Thanks for all your guys' help it is appreciated, will get back with you when I have results.

Hay, can I jump in for some help? I have a 1985 250R ATC stock with fatty pipe and K&N filter, no lid on the air box. the bike runs like crap in 1st and 2nd bogs when you hit the throttle and won't come up (bogs like it is cold) then third gear and up power comes on hard and screams ( runs great). I checked the pluug and is is black/damp. has anyone had experience with this and is it a jetting issue.

Well black/damp is definately rich, but why it only bogs in 1&2 is a mystery to me.

What position is your needle in? The 2nd position is best for the dunes. Do you run an outerwear on the filter? If you do, take off the outerwear and then run it. This will lean it out(more air) and let you see if your bike is running too rich. If it runs good with the outerwear off, then I would go down one jet size. What size jet is in there now?

Boggin in 1&2 would be from loading up.. By the time third hit it would be blown out.. if he went from 3 back to 2, I bet it would run better. Just a thought.. My KX is like that for 1st gear.. after sittin at idle for a few seconds it bogs in that gear.. 2nd it well OPENS the F up and all hell breaks loose!

The needle is in the 2nd position and there is no outerware on the filter. and the problem is much better (but not gone) when coming from 3 rd to 2nd. and if you idle around then nail the throttle the bike alnost dies. Could this be a low speed jet problem and what is its function. Is there three "jets" in this system.Idle,slow and high or just two. thanks for all the help.

there will be two jets. pilot (idle) and main (WFO).

Your problem is Idle to 1/2 throttle. Look at the chart in my above post. that would be the Air screw and the pilot jet.
Does it idle good? maybe your air screw is to far out. Try giving it a 1/2 turn in (Im pretty sure in, the manual will tell you which is correct. In my carb, the air screw moves the slide up when turning it in thus giving more air). If that does not help it out, then return it to 2.5 turns out and change the pilot jet down in size.
RRon3 knows these 3 wheelers best, but you might have to wait till later tonight for him to post. Might send him an email as well.

MAKE SURE THE FILTER IS CLEAN!

[ 01-15-2003, 09:14 AM: Message edited by: Chummin ]

Hey you guys sorry it took so long to get back at you, it's hard to get a good test run during the week, moved the needle to the second position, wheelies up hill from take off now....WOW! plug was lookin pretty sad put in a new one, put in a #200 (lack of any size between it and the #220 that was actually in it), did the full throttle trick, the plug was a little tan (not quite what I would call cocoa or even brown) around the electrode, so now I must get some more jets in this neighborhood.
Thanks again for all of your help, it will be useful till carbs are no longer on ATVs. Awesome!

Been reading the post, and it seems that I have similar issues with my 86' LT 250. I guess that I need to spend the time playing with my jets, and stuff, but I don't know what all this vocabulary is new to me. What are the positions and stuff. I want to know all that I can so that I don't have to rely on others.

Actually, tan is good!!

Dreamer, the needle will have little notches cut into it for the clip that holds it on at the top(fat end where the spring is). There should be 4. A good place to start is "in the middle" which is usually the second "notch" from the top.

BUY the manual for your bike FIRST! It has pictures with arrows telling you what is what. Im telling you now that will be the most important thing to buy.

CHUMMIN, GOT THE BOOK, AND IT HAS BEEN A LIFE-SAVER. I AM JUST TRYING TO VIZUALIZE THE CARB, AND WHERE THESE THINGS ARE. ARE ANY OF THEM VISIBLE FROM THE EXTERIOR OF THE CARB? I GUESS THAT TONIGHT I WILL FIND OUT. WISH ME LUCK.

Needle is on the TOP in the slide which is attached to your throttle cable.

Main Jet is in the bowl on the bottom
Pilot jet is in the bowl also.

BECAREFUL when you pull it apart. Do it over a towel so when or if parts fall out you dont lose them.

Here is a blow up of the stock carb for the 86 lt250.

http://216.37.204.202/suzuki_oem/SuzukiATV...Type=13&A=2&B=3

SO, IS THIS WHAT I SHOULD DO?

STEP 1. ADJUST CARB TO SETTINGS PER BOOK.

STEP 2. THROTTLE CHOP

STEP 3. ADJUST MAIN AND PILOT JET PER INDICATIONS OF SPARK PLUG.

I GUESS, I JUST DON'T KNOW WHERE TO START.

AND ONE MORE QUESTION. HOW DO I KNOW WHETHER I SHOULD BE CHANGING THE MAIN OR PIOLT?

All that stuff is inside the carb. The pilot jet is for idle to 1/4 throttle, needle 1/4-3/4, and main from 3/4 on. So it depends on where your bike is acting up as to what needs changed. Refer to the diagram Chummin posted above.

exactly what Shane-O said.
First you must identify the exact problem you have. Then you can find where to start at.

