AR93

I got an ar80 from dougler over the summer, and have been riding the hell out of it. The timing slipped at one point (flywheel completely came off the crankshaft) due to the kickstart being broken and having to bump start it. After i fixed this (incorrectly), it ran beautifully and would do 60mph no problem.

Last weekend i took it to bombourbon run and on the way back i blew a hole in my piston due to the timing being too advanced:

So i bought a 93cc kit for it from here expensive as hell, but parts for these are super rare and shipping from the UK was more than the kit itself. it arrived within a week and they sent me an extra piston, and gasket set along with a note that said they sent an extra one because they value their overseas customers. Rad dudes for sure.

I removed the old cylinder and cleaned out the crankcase of piston debris. I installed the new piston and cylinder but broke a ring in the process. Fortunately they sent that extra piston and i was able to use one of the other rings they sent me and was able to install the new kit successfully.

I removed the old airbox, tacho and speedo (they also broke on bombourbon) and i plan on building a mount for my gps unit where the instrumentation previously was housed. I also need to get a K&N style air filter, new jets, and some more plugs. And last but not least i need to fix the timing correctly so that i dont blow a hole in another piston. With the added torque and power from 13cc's i'm going to probably get a bigger front sprocket going from a 14 to a 16 tooth and perhaps a smaller rear if i think its necessary. i'm hoping to be able to do a comfortable 70mph cruising.

Thought i'd share. come check it out next time you're in cincinnati.

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really enjoyed the writeup, its a rad looking bike. you'll have to let us know how the new kit works out for you, and keep an eye on that flywheel.

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i forgot to mention that i did start it last night but it would only run on choke. no air filter + larger cylinder means i definitely need to upjet. so i'll be heading to the local motorcycle shop later today to get a filter, some jets, new plugs, and perhaps a new chain.

i ordered a flywheel puller a while back and also will be adjusting the timing tonight. I'll update this thread with my progress.

I also fixed the kickstart a while back so I'm hoping the timing wont slip anymore from bump starting it.

anyone have any opinions on running this thing premix vs. oil injected? injected would provide oil based on rpms, premix would be based on throttle position, right? seems like it would be better to run injected, but everything is breaking on this bike because of old age. maybe it would be best to just go premix and not have to worry about the injector breaking?

thanks for the kind words dwegs.

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nice to see it running again paul.

will you upgrade the pipe as well?

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don't think i'll upgrade the pipe. the stock expansion chamber is decent but not great. i only want to be able to do 70 on this bike. spending another 300 bucks on a pipe just isnt worth it to me right now. maybe in the future if i come into a large sum of money from a rich uncle.... maybe. or if motomatic wants to donate one... ha

besides i dont want to blow it up. if i keep the stock gearing, it'll be screaming at 14k rpms at 70. with new gearing i'd like to keep it at about 10k at 70mph.

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i fixed the timing properly last night, installed a new air filter, and got it to idle without the choke. checked for air leaks and found one at the base of the cylinder. i need to rip it apart and clean the surfaces a little better. i have a sneaking feeling that paper residue from the original gasket on this thing is causing the mating surfaces to be uneven and cause the leak. lets hope i dont break another ring when i put it back together or i'm really screwed.

i tried to find some jets at the local motorcycle shop but they didn't have the sizes i needed so i ordered some online. i also ordered some new tires... the old ones have some dry rot and cracks. hopefully i'll be able to ride this thing by the end of the week.

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wow rad

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I can't wait for its winter rebirth.

were the transfers the same size?

do you think that pipe could survive sand blasting, or would it blast holes in it?

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maybe you'd be better off sanding off some of the rust and then priming it with high temp rustinhibiting primer and then hi temp black.

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the pipe might survive... maybe. i dont know if i want to chance it though. if i spend that much money on getting it blasted and repainted, i might as well just get an aftermarket one. i'll just repaint this one myself and if it breaks/rusts out, then i'll get an aftermarket one.

transfers are huge on the thing, take a look at the original cylinder thursday. they are roughly the same port map. after removing the air box and putting on the k&n filter it sounds super mean. its got that throaty intake sound now, which is awesome.

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YES!!! This thread is AWESOME!

I've been thinking about getting one of those 93cc cylinders for my AR80 too, but I was told by the dude on Ebay that they're cast iron and weigh a ton....making shipping MAD expensive. Mine run so well right now that I'm happy to just go with what I've got.

Hey....can you explain why bump starting it would cause the timing to slip? I'm not really understanding that one. No points in these things. CDI only. I haven't really gone through the manual enough to see how the crank is configured on the starter and on the flywheel.

FYI - if you want to repaint that tank, use GMC red color coded spray paint # 5321. It's basically a perfect match.

I also talked with a few dudes at my local motorsports store and they said the same thing about the pipe. It's definitely good enough to rip hard (I mean...mine wheelies in first and 2nd gear if I'm not careful)...but top end could be improved if you just take out the baffle in the back. It'll obviously make it louder, but it'll give a boost on the top end. Mine runs at 68mph at 10.5k RPM. That's redline. I would absolutely regear that bitch with the big kit. You'll blow the tranny for sure at 13-15k RPM.

