85 250r too rich

[Auto_Demon]

K so i just bought a full fmf exhaust system for my 250r and it made it more rich than before? I bought a bigger size jet like everyone says but its too rich, and by the looks of it the jet i bought is smaller than my existing jet. I dont know what to do, the clip is on the leanest setting on the needle, running 32:1 with airbox and lid (no holes). It was running perfect without the fmf exhaust and when i put it on, same settings and eveverything, it made it more rich. Does anyone have any suggestions? I dont want to change the ratio but i will if it means it will run better.

[manbearpig]

Take the airbox lid off. what are/were the numbers on the jets you have?

[Auto_Demon]

Drilled holes in the airbox lid, bought a 148 size main jet for the exhaust because everyone said it will lean it out so you will need a bigger jet but by looking at it it looks smaller than the one i had on there already

[barnett468]

Simple, if you're sure it's rich get a smaller jet from the same vendor. some of the aftermarket jets are not equal in size to the oem ones.

[manbearpig]

ok well stock jet for your bike is a 142. i have had great success with that carb jetted at 142 with a ported, polished, milled, and piped setup.. and could even step it down and still be safe. if youre concerned with your jetting and dont want to run the stock jet for fear of running too lean, but feel that 148 is too fat, drop a 145 in there and start playing with the clip on the needle.

...and, as always, DO YOUR PLUG CHOPS!

[Auto_Demon]

But its not the stock carb, its a chinese 36mm flat slide, the jet that came with it looked bigger than this one

[barnett468]

But its not the stock carb, its a chinese 36mm flat slide, the jet that came with it looked bigger than this one
Simple, if you're sure it's rich get a smaller jet from the same vendor. some of the aftermarket jets are not equal in size to the oem ones.Get a jet from the same place you bought your new jet from.

[yamaha225dr]

What exhaust did you have before?

[Auto_Demon]

What exhaust did you have before?
Stock exhaust

[manbearpig]

swap out that mikuni. if you like the flow of a 38mm, look into the Keihin PWK 39. there are guys on here that'll swear by it.

[yamaha225dr]

Something is wrong if an aftermarket exhaust richened the air/fuel mixture or the stock setup.

[Auto_Demon]

Its not a mikuni, its a keihin knock off cuz it takes keihin jets, its an "oem std" 36mm flat slide pj, i have a 38mm keihin pj but im waiting for the guy i got it off of to get me the cap and slide

[82 250r]

I bought a bigger size jet like everyone says but its too rich,

The FMF website recommends that no jet changes are necessary for the 85-86 Honda 250r. In other words, if the trike was jetted correctly before, a FMF pipe won't change that.

http://www.fmfracing.com/RiderSupport/JettingCenter

[Auto_Demon]

Well im going to have to now, i didnt change anything when i put the exhaust on and now its super rich

[2fiftyR]

I had the same problem with my 85. I jetted it down and tuned it so it ran great with the airbox lid off and crappy(rich) with it on....dont know why,that was three years of HARD riding ago so there couldnt have been something else wrong or it would have melted down long ago.I dont remember what jet size went in it so I cant help there. This winter I see a teardown comming because I just want to see whats going on in the motor(no catastrophic failures)

[barnett468]

Well im going to have to now, i didnt change anything when i put the exhaust on and now its super richFrom post #4.
Simple, if you're sure it's rich get a smaller jet from the same vendor. some of the aftermarket jets are not equal in size to the oem ones.

[jb2wheels]

Something is wrong if an aftermarket exhaust richened the air/fuel mixture or the stock setup.

I've had four strokes need leaner jetting with a pipe. Essentially the pipe was efficient or tuned enough to create a a stronger "signal" at the carb. I imagine a 2 stroke could have the same problem?

A little off topic... I had it happen with a Bill's pipe on a 185s. I remember because I could not get it sorted and I was a know it all teenager at the time.

My dad, of course, told me it needed to go leaner. He had the same thing happen on an old Roundtop. I finally relented and did what he said and sure enough, he was right...

[Auto_Demon]

K so i put a 138 main jet in, holes drilled in airbox and running 50:1 and its STILL rich! What the hell is going on, i dropped a full 10 main jet, went from 148-138

[Slingblade]

Go back to 32:1, 40:1 at most. Never change your pre-mix ratio to tune your bike.

