1985 250R running like CRAP HELP

[pepsicolla]

Ok so I just bought a 1985 250R. It had ben sitting for over 5 years so I immediately pulled the carb and cleaned it out. But as the 250r gods would have it the I over tightened the main jet and broke the "set" guide for the jet.
SO pretty much I need a new carb but I have several carbs around that all came off worked 250R bike from ebay. My 250R has a fmf full exhaust, V-force reeds, and a open intake so I figured no big deal just throw on one Of the 38mm carbs I have laying around. The bike started RIGHT up and idles like a dream. Responds awesome to throttle while in neutral. Problem is as soon as you put is in gear and give it gas its BAAAAAAHHHHH at 1/4 all the way up to full throttle. So I figured wth throw the other 38mm carb laying around and the exact same result. The Main and pilot in both carbs are 172 and 55.
I installed a New plug as well.

I was hoping someone running similar modes with a 38mm could give me a little help here. I expected it to need fine tuning but to have no power all through the range has me scratching my head. Anyone???? Im in upstate NY for elevation.
I havnt compression tested it yet but I Really dont think thats the problem as it feels like it has more then enough and starts so easy.

[yaegerb]

48 pilot, air screw 1-2 turns out and 165 main. Needle clip in the center slot. Try that.

[Onetrackmind]

I was in a similar situation as you and yaegerb got me straightened out in no time. My advice is to take HIS advice. :lol:

[pepsicolla]

Thanks for the replies guys. I will try what yaegerb said. I just looked at the 2 Keihin carbs and they mic at 38mm and the serial numbers are PJ 27C A CG and the other one is PG 26 A.... Id did a little research and it looks like they should of come off a 87 CR500?? Is that going to be a problem? Is there a way to look up Keihin serial numbers so I can order the jets yaegerb suggested?

[yaegerb]

Click this link, take some measurements according to the guide to see what carbs you indeed have.

http://www.carbparts.com/keihin/pj_jetting_and_dimensions.htm

[oscarmayer]

Change the jets and you should be ok. As mentioned. You are probably rich.


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[dgm635csi]

I'm not sure if this is relevant here or not, but if the carbs you have came off a cr500, the jets inside the carb would be smaller. A 500cc creates a much greater venturi effect through the carb, and thus smaller jets were used because more fuel is drawn through the same size jets when compared to a 250cc.

[pepsicolla]

Ok so its definitely a PJ 38mm as per the chart yaegerb supplied. I have a 50 pilot laying around Ill try that today, while I wait for the jets to arrive and let you guys know. Thanks alot.

[yaegerb]

here's a general rule of thumb for setting your pilot correctly. Start the bike and set the idle higher than normal and lightly seat your air screw (turn it all the way in....LIGHTLY). Then at 1/4 turn at a time screw it out until it is at its highest idle, is crisp on throttle blip and comes back down to idle quickly (should be 1-2 seconds). Be sure to give the motor time to catch up to the adjustment....depending on the condition of the engine it may take longer for the carb to respond due to air leaks, etc. While you are doing this record how many turns out your air screw is. I prefer 1.5 turns out. If you are greater than 2 turns then your pilot is to big (you are letting more air in to compensate for a rich pilot). If you are less than 1 turn then your pilot is too small (you are allowing less air in to compensate for a lean pilot). After you adjust and figure out what pilot you need return the idle back down to normal.

[RIDE-RED 250r]

I agree with others that your jetting sound rich. Most guys with 330's are running mains in the 172-180 range depending on the usual variables.. And that pilot is waaay rich. My 350 likes a 48-50 pilot depending on conditions...

And no, larger displacement engines do not take smaller jets than smaller displacement engines of comparable design. (Sorry dgm635csi, you are incorrect about that.) Matter of fact, those jetting numbers pepsicolla has now sound just about right for a stock-ish CR500.

And I hope your intake isn't TOO open pepsicolla...

[dgm635csi]

Not trying to hijack, but my 85 cr500 runs a 168 main and that's on the rich side. 1988 cr500; 175 main, 58 slow , 1988 cr250 with the same exact carb; 185 main, 62 slow.

[RIDE-RED 250r]

Not trying to hijack, but my 85 cr500 runs a 168 main and that's on the rich side. 1988 cr500; 175 main, 58 slow , 1988 cr250 with the same exact carb; 185 main, 62 slow.

If Pepsicolla would pardon me for a tad more hijack here, I stand corrected, to a point. Meaning that it's pretty well known that the 500's were quite detuned in stock trim as compared to the 250's and 125's in the bikes. I have my suspicions as to why, but maybe we could start another thread to further discuss that topic.

But regardless, this is simply not the case with the 250r. Bigger CC's always require more fuel on the R's. If I were to run stock jetting or leaner on my 350 BB, she wouldn't last 5 minutes. Currently running a 41.2mm PWK, 192 main, 48 pilot, DEJ needle.

