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.

PARTS: Ignitec Ignition box

 These look interesting:
The guys over at CCM have been putting them on the 604 power plants with various mapping and have had what seem like good results
Read more here

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.

REPAIRS: Resurrection Threads on BARF and ADVRider

If you haven't read through this entire thread, you owe it to yourself to do so. It starts with an abandoned ATK on a dock in the bay, and ends up with a beast that a 5 foot 5 inch woman can ride comfortably. Engine work, frame mods, foot peg relocation, seat height adjustment... this has it all. I wish I had this amount of awesome to post on this blog, but I'll just have to settle for linking to it.

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This is another good one by GCRAD1 over on ADVRider about his adventures in working on his 605. Pretty cool pictures of petcock refurbishing, carb maint, bearing repacking, and also him meeting Ron Woods, and visiting De Wayne Johnson's suspension lab, and American Dirtbike.

HALL OF FAME: ATK Founder Horst Leitner inducted to motocross hall of fame

Motocross Action Magazine has the story.

Dude saw a problem and made the custom happen! Coincidentally I had come across this in my google searching and I wondered what the hell it was:

Turns out it is just a static representation of the actual ATK namesake. As found on AMP Research (Horst's company).