What are the weakest links in the 83-85 200x motors when heavily modified? Other than the connecting rod.

 

You might need to run 91 octane. My friend didn't find that out after he blew his.
I heard the kick start might be a problem.

 

In this day and age, since there is no 200cc three wheeler class to race in there is no point in really doing mods to a 200X.
The best and most cost effective mod for a 200x is to sell it and replace it with a 350X.
You get more power, better suspension without sacrificing reliability.
You could spend more than the cost of the 350X modding the 200X and still not be as good.

Don't get me wrong, I love my 200x, but I love it for what it is.

 

The rod problems are from stopped up oil filters......a lack of maintainance issue in my opinion. These bikes were just ran harder than your other ATC models and required a little more TLC that they never got. Alot of guys argue saying it has no oilfilter, but if you have been into one of these engines, you know the filter that I am talking about and by the time you realize it's stopped up, it's too late.
The SAME rod is used on all the other 185/200 trikes as well as the XR200R.

The only issue I have with engine overheating when modified. Once you go to the 67mm piston AND a +6mm stroker, the oil cooler is mandatory. My 245 has a redline just shy of 14,000 RPM. That is high for an engine that has a cylinder wall that you can bend with your fingers!! This does cause a bit of flex because the cases do not support the cylinder well. I had my last one done a bit differently. We made a brass sleeve to snug up the cylinder and it goes further down by just a few thousandths of an inch, but anything is better than having that gap. Only time will tell if our mod works or not.

2nd and 3rd gears on the counter shaft have been a problem on modified engines as well.

 

I know that it might be cheaper to sell and get a 350x. I used to build Drag Bikes and I really enjoy making things perform way out of there own league. Sleepers per say. I am currently running an xr200 gear set in my 200x. along with the xr piston, and 26mm carb. I intend on building a sleeper x. It will be a change out motor for my superb xr200x set up. I love the 6 speed in the woods. How thin is the cylinder wall when it has the 67mm piston? Do you think that the 2nd and 3rd gear problems are from an over torque situation or shock loads from speed shifting? Has your 245 held up well? I my be trying something a little larger than that. But it wont be designed for the rpms that you are running.

 

Unless you plan on running some cylinder/piston combo that I have never heard of, I don't see you going bigger than a 245.

You would not believe how ground down my rod is to clear the mainshaft gears on the tranny. Not much rod area there left...LOL

Now....if the XR gear setup allows you more room and have a special built crank made...along with an all new rod....you may have something.

I remember measuring my cylinder wall the last time I built one but do not remember the spec. It's scary to look at.....and touch...LOL

By the way, I have another Powroll +6 crank assembly here with new rod, crankbearings, and rod bearings. This one hasn't even been put into an engine yet. I had it as a spare so when I need it, I can swap out and have the other one being rebuilt, and so on, and so on.

 

The stock con rod hits the main shaft with 6mm stroke. This is the kind of info I like. I am looking at resleeving my 200x jug with a trx300 sleeve. It has a 74mm bore. I am going to have to take about .090 out of the case bore and turn down the outside of the trx300 sleeve as much as possible. From the bottom of the 200x jug down. This also means that I will have to make a steel base plate which will be mounted with as many as I can fit 6mm counter sunk screws. The base plate will be threaded for the head studs. The six screws will be installed to help support the threads on the inset head stud. .090 boring of the case bore might get into the jug threads on the inset stud. That's why I need the steel base plate. I think that the other three studs will have engouh meat still in the cases. I will definetly run an oil cooler. I will need to fabricate an external oil line to go to the head anyway. I need to check with some xr builders and see if the main shaft will give me any more room I was hoping for more stroke but mabye not.

Does anyone has a 200x jug that could measure the outside of the sleeve? I need to calculate the wall thickness of a 67mm bored jug. As long as I can turn down the trx300 sleeve enough without getting it too thin (it is going to be close). I think I can get this to work.

 

kick staters are definately weak.

 

tdup,
Sounds like a hell of an X engine if you get all that together and it works out. Keep us posted.


I have several X cylinders here......but unfortunately, don't have a mic here with them to measure.

I'm leaving early morning to a race in Tennessee. When I get back, I will mic one and post back, if someone elses hasn't already done so by then.

 

Thanks Knowsalot. How much would you want for a jug that needs resleeved?