Sudco manifold and Mikuni carb

[crackshot]

I won a bid on a Sudco maifold and Mikuni carb. I came in today.
I do not know what size it is. I measure intake I.D. and is 24mm.
Also, anyone have one of these manifolds? Seems like when its mounted that the carb sticks out to the side a litte more than stock carb that hugs the frame.

[deathman53]

that looks alot like what is used on honda 50's

[WIkid500]

that looks alot like what is used on honda 50's

thats what I was thinking, or a trail 80 mini bike!

[crackshot]

It seems to be a bigger carb than the one on my daughters 110 and looks like the carb will bolt up to stock manifold. I will give it a try.
Her carb is shot and the poor kid wants to ride!

[Vealmonkey]

crackshot, you picked up an aftermarket intake and 24mm mikuni for a modified atc90\110. The carb does stick out farther to the side than a stock manifold so a larger carb can be used to flow more fuel and air. The intake manifold is larger than a stock 110. To get the full use of that intake, you would have to match the intake port on your head to the size of the port on the intake, you would have to use a die grinder or dremel tool. Go slowly in doing this is you try. You also have to enlarge the insulator gasket and the intake gaskets that you use. If you are not using a big bore piston and cam on a honda atc90\110, that manifold and carb will drown out a stock 110. You would have to rejet it down but you would lose alot of your bottom end of the 110. Those intakes were mostly used on 110s' that people held the throttle open alot, like racing or the dunes, they are not very good for tight trails. Good score. I was watching that auction myself but I ended up getting called out to help a buddy of mine who had broken down and didn't bid. If you can't use the manifold and carb combo, I would gladly buy it off you. Hopefully you have something nice to use it on. There was an article in a 1981 3 wheeling comparing intakes and the sudco finished#2, the PK Racing finished #1 as far as air flow numbers were concerned. About the biggest carb you can use on those is a 26mm. And you better be pushing about
180ccs' and head ported and cammed to the max for the 26mm. Great score.

[crackshot]

Thanks monkey for the info. My daughters engine is stock but having a hell of a time finding a stock carb so that is why I am going to this mikuni.

[Howdy]

I probably have a good carb for you. I am also interested in the one you just got. I have a modified motor here that needs more intake.
Howdy

[ParrotGreenUS90]

I was looking around one day on the forums and found a 134cc kit for the ATC 90. I have a ATC 90 engine with 110 bore, a clutch and everything to make it oil cooled. This engine I saw was identical to the one I have except it was a semi auto transmission. Any idea where it is on the forums, I would like to read about it some more and find where I can get a 134cc big bore. I plan on building a rocket of a US90. Does anyone know where I can find a clutch kit also, I have found kits for the 70's but nothing for the 90's.

[Vealmonkey]

Isn't your 90 auto shift? If you want to build a rocket, find yourself a cl90 or sl90 engine to start with. That way you get a kickstarter and a clutch and better plates and discs that will hold more power alot better than an auto shift. And if your in the rocket business, bore and stroke is the way to go. If you get yourself the sl90 cases, it will already have a better cam in it than the stock atc90 cam and it was pretty much the first hi performance cam for the atc90. You can pick up much larger cams from webcam or from powroll. Powroll will also sell you a nice little bore and stroke set up for the atc90 or the sl90 which uses pretty much the same cylinder and head set up. With a big bore and stroke 90 you want to relieve head and engine case pressures that come with a high revving 90, so you will want to vent them by installing a vent in your top cam adjustment cover and some type of vent on the engine cases. An extended dipstick vent is the best bet if you can find one or you will have to vent your engine case some other way, most likely by drilling and tapping and installing a vent. A bigger carb and an aftermarket intake are a must. Head work would be advised on a large bore and stroke engine. I know there is a guy in California that I have some info on, just don't have his name and address handy right now. With the cl90 of sl90 engine cases, you get rid of the hi/lo gearbox too, which is very nice. Then you can use convential front and rear sprockets and not worry about that power robbing hi maintenance hi/ lo gearbox assembly, a chronic weak point for a hi performance atc90. You'll probably need to score a nice aftermarket frame that is a little longer which helps handling and is way sturdier and safer than a stock frame. You will be tieing up some money in this adventure though and some time too. Building one of these old dinosaurs doesn't come cheap. They are a labor of love. If you are a glutton for punishment and have a good deal of spare cash, have fun. If money is a little tight, buy yourself a nice 200x. It was be about as fast as the tricked out 90 and have suspension and disc brakes. Whatever you decide have fun. Tricked out 90s were quite a little project when the parts were readily available, now they are true labors of love that will take you a fair amount of time to source the parts and have all the work done. Most of the people that did this kind of machine work are long out of the business, so just finding someone that will do your mods is a chore in itself. Do lots of research, you will be doing alot of the work yourself. And the real rocket atc90s, used high compression cb750 pistons with a ton of hand work and modding. So just imagine on cb750 piston where your stock 90 piston is now and that should give you some idea of what has to be done. Have fun.

[ParrotGreenUS90]

I already have a motor with all the goodies except a 134cc big bore. I got the motor expecting to have just a manual clutch. I got it and discovered that yes it has an oil cooler system. I got it from a guy out west, maybe we are thinking of the same person. I have the motor mouunted to a US90 that I put away early in the summer. It moved great, just tough to get used to when riding and flipping between trikes. It has the extented dip stick and vent, I had the hole covered thinking it was for routing oil around when I did not have a cooler yet, now I know what its for. I have a monster carb and intake that came with it, it makes a stock 90 carb look tiny. I will get it set up 100 percent this winter and take it out and ride it like it was meant to be. It would be nice to build a motor up, I like the CB750 idea now to find a motor that I don't have to worry about.

[Vealmonkey]

We need to see some pics.

[ParrotGreenUS90]

I have an identical carb along with a PK intake. What throttle cable should I use for it. It will be mounted to a heavily modified atc 90 motor. I see this is an old post but I have been looking high and low for any information on this combination.
Thanks

[Vealmonkey]

The stock cable should fit unless you have an aftermarket frame. If it is an aftermarket frame, then you are looking to atleast need a +3" cable is pretty much the norm. You could get them over the counter at one time quite easily, nowadays it's quite an uncommon find to run across one. You might end up having to use a throttle cable off another trike and solder the atc90 end piece onto the other cable. You need to do some measuring and some investigating. Also, unless your running a bigger piston and carb, this kind of setup won't run very well on a 110 or an overbored 90.

[ParrotGreenUS90]

I tried this out today with the cable from my 1972 US90. My cable is longer than I need, I am able to move the slide about a quarter od the way. I do have an adjuster on the top of the carb and when I adjust it up I am able to get the slide to move halfway up. Am I suppose to have a different top for the cable to set in or do I need to find a different cable. I do see little about these carbs being mounted on atc 90's but alot of atc 110 have this carb. I read above in this post that it was being planned to be used on a 110 but that is about as far as the post got.
My motor has been modified, I have a manual clutch conversion, BAPP oil cooler minus an oil cooler, vented head, and this PK intake with Mikuni Carb. I am not sure what size the engine is, I bought it from a guy who built it years ago. I was told it was running with this carb and then put away once ATC racing was over.

[ParrotGreenUS90]

Here are the pictures of the carb.