years have been a Ducati Hypermotard and a BMW GS1200. Those are bad baselines for comparison. I ride with a guy that has a 650 KLR and a Vstrom, and while I don't feel he can really get away from me in the twisties, his comfort at a sustained 75 is a lot higher than mine. Granted, I have a weight and vibrational disadvantage. I already CHANGED THE GEARING

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Where are gains to be made? Some Harris Matchless G80 devotees pointus in the direction on Page 3 of a Jampot PDF. This gives a few pointers, but no how-to's:
 

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CCM MAD Forum 604 rebuild and tune

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INCREASING COMPRESSION RATIOS:
Dynamic vs static
Compression Decking- AKA Milling the cylinder head or using no head gasket, or even a thinner head gasket (copper)

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CAMS Jampot pdf on why to fit a softer cam, and instructions on how to change the cam

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HEAD WORK / VALVES
Porting and Flowing head: CCM MAD has good pics comparing heads pre and post porting / flowing here.
Engine Dynamics in Petaluma works on heads
Valves: Please see Ron Wood

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FUEL AND AIR FLOW
This is an internal combustion engine right?
CARBURETOR / EXHAUST
 Accelerator pump?
Jets?
Mikuni VM44 vs Del Orto- Lee loves the delorto

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NO REPLACEMENT FOR DISPLACEMENT:
Ron woods 676 Cylinder Ron Woods 100 cc Piston kit
Sportax in UK 640 kit.
Here is a write up about their 348 to 405 conversion.
Downside is reliability and needing to use race fuel. Bones describe this problem on the ATK rider Website in this thread.

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GEARING

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WEIGHT:
Exercise and Diet-Just lose some weight fat ass, riding on the road and not just a dyno is all about power to weight ratio and not just power.
Shorai Battery: Mild weight difference, but some say is noticable compared to the Yuasa.

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ELECTRONICS
Rewound stator: Rex's speed shop claims 2-3 hp gains using a rewound race stator on the MT 350 and MT 500s.
 
CDI Box: The CCM folks claim that the programmable ignition delivers more consistent power across the rev range.

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SUMMARY:
I really just need to get the 490 on the dyno, but for now I just bought 3 boxes worth of a 605 that I am putting together to do a side by side comparison of power... But that post is for another day.

RESOURCES: MANUALS!!!

ENGINE REPAIR MANUAL

ATK 605 OWNERS MANUAL

STEP BY STEP CAM BELT CHANGE INSTRUCTIONS

ROTAX TYPE 348 Part #s and DIAGRAMS

HARLEY MT350 OPERATORS MANUAL

STEP BY STEP SPRAG CLUTCH REPLACEMENT

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I started this post with the links that I had, but searched on the ATK RIDER FORUM and realized Pantera had already compiled these in 2012, so I stole some links from him. Give credit where it is due. Also, I claim NO ownership of the materials linked to here.

MAINTENANCE: VIDEO: Checking valve clearances

Here's a video from across the pond of checking valve clearances on a Rotax type 348 powered MT500.

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Depending on who you ask, and which way the wind blows you will get exactly 4397 answers as to what proper valve clearance is. The manual says 0.002" (0.05mm) Cold for both intake and exhaust. Lee at ATK says go with 0.004" for break in period, then you should be fine to snug them down to 0.002". If you go to Ron Woods he says 0.005" for racing and 0.004" for routine operation. Whatever the case may be, here is the ATK Service Manual Instructions:

1. Turn fuel Petcock to OFF

2. Remove Fuel Tank

3. Remove decompression cable from cylinder head

4. Fix crankshaft at TDC

5. Remove the six 10 mm hex head bolts retaining the valve covers. Remove the valve covers. (I would do this one at time)

6. Adjusting one valve at a time, loosen the 11 mm hex head lock nut with a box end wrench (spanner) at the top of each valve adjuster

7. Insert the correct size feeler gauge between the valve top and the valve adjuster

8. Tighten the valve adjuster with a straight blade screwdriver until the feeler gauge provides a small amount of resistance when trying to remove

9. Hold the valve adjuster in place with the screw driver while tightening the 11 mm hex head lock nut (Gonna need the spanner again) with the box end wrench

10. Repeat steps 5-8 for remaining valves

11. Reassemble the motorcycle making sure to set the valve cover o-rings properly to prevent any leaks

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In the ATK service manual there was no mention of the cam position during this adjustment. You should probably think about hooking the decompression cable back up too. Hope his helps.

