85' 250R stator question

[riverrat]

Is there a way to test the stator to tell if it is putting the proper power?

I ask because, my bike is breaking up mid-range rpm's while hold throttle wide open. It was running fine on Saturday, then Sunday it wasn't. I want to just change the stator because it's so old, but I just spent like $1200 getting the bike up and running, and I am bit tapped out. I don't feel like taking a chance this month just to see if it is it or not.

Between Saturday and Sunday, I added two new springs to hold the exhaust on, and changed the oil I was using from TCW-3 30-1, to Bel-Ray 40-1.

I had bought a new mukini carb from ESR, and threw that on, and the bike was doing the same thing, maybe a bit worse. I tried jetting it, I went from a 440 jet to a 350, and the leaner I went, the worse it got. It happened with both tanks of gas. Sunoco 93. I will do a compression test later.

I am going to tinker with it tonight, and tomorrow, so I am looking for suggestions. I will be pulling the reed block out, and inspecting, to make sure there is no chips or whatever, since it sat apart for a year and a half.

Oh, and top speed wide open in 6th gear seems to be fine, once it gets there, maybe a little down on power, but that could just be jetting. Idle is fine also, and slow speed is fine also. Plug has carbon on it.

I would like to get it right so I can go to RAffa's!! :w00t:

[ceaserthethird]

Well put in a new plug and see if it's in the Fuel Area by doing Plug Chop's / Test .

If not , Than look at your Ground, Coil , CDI , Stator.

What Work has been done ? ? ?

[deathman53]

my thoughts are way to rich main jet, needle might be too rich also and by leaning the oil/gas mix, you are dumping more fuel in it. You are fouling the plug and that is why nothing has changed from the drastic main jet change. I'm using 170 and 175 mains on my r's, that would be close to a 340-350 mikuni.

[riverrat]

Thanks for the replies. I did some checking tonight, it's f+++in cold out there.

It has a wesico piston, and the compression was 170. I tested the exciter coil, spark coil and secondary, and pick up coil, or inducer. That all checked out.

The plug is a week old, and has some carbon on it, but as I said, if I started leaning the jet out, the condition got worse, and I thought I was going to blow it up.

I did a chop test, and the plug was black, but it was black to begin with. It sounds like I am not getting a complete burn in mid-rpm, so that would make the plug black also. When I leaned it out too much, it even ran too hot, I could tell that 350 was too lean.

It has a wesico piston, FMF gold fatty pipe, stick bore, boysen reeds, and now a 38 mukini carb. Some mild port work as well.

The reeds looked perfect.

I changed the plug back to the one I got with the bike, but it did run fine one day with the plug I got. On the first blast it would stutter, but once cleared out, it would run fine, now it just stutters all the time mid-rpm (WOT).

WOT top RPM is fine. I can do 90mph all day it seems. It starts right up also, and idles perfectly.

I don't think the needle setting has anything to do with it, because these problems I am having are all at WOT.

Thanks for the help.

[riverrat]

I'll have to get a new plug to do a chop test.

[riverrat]

Well problem solved. It was one of two things. My intake on the cylinder has a crack in it, that I welded, but it may have still been sucking air, so I sealed it up good for now, until ice is out, or the plug. I put the old plug in it, which is a bpr5es, as opposed to what I was using a br9es. Not sure if this is the right plug, according to the manual it's not, but it's working. I'll pick up a br8es this week, the manual suggests that for cold weather.

[ceaserthethird]

Yes Run the BR8ES NGK , The 5 is to Hot for my Taste !

7 is the lowest i will run.

.................................................. ........................................

Buy a New Cylinder

[deathman53]

a 5 series plug is way too hot to use, just about the only reason I could see someone using a 5 plug is if they have a really bad jetting(really rich) and it fouls plugs constantly. I use br8eg, br8ev, or br8es. I have iriduim plugs also, with correct jetting, they last forever.