new to atc's got a 90 and 200s +bolt on supension. lots of questions.

[mtk]

alright, a couple weeks ago i bought a pair of atc's
one is a 78 atc90. it doesnt have the hi/lo selector on the side. just an exposed chain and a chain tensioner made from skateboard wheels. nicely constructed though.
the previous owner knew nothing about internal combustion motors and said that his buddy "modified it to run like a 125". the jug is a 89cc, has a bapp intake and mikuni carb. sat for two years. put in a heli-coil and got it running but the carb was dirty and i couldnt rev it up. putted it around camp now it seeps oil very slowly around the head gasket.
i cleaned the carb a minute ago but didnt have time to play with it.
any ideas? what could the p.o. have done to make it run like a 125? i put in mid grade fuel just in case its running higher compression. figured it couldnt hurt.

the 200s had a broken string, i replaced it and got spark but no time to mess with it yet.

the week after i bought these i found two parts bikes which turned out to be 185s' which didnt have many useful on them but i bought them anyway because one had full bolt on suspension with some sort of gas charged motorcycle forks. i plan on bolting all that junk onto my 200s.

i bought these for my friends and girlfriend to play with when we go to the desert. i have a sandrail that only seats two and is scary to drive and ride in. now im in love with atc's. its been less than a month and i have 4!

thanks for the help guys. i know its a long post and ill try to get pics up this week.

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[barrett8]

the atc 90 probably has a 108cc or 125cc big bore piston if you replace your head gasket just measure the bore and you will know. great find!

[ridered86]

Sweet find. Not any answers for you, but I too would like to know why the Hi-Lo is missing off the 90! You may find yourself riding the trikes rather than the dune buggy once you get them going! :D

[thestud25]

Post some pics of the suspended 185 frame. Those are pretty sought after.

[barrett8]

the hi low is missing because with it gone you have a better choice for gearing on the front sprocket also it is less to go wrong and lighter. a normal 90 sprocket is 40 to 50 dollar with the hi low gone the sprocket you use cost 10-20 dollar Also when you build a bike like this you no longer need low.

[1984 honda 200s]

i have a 200e like that too, missing hi and lo selector. nice find for sure!

[mtk]

alright, got a chance to start up the 90 after cleaning the carb. works a little better but still stalls or backfires with even the slightest twist of the throttle. maybe i did a bad cleaning job? i hit it with break free and boiled it for an hour. ideas?

when i started to take photos my phone died. charging it now. pics up soon i promise.

thanks for the help so far, been doing tons of research. ive learned alot.
for the atc90 im thinking tube frame (any pref between bandito and joker?) and 200s suspension forks (already have them), then new gskets to stop the leak, replace bulb and tail lense, maybe paint or chrome....im getting obsessed with chrome.

the 200s is on the back burner. swingarm needs bushing or bearing. cant even tell what was there its worn but otherwise looks great.

[shortline10]

Looks like a vm24mm mikuni . clean both jets pilot and main and make sure their is a rubber O ring seal were the float bowl mates to the main jet tube .
The main jet is in the float bowl , remove that 10mm bolt and that's it .

[TrailerRider]

Can't wait for the suspension pics! Also back firing is a timing issue, normally. There are free manuals here on the site. http://www.3wheelerworld.com/showthread.php?56218-Get-your-trike-service-manuals-here!-Updated-9-13-07 Keep us posted :)

[Crash5291]

Also Syked to see the suspended 185 photos

[taz]

suspenson pics please

[ctbale]

pull off the points cover, check to see if your advancer is free, if its stuck, will run ok at idle but crappy upper/mid and wide open, set your points to .012" max, THEN with a light or meter get the points to break open at the F mark under your pull start, get a new plug too, NGK D8HA, valves to .002". before the carb is clean and set up, get some inline filters. I have a 2 stock 90 1978s they are slow has hell, fun to putt around on!!!!

[mtk]

Looks like a vm24mm mikuni . clean both jets pilot and main and make sure their is a rubber O ring seal were the float bowl mates to the main jet tube .
The main jet is in the float bowl , remove that 10mm bolt and that's it .

do you think a bad o ring could cause these problems? the o-ring was pretty nasty and cracked in a spot. figured it would work okay though. it idles high and backfires out the exhaust.


pull off the points cover, check to see if your advancer is free, if its stuck, will run ok at idle but crappy upper/mid and wide open, set your points to .012" max, THEN with a light or meter get the points to break open at the F mark under your pull start, get a new plug too, NGK D8HA, valves to .002". before the carb is clean and set up, get some inline filters. I have a 2 stock 90 1978s they are slow has hell, fun to putt around on!!!!

i dont think anything changed as far as timing since last time it was ridden. been sitting for two years after the spark plug stripped and p.o. lost interest. tossed in a heli-coil and new plug. started right up but cant throttle. p.o. said it was a wheelie machine and he was well over 300 pounds.


its dark but i grabbed some teaser shots. once i get it all pulled off and cleaned and remounted on the 200s ill take better shots. i guess the teasers will hold you off for a week or so. they got all mixed and im lazy. you can tell whats what. im stoked on the bapp manifold after doing research. those guys seemed rad, i want a bapp t-shirt!
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thanks guys.

damn those are some nasty pics....sorry

[shortline10]

That seal has to be a Perfect sealed fit or the main jet isnt working and will suck fuel from around the seal area .



do you think a bad o ring could cause these problems? the o-ring was pretty nasty and cracked in a spot. figured it would work okay though. it idles high and backfires out the exhaust.
theres no way the timing changed from last time it was ridden. been sitting for two years after the spark plug stripped and p.o. lost interest.

thanks guys.

[mtk]

I met up with "lardog" this weekend and got a tube frame and some great tips.
He's an awesome guy and helped diagnose my carb problem. After I replaced the o-ring the main jet was still clogged. I poked it with a wire yesterday and blasted around my yard.

The atc 90 is really peppy. It really wants to pull the front off the ground, looking forward to the longer frame.

I'm taking it out to pismo this weekend along with my sand rail. Anybody gonna be out there?

[Bretmd94]

I am pretty jealous of that full suspension for the 200s! Nice bikes, I have a 90 just like yours minus the goodies. Good find!

[mtk]

Yeah I'm stoked to have all this cool stuff laying around now. Bretmd94, did you make the us90 video in your sig? Its really cool. I watched it twice.