Awesome dude! This post is so rad! Keep the updates coming. Here's mine:

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Also....if you want to drop some SERIOUS CASH....go here:

<www.bdkraceeng.co.uk>

Sorry if I just emptied your bank account.....these guys have everything to make AR's ridiculous. Titanium pipes!!

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ben... i was wondering when you would chime in on this ha. you're bikes lookin sweet. good job on that tank.

i'm assuming that link was supposed to be to bdk's site. they have amazing stuff there. 98mph crazy!!! i emailed them actually when i was looking to get the 93cc kit, but their communication was iffy at best, and they have yet to return my last email about buying parts.

and yes shipping was insane. the kit was 67GBP ($110). shipping was more than the kit itself at 97GBP ($158). i hope this thing is worth it.

about the pipe. yeah i'm only looking to be able to actually PULL up to 70. dont want to have to wait all day to get there. so no need for a super high rpm pipe. i'll stick with this one for now.

i think i'm gonna repaint/powder the whole bike with a black and yellow paint scheme. i'm thinning my flock of bikes down, and going to keep three: the yellow/black garelli, the ar (soon to be yellow/black), and my tomos (also soon to be yellow/black). keeping it consistent.

ok cdi and timing explanation. it's kind of complicated and long, but here goes. back when i was bump starting it, i lost my spark. whether it was from the actual bump start and the jolting involved with that, or just vibrations from riding, i dont know, but the nut holding the flywheel came off. then one time when i tried to start it, it backfired and the spark was gone. i took the flywheel cover off and realized that the nut had fallen off, and the flywheel was spinning freely on the crankshaft = no spark = sheared woodruff key. so i took the flywheel off and realized i had sheared the woodruff key, which is really just a pin like on tomos crankshafts. not having a replacement handy, i eyeballed putting the flywheel back on. i tightened the nut down and found a mark on the flywheel that is supposed to line up with a little arrow on the case to indicate if your timing is right.

i got out the timing light and the two marks lined up perfectly with the strobe. i assumed all was kosher, put the flywheel cover on and rode off into the sunset. little did i realize at the time (in my early and seriously lacking timing skill and knowledge) that these marks would ALWAYS line up if i didnt change the position of the stator plate - even if i attach the flywheel 180 off. so in theory, if i put the flywheel on and line up the keyway in the flywheel on the OPPOSITE side of where the key would sit in the crankshaft (essentially 180 off on the crankshaft) the two marks on the flywheel and case would STILL line up at spark even though spark would be happening close to BDC. this is due to the sparking mechanism being independent of the crankshaft, and only depending on the position of the flywheel and stator plate.

i hope that makes sense.

so after i blew a hole in my piston, i realized my error. I checked the timing last night and it was set at about 3.8mm BTDC when stock is 2.3mm or 20 degrees. I set it to 2.3mm and she seems to like it there.

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LOL, why drop serious cash to make an AR80 93cc?? Why not just get a ke100?

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The stock US AR80 has a non adjustable stator plate and carb. I'm planning to go to a 21mm dellorto, and drilling holes in the stator plate to make it adjustable.

Is that the same kit on 50cc.nl?

I figure I'd order it once the cylinder looses it's plating.

I stripped the flywheel pin then I shattered the back of my clutch. It was backfiring, and just took the damn thing out.

The oil pump goes by rpm and throttle position.

Is your kickstart lever worn and saggy? mine hits the foot peg.

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colin im rich dont worry about it. also these bikes are wayyyyy cooler than the ke100. so it's totally worth it.

my stator plate is adjustable. thats weird that yours is not. i might go to a 21 dellorto if i can fab up an intake at some point. but for now the 18 should be ok.

it is that same kit as 50cc.nl i'll let you know how it performs once i get it tuned right.

yeah the back of my clutch exploded too. when i bought it, the kickstart was not working for that reason. i bought a new clutch bell off ebay and fixed the kickstart that way.

i guess i'll leave it injected for now then.

my kickstart lever was worn and saggy and hitting the footpeg, then i bought a new one (ebay) and it no longer hits the peg.

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also colin, same reason you ride a moped and not a CB350. i guarantee you've spent way more money on mopeds than if you wouldve just bought a new motorcycle.

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hahaha, true, ar80s are cooler than ke100s. And I have dumped a lot into mopeds. But an AR80 is not a moped anyways so you might as well get a cb350. :P

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close enough to a moped.

vintage, small engine, 2 stroke, in need of repairs, potential to make it go faster than they were meant to. thats all i need.

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Got it Paul - didn't catch that you sheered the woodruff key. That makes all the sense in the world.