The guy before had way to big of a main for the needle he was using so the bike would load up. Once he got out of first and second gears WFO the bike came to life. SO the transition was bad and that can be the taper of the needle, the position of the clip on teh needle, or to big a main.

Try to keep the position of the clip in the middle if you can. That way for elevation changes you and just bump one clip and still be decent.

THIS IS STARTING TO SOUND REALLY COMPLICATED. AS OF RIGHT NOW, THE BIKE HAS NO TOP END. IT IS ALL STOCK, EXCEPT FOR AND OVER SIZED PISTON FROM A TOP END REBUILD. I WOULD THINK THAT IT SHOULD BE CLOSE TO THE ORIGINAL SETTINGS.

ALSO, HOW MUCH COMPRESSION SHOULD I BE GETTING FROM THIS THING?

IT SEEMS THE MORE I LEARN, THE LONGER THE LIST GETS WITH THINGS THAT ARE NOT RIGHT.

If the bike is stock. stick with the stock jettings.
being bored once, twice, or even three times should not really effect the jetting that much.

If you have NO top end and all is stock, then you might just need a good cleaning of the carb and components. Could very well be you need a new top end as well. Call your local shop for the compressoin #'s.
If the bike ran great previously then dont mess with the jets at all. Leave them alone. There is something else wrong with the bike. Clean the air filter. change the plug. check the compression.

here is the latest.

Compression., over 150

Carb clean and set to the settings recommended in the book. When adjusting the air mixture screw, which direction will lean it out? IN or OUT? I could not find any info on this in the book.

Air cleaner cleaned and re-oiled. Still running the stock air box with the uni filter. should I ditch this and go for something less restictive?

Gas, 92 octane pump gas mixed with Super M synthetic oil, 20:1. Bike still smokes like crazy, and there is a lot of un-comsummed oil in the exhaust. Should I reduce the amount of oil in the mix, more like 30:1?

Over all, it seems to run good, but the smoke is way too much. I don't think that I have a bad head gasket, there is no sign of loss in the water level.

I am going to try a different plug,(hotter) and change my fuel mixture. Any other thoughts?

32:1.
Do a throttle chop on a new plug and check it.

20:1 is old school stuff. Todays oils are better etc..

ScottCalvin went from 20:1 to 32:1 and woke that mofo bike of his UP!

20:1 is too much oil. At the most I would run 32:1. You could probly get away with 40:1 Thats what I usually run. Hey Rob, you and I should start charging for this...

[ 01-24-2003, 02:08 PM: Message edited by: Shane-0 ]

40:1 risky? NO WAY!!!!! I run 50:1, so do a lot of other people. Especially those that run BelRay. I use BelRay H1-R now, used to use MC-1. You just buy a little bottle and dump that into 5 gallons.

Look, the oil ratio is all up to you. The 20:1 was for when people used something like 30W oil. Remember, the more oil in the gas, the thicker the gas, the bigger the main jet needs to be. For example, I run 50:1, if I were to dump a bit more oil into my mix and make it 45:1, I would run leaner because the gas is thicker and cannot get through the jet as good. Now, you're at 20:1, you say it's smoking. You'll go down to...say...32:1 and you're bike will run richer, most likely (if it's jetted for the 20:1.) Just take your Super M, buy a Ratio-Rite and run 32:1. Don't forget to totally take all the gas that's in your tank now, OUT. Start fresh. But remember, if you used a castor oil to start with, stay with that. If you don't, the oils will not work and you can toast your crank. Just run 32:1 and jet like stated above.

BAM BAM,
YOU SAID THAT I NEED TO STAY WITH THE SAME TYPE OF OIL. COULD YOU ELABORATE ON THIS A LITTLE? IT JUST DOESN'T SEEM LIKE THE DIFFERENT OILS WOULD DO ANY HARM. THEIR JOB IS TO LUBE THE BEARINGS, AND THEY DO JUST THAT.
IF I WERE TO DECIDE THAT I NEEDED A DIFFERNT OIL, WHAT WOULD I NEED TO DO SO THAT I WOULDN'T FRY MY CRANK LIKE YOU SAID?
I KNOW THAT THERE HAS BEEN A PREVIOUS POST AS TO THE BEST OIL, BUT, IS WHAT I AM USING CRAP?

Don't quote me 100% on this, but I've been told that Castor based oils pool up in the bottom of the crank and lube it that way. Synthetics don't. If you use a synthetic in the same case as the castor based, they won't mix. They will actually separate and you won't have any lube what so ever. Also, it's not good to switch brands. They all mix with gas different and will have a different effect on the jetting. You wouldn't put 10w-30w Castrol in your car then top it off with 5w-50w Quaker State right?

