Xr200 head on atc 200x

[plevib]

I just got a screaming deal! 82 xr200 top end ( head with valves and spings, cam, rocker box and rocker arms) all in decent shape for $50. I mostly bought it for the xr cam for my atc 200x. But I've heard somewhere that the xr head has bigger ports? Is that true?
What do you guys think? Use the whole xr top end or just the cam and stick with the 200x top end?

[plevib]

One other advantage of the xr head is that it has a decompression assembly. I know the 200x motor doesn't have a kick actuated decompresor, but I could use a manual lever. Could help to keep my very well functioning kick starter in that condition

[YTZ drew]

The 200X cylinder has larger fins than any other jug of that engine family, so that's the jug to keep if it's in good shape. The XR head MAY have bigger ports, but I don't know for sure. I know for certain that XR and XL185 heads have the same valves and ports as a 200X, but I've never had an XR200 head on the bench to measure.

And I like your decomp idea! I'm planning to hook one up to my 200X (running an XL185 head and jug w/ XR piston), just haven't found an off the shelf cable that works yet. Probably will have to make my own.

[plevib]

Thanks, yeah I had heard the atc jug had bigger fins, and last time I was in that engine it was in perfect shape. Factory bore and it still had the original hash marks! (Although there is a guy on ebay selling 223cm3 kits for honda 200 motors so that's tempting haha) but I'll probably stick with that jug and and 10.25:1 piston. I forgot to mention that the deal comes with a xr intake as well, so if that fits I'll use that and an xr carb too. But when the head comes in I'll take some pictures and measurements and post them here so we'll all know for sure!

And with your cable dilemma, would the assembly off of a xl600 work? That's what I've been thinking about using on mine

[oscarmayer]

valves and such are the same. porting is the same. there really will not be any advantage over the decom lever (which the 200s,e,es,200 and 185s all have) the came is a very slight bump and not enough to honestly tell. piston is a slightly higher comp than the 200x, but I always went with Wiseco to a good solid piston with known compression.

it will work fine and will feel like your 200x. I am not 100% certain other "fin" sizes as I think that needs to be measured before that keeps being put out there. DOHC made those statements but no evidence was ever posted to support it. (Does someone have a 200x head they can measure the fin sizes? I have a 200s head I can measure) All in all I do not expect you to find any advantage of the xr200 head over the 200x other than the decom lever.

sorry so garbled. trying to pass info while in a meeting so it may be short and garbled.

[YTZ drew]

I can take pictures for you of a 200x jug next to a plain 185/200 one, the difference is about a half inch all around. The heads do not have different fins.

[arlaunch]

Slightly to way off topic.

This link is an interesting read into 200x performance upgrades.

I like the part about not spending an arm and a leg.

http://atvconnection.com/forums/atc-3-wheelers/192536-help-rebuilding-motor-85-atc-200x.html

[oscarmayer]

^ that is a cheap way, but mind you, none of that aside from the piston will help give you much of a performance hit. to gain what you need, you need to get a web cam, springs, retainers, hardened rockers, and valves. Have the head "professionally" ported by someone who actually knows something about them if you try to do any more than 1" of port matching you will screw up the flow and make it run worse than factory.
good head pipe such as a complete supertrap system will do wonders for you. the crappy DG stuff is just that. crappy....
carbs, the xr200 carb is a 26mm carb. if your doing a ton of work, move to a 28mm mikuni. they cab be had new off eBay for $80 shipped. they order a jet kit with it for idle and mains and your set.
doing things the right way for your needs means a lot more stable and solid when running. yes you can build it so much that it brakes a lot, but what is the point? if your trail riding then xr200 parts are fine. if your racing, you need real upgrades. nothing substitutes real quality designed for that need.
I think the OP was wanting a trail rider. a mikuni 26mm carb is fine and in the end cheaper. no purchasing the carb, then a rebuild kit, and finally jet kits. in the end costs will be the same but the slide could be worn and that means a new carb anyway.
good luck with your choices.
yes running thinner walls will cause weakness on the cylinders, but unless your running the max bore and not properly maintaining the engine while racing, chances of it cracking are slim.

[plevib]

Thanks for all the advice guys. Good stuff. With this build cheap is the name of the game. I will likely be racing this machine some this summer (depending on how my 500x build pans out on a track http://www.3wheelerworld.com/showthread.php/177712-1984-ATC500X-Project!!!-(1984-ATC250R-XL500R-engine-conversion) ) but three wheeler races are just barely starting to come back around here (north dakota). The last race I went to I ran a 185 against a handful of other 185's and 250sx's. (There was a two stroke class that had some serious rigs) So I figure a little work on this engine and she'll wipe the floor in the four stroke class. I'll start a thread later tonight with pictures on it. I've already done the resurrection work (new chain, new wheel bearings and axle bearings, rebuilt forks, new rear plastic and seat foam and cover). I visited TW and hooked me up with an rusty dg pipe that's way bigger than stock that I'm gonna clean up, as well as a 200x bottom end (mine blew a bearing the day before the race :( ). So I'll go with a 225 cylinder kit (dirt cheap on ebay) and/or a wiseco. I may use the stock carb, I haven't decided yet.

[greenhuman]

You will find the 223 cylinder will be 8mm longer than the stock 185/200x cylinder. Its the same length as a CRF230F cylinder.

[plevib]

http://m.ebay.com/itm/Cylinder-Kit-223CM3-250cc-for-Honda-ATC-200-XL200-Piston-65-5mm-Bore-Rings-Pin-/191596279700?nav=SEARCH

This says it fits atc 200's? I don't know what a valid height is but it does say something about that in the description. Translation please? Haha. ...

[oscarmayer]

^ and you trust ebay for this info? I can tell you countless stories of mis-informed info. the other day we got a 86 200x rear shock for cheap because the person thought it was a 84. so, yea don't trust ebay. trust the guys here who know.

[DohcBikes]

Holy smokes.

The ebay cylinder is for a 230f. I've been over this before.

The fins on a 200x head are larger. Anyone that has owned and worked on these engines knows that. Drew made it clear.

XR200 pistons are not higher compression in an ATC engine. The compression height is lower which makes them a terrible choice for an ATC engine. Argue if you'd like, I have all the pistons here in my motorcycle and ATV repair shop.

What is it that you want? More air? Get an oversized intake valve and have the job done on a SERDI.

[86125m]

Yea do not trust ebay. I can't tell you how many times we have gotten something dirt cheap from ebay because the person did not know what they had. Like an nos fender for 20 dollars or an nos headlight bucket for 10 dollars and the list goes on and on.

[plevib]

Here is the new thread on this build. With pictures! :D

http://www.3wheelerworld.com/showthread.php/179584-1985-Atc-200x-Rebirth-of-childhood-machine