Wiseco 12to 1 piston for 200s?

[207wheelin]

I am gathering parts for my next project. It's an 85 200s that has a smoking problem. It doesnt smoke that bad but riding behind it on the trail is no fun. The engine is also a little hard to start in the extreme cold.

I want to freshen this engine up with a fresh top end. I plan on taking a cylinder in and having it bored to clean it up and adding a high compression piston. Wiseco offers a 10 to 1 or a 12 to 1. I've used the 10 to 1 before with excellent results.

I was considering trying a 12 to 1 pisto on this project. My question is will it work on a trail machine? Can it be made to work? I have an XR200 cam to go with it and plan on adding a DG pipe and muffler. Also plan on rejetting.
I run 93 octane Ethanol free fuel in my ATC's. Would this be a good fuel for 12 to 1 compression?
Any advice appreciated
Be well everyone
207

[shortline10]

Their rough on the recoil and you will need to run 100+ octane .
If running a stock carburetor you’ll need at least a 112 main jet .
The plus is you will feel the power increase over the 10.25 wiseco with the 12:1 .

[ATC200X4716]

100 octane or use sunoco 94 if you can get it mixed with 100 octane or higher. I've had good luck mixing 94 50/50 with race fuel. It will just run better the higher the octane. Being air cooled if you run low octane it will actually run hotter and be more prone to detonation. It will be more crisp, but without a cam change it won't be vastly different but it will still feel a bit better.

[ATC King]

If you've got 93E0 available, you're better off that many.

If you don't have a Sunoco station nearby for anything higher, there's always the airports that will sell avgas. I think just about any of the 100+ ocatne fuels will have lead though. Maybe the local airport has 100LL. The lead would mean more frequent spark plug changes and it'd be a good idea to increase oil change frequency too.

The only off the shelf octane booster I know of that actually works is Lucas.
https://lucasoil.com/products/fuel-treatments/lucas-octane-booster
https://lucasoil.com/media/k2/galleries/348/10026_OctaneBooster_800x950.jpg

Many WalMarts carry it. It was off the shelves here for a while, but it's back. Not for two cycle use and it contains Methylcyclopentadienyl Manganese Tricarbonyl (MMT) as the octane booster, if you want to look that up.

[207wheelin]

As much as I crave MORE POWER!! I dont want to overcomplicate such a great machine. I'm just gonna go with the 10:1 piston and XR200 cam. I'm in the process of ordering parts and preparing to teardown the machine. Probably going to take it to the carwash today for a good cleaning.
Thanks for your advice guys! I'll take some pics as I go.
Take care and be well
207

[Scootertrash]

As much as I crave MORE POWER!! I dont want to overcomplicate such a great machine. I'm just gonna go with the 10:1 piston and XR200 cam. I'm in the process of ordering parts and preparing to teardown the machine. Probably going to take it to the carwash today for a good cleaning.
Thanks for your advice guys! I'll take some pics as I go.
Take care and be well
207

The above is what I did to my '84 200S, with the addition of an XR200 carb and a SuperTrapp exhaust. None of my neighbors or friends 185's or 200's could keep up. I got something like 55 mph out of it on the flat straight away in front of my house using GPS and my chin on the handlebars..:lol:

It's been sitting under the deck for 2 years, I'm currently working to get the garage clean so I can bring it in, clean the carb and fire it back up.....

[207wheelin]

The above is what I did to my '84 200S, with the addition of an XR200 carb and a SuperTrapp exhaust. None of my neighbors or friends 185's or 200's could keep up. I got something like 55 mph out of it on the flat straight away in front of my house using GPS and my chin on the handlebars..:lol:

It's been sitting under the deck for 2 years, I'm currently working to get the garage clean so I can bring it in, clean the carb and fire it back up.....

