Another Supid Newbie 250R Problem

[Redryderr]

Hi all,
I've been lurking and absorbing info here for quite a while, first post. This really is a great site with a lot of info! I've searched through several thousand messages and came across a few that may pertain to my problem, but would still like to ask for some educated input as to what to look for.

I Recently aquired an 85 250R, this is my first two-stroke. I wanted to go fast on three wheels so I paid way too much for a machine that isn't in that great of shape. (anything is restorable, right?)

The problem is that it misses really bad at about the spot where the I think the power band should be kicking in, like I said this is my first two-stroke, not real sure what to expect. I had it out in dunes this weekend and it's a real dog. My 200x with a worn piston could go more places than this thing...

Here's what I know about this machine:
Starts up on about second kick consistently and runs great at low RPM, don't usually need to choke it either.
Compression checks at about 170 PSI, engine warmed, choke on, WOT, switch off (took a fair amount of kicks to get the gauge to 170)
Has 0.50MM oversize piston
Cylinder is marked Paul Turner (can't find any reference to this turner cylinder anywhere, only to pipes?)
Currently has unmarked aftermarket pipe and stock muffler on it. (Put stock muffler back on so I wouldn't burn down Silver Lake dunes this past weekend!) Have tried all combinations of stock pipe/muffler, aftermarket pipe, and DG Type 2 silencer.
Using Bel-Ray S2 oil mixed at 32:1 (tried 20:1 per the manual first, thought maybe that was the problem so I tried a little leaner mix)
NGK BR9ES (seems to foul pretty fast)
New crank seals
New K & N filter
Reeds: not sure on brand, look OK visually, I do know that the stock reed limiters (or whatever you call them) are not there.
86 flatside carb
Jets: I had 'em wrote down but lost the paper... seems like it was a 150 main, I remember thinking that it was a lot richer than the manual says is stock for the year.


It seems like this thing is going to kick ass until it starts to get into higher RPM's then it just starts missing like crazy.

From what I've read in previous posts, it seems that since it starts so easily and runs good at low RPM, it's probably not a piston/cylinder issue. Sounds like maybe an ignition or jetting issue?

If you've read this far, you really are bored aren't you? Thanks for taking the time...

Stupid Newbie, Red

[Dammit!]

Probably jetting. Is the airbox lid on or off? Filter clean? Have you cleaned the carb real well yet? What position is the needle clip in? Have you done any plug chops?

Electrical isn't real likely but there's some easy things to check. Is the coil wire and plug boot in good shape? No cracks? Ground wire attached firmly to the frame? A quick way to make certain your plug boot and coil wire are ok is to spray some water on them while it's idling. If it dies all of a sudden, there's a problem.

Have you checked for intake leaks? While the machine is running (prefferably at a fairly high idle) spray some starter fluid all around the carb and intake area. If the idle changes by any substantial amount you have an intake leak.

Another possibility is a bad crank seal. If no amount of jetting cleans it up, you exhaust the electrical possibilities and there's no intake leak, it could be sucking air through the crank seal on the stator side. If the other side was bad it'd be burning up gear oil and fouling plugs left and right.

[x.system]

Where in Michigan? Any other markings on the cylinder besides Paul Turner? It's probably just jetted to fat and is getting to much fuel to clean out. Plug gap could be open to far as well. If your close to me bring it over and it will RIP :naughty:

[rustyhondas]

put the good pipe and scilencer back on it, take the carb off and clean it good, gap the spark plug. if it starts easy the reeds are good,and the compresion is OK.

So if the plug is wet start droping main jet sizes until she runs good.

I wound up buying over the years a few dozzen size jets because of stuff like this,it is part of owning a 2 stroke.no big deal realy.

heck it's part of running a 4 stroke to ,but there more forgiving usualy.

[InPiEcEs]

If the airbox lid is on it, try a quick ride with the cover off, then you will know for sure it's too rich.
Definitely go through the carb and stuff first, and the filter, then run it, and next, try the lid off.......see what happens.

[Billy Golightly]

Welcome to the forum :) Gap your spark plug at 12 thousandths and see if it happens to run any better before you do any carb tuning. I've recently discovered that this little trick can clear up a lot of issues that seem to be jetting related. Give it a try first and then we can help the diagnosis from there.

[Redryderr]

Thanks for all of the replies!

Air box lid is on now, has 6 holes about 1/2" each drilled in it, with a brand spankin' new KN air filter.

Couldn't find any other markings than Paul Turner on the cylinder

Not sure of needle clip postition or jet sizes, but I did have the carb off and soaked and cleaned good before ride this weekend.

x.system - I'm in Western Michigan...... let's say Grand Rapids. You?

I'll try some of the stuff you guys suggested tonight and see what happens and post back here with more info.

[Lomax]

[QUOTE=Redryderr;491219] I did have the carb off and soaked and cleaned good before ride this weekend.
QUOTE]


I am prolly gonna get slammed for saying this but in my experience if you soaked the carb (as in put the whole thing in a bucket of b-12 or someother type of carb cleaner) then you might have damaged it ( I said MIGHT ok). There are lots of small o-rings and seals in misc places that when allowed to set for a while, cleaners like that will damage and cause issuse. I have seen it happen more than once. I have an issue with my old 86 250r's stock carb bogging and not wanting to run out very well. I talked with people more experienced than myself about it and said they had seen issues with the choke valve port cracking and causing a flood of fuel while normal riding, that would cause it to have issues getting on the pipe as well. I installed a new 35mm PWK and while i never did jet it out correctly ( Billy) it ran SOO much better i couldnt hardly tell there was anything wrong anymore.
-Will

[x.system]

I'm in Ionia, about 20/30 minutes east of GR depending on which side your on. Let me know the next time your going to head up to silver lake. I have to rejet when I go to the dunes, my bike runs a little to lean up there if I don't.