BIKES: 605 Supermotos from Around the Interweb

The internet, apparently it is not just for cats. In my usual google perusal of any combination of "ATK, Rotax, Supermoto, 605 etc..." I've come across a few pretty distinct SM customs, some better than others. I hope I don't come off as snide, because I think it is awesome what each of these people has done to make their vision become a reality.

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#1 I'll call this one "OLD YELLER"

Yellow Frame and plastics? It almost looks factory! Wave rotor hotness. Black Tank. Black swingarm. Are those fork tubes anodized? And note the Non-ATK rear fender!

Swingarm seems to indicate 600 like the DT models... hmmmmm...

The 17's and especially these footpegs probably make this a whole lot more fun to ride.

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#2 Yet another terrible alien supermoto headlight with a red white and blue motiff on this next one I'll call "ILL EAGLE ALIEN"

RED seat WHITE Tank BLUE Frame.

Terrible headlight is almost visible in this one.

The lack of number plates looks okay from the left, but that battery box begs to be hidden by some square footage of plastic.

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#3 Sometimes dipping goes a little too far. This one I'll call "Midas Touch"

The black rotax looks pretty sharp, I'm just hoping they used something relatively high temp resistant on that motor and Supertrapp. Can't tell if that's a sprocket protector or not from the pics. The 320 mm rotor in front for stoppie time. It kind of reminds me of this one

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#4 Fully stock looking except for the tiny wheel and custom fender, so I'll call this one "LITTLE FOOT"

This little 350 is a sleeper though because the owner did some engine work described later. Looks like they left the 18" in back. No additional views were available on his photobucket account, and no information about the fender on ADVrider where this was originally posted. The owner indicated on the forum that this was a 350 that he bored out to a 440. you might wonder why not 494 or 605. Well, a it turns out if you do the calculations, the limited stroke of the 348 (70.4 mm as compared to 79.4mm for the 494 and 81mm for the 605) means that even bored to 89 mm (494 bore)the total volume of the compression chamber will only be 440 cc. Even if he sleeved it out to 96.5 mm (bore of the 605), he would have only ended up with a 517 cc. That's enough math for now.

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#5 I'll let you guess what the most prominent feature on this one is, meanwhile I'll call it "Hot Wheels"

Looks pretty standard except for the Yamaha tri spoke cast wheels.

Which is a pretty big accomplishment given that the ATK Talon size is seen as a "unicorn" fitment and so many people fret about destroying their dirt wheels to make a supermoto set. I wish there was more information available on how these bad boys were jimmied into position (Link up above to the description). It's not that I want tri spokes on the 490, but it might help the many of us interestd in not tearing apart the dirt set, and might give more options for rear braking given the "unobtanium" status of the rear brake rotor.

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#6 Supermoto style with minimal investment! I'll call this one "18 WITH A BULLET"

I've often wondered why I shouldn't just relace the front hub to an 18" hoop to drop the bike a little and get a supermoto look. This guy did more than just wonder.

It might look better with a smaller front fender but overall the look is acheived.

The big drawback to this approach is the limited amount of tires available in 18" format. You might get the supermoto look, but you will likely end up mounting a rear tire on the front. This is somewhat contrary to the idea of making your bike into a SM, because the high sidewalls and lack of taper to the contact surface means no significant gains in cornering performance.

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Well, that's it for this installment, I'll be keeping my eye on CL and eBay for other sweet custom rides. If you have any pics of some SM ATK's post them in the comments. NOTE: I omitted Bones and Michaelangelo's SMs because I have already posted them in previous blog entries.

FOR SALE: ATK... No really, ATK is For Sale

Don't exactly know what this means for us as a whole, but should be an interesting new chapter.

Screengrab from ATK Facebook Group.

MAINTENANCE VIDEO: NEW CAM BELT CHANGE VIDEO

The link to the old video went dead, so here's a new one based on the MT500

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PICTURES: Best Shots From The Road

Alright, I admit, mostly this post is bragging, but who doesn't like to see a single sided frame with a nice bit of windy road in front of it? Also you might get an idea of what I think is the most photogenic angle of the bike.

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MODIFICATIONS: 48t to 44t Rear Sprocket

One of the complaints of my riding buddies with KLRs and VSTROMs is my lack of range on the ATK (~100 miles / tank), but another has been my comfort for running the 494 Rotax at 70 mph on the highway for any lengthy period of time (>20 minutes). I know this thing can go fast (I might have seen 95 mph before I cut back), but I just never liked the feel of running at such high RPMs for a long period of time (not only on the motor, but also on my ass). In looking at things I could do to improve my situation it looked like changing gear ratios might be the easiest and cheapest way to make 70 more comfortable.