Damn....that makes me nervous. My kickstart works fine and but I put a 21mm Dellorto on there because the 18 Mikuni was pretty shot and giving me a lot of problems. The 21 fits on without any real hard mod, although, I can tell it wants a bigger intake to match perfectly. Mine needs a choke which is why it doesn't start with the kick start. Bump starting it works fine, but it's getting harder in the cold weather. I think I'm gonna have to go with a longer suicide choke cable for the carb in the spring.

I have noticed that with the airbox out and the bigger carb that the bike pulls hard all the way to 60. Get's there super fast. Lots of torque. It's great. I can't imagine what a big bore kit would do! I mean...the bike only weighs marginally more than a Puch Magnum.

BDK racing makes an aluminum it which could be scary good. And yeah....they completely suck at customer emails. Ha. It's like they don't want my hard earned money!

Also....bought a 1972 500cc twin Suzuki 2 weeks ago. Just got it running last night. I only own one moped now....my super Moby. Then the AR and the T500. Small....medium....large. It's all I need. Like you, it's all about thinning the heard and going with your favorites.

Man...let's keep this thread going. This shit is awesome.

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sigh...

you all are making me wish i didn't all this family stuff going on so i could finish my AR.

saggy kickstart? yep. i was just moving the peg up so that the lever will clear. mine only takes a couple kicks to start anyway. finding neutral is a little tricky at times, though. unfortunately i still haven't taken the parts to a painter yet. they're just sitting in a milk crate ready and waiting for a new dark blue coat. otherwise i'd have been risking life and limb all this damn time instead of wishing it were so.

careful fixing that leak, Paul, pretend you're playing doctor. it's great to hear how you've progressed so far, though... we all owe you a coke, or something stronger.

good luck,

marc

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update:

worked on the bike all day today... first order of business: fab up a keyed ignition holder and gps mount. i used a piece of metal laying around the shop and bent it to fit on the old instrumentation mount. i welded it on and made it work for both holding the key and my gps mount.

looks pretty good i think. it'll look better once i grind down the welds and paint it black too.

then i tackled taking the cylinder apart and fixing that air leak. i removed the exhaust and carb then took the cylinder off and cleaned all the stuck paper gasket off the surfaces with some steel wool. i then sprayed copper gasket sealant on the new base gasket and installed the cylinder. did the same for the head gasket and put the head on. when i was putting the exhaust back on i noticed a funky bend in the exhaust gasket, but thought nothing of it really. after everything was back together i was able to start the bike and noticed that it wouldnt die when i took it off choke. thats an improvement. i sprayed some carb cleaner around the base gasket but still had a leak where i had it before: transmission side.

coincidentally this is the exhaust side too. i think i might actually have an exhaust leak instead or in conjunction with the base leak. i did have to do some modifications to the exhaust to get it to work with the new cylinder, so that may have caused some problems. i tried to tighten the exhaust bolts down and broke one of the exhaust studs, which actually sucks pretty hard because they have two different size threads on either end of the bolts. one is a 10mm and the other is something like 12. i'm gonna have to figure something out to fix this problem. i ran out of carb cleaner too and it was getting late too so i left it at that.

so now i need a new exhaust bolt/nut and i need to isolate the exhaust when testing for leaks to find out if it's the exhaust, base, or both that are leaking.

any recommendations on how to fix the leak if its the base? i really really cleaned the surfaces and even used the copper sealant stuff. why is it still leaking??? :(

i like how this has become my pseudo blog for this bike. awesome. thanks for the kind words. we'll have to get all these ar's together and ride sometime.

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That copper gasket sealer is not resistant to gas so it's probably not the best stuff to use. Cut a new base gasket- maybe slightly thicker paper would be more forgiving.

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Paul! I can help you with the leak if you want... Thursday or Saturday. I'm good at fixinng those...

Also, Beck's Hardware definitely has those 10mm/12mm studs in their metric hardware section.

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YES PLEASE TIMOTHY! Thursday would be awesome.

i'll check out becks tonight for those studs.

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i found those studs tim. thanks for the heads up.

they are some funky studs though. i've never seen these kind before.

hopefully my jets show up tomorrow and we can get this beast ripping.

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Other Quinn /

I think i might be picking one of those up soon, if i'm lucky.

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Last week tim and shay helped me fix that air leak. thanks guys.

my jets arrived and i dialed in the main, but was still getting some lean bog on the lower parts of the throttle. i didn't even realize that there was another circuit in the carb and it does actually have a pilot circuit. so i had to order some larger pilot jets. they should be here by friday. i hope i dont find out i'll need to order other needles as this carb does not have adjustable needle heights, only different needles with different tapers.

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Man, with that setup i would have jumped up to a keihin 28 for sure.

Sick bike, sounds like you're doing great getting it back up.

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I had a bad time finding a good set of handlebars. I finally firmed mine up by using the clamps off a dirt bike handlebar's cross-bar, over the joint where the bars attach to the top plate.

You can also mount the bars under the top plate, if you are short enough, for cheap dropped bars.

You can still get all the seals from places like bike bandit, the AR80 is in most fiche places as mini GP

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