[Redryderr]

Lomax - thanks for that heads up. I'm pretty dang sure I got all the o-rings and seals out before I soaked it. And yeah it was that bucket of nasty smelling B12 or whatever it is. I know I wear rubber gloves whenever I come within 10 feet of that can, get that stuff on ya and you smell it for three days. Never had had a problem with cleaning carbs like this before tho......

More info and stuff:
I put the DG silencer back on, put in a brand new plug gapped at 0.012" (manual calls for 28-31, 12 seems pretty tight??), took air box lid off and warmed engine.

Checked for intake leaks, seems fine. Water didn't shut it down either.
Then I took a few rips down the path. Quite a bit better now, but still not all the way there yet, still missing at the top end. I cranked her up in fourth then killed it and checked the plug, see the attached picture. I put the lid back on and ran it some more, couldn't tell much difference, almost seems like it might have run a little better with the lid on.

Carb jetting as follows:
Main = 150
Slow = 48
Slide = 60
Needle = NR1468
Clip was on second groove


X.system - I'm about 20/30 minutes the other way of GR. I'll prolly be back up to Silver soon, maybe for the hill climb. We have a buggy we run up there too.....


Thanks again to everyone for the help!

[Russell 350X]

Lomax - thanks for that heads up. I'm pretty dang sure I got all the o-rings and seals out before I soaked it. And yeah it was that bucket of nasty smelling B12 or whatever it is. I know I wear rubber gloves whenever I come within 10 feet of that can, get that stuff on ya and you smell it for three days. Never had had a problem with cleaning carbs like this before tho......

More info and stuff:
I put the DG silencer back on, put in a brand new plug gapped at 0.012" (manual calls for 28-31, 12 seems pretty tight??), took air box lid off and warmed engine.

Checked for intake leaks, seems fine. Water didn't shut it down either.
Then I took a few rips down the path. Quite a bit better now, but still not all the way there yet, still missing at the top end. I cranked her up in fourth then killed it and checked the plug, see the attached picture. I put the lid back on and ran it some more, couldn't tell much difference, almost seems like it might have run a little better with the lid on.

Carb jetting as follows:
Main = 150
Slow = 48
Slide = 60
Needle = NR1468
Clip was on second groove


X.system - I'm about 20/30 minutes the other way of GR. I'll prolly be back up to Silver soon, maybe for the hill climb. We have a buggy we run up there too.....


Thanks again to everyone for the help!


Wow, you look to be running a bit lean. White plug, to lean. Black plug, to rich, tan plug, just right.

[torker]

Yep, if that is a pic of your actual plug, your seriously lean.

I'm starting to think that you may have a lot of engine work on that PT engine and need some serious carb tuning, try changing it for another, maybe from a friend that you know it's working properly, maybe a bigger carb.
Take it easy as you don't want to ruin that engine just to start all over.
BUT KEEP AT IT!!!

TORKER.

[x.system]

150 main is to small, you should be up around 160/170 area with a ported motor at our elevation. I can usually throw a 170/175 main in any of my motors and fine tune from there.

Did your motor seem to get hot quick up at the dunes or at your place? Sure sign of to lean, starving for fuel. A good way to tell is if you have a decal on the silencer and it shrivels up/melts away. What I don't understand is how you are fouling plugs with a 150 main. I gap my plugs at .018

[Erics350x]

Did you clean the petcock out?

[Redryderr]

Yup, that's the actual pic of the plug. Maybe I didn't do a good chop? I don't have a real big area here to ride. 4th gear comes real fast, maybe I wasn't really at WOT?

Didn't notice motor getting hot....

I'll try cleaning the petcock, you think maybbe I'm starving for fuel at higher RPM?

[x.system]

Its hard to say without hearing it but what I would do is put a bigger jet in it, open the gap a little to around .018/.020 and try it. Do one mod at a time and try it so you know if it worked or not.

You've done a compression test, have you done a leak down test?

[Redryderr]

Stupid Newbie getting happier!

Adjusting the needle clip made a big difference, based on the plug looking lean, I richened up the needle (moved clip down), that made it worse. So I leaned out the needle (moved the clip up). It feels like it's about there now, but the clip is in the #1 position, thinking I should pick up a few diferent jet sizes and play with it a little more.

I haven't done a leak down yet, I'll keep trying one thing at a time to see what works.

x.system - you gonna be at Silver anytime soon?

Thanks All!
Red

[Redryderr]

Maybe this will help someone else in the future, if they have the same problem I had.

I finally picked up a couple of different sized jets this week and went to eat some sand. (I only endo-ed over one hill!!). I ended up going from a 150 main down to 145 and it seems very usable now. Might try putting the needle back up a notch and see how it runs next.......

Thanks everyone for the help so far.

[Billy Golightly]

What does your plug look like now? I can tell you from the last picture you posted if you kept running it at that mixture your going to have a hole in your piston as part of the aluminum from it is already melted onto the end of the ground strap

[Rustytinhorn]

I hate mixed results. It was lean at 150 but it runs better with a 145 in it? huh?
My 250r does the exact same thing as yours. Sputters, sputters, sputters... I have spent the last 6 months tryin to get it to clean up with no luck. I'm tearin apart the water pump tomorrow cuz I think its running hot. After that I will only have a few electric parts left to test, and then replace my crank seals as a last resort. Let me know how your jetting turns out.
Make sure your petcock and fuel line, (and inline filters) arent restricting any fuel flow. That would cause it to run lean.
Good luck