~HELP~250R jetting issue, maybe!!!??

[Endurance]

I'm picking up an 87' 250r tomorrow. It starts easily on the first kick, little to no smoke. It doesn't spit or sputter. It just doesn't hit like it should, it doens't open up!

When I ride it, it just doesn't open up. I hit the gas, it pulls and takes off but it doesn't really hit like a normal R.

You know how when you gas it, there sometimes is a slight pause, then pow, it takes off. Well this just takes of like a for stroke kind of!

The owner said something about it had a cold weather jet in it, so do I need to go bigger now with hot weather or what?

I'm pretty sure its a fuel issue. Can it be my reeds also, I have no clue!

This thing simply is not hitting the power band

Any help would be appreciated.

Thanks,
Bryan

[my88r]

what main, what needle is the clip on, whats the pilot

[312R1]

Is it a PV cylinder?

[Endurance]

It's not a PV cylinder, and I wont actually be able to pull the carb until tomorrow to look at the jets and needle.

[Scott-300ex]

Yeh, PV's won't hit like they would.

And I'd say just a richer main.

[wilkin250r]

It could be many things. It could be an air leak, it could be jetting, it could be a clogged air filter, it could just be bad gas.

Do the normal routine stuff. Check or change the oil, check the air filter, check radiator fluid (obviously not the problem, but it should still be checked on ANY new quad).

If it still runs bad, the FIRST thing to check should be the plug. Run it until it starts cutting/bogging/sputtering/whatever-it-does, and check the plug (make sure you kill the engine properly for a good plug reading). This should tell you what is going on inside the cylinder, and what changes need to be made.

Once you have that information, THEN pull the carb, check the jetting specs, and inspect the reeds.

[Endurance]

Ok, I have the R home. I'm gonna pull the carb off, clean it, check the jets, and put in new reed valves if needed while the carb is off. I'll put in a new plug too.

Can someone tell me where I can find the info on my motor with the case number??

Thanks....

[Endurance]

Ok, here are my jets, a 170 main and the slow jet is a 58!

Ok, any ideas people?

Please help :(

[Endurance]

No one out there has any ideas?

:confused:

[Scott-300ex]

Oh man dude. Thats RICH!!!!!!!!!!!

Stock is like 150 and 43

Especially if that is stock bore, wut mods are on it? If its just pipe and reeds thats still way to rich.

58, is real rich.

170 is pretty dang rich too.

If its stock bore I'd bring it down to stock if its stock and maybe go up 2 or 4 on main and 2 on pilot/slow if it has outer motor mods.

You plug is prolly dark then.

I would get like a 150 and 43 first.

[Endurance]

Well, It's an 87' and I don't right off the top of my head remember the stock jetting. The plug is dry, dusty black, not oily at all.

The reeds I think are totally fine, they're Boyesen carbon fiber. I think all it has is the full pipe, an ESR.

[Endurance]

I also noticed this, in my service manual it shows a spacer on the intake by the reeds on 87's. Mine doesn't have this. Just carb to reeds to cylinder, and it's an 87'.

Is this an issue possibly too?

Thanks..

[wilkin250r]

I'll just reiterate what has already been said, so you've got more than one source.

It all sounds REALLY rich. A 58 pilot sounds rich for ANY carb size, but that would only affect idle. It's not the reason for the powerband.

170 sounds rich for the stock size carb, but it wouldn't sound rich for a 38mm carb. Do you know the carb size/type?


The spacer shouldn't be a problem, but we might be able to give a more definite answer if you post a picture of it.

