Honda Enginge Compatability

[KAD185s]

HI,
i have a 1981 honda atc 185s. i love the size of it and i like the amount of power it has but after i rode my dads 200m that extra little kick was great for pulling hills in road gear. i want to take the engine from a basic 200 and put it in the 185S frame so i have the power in a smaller package. my question is will it be a direct bolt for bolt swap or will i need to do some custom fabrications?
any input is much appreciated. thanks a bunch!!

[fabiodriven]

Your problem is not the engine because those two engines are almost exactly the same. I think one may have a slightly bigger bore, but it's such a small difference you would never feel it. The difference in power you are feeling is most likely either in the final drive gearing or your engine is tired. Yes, the 200 engine is a direct replacement, but unless you're replacing yours because it's tired you're wasting your time. The horsepower numbers are probably near identical when both engines are running correctly.

[KAD185s]

how do I know if my engine is getting tired? it does not smoke, when I first got it, it smoked pretty bad and I replaced the rings in it, I also did a carb kit, maybe my carb is not set properly? it runs good but does not idle on its own until its warmed up good.(ive always just marked it up to the fact that its a carbureted engine)

[fabiodriven]

If it's not smoking and runs good then you're probably OK in the engine department. You could make sure your valves are adjusted right but that's most likely going to effect how it runs if they're not. I don't know what to tell ya bud.

[placek59]

Check the sprockets of each and count the teeth. Maybe the 200 is geared slightly different?

[placek59]

After taking a quick look at the oscarmayer online manuals it appears they each have 13hp but the 200 (192cc) has 10.6 ft-lb of torque compared to the 185 (180cc) 9.26 ft-lbs so that's roughly 10% more torque... Don't know how that would translate to the "seat of the pants" feeling but there is a difference there. Don't know if a cam swap would help or is even feasible? Do each of them have the original carbs or is one a chinese replacement by chance?

[86125m]

no the cams between both motors are the same the only difference between the motors is the 12 cc. However do you know how your dads 200m motor is built as my 200m motor has a high compression piston and it has alot of kick.

[fabiodriven]

Check to make sure the throttle is opening all the way as well.

[Ghostv2]

If you would ask me, I would say the 185 would beat the 200m in a race. Pretty much identical motor in a smaller simpler package. 302lbs dry weight compared to 328lbs dry. Most 200m's I've had has had rear and even sometimes both racks on them. There's a few more pounds. Maybe it's just because I associate the 200m as kinda like a utility 200cc trike. Not quite a 200s, not quite a 82/83 big red either. But closer to the big red than anything. Just no dual range transmission and small little designs. It had the two piece fenders like the big red. More of the utility look, especially all dressed up with racks and the electric start. Maybe it's just how I look at it.

The 185 is a smaller, simpler machine with basically the same engine. No front suspension. Lighter weight. No frills. I would just expect it to get up and go quicker than a 200m. But like everyone else said, after 30 years and countless owners it could be for ANY number of reasons why the 200m feels like it has more power over the 185.

[barnett468]

You could also do a compression test with the gas off and throttle wide open on both of them.


PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

[350for350]

That could tell you a lot right there.

[MonroeMike]

Check the sprockets of each and count the teeth. Maybe the 200 is geared slightly different?

Stock sprockets

1981 185s 11/41

84-85 200m 11/47

Transmissions below
<- 185s 200m ->

[KAD185s]

wow, the amount of feedback is amazing. Thank you guys so much! I think what I am going to do is gear mine down. because my 185S has a higher top end then my dads. I would pass him once we both topped out. it has to be a difference in the final drive between the two. all the input is much appreciated!