Pepsicolla is way rich for his OEM cylinder with pipe and reeds. He is a larger carb than stock, so he will need to be running larger than stock jetting. Personally, I would say his pilot is off by a larger degree than his main. Yeagerb's initial recommendation should get him in there close.

Pepsicolla: When it is bogging out, is it a smooth bog, or blubbery with excessive smoke??

[YTZ drew]

I think what dgm635csi was getting at is that when you put a larger carb onto a smaller machine, the stock jetting of the larger carb is often too lean for its new home on a smaller displacement engine. I have experienced this a few times when putting larger carbs onto smaller engines. Actually had to jet UP to compensate for the lower vacuum signal.

But, I don't think that's Pepsicolla's issue. It does sound like he's rich.

End hijack.

[pepsicolla]

Well as per Yeagerb's advice I bought and installed a 48 pilot and a 165 main and she runs pretty good. Under full throttle pulls it has great torque from 0 to 1/4 but still has a touch of hesitation (boggy) 1/4 to 1/2 throttle especially when she isnt warmed up. After that from 1/2 to full throttle she really kicks in like a animal.
Thinking the A/F screw needs adjustment or maybe a different pilot?
Thoughts?
Maybe Ill take a video to better explain.

[Mr. Clean]

Pull the stator cover and make sure it's not rusty and full of corrosion.

[barnett468]

Well as per Yeagerb's advice I bought and installed a 48 pilot and a 165 main and she runs pretty good. Under full throttle pulls it has great torque from 0 to 1/4 but still has a touch of hesitation (boggy) 1/4 to 1/2 throttle especially when she isnt warmed up. After that from 1/2 to full throttle she really kicks in like a animal.
Thinking the A/F screw needs adjustment or maybe a different pilot?
Thoughts?
Maybe Ill take a video to better explain.

ok, your problem is a bit odd if it runs goo from 0 - 1/4, bad from 1/4 - 1/2, then good again from 1/2 to full.

in addition to checking the stator for rust as suggested, if the description above is accurate, the pilot jet is likely not the cause imo . . some of the other things that can cause this are the needle taper or the choke height on the needle jet which is uncommon if the needle jet is stock and you are near sea level.

as RIDE-RED250R was asking, or saying, if it burbles and sputters/misses when accelerating, it is rich . . if it simply seems like it runs out of gas for a second then accelerates, it is lean.

i would look at the needle and see what clip position it is on and let us know . . i would then try it with the clip all the way up and all the way down . . imo, your description suggests a slightly lean condition and you may see some improvement with the needle in the highest position which is the clip in the lowest position.

it would also be helpful to see a photo of the end of your spark plug or a description of the color.

i would also try the air screw as you asked, it cant hurt anything.

[pepsicolla]

Funny you should all ask about inside the stator cover. Yes there is a fair amount of rust inside it. Is it your thought Im getting weak spark due to?
I should definitely clean it out Im just going to have to get a puller to do it right. I thought due to how easy it starts it probably wasn't a issue but maybe its effecting it in the mid range?
I will though get back to you on my needle clip position but I believe its in the middle.

[RIDE-RED 250r]

Funny you should all ask about inside the stator cover. Yes there is a fair amount of rust inside it. Is it your thought Im getting weak spark due to?
I should definitely clean it out Im just going to have to get a puller to do it right. I thought due to how easy it starts it probably wasn't a issue but maybe its effecting it in the mid range?
I will though get back to you on my needle clip position but I believe its in the middle.

Yes, corrosion on the pickup coil and magnet on the flywheel can cause ignition issues that can be strange or inconsistent in nature. I myself have chased my tail with jetting only to have it turn out to be an ignition issue.

Definitely worth a good cleaning to make sure.

[barnett468]

Funny you should all ask about inside the stator cover. Yes there is a fair amount of rust inside it. Is it your thought Im getting weak spark due to?

you can put your bike in the shade then remove the plug and lay it on the head and kick it over and look at it . . if the spark is pale blue, it is a very good spark . . if it is yellow, it is far weaker than it should be.




I should definitely clean it out Im just going to have to get a puller to do it right.

no, you need a special puller.




I thought due to how easy it starts it probably wasn't a issue but maybe its effecting it in the mid range?

it would not have good spark at low rpm then bad spark at mid rpm then good spark above that again but if the flywheel and coils are rusty, they should be cleaned irregardless to keep it from being a problem later and it will eliminate the rust as a cause . . a rusty stator can cause a weak spark that is yellow.




FI will though get back to you on my needle clip position but I believe its in the middle.

xlnt.

[250rAL]

My 36PJ had a bit of a dead spot between 1/4 and 1/2. I put a needle with a different taper in, per recommendation, and that fixed it.

[yaegerb]

How many turns out is your air screw? If it's boggy 1/4-1/2 then go up 1 clip on your needle. And yes, clean your ignition as well if it's rusty.