[Jason Hall]

If you gave the carb size & type that would make this much easier. Is It a oval slide with the Idle adjuster on the choke knob? If so make sure the slide Is'nt In with the cut away facing the front, that always goes toward the rear of the carb. I would put a new plug In. Then drop the pilot jet to a 42 or 45 set the air screw to 1 1/2 turns out. After that turn the choke knob until It will Idle good fine tuning with the air screw. Then ride It If It feels dirty or blubbery just off Idle, start dropping the needle (raise the clip). Next run It wide open for a bit to see If It spudders or chuggles top end. If so then start dropping the main jet size one size at a time. I would think If the cylinder Is ported you might leave the 170 In. If It's not ported you will probly want around a 155-160. Another thing to check Is the plug boot where It threads onto the coil wire. I've also seen bikes with the wrong plug boot. One style uses the cap on the plug & some others don't. If you have a boot that need the plug cap on & the top Is'nt on, It won't have a good connection.

[Endurance]

Ok, here's where I'm at. A 150 main, 55 pilot (smallest I could find today) and the clip on the 4th notch. It's totally coming out of it. I wasn't able to go out in the street and hit it hard with the 150 and 55 combo, but I will tomorrow, it's getting late.

I think she's starting to wake back up! I had the carb miked today, but they only did the side that goes into the reed cage, they told me it was a 40mm opening. WELL, that probably doesn't tell me anything. I need all the openings and the heigth too dont I? They tried telling me it was a 40, but if anything I'm guessing a 39mm PWK carb.

It looks totally stock, just like in my service manual, what is the stock 87' carb?

Thanks for the help guys, keep it coming!

[Jason Hall]

How do you adjust the Idle? With a screw In the side of the carb PWK, or with the choke knob PJ oval stock style?

A stock 87r should have a 34mm oval slide PJ carb stock. It sounds like It has a 38mm oval slide though.

[Endurance]

The carb is a PWK, as for what size, I dont know.

It says 72 something on the side of it after the letters PWK. It has a choke knob, and a plastic coated screw on it behind the choke knob (to the right) and an air screw which is all metal directly below the plastic screw about and inch and a half. The metal screw is the one that should be turned out about 1 and 7/8 turns according to the service manual.

Does this help tell you what carb I have? :)

[wilkin250r]

Did you measure the inside or the outside of the opening?

A carb "size" is technically the ID of the slide section, but you can't really measure in there easily with a standard micrometer or caliper. However, it's almost ALWAYS the same size right at the intake to the reeds.

Measure the inside diameter at the reed-side of the carb, that should tell you the size.

The plastic screw feeds through to the carb slide, and holds it open slightly. This is your idle adjust, and this most DEFINTELY tells us you have a PWK carb. On the PJ carb (stock), the idle adjust is on the choke knob.

The metal screw is the idle air screw, used to adjust the mixture at idle and low-throttle settings. The pilot jet size is a rough adjustment, the air screw is for fine adjustment.

[Jason Hall]

Originally posted by Endurance
The carb is a PWK, as for what size, I dont know.

It says 72 something on the side of it after the letters PWK. It has a choke knob, and a plastic coated screw on it behind the choke knob (to the right) and an air screw which is all metal directly below the plastic screw about and inch and a half. The metal screw is the one that should be turned out about 1 and 7/8 turns according to the service manual.

Does this help tell you what carb I have? :)

Yes, that tells everything. One of the first things you should check Is the float level, that Is very Imprtant to the Idle circuit.

The plastic screw hold's the slide open. The air that passes under the slide opening Is what determines the size of your pilot jet. The air screw fine tunes the slight slide opening to the pilot size. The transition to mid range happens when the carb comes off the pilot & the engine starts to draw fuel around the needle through the main. Wide open Is all main & total carb Diameter.

If your carb Is rich at an Idle, It will load the cylinder with fuel. Then when you open the throttle, It has to burn off the excess fuel, causing nasty throttle response or bogg. With a PWK, you can adjust the pilot ALOT easier than a PJ. You can raise the slide a little to make up for a big pilot. But then you run Into a problem on trasfer when you start opening the throttle. To big on the pilot usually = bad throttle response just off Idle.

I feel the key to tuning any carb Is to start with the Idle, get that right then work on the needle, then the main.

I still suggest a 45 pilot. That size pilot seems to be where I always end up. Needle on the top or one from the top. About a 160 main to start, then maybe drop the main If It's to rich wide open.