85 200x issues

[Chickenhawk327]

ok so late summer last year when I finally got my 200x back up and going after 5 years of sitting one of my first rides out it siezed trashed the piston cylinder etc. This past Saturday I went riding (mind you here in Arizona where I went riding it was 105-108 degrees) but 4 miles into my ride she quit again:(, kicked felt draggy with no compression, towed it back rode with a friend the rest of the day..... pulled it apart today and it is the same as before piston and cylinder are done, scarred marred beat etc. just wondering if I have an oiling issue or? When I pulled it apart today there was oil up in the cam valley so im guessing passages are ok? Plug is darker than it should be so I was running slightly rich, ruling out a lean condition, most of the ride I was running a bit over half throttle in 5th, and would jump to WOT to speed up on straightaways, but wouldnt hold it at WOT for more than a minute, minute and a half, any help would be nice!

ALSO thinking of any upgrades besides 67mm wiseco, cam for the rebuild, might do xr200 carb and intake? not too interested in doing a stroker kit.

[yaegerb]

I wouldn't be thinking about aftermarket parts until you can figure out why you are destroying Pistons.

Need more pics, top and underneath of piston would be helpful. The shiny bits on the strap of your spark plug are melted piston and the color is gray not black. Signs of heat damage to me by the looks of the plug.

Couple questions for you:
1. Was that side the only side that shows damage on the piston?
2. Did you get the cylinder bored or honed?
3. New rings installed?
4. What are the jets in your carb?
5. What kind of air filter are you running?

Let's start there and see where this takes us.

[Chickenhawk327]

Yes, went to 65.5mm piston (wiseco 10.25:1) last time and cylinder was bored, running stock jets, 110 main, throttle needle on richest setting, wouldn't run right anywhere else, and moose air filter will get some more pictures here in a bit.

[yaegerb]

Yes, went to 65.5mm piston (wiseco 10.25:1) last time and cylinder was bored, running stock jets, 110 main, throttle needle on richest setting, wouldn't run right anywhere else, and moose air filter will get some more pictures here in a bit.

That is a pretty lean main for an aftermarket filter and an increased bore/compression piston. Depending on exhaust, I would have started with a 40 pilot (stock) 118 main and bottom clip on needle.

What exhaust are you running?
Did you wash the cylinder out with warm soapy water after the shop bored it?
Did you break the freshly bored cylinder in properly?

[Chickenhawk327]

Running DG RCM, yes I did wash cylinder and yes I broke it in properly, and when the last time I set my carb, after a 2hr ride my plug was brown. I'm just thinking it has to be something else or just the extensive amount of periodic high rpm for 4 miles straight, when it did this last year the bike was completely stock never rebuilt before, so it has done it now with stock everything, and again with aftermarket piston and bore.

[yaegerb]

Ok, I can tell you that with the aftermarket exhaust and filter it's gonna require a larger main. Stock main will not hold up to High temps in Arizona couple with the demands of an aftermarket exhaust and filter. You might be able to get away with a flex hone on that cylinder and a new piston/rings. That is, if there are no marks in the cylinder wall that you can catch your fingernail on.

More questions:
If you pull up and down on the rod is there any play?
Have you stuck a feeler gauge in the big end Conrod bearing to see if it's within spec?

[Chickenhawk327]

I checked crank to rod clearance when it went back together last was within spec. Havent pulled on rod since I took it apart, going to have to press wrist pin out and get new rod as well.

[yaegerb]

Ok, the more I look at that piston and plug, you have two things going on.

1. Your jetting is too lean
2. I think you have too much slop in the connecting rod bearings and/or crank bearings.

[Chickenhawk327]

Here are some more pics

[Chickenhawk327]

Couple more, Just wondering how could I be that lean with a plug that was brown 2 weeks ago? Still doubting the lean condition, due to the fact that this happened before the exhaust and air filter once already and my last plug reading. thanks

[fieldy]

I agree with Yeagerb, jet seems small. I am running a minimum .028 main in an 86 200 x with stock carburetor/bore and dg/k&n. I am going to keep an eye on it as temperatures climb.

