XR200 camshaft just arrived! (ATC200s)

[Studytime]

The nice postlady just dropped off my XR200 cam. This will be used as an upgrade for my 1984 ATC200s.

It'll still be a while (few weeks) before I can have it installed and be riding again, but I'm excited nonetheless.

I'll keep everyone posted. I'll be adding the cam and cylinder head port work while it is apart.

Really the bike has no other mods to speak of (besides a K&N). It has stock compression and the stock exhaust.

EDIT:: Also, wanted to add these two links; in the first one the 200s is quoted as making 13.8hp (http://forums.atvconnection.com/mess...did/385182.cfm); whereas, in this one (http://www-staff.lboro.ac.uk/~elvpc/papers/XR200.html) the XR200 is supposedly making 20hp @ 9K RPM. That's a big differene for a 278lb bike! Other differences include exhaust, larger carburetor, & more compression.

Studytime

[atczack]

Yeah man, keep us posted. I never thought of an xr200 cam. How doe's it differ from a "big Al's" cam or another after market comany's cam. Does it have more lift or longer duration or anything like that to make you decide on it instead of another type?

[Studytime]

Yeah man, keep us posted. I never thought of an xr200 cam. How does it differ from a "big Al's" cam or another after market comany's cam. Does it have more lift or longer duration or anything like that to make you decide on it instead of another type?

Well, I perfer not to get into a long discussion about lift, duration, lobe seperation angle, ramp rates, or intake centerlines, BUT

yes, it does have more more lift and duration than the stock cam has. The XR cam is also hotter than the 200x camshaft.

With that being said, the majority of the aftermarket cams are probably more powerful grinds even still. Honda went for more power but also reliability so you won't find super aggressive ramp rates on a 20+ year old cam grind.

Why did I decide to go with this grind? Because it's more powerful than stock, but doesn't require other modifications such as hardened rockers as some grinds may require these. Also my low, 7.8:1 static compression would not team up good with a much longer duration intake lobe.

Lastly, the XR cams can be had for cheap if bought used, and can be purchased for $60 from service honda. When your cam comes in, just be sure to spec it and make sure its not burnt if you're buying second hand.

On last point is that the XR's max power occurs at 9000 RPM. I don't know the exact speed of the 200s's peak power, but it's probably ~3000 RPM less than that. To stand up to these higher RPM the XR uses stiffer valve springs.

I will also be clearancing my retainers for the new cam's additional lift. Don't worry, I'll report back.

Studytime

[cliff2302]

My one buddy puts XR cams in all his 200x's and they really waxke up those motors. You can also get an XR head because the ports are larger and so are the valves and an XR carb (bigger). He also uses XR bottom ends with a 200x forward kick start because they are 6 speed trannys but they bolt right in a 200x frame. Just some ideas for you guys. Your 200s is gonna be scary to ride with all that new power and no suspension. lol

[atczack]

Cool man, thank's for the tip's. If I ever blow one of my 200x motor's I will do all that stuff for sure!

[thefox]

My one buddy puts XR cams in all his 200x's and they really waxke up those motors. You can also get an XR head because the ports are larger and so are the valves and an XR carb (bigger). He also uses XR bottom ends with a 200x forward kick start because they are 6 speed trannys but they bolt right in a 200x frame. Just some ideas for you guys. Your 200s is gonna be scary to ride with all that new power and no suspension. lol

The valves are actually the same size for both the XR and the X. I would think the ports are the same but I have heard that the 200x has a better port design but knowone seems to know for sure. The XR is suposed to have slightly stronger valve springs though.

[Studytime]

Well, the cam is getting closer. I decided to put it now and port the head later. I learned that the cam could be installed without having to remove the head so I'm working on doing just that now.

So far, the XR cam in comparison to the 200s (which is the same as the 185s cam) is visibly taller and broader.

If anyone is interested you can still buy these cams for the 185/200 cc Hondas from service honda for just under $60 plush shipping.

See this thread as I ran into a hiccup;
http://www.3wheelerworldforums.com/s...ad.php?t=28701

Studytime

[kowboy]

Thanks for the post guys This is what I will to to my 200e big red fat ass conversion(http://www.3wheelerworld.com/showthr...HE-Fat-Ass))My build thread Check it out.http://www.3wheelerworld.com/attachm...6&d=1398046597