Hey gurus, I was doing some frame repairs to my quad, had to remove the exhaust to repair the mounting tab looked down the hole to the piston and noticed the top of the piston is eaten away, almost down to the first ring just at the exhaust port, I'm sure I will need to put a new piston in soon, I have maybe 60 hours on the rebuild, this seems like excessive wear, is it because I was running to big of a main jet, or due to not having the exhaust sealed at the flange?

not soon more like right now ,no sense in trying to get a sick bike to run right.you need to pull the top end off and get a good look at that piston. you will probally figure out whats up /w/ the rest of your probs.

Right, by soon I mean before the next outing, however if this is the normal behavior that's cool, but if I have a problem I would like some expert advice to what causes the piston to be eaten away, in the guru's experience, is this premature or does it just happen, should I buy some gunk to seal the flange to the pipe or Is that just not needed? Should I try a different company for the piston, or is weisco the best? Should I just sell the damn thing and buy a Banshee (he, he, he)? I would but Who would pay $5000 for my bike

IF YOUR GETTING SEAPAGE OUT THE PIPE I WOULD REPLACE THE O-RING THAT IS INSIDE THE PIPE THAT WAS NOT THE CAUSE OF YOUR PROBS . BY EATIN AWAY DO YOU MEAN MELTED MELTED IS TO LEAN IF IT LOOKS LIKE SOMETHING WAS BOUNCING AROUND IN THERE CHEWING THE PISTON YOU WILL NEED TO DETERMINE WHAT IT WAS . IF IT'S JUST SOME WEAR AND TEAR ON THE SIDE OF THE PISTON THAT IS NORMAL WEAR AND TEAR.WHILE YOU HAVE IT DOWN I WOULD LOOK AT YOUR SEALS AND BEARINGS 86 WAS A LONG TIME AGO .

Alright, the piston is melted away, but for the longest time I was having a jetting problem, I was running too rich, if you have read all the posts on this topic. So I changed my jets to a leaner mixture, runs great now, but I've noticed that my piston looks bad just at the exhaust port, after rejetting I only rode for around 3 hours, so could this damage have been done in that short amount of time? Or is something else the matter, could my plug be too hot or too cool? That would show in the top of the piston right? Would some one please explain why I run a stock jet with all the engine mods I have and it seems like every one else runs bigger jets with theirs? If you read my original post you'll see what I've got, should I run a larger carb? Does the porting and head job equal out the K&N and FMF? I love riding my bike it is great to ride, I do not like not knowing why things are the way they are, I have read so much on banshees and trx250rs that my head spins, for ex. the same mods on a trx require a #310 main jet, yet mine sputters with a #220, sup with that? Now I hear that I've been running too lean so my piston is melting away, I'd hate to go & top end every three or four holidays, What about lower octane fuel I currently use 91 or 92 would using lower octane fuel be better? All help is appreciated, thank you fellas so much for all so far.

Ok, the piston being "eaten" away is VERY BAD. Something is wrong. About the exhaust pipe not being 100% sealed at the flange is no biggie. Most 250Rs do that. I add a little bit of hi temp Silicone to stop the oil from coming out.

Now, remember, what size jet isn't important, it's how good your bike is running. You can have a 260 in your bike and have it jetted perfect and I can have a 270 in mine and run perfect. Every bike is different. I run a 38mm Mikuni carb so I couldn't tell you what size jet to run. From the sounds of it, you're still way to lean. If your bike is sputtering on the bottom, you need to adjust your air screw according to the book. Get it running right. BUT, you should tear your top end down again. Rebuild it, make sure you have no leaks and rejet it again. BE SURE TO BREAK IN THE BIKE RIGHT. Pistons should not be damaged at all, just covered in a bit of carbon.

Now, octane doesn't make a gas burn hotter or better, it makes it burn slower. Bikes with more compression need higher octane to stop detenation.(sp?) That occurs when the cylinder is hot and the gas explodes from the compression/heat before the piston reaches top dead center and it's REALLY bad, so keep the higher octane. With the porting and polishing you should mix a little bit of race gas. I run 2 gallons of VP 112 leaded to 3 gallons of 91 Unocal 76 gas.

Anyway, put the thing together, break in the bike right, you shouldn't be able to sieze it just breaking it in. Be sure your needle clip is in the middle position. Then jet it like stated before. Don't make the plug the grayish cocoa color that is perfect, make it more of a chocolate brown, it's safer to run a bit richer. If you have questions about it, take the plug to the motorcycle shop and have them look at it. Make sure you are throttle chopping it right though. That's very important, go full throttle in 3rd, 4th or 5th gear for a few seconds then pull in the clutch, let off the gas and turn off the bike all at the same time and coast to a stop.

Good luck.

Thanks BAM BAM, good info, will do the rebuild thats a must, check for no leaks? of compression, intake, exhaust, or seals, most seals have been replaced just before labor day 2002, Thanks again.

check for leaks in all the seals, especially the cylinder base gasket and head gasket.

20:1 is way to much oil......32:1 at least...but dont jump up to high to fast! Like going straight to 50:1. Jetting is a pain but it is worth it!