1970 US90 project

[cirose]

Well i posted in another topic regarding info on a sprocket for a atc i just bought. after exchanging a bit of info the " atc 110 unknown year" trike that i bought turned out to be a 1970/71 US90 much to my surprise.

This is the first 90/110 ive ever seen in person and they are beyond rare around these parts. its a shame the bike was turned into someones beater! fibreglass fenders are very rough, bike is painted black.. only has 2 of the 3 balloon tires.. sprocket is broken and the dampers/holders are beat up. bearings in the rear end and forks are sloppy. has a home made seat with wooden base. fenders have no mounting brackets. looks to be BMX handle bars.. metal fender is still there in ok condition.

bike starts and runs.. could prob use a carb rebuild.. missing the air filter also. not sure what the front tire is off. looks to be a lawn mower or something lol

so with the very unlikelihood of finding balloon tires, tank, and fibreglass fenders/seat for a 70/71 US90 i have come to the conclusion that im going to do 110 parts on this bike to get it back in decent condition. i plan to keep this bike around for my children to use one day.
236751236750236752236753236754236755236756

it would be a great help if anyone could point me in the direction of what 110 parts will/wont fit on this us90 frame. above are the plastics i just bought for an 82 atc 110. i have no mounting brackets for them yet though. i am also in search of a seat and tank for an 82 atc 110, unless there are other years that would work with the 82 fenders?

Also this sprocket someone listed in the other thread for a 110 that deletes the dampers and stuff to make it a direct mount, wondering if this will work for the 1970 us 90? http://shop.pbisprockets.com/searchquick-submit.sc?keywords=3132

are all atc 90 parts pretty much interchangeable? because most sites have parts only listed 74-78 for the 90 for the atc 110 they are 79-80, 81-83 and 84-85

[Ghostv2]

The rear right tire is actually your front. The chevron style one is the rear.

[gimmeamidget]

The tank is correct just missing the "Honda" badges on the side. The fiberglass rear fender and all the seat parts have been repopped and can be bought online. The tire will be harder to locate but they do show up on eBay all the time. Many atc 90/110 parts work on the us90 also.

[cirose]

The tank is correct just missing the "Honda" badges on the side. The fiberglass rear fender and all the seat parts have been repopped and can be bought online. The tire will be harder to locate but they do show up on eBay all the time. Many atc 90/110 parts work on the us90 also.

I do have the original badges they were included with the biKe. Also, it was a lime green us90! What a damn shame it got neglected so bad. Im gonna try that sprocket listed above I think.. And I really wanna keep balloon tires on it! Even if it looks like a 110

[Ghostv2]

You can keep all the original parts on it. You can get everything you need to repair fiberglass even at Walmart. The tank you can strip, bondo out all the dents and re paint it. If it leaks you can seal the inside. Paint isn't permanent. No sense in spending money when you have useable parts right in front of you. Keep it original, keep the value.

[cirose]

You can keep all the original parts on it. You can get everything you need to repair fiberglass even at Walmart. The tank you can strip, bondo out all the dents and re paint it. If it leaks you can seal the inside. Paint isn't permanent. No sense in spending money when you have useable parts right in front of you. Keep it original, keep the value.

That is true although i have no experience with fibreglass repair and very limited body work experience im still going to keep the us90 fenders for a future repair project. The tank i might try and repair. It looks pretty similar to the 82 110 tank from what i can tell so might as well just re work mine.

Can someone post a pic of the fender and seat mounting hardware im gonna need for the 110 fenders?

[Ghostv2]

Fiberglass work is easy. All you need is fiberglass, resin, hardener, and something to prep the surface like an acetone. I do it at work every week repairing molds and all. YouTube has many tutorials for beginners.

I can get a pic of the mounts when I get home tonight.

[cirose]

Fiberglass work is easy. All you need is fiberglass, resin, hardener, and something to prep the surface like an acetone. I do it at work every week repairing molds and all. YouTube has many tutorials for beginners.

I can get a pic of the mounts when I get home tonight.

Cool thanks. Any idea what other atc's came with the same handle bars as the 90? Im looking for a set now. Will get more pics of the plastics too. I compression tested the bike yesterday and it showed 120psi hot and cold. Manual calls for 142-170... Wonder if my tester is inaccurate

[Ghostv2]

Pretty sure all the 90/110/125's were the same handlebars. If you want some period correct aftermarket handlebars there is a Helm & Son one on eBay. I have these bars on my pauter framed 110 racer.

https://www.ebay.com/itm/162243578835

[cirose]

so did the 90/110/125 have the support brace in the middle of the bars too? because im not a big fan of em. would the kill switch and handgrips on a 90/110/125 be the same also? just incase i come across a fully dressed set of bars. mine has the kill switch but its not in the best shape

[cirose]

hauled the carb out tonight to see if it was worth buying a rebuild kit for or if i should just get a chinese knock off the only real problems i see are that the round knob on the bottom is bent, and the float seems to be dented on one side, what would a rebuild kit come with? because the float is dented pretty bad some how.. let me know if you think this is rebuildable? ordered the solid mount rear sprocket yesterday also.
23683623683323683023683723683423683123683823683523 6832



this might sound dumb but how do i get the old sprocket off? the owners manual doesn't really go into detail on it..

also, im really starting to wonder if i should try and rework the fibreglass fenders... took a bit of brake cleaner to the tank, fenders and forks and seeing the black paint wash off and the original green paint coming back to life has me thinking if i wanna re do this bike as a red 82 style 110 or to try and make this back in to a 1970 green us90..

also i see a lot of bars on ebay that say they were taken off a atc 200 but fit a 90/110... were they many differences between the 90/110/125/185/200 bars? i tried a spare set of big red 250 bars tonight but they dont fit.. the grippy surface for the bar clamps are too wide on the 250es bars

[Hopper055]

I would see if the float leaks first. If it's fine I would give cleaning it a shot. I had bad luck with an atc 70 ebay carb once. I prefer to stay original if possible.

