1985 ACT 110 Engien rebuild/performance mods

[george.361]

Hi everyone, new to the forum, what a wealth of knowledge this place appears to be. I have a 1985 Honda ACT 110 and am getting ready to do an engine rebuild. I figure I might as well go all the way and am looking for a big bore piston/stroker, high compression piston anything to beef er up. I would also love to hear of any other performance mods that would be worth while. Also Does anyone know the gear ratios for these things, I have been looking everywhere for them. I downloaded a manual and it doesn’t have gear ratios. Has anyone seen improvements with different gear ratios/crank and finial drive sprockets. I have heard people through the idea of using a 125 piston but have no conformation if this is possible. Any ideas?

[Vealmonkey]

I hart to burst your bubble, but here is the reality of the situation. After the atc90 hit the market, and that was all there was, many people came up with high performance parts for those trikes. Big bore, stroker, cams, frames, plastic and sheet metal, the list was pretty extensive. Then honda started making the 110, which is a little different engine-wise, but enough that some parts would work with the 110 and some didn't. Well, right after that, Honda came out with the 185 and right after that, the 250r. Well, then there wasn't as much need for the atc90/110 parts that people were making and it sort of spelled the demise of the earlier aftermarket parts for the atc90/110 since you could just go out and buy a larger displacement trike. There were a couple of suspension frames, but the writing was on the wall.
Now when it comes to the last generation 110 with cdi box, not much at all. I hate to tell you about all you will find is maybe a 124cc piston that may or may not be a high compression piston, an exhaust, a cam-but not real radical since radical cams don't work well with the cdi ignitions and if you're lucky, you can find a bigger intake and carb and that's about it. You can change the rear chain sprocket easy enough and I really wouldn't mess with the front since they have that ignorant hi/lo gearbox set-up with that intermediate gear. Somepeople change those front sprockets out and never quite get those hi/lo gearbox assemblys right again. The stamped steel frames aren't that sturdy anymore being that they are over 20 plus years old and some have been very mistreated. Hardtail suspension has not helped with the stamped steel construction either. My best advice would be to just by a larger engined trike! The honda 125m pistons won't fit the 110, not without machining the engine cases anyway. If you want to build a 90 engine, there are alot more things that you can do to the engine since there were just alot more parts available. You can mod the early 110 engines with the points ignition pretty much the same as the atc90 engine, but not many options for the later cdi engines. You can even change engine cases on the early atc90/110 engines and have kick-start and manual clutch and do away with the hi/lo transmission, which is really the hot ticket if you are at all serious about any power since the semi-auto clutches don't like lots of extra power applied to them. An aftermarket frame is a must for more power or at least highly recommended. Seeing a stock frame break while someone is riding it is very scary and bad for the rider to say the least. Some people look a long time to find the right combo of parts to build a stroker,big bore 90 and some never find the parts and have to make them. It's not a strictly bolt on and go affair either. Some of the speed secrets have not been used in over 25 years and have almost disappeared. The parts are getting near impossible to find. People like me have been hoarding parts when they find them! LOL And unless you just like being a dinosaur, the trike you just built will be outrun by a mildly modded 200x with better brakes and better suspension factory stock! So, if you still want to mod your 85 110, there are a couple things you can do, but don't expect much. If you have to mod a 110, there are alot better ways to go, but they will cost you and take time. If you just want to go fast, cheaply, get yourself a bigger trike. I've modded atc90/110 trikes and I know what's involved. I'm modding one right now, and I'm waiting for a particular part. And all it takes to hold up a build is one part. I'm not trying to discourage you, just presenting the facts. I will be happy to try and answer any other questions you might have either way you decide to go. I know I personally enjoy my dinosaurs and I have some crazy machines. I've helped several people with parts and advice. When I was first involved with trikes, there was only the atc90, so they hold a special place in my heart. I remember when racing was only modded atc90's. And it wasn't near as big around where I grew up as on the West Coast.. Trikes raced at the local county fairs. Whatever you decide to do though, have fun and I will help you however I can.

