Jump to content
kato

edit: that atk WILL see the trails again

Recommended Posts

If the rod bearings are too loose, or if the head is worn where the cylinder meets it the piston can touch the head when in operation and can lead to broken rings. A manual or Ron Woods would have a spec for deck height, the distance the piston sets below the top of the cylinder and/ or head.

Thanks for helping.

I just checked the rod it has a bit of play side by side like a bearing has, but none up and down. Feels good to me

There is a 8-10mm carbon deposit ring on the top inside of cylinder, so the piston has some clearance apparently

Share this post


Link to post
Share on other sites

Wel now i checked the cylinder with a bore dial gauge and it seems plenty good within specs for ovality, taper, and bore.

and my ignition coil is getting delivered today too.

Now to find a piston for that thing

Share this post


Link to post
Share on other sites

Wel now i checked the cylinder with a bore dial gauge and it seems plenty good within specs for ovality, taper, and bore.

and my ignition coil is getting delivered today too.

Now to find a piston for that thing

I was worried about the bore! Thats really good news!

Share this post


Link to post
Share on other sites

Spoke w/ ron wood he suggested the engine got overmalted, i mean overheated, and on my way up to get the piston.

Im like an addict who needs his dope, man on a mission!

Share this post


Link to post
Share on other sites

Wow, the bike looks like it was rode pretty hard to do that. Bummer that you got it this kind of shape, but glad to see it is getting taken care of. Trust me, in good running shape these bikes can MOVE! It will be worth the work. I had no idea about the cam you pulled out of there, very cool. You got a good bike with some nice unobtainium on it, between the cam an full uptime exhaust. Are you going to use a stock compression piston in it? There are some high comp piston kits floating around out there, I remember keeping an eye out for one with my last ATK.

Keep up the work. You have touched base with all the ATK rotax gurus out there and this should be an awesome bike when your done with it.

Share this post


Link to post
Share on other sites

Was this thing tuned for all out racing HP at 9500 RPM? At over 600cc you might not enjoy that on the trail or street. Then again you might love it, like turbo lag too BAT OUT OF HELL hahaha!

Is there any way you can get the specs for that cam? If it has a ton of intake/exhaust overlap it might run like crap for a trail bike (off idle to 5k bogg master). My bike has the HRC cam tuned for higher RPM performance and I sometimes wish it had the stock low RPM bump stick in it. You might be able to get a pretty penny for your hotrod cam and buy a fresh torque oriented cam profile, just a thought. Also, if your aftermarket cam is high lift be very careful of valve-to-piston clearances, if the deck or head have been machined to increase the compression ratio things might be really tight in there. With the HRC piston @ 11:1 my bike requires a "need to order" plug, put the standard plug in and it will smack the piston! :o/>/>

hvwyt might be onto something about "cheap gas" aka 91 pump gas. If the bike has 11:1 or higher compression, at load 91 will likely cause detonation when you have it WFO and the engine gets some heat in it (I have to keep a close ear on my engine on warm days and long freeway grades, hear da PING = back off da throttle or else!). Extended or severe detonation at high piston temps could cause your rings to "hammer" the ring grooves <_</>/> . If it turns out to be 12:1-or-somthing compression could you install a... GASP! head gasket? hahahaha this engine is a FREAK!!!

Share this post


Link to post
Share on other sites

I had a good day driving up to Ron Wood Racing, nice people. It makes me feel that much better owning this bike knowing they're around. He hooked me up NICELY with an OEM piston/rings/pin, we chatted about this and that, like how this rotax engine puts every other to shame heheh (but really the rotax thumpers they race put out 75whp), he inspected my cylinder briefly and said "these are indestructible don't worry about it" (and he's right because I measured .003mm off the original bore and this looks to be the original cylinder, i.e. 20 years old almost..), he checked out my camshaft, liked the craftsmanship on it and said that it didnt look like the "860" aka flat track camshaft (the one I dont want for trail riding), and well I was on way back to SD.

since I grinded a bit off (maybe .2 mm or so) the head to flatten the surface I slightly increased my compression already. I might go with the higher compression next time, maybe some porting too because I didnt do much cleaning this time, we ll see.