Good luck with your S.. I'm cleaning the shop out and getting ready for the teardown. While I'm waiting on parts I plan on cleaning and painting the frame, skidplate, and chain housing.
I picked up an x cylinder and Shindy piston, an XR200 cam, and new clutches. The clutch on this machine was just starting to slip in high gear and in my limited experience adding more power will just finish it in short order.
Take care
207

[207wheelin]

So between massive snowstorms and the breakage and repair of snow removal equipment I found time to tear down the 200s. This was sold to me as a low hours rig that was stored for many years.

Tearing it down it was apparent that the seller was honest about its condition.
The inside of the combustion chamber was fairly clean with a little oil residue from leaking valve seals. The shift clutch is worn and I'm not surprised as it would slip a little in the higher gears under hard acceleration. Also the springs were quite compressed.
My 200x cylinder I got from ebay wasn't what it was supposed to be so I sent it back. Having my cylinder checked at the machine shop turned out to be a money saver. They said it was within spec and to give it a quick hone and I'd be fine.
I ordered a Wiseco piston,XR200 cam, full gasket set, Barnett clutch kit, and a carb kit. I plan on replacing the valve seals and getting this machine back together in a couple weeks. I will need it to pull a small trailer tank for collecting sap to make maple syrup once the snow has melted. We also use the wheelers when our driveway gets soft during mud season.

Once this machine is finished I have a few other ATC projects planned.
Take care
207

[350for350]

Be sure to post some pictures and tell us how it goes. The reassembly, the test riding, and even the work.

[207wheelin]

Still waiting on parts. Got my gaskets all scraped off. Did get my Barnett clutch kit yesterday. Installed it after a 24hr oil soak.
After watching a Mr. C video I went and ordered a stainless exhaust system from Amazon. Once the engine is installed I will work on modifying it to fit this application. I got new valves and lapped them in but need my gasket kit to continue. Parts are cleaned and waiting.

Couple pics coming up!

[207wheelin]

It was always easy for me to post pics here. Now they wont load. Any shortcuts to posting pics!

[207wheelin]

Today I reinstalled the engine and started to put this machine back together. My muffler was a little rusty but with a few good taps it became apparent that it would need a patch. I decided to go with a complete stainless exhaust. I saw this exhaust on MrC's YouTube channel. He made it fit on his XE so I figured I could make it work on this ATC200S. With some dimples, a couple cuts, and one weld I made it happen. I'm anxious to see how it sounds! My Daughters S is almost the same engine build and it sounds sweet with a DG exhaust. Another day of tinkering and this rig should be ready for break in and a test romp! Still having issues with pics. But I'll figure it out!
Take care
207

[knappyfeet]

It was always easy for me to post pics here. Now they wont load. Any shortcuts to posting pics!

Try the tapatalk app.

I couldn't load pictures as well for awhile and didn't know why.... on this site....now it works.

I can't wait to see the pics. I want to see somebody else knee deep in gunk like me!

[BarnBoy]

It was always easy for me to post pics here. Now they wont load. Any shortcuts to posting pics!

Yeah its been a royal PITA lately. Only way I can load them is by taking a screenshot of the photo on my phone, and then it will allow me to attach the screenshot. I guess my photos must be too high resolution or something, its annoying.

[207wheelin]

Let's try again.
269145269146
269144
Now to get some pics of the exhaust.

[207wheelin]

Got jetting figured out yesterday. Had to go through my Box O Carbs to do it though. Used the factory 200s carb with a 200x bowl and jets. 40 idle and 108 main. I took it out for a ride this afternoon and it's a blast! It has an 11 tooth front sprocket and 18" tires. Its geared low and it should be great on the trail. I plan to go a bit larger on the tires before riding season starts. Thinking 20's should be about right. Even after adjusting the cam hain I'm getting a tick but I think a new cam chain will remedy it. Started a new thread for advice on what parts to change and what brand of chain and guides.
Gonna get some pics as soon as it gets a bit warmer. Its freezing here again.
Take care
207