Post #3, the bike was asking for more fuel. Post #10, previously lean. If you go to rich you won't hurt anything.
For some reason you were reading the plug as ok. Had you ridden it hard/wide open and the plug was brown?
Buy some jets in big step increments. Example....020, 025, .030. Then find the one obviously too rich and buy smaller ones in smaller steps. Example.....028, .026. Especially know whats going on at wide open throttle. I personally like the needle clip in the middle so you have some adjustment left.
Thanks for posting and good luck on the repair.

[John Tice]

This situation should be learned by all of you readers; if there is the slightest change in your cranking compression, something is happening. I’d suspect since there was a notable compression drop that there was something wrong from the last ride. Whenever the outside temperature is up there close scrutiny should be taken with the cylinder. In the summer time, I’d suggest that the cranking compression be checked & noted in book or something after every ride.
Pistons have a tendency to scuff after they wear & skirt clearances increase, & there’s high time on the engine.
I have also found that the suggested skirt clearances on the Wiesco box are a tad tight. Whenever I fit a Wiesco piston I most always give the piston .0005” extra room.


John Tice
503-593-2908 Alternate 541-508-3944
www.smallenginemachineworks.com & www.nwsleeve.com
Turning Custom Cylinder Sleeves Since 1971
http://forums.everything2stroke.com/threads/49513-How-It-s-Done-Projects-around-the-Shop.com

[yaegerb]

Couple more, Just wondering how could I be that lean with a plug that was brown 2 weeks ago? Still doubting the lean condition, due to the fact that this happened before the exhaust and air filter once already and my last plug reading. thanks

Pull the piston and flip it over. Is there a dark spot in the center under the crown?

Do you run this bike with or without the airbox lid on?

[Chickenhawk327]

Hmm ok, yes last time I checked the plug I rode it pretty hard for a couple hours and ran wot several times and ended up brown, the bike ran great where it was but I hadn't tried a bigger main, will have to keep that in mind.

[Chickenhawk327]

I noticed the difference on cranking compression after it died not after the previous ride.

[Chickenhawk327]

Yaegerb, I will have to pull the case apart to get it out, wrist pin is pretty siezed, I will try to get it to work and press it out tomorrow and I run it with the airbox lid on, no holes in it, too dusty here to leave it off imo

[Leevvii]

just wondering if I have an oiling issue or?
Something worth mentioning, there is a small rubber plug residing in the head, which blocks or may redirect oil flow to the cam, might be worth a check.232848

[Chickenhawk327]

Yes that plug is/was in place, one of the things that was pointed out as important when I read through rebuild details

[Mackus84]

Yeah man, i have EXACTLY the same setup on my 85 200X, except i have the airbox lid off... i have a 65.5mm 10.25:1 wiseco, moose filter, and DG Rcm exhaust. I also run an Xr200 carb. I run a 40 pilot/slow jet, and a 118 main and im still lean up top. I need to go up to a 120 at least, or maybe even the next size up. And im in florida, its not as hot as out west, but its still in the mid to upper 90's right now. I think it ran too lean, too long. Just my opinion.

[Chickenhawk327]

Hmm, well once I get it back together I'll jump to a 118/40 and see what she does, too busy right now with other racing projects for 4th of july. Anybody know how the 12:1 Wiseco does?

[yaegerb]

Hmm, well once I get it back together I'll jump to a 118/40 and see what she does, too busy right now with other racing projects for 4th of july. Anybody know how the 12:1 Wiseco does?

It does very well but requires race gas. You can run lower octane fuels with it, but you may end up where you are now. I would stick with the compression you are running currently.

[Chickenhawk327]

Ok nevermind with that then, I ride wayyy too much (probably 8-10 hours a month) to be buying race gas, I like paying for 91 not to mention out of all of my friends I use the least amiunt of gas haha