[george.361]

That is what I was afraid I would find out, thanks for the information. Do you know of anyone reworking the transmission to get better top speed? I know I can get/machine a smaller finial drive sprocket and that would help. Do you know the gear ratios on the atc 110, I would like to crunch some numbers and see if I can't come up with anything. I was not planning on using the factory frame and am defiantly not going to be using it after your words of advice. I would enjoy seeing/reading about what you have done to your atcs. Your right that upgrading to a bigger engine would ideally be the way to go but that takes all the fun out. I am not sure if you would be interested but, I have some extra parts left over from my parts bike if you would be interested in anything let me know.

[mgenest]

I have the same bike and perfromed the following upgrades:

Cam = $25
Cobra exhaust = $110
24mm carb = $45

Took me 2 hrs to put all of them on the bike. The cam made the biggest difference. It only took me 10 minutes to put it in and I am an idiot.

All parts were purchased here:

www.dratv.com

As far as performance gains over stock, it is a night and day difference.

[george.361]

Did you go with the 90 cc performance cam. This fit on a 110 atc?

[mgenest]

Yes I did. it fit perfect and made a huge difference on the low end and mid range.

[Vealmonkey]

Well, my atc90 has a stroker crank and conn rod, a modded cb750 piston, sleeved cylinder, bored out spigot on the cases and the lower part of the cylinder is relieved to clear the stroker crank. I have a set of cl90 and sl90 cases so I can switch over and get the kick start and manual clutch. I have a vented/extended dipstick. I vented my rocker box to relieve excess pressure in the head. I have a side cover drilled and tapped to take an oil cooler. I have a head that has a larger intake vavle and is matched ported and polished for a larger intake for the carb and ported and polished exhaust. I have a larger intake and carb. I have several different aftermarket exhaust to choose from and none are a cobra, thank goodness. If you looked at the outside of my atc90 engine, it doesn't look any different than a stocker except that if you look at the head really close, you can see the shiny sleeve in between some of the fins and as soon as I high temperature paint the cylinder, you won't even notice that. You will notice the vented dipstick and the vent on the rocker box cover but that is about it. The other lower ends I have, once they are machined out for the larger spigot, will have the kickstart and manual clutch side covers and they won't have the hi/lo gearbox, but the average person won't really notice those differences either. The frames I have are another story. The frame I have the stroker in was made from flat sheets of aluminum except for the neck. It is a very old aftermarket frame made in the 70's. Sadly it is the version that uses an atc90 fuel tank. The other racing version had the fuel tank built into the frame and looked really wild.

[mgenest]

We need a pic if this bike... That is a lot of custom work. I am interesrted in the frame.

BTW - I am now the owner of edog's GPX177...

[Vealmonkey]

For some reason the site won't let me repost the pics it seems. Yeah, it's alot of work and some of it was done by someone else and I learned from what they did and did some more of it on my own by talking to a couple people and reading in some of the old magazines. Very time consuming. Not to mention the parts are harder than ever to find. If you do a search, you will find pics of this frame in 2 different posts. The newer post shows my rebel flag painted tank and my chromoly/nickel plated front forks with the double axle positions on it. I haven't seen another frame like that since the 1980's. If you knew someone that was a major fabricator and tig welder, you could probably duplicte the frame. There really is only one bent piece of aluminum on the whole trike, the rest is just flat sheets except for the neck! Insanely light. If I wanted it any lighter I have to fab a front axle and do something about the rear drum brake, maybe drill it out and then the heaviest piece is the axle. That would be pretty costly to remake in something lighter. I think aluminum would twist too easy, but I'm not sure of the strengths of all the different grades of alunminum. Maybe aluminum for the dunes. I can't imagine what it would take to get done in chromoly or titanium. I have a trike that has a hollow axle though and that could be an idea, chromoly pipe I believe. I mean how crazy does one want to get and make it rideable. The thing is almost a hand grenad in a frame anyway. Then you have differnt fuels you can run depending on your level of insanity.