About the sprocket I have never worked on this old of an 90/110 but I believe your going to need to remove the axle. The heads of the bolts should face the carrier.

[cirose]

I would see if the float leaks first. If it's fine I would give cleaning it a shot. I had bad luck with an atc 70 ebay carb once. I prefer to stay original if possible.

About the sprocket I have never worked on this old of an 90/110 but I believe your going to need to remove the axle. The heads of the bolts should face the carrier.

wouldn't the carb kit come with a new float valve.. isn't that what makes a carb leak and not the actual float itself? the carb dont leak now but the bike is surging when idle, throttle response is off a bit too.. might of needed a bit of adjusting but im gonna try and check the timing first,then rebuild or replace the carb. how about that fuel screen thing, would the kit come with that? mines pretty rotten

[Ghostv2]

I'm not sure that other bars fit a 90/110. Like the 200 models, not sure.

As far as the rebuild kit, yes the come with the float needle, no they don't come with a fuel filter. I looked at it this way, I can spend $20 and get a brand new carb or I can spend $20 and rebuild a 30 year old carb that would need a sonic cleaning. I have had a Chinese carb on my 110 for about two years now with no problems. You will need to put the old jets back in, that's it. And I am using that Chinese carb on a hopped up 110 with motor performance mods with no issues. Keep the old carb as a backup if you wanna put it back to all original, you can always rebuild it at a later time or sell it. Because they did change carbs with the later 90's and they didn't have the altitude selector and all that so they are desirable.

I have a 90 style throttle with the built in killswitch and all of you need one. I also have 110 bars and all that good stuff if you are looking to buy some parts. I won't charge you what eBay charges either. Just let me know.

[cirose]

I'm not sure that other bars fit a 90/110. Like the 200 models, not sure.

As far as the rebuild kit, yes the come with the float needle, no they don't come with a fuel filter. I looked at it this way, I can spend $20 and get a brand new carb or I can spend $20 and rebuild a 30 year old carb that would need a sonic cleaning. I have had a Chinese carb on my 110 for about two years now with no problems. You will need to put the old jets back in, that's it. And I am using that Chinese carb on a hopped up 110 with motor performance mods with no issues. Keep the old carb as a backup if you wanna put it back to all original, you can always rebuild it at a later time or sell it. Because they did change carbs with the later 90's and they didn't have the altitude selector and all that so they are desirable.

I have a 90 style throttle with the built in killswitch and all of you need one. I also have 110 bars and all that good stuff if you are looking to buy some parts. I won't charge you what eBay charges either. Just let me know.


wish i knew you had stuff for sale... inboxed you my email address!

[cirose]

anyone know what model this carb is? http://dratv.com/19ctcafik21.html

i've been searching high and low for it on ebay but cant seem to find an exact match. being from canada it would help if i could find one here vs getting it from the us and paying double! from what i can tell it looks to be a keihin pz19 variation of some sort. possibly from a 50-110cc chinese quad with a 35mm filter on it. hard to tell because it appears they have the brand name grinded off in the display pictures.

if not this one then can someone point me to an oem style replacement for an atc90? most i want to modify is putting my oem jets in it.

thanks again - Cory

[Big G]

I have a whole whack of ATC 90 parts. Let me know if there's anything you're still looking for. I'm in Canada too so shipping may be reasonable. I'll PM you my email address.

[vintagemotorsports]

if you guys are looking for anything US90 related shoot me an email with a list of what you need we have the largest inventory of US90 parts probably on the planet . i have been restoring these bikes for over 20 years mike@vintagemotorsports.net

our site www.vintagemotorsports.net

[cirose]

Thought i'd give an update.. so far I have the 82 110 fenders but I am still in search of a seat. Literally none have showed up on ebay or locally since I bought the bike. At this point I suppose you could say it's going to be an ATC 90/110 looking build with balloon tires. I don't think she will ever be a museum quality piece I just want it for a conversation piece mostly.. something to look at in the garage or keep for my kid if I have any.

I bought an ebay carb and got the firestone replacement tire, solid rear sprocket and had the bike out for a little test run. these things haul ass! I thought to myself hmm... not too bad I suppose for a 90.. looked down and it was in low range. I bet these bikes will do close to 40 mph! I was too nervous to take it past 3rd gear on my street in the snow haha.

- Another thing i've noticed is the Firestone replacement tire its noticeably smaller then the ohtsu balloon tire... so I guess i will be looking for another rear Firestone or putting it on the front for now. anyone have any leads on one?

- Gas tank has been in the garage with apple cidar vinegar for a couple of weeks now. still showing rust though. gonna try fresh stuff again soon and hopefully get it clean some time this winter.

- Chinese carb came in and I didn't notice the choke was on the wrong side when I bought it.. it wouldnt fit on the bike without hitting the frame so I ended up grinding the choke lever handle off and I have it modified with a paper clip to open and close the lever....