FOR NOW, I am happy to let you know that I JUST finished putting the bike back together. I decided to reassemble rings and piston DRY (just deglazed a tad with a scotch brite + wd40, cleaned in sink, spray brake cleaner and let dry, oil only on the pin, nothing more). ring gap was within specs. I can not wait to see what will happen, if it will spit fire, if it will blow up, who knows. But it is getting late, the atk will be a bit loud now that I installed the 10 or 12 disks I got from desertrunner, and although I am moving in 3 days I still care about my neighbors so i will push the magic button tomorrow in the morning and.. well hopefully magic happens right

thanks all. and good catch John, my buddy put it there and we were wondering if anyone would see it ahah

Share this post


Link to post
Share on other sites

Kato- I think this is awesome!

You now have a rare bike, put back together with your own hands...lighter than my drz, with nice suspension and big power from a bullet-proof (well...usually) rotax powerplant

I want to be there for the initial trail ride

Share this post


Link to post
Share on other sites

Kato- I think this is awesome!

You now have a rare bike, put back together with your own hands...lighter than my drz, with nice suspension and big power from a bullet-proof (well...usually) rotax powerplant

I want to be there for the initial trail ride

thanks Bob, very nice words. I was happy with the work I did on the KLR (so is the new owner who knew about sdar btw) but this is definitely next level. good feeling knowing every nut and spring in your engine. If this atk comes back to life the way it's supposed to I will start customizing things like the seat for instance, really make it my bike you know, and I doubt I'll ever part with it.

Share this post


Link to post
Share on other sites

Keeping a bike forever?!?!

Enough with the crazy talk... Bikeslut does not comprehend such talk

Share this post


Link to post
Share on other sites

Well there we are, this morning the ATK went for its first 10 miles with its new piston and.. it pulls HARD!!! needs minor carb adjustments (one tiny dead spot on WOT somewhere in the lower mid range, no backfiring) but it idles somewhat good.

Sure looks like I did it, hard to keep my butt on the front of the seat when I open up ah!

PHOTO_20130530_093113_zps4b40d86b.jpg

thanks for the support/tips during the rebuild!

Share this post


Link to post
Share on other sites

Awesome job on the rebuild! I look forward to seeing it in person one of these days.

thanks. and also for the supertrapp rings! i repacked the muffler too and although it is definitely a bit loud it is not obnoxious to my ears (yet), it will definitely sound proper on the dirt. I'll probably just ride the Ramona area for the next 500 miles or so to limit the slabbing during break in period (I don't have a truck/trailer). Santa Ysabel truck trail maybe Sunday

Share this post


Link to post
Share on other sites

YEA! Thing looks good! :coolio:

Share this post


Link to post
Share on other sites

Awesome job on the rebuild! I look forward to seeing it in person one of these days.

thanks. and also for the supertrapp rings! i repacked the muffler too and although it is definitely a bit loud it is not obnoxious to my ears (yet), it will definitely sound proper on the dirt. I'll probably just ride the Ramona area for the next 500 miles or so to limit the slabbing during break in period (I don't have a truck/trailer). Santa Ysabel truck trail maybe Sunday

Post up if you are going Sunday. Lurking.........

Share this post


Link to post
Share on other sites

Post up if you are going Sunday. Lurking.........

Will do, but it will be a last minute post because its all going to depend on saturday (moving into my new place).

Share this post


Link to post
Share on other sites

Was on a 4 day ride and just saw this thread. Holy crap, Kato! Nice job on the rebuild.

Post up if you are going Sunday. Lurking.........

Will do, but it will be a last minute post because its all going to depend on saturday (moving into my new place).

Share this post


Link to post
Share on other sites

Good job on getting that bike running. If there's anything I've learned from this thread it's that you guys have way awesome skills as far as feeling feedback from the motor like sounds vibrations. I wish I could feel or here all those things.

Good stuff to read.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information