Modding my 85 200S

[Scootertrash]

Hey guys,
New to the site and first post. After cruising the site looking for tips on upgrading the engine in my 200S, This is the set up I have come up with:

Cam: late 70's early 80's XL cam

Carb: XR200 or 200X (Is there a difference? Which one should I hunt down?)

Piston: Wiseco 10.25:1

Cyl: Stock cylinder, looks like I can get by with just a deglaze/hone job.

Head: planning a valve lapping, don't think I need to regrind the seats. I'll do a port/polish on my own.

Exhaust: I already have a DG pipe, so I'll stick with that

Airbox: I have a lid I modified by drilling 2 large holes in the top.

So my questions are:
Which carb XR200 or 200X?

Should I bore it out a bit? Cylinder looks nice and I could get by with just a deglaze/hone job

Should I shave the head or deck the cylinder at all?

Any other tips would be welcomed!!
TIA
Scooter

P.S. I'm not a hard core mudder or hill climber, I just like pepping up my toys so I can make my friends wonder why I always leave em behind ;)

[ShaneNP123]

Get the XR carb, and a nice air filter and get it jetted correctly for the pipe, maybe go up one tooth on the front sprocket for a little extra speed.

[camoweasel]

I would not recommend saving the head. It can take away tension in the cam chain leading to reliability issues. A 10.25 piston is a safe way to increase compression.
You need to do a leak down test to determine whether or not, your valves need done. With the head off, squirt some soapy water or some brake parts cleaner onto the valves and then take an air compressor and shoot air as best as you can into the ports to determine if your valves need worked. If you see bubbles, you need a valve job. As for the port and polish job, are you going to be using a flow bench to determine if your head flows better?? Chances are if not, you could actually be making it flow worse by removing any metal.
Also anytime I take an engine apart to do a top end, I ALWAYS, bore the cylinder to ensure I have the highest amount of compression possible and that it will last the longest. Believe it or not, just because a bore looks "ok to hone" doesn't mean it's going to be ok. After time, cylinders can begin to wear into the shape of an oval and lose their true bore. You need really good tools to determine if your bore is true and not ovaled.
As far as the cam and carb go, the best cheap option is from a XR200, but a 200X is also an upgrade as well as compared to the a 200S.
In my opinion though, building up a 200S will not result in the performance your probably hoping for.

[edmonster]

My 200s is my favorite trike to ride. They definitely have some nut for what they are

[Scootertrash]

Thanks for the replies guys!! I've had this 200S for about 10 years now. It was given to me by a buddy who had let it sit for several years, so I had to get it running again.
I'm not looking to be able to burn rubber with it, I,m just looking to give her a little more pep.
I've been turnin wrenches for over 35 years now so I have a pretty good grasp on what is involved in a rebuilt and the various pitfalls of these endeavors. Just have never done one of these yet, that's partially why I'm doing it. I mainly do it for fun, or maybe to hit an occasional radar run just for kicks. I found this forum and researched old posts, just wanted to see if anyopne else had any other suggestions, and you guys did excellent.

I wanted a reliable build that wouldn't over power the clutch and it sounds like I have one. I'll let you guys know how it turns out!!

Oh, 1 more thing. camo: You think that .025 off of the head would really loosen the cam chain that much? I would think the cam chain adjuster would take up the slack. Seems to be quite a bit of room on that adjuster.

P.S.S.
There were a couple of guys on ATC 110's with some kind of 150 motor (looked like a stock motor to me, maybe just bored to the max?) One guy was doing low 50's on radar, the other guy was doin low 60's. Impressive!

[camoweasel]

In a reliabilty stand point, I would not mill the head. Jumping time on an ATC, is a common occurance that happens alot with these old motors. I have had two chains jump time and a chain actually snap. The chain that snapped wasn't more then a year old on an old 185.
If you go with a Wiseco 10.25 piston, that will be a safe an effective way to increase compression. Hell, I just did my 350x with a wiseco, and a kit off ebay can be had for around 100 bucks i'd bet.
With any more compression, as if you did decide to do the piston and head, you would be required to run fuel octanes well above the standards for pump gas. 10:1 is about as high for pump gas. Any higher and then I would start recommending either 100LL aviation fuel, or pump gas with mixed with tolune.

[edmonster]

I think you should be fine shaving the head as far as cam chain tension goes. it would cause the chain tensioner to bow even more than stock. So in theory it would only get tighter. At least thats what I'm thinking.