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As it was I was running 16t countershaft with a 48t rear sprocket. That equates to a exactly a 3:1 ratio. A 17t up front with a 48t in the rear would equate to a 2.82:1 ratio. A 16t countershaft with a 44t rear would be 2.75:1 ratio. A 17t countershaft with a 44 t rear would be a 2.58:1 ratio.

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I decided to just go with the 44t rear sprocket to see how that affected low end torque before jumping to the 17t countershaft. From silly internet research and ZERO math I have come to understand that for every tooth increase in the front is worth 3 teeth in the rear. The 44t with my current setup would put me right at 2.75:1 ratio... That I can live with. Plus Lee told me not to mess around with a 17t, and that these bikes can do 90 all day wide open with stock gearing and why go any faster than that?

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Artsy comparison of the 44t to the 48t

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I will need to remove a link out of the chain since this pushed the rear axle all the way to the back of the drop out, but I am liking the speed in 5th at half throttle. I have not noticed any real change in the lower gears, torque in the corners persists despite the ratio change.

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Probably won't be going to 12 o'clock any time soon, but look at that rear sprocket!!!

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COSTS:

Rear 44t Talon Sprocket $59.99 + $15 Shipping = $74.99

MODIFICATIONS: New Tread AKA "Goodbye to the supermoto dreams"

Since I got the 490 in 2010 I have dreamed about having two sets of wheels thinking a set of 17's would make road riding that much more awesome. After 3 years of rolling on two sets of 80 / 20 21" / 18" Pirelli MT Scorpions, I decided that I hate the slippage on the washboard sections of dirt roads and that I would give a try to a set of 50 / 50 Mefo Explorers.

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I never liked that skinny 21" Pirelli on the Front. The 140 18 looked super beefy by comparison.

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Amazing that such a simple frame and motor can bring so much happiness to my life.

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Not quite knobbies...

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But perfect for the numerous Humboldt County loops.

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The thought of spending more on a set of supermoto wheels and tires than I paid for my bike has never appealed to me, but getting to and making it out of tiny corners of the world that the ATK has given me access to appeals very much to me. I have yet to see how the Mefos hold up to lots of road wear, but so far they are holding up to the curvy sections of HWY 36 at the speeds that the Scorpions would tolerate without all the slippage on the washboard.

MODIFICATIONS: Tank Bag

About 4 months ago I loaded up all the spare bits and pieces I had accumulated and went to a local moto swap meet hoping to rid myself of some shed clutter. I came out of it with a nice set of 24" tire irons and one of THE BEST MODIFICATIONS I HAVE MADE TO MY BIKE!

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I was packing up an old set of WP forks from a 560 I had got in a trade (I'm the sucker) and a guy I had been talking with for a while offered me this old KTM Equiptment tank bag off a 990 adventure minus the zippered attachment points for the forks straight up. I said hell yes and it was on.

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I bought 6 feet of 1" Nylon Webbing from ACE, some heavy duty nylon thread and got to sewing.

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Needle drivers are a great investment if you are planning on sewing nylon. This stuff is TOUGH! These tools can be found at most surgical supply places, but are more commonly found where any fishing gear is sold. The surgical quality ones are better, but anything to give you a good grasp on the needle as you punch it through three layers of thick nylon.

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Essentially I just folded the webbing in half and sewed around the existing zipper attachments. I left four straps coming off at four attachment points a the front and back corners. I then put on some ABS strap clips from ACE on the four straps.

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I used 18" velcro 1" straps that I could easily take off the bike if need be to clip into the bag. This allows for quick access to fuel up just by undoing the clips and not the whole strap set up.

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It does limit forward movement on the seat a little bit, and standing is not as comfortable, but I gladly sacrifice that for carrying 3 liters of fuel, a map holder, a tool roll, an emergency rain suit, and my cable lock.

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This bag has opened up a whole new group of roads to me with the extra fuel I can carry. It also sits center mass over the tank so I don't notice the weight as much as I did with saddle bags.

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COSTS:

KTM Equipment Bag -$Free although it does resemble this FAMSA bag

Nylon Webbing 6' 1": $1 a foot x 6 from ACE = $6

Strap Clips: $1.49 x 4 from ACE = $6

18" Velcro 1" loops from ACE $3.99 x 4 = $16

Total: $28