Was the exhaust new or used? Check your silencer packing.

Did you put in a new plug with the jet change? How exactly does it run?

[Auto_Demon]

brand new fmf exhaust, put in a new plug when i put the jet in, it runs fine until wot then it sputters, but it smokes alot

[Slingblade]

Did it help it going from 148 to 138, or run about the same?

It could be a crap shoot with that carb, I know nothing about them.

Just make sure to do a wot plug chop to be certain your not headed the wrong way.

Check the choke circuit in that carb, make sure it's closing off, that would do it.

[Auto_Demon]

it did help a little bit, it smokes less than it did before. i did a plug chop, just waiting for the bike to cool down so i can check it.

[Auto_Demon]

plug is slightly wet and black all the way down inside with a slight brown hue

[Auto_Demon]

Well it looks like im getting even smaller jets

[barnett468]

brand new fmf exhaust, put in a new plug when i put the jet in, it runs fine until wot then it sputters, but it smokes alot

plug is slightly wet and black all the way down inside with a slight brown huecan you post a photo?

yes try around a 130 if 135 was the last.

what color is the smoke, lite gray or dark black?

does it linger or dissipate after a few seconds?

You plug should be bone dry when you remove it hot after 30 seconds because the heat will dry the gas up. if it is even barely moist 30 seconds after removal it is oil.

i suggest a leak down test. you might be sucking oil from the gear box due to a bad crank seal

:Bounce

[Auto_Demon]

Ill post a picture tomorrow. Smoke is light greyish blue, and it lingers for a long time. I checked the chaincase oil and its at a good level, rode it around for a good 5-10 minutes and checked it again and it was fine

[Auto_Demon]

I guess i should have mentioned this before but if you put your hand behind the silencer and rev it you will have oil on your hand and there is oil leaking from the pipe

[yamaha225dr]

I guess i should have mentioned this before but if you put your hand behind the silencer and rev it you will have oil on your hand and there is oil leaking from the pipe

Splooge is normal on an improperly jetted two stroke but if I were you I would ditch that carburetor and do a leak down test. Something is wrong with your machine and it sounds like you are gonna just chase your tail trying to get it resolved just throwing jets at the carburetor. There is no way going from a stock exhaust to an aftermarket one is gonna require you to lean out the air fuel mixture that much! Which brings up another point. Have you checked the packing in your silencer? Any dents on the expansion chamber or any chance something is inside the exhaust obstructing the exhaust flow?

[3wheelrider]

What carb do you have exactly.- something is wrong with that carb it seems.
The needle in the leanest setting? that alone isnt right. -Could it be a problem with the choke interfering with jetting?

[Mosh]

I have been watching you start thread after thread about running problems on this trike.
a few weeks ago you post about how this thing just shut off randomly and would not rev out right and installed a new stator, and still seemed to have running problems..

http://www.3wheelerworld.com/showthread.php/159672-Symptoms-of-bad-crank-seals

http://www.3wheelerworld.com/showthread.php/160281-Here-I-am-with-another-problem...


You posted pics of a severely scored piston here...http://www.3wheelerworld.com/showthread.php/160301-85-250r-worth-it-to-rebuild?p=1246100#post1246100

You posted pics of a major problem with the crank bolt coming loose and gouging the side cover and probably damaging the right side crank seal here...
http://www.3wheelerworld.com/showthread.php/160287-1985-250r-leaking-case-oil..

Now you are asking why it runs too rich..My guess based on your previous posts are that the crank seal is sucking oil on the right side, you have massive blow by due to a badly worn piston and rings, and I am willing to bet that your balancer bearing is shot too, and that is why the crank bolt worked loose..

My friend..You need to yank that engine and do a complete overhaul on it IMHO.
Other wise you are going to cause more damage and and just keep asking questions on why it does not run right and end up taking the advice of "buy this" or "get rid of that" from folks that may not know the whole story..

Not trying to be rude, but I think you bought a trike that has been neglected and it is time for you to fix it right and not waste money in the process.

[yamaha225dr]

I never realized the same guy has been posting all of these threads and I have replied to a few of them. Yea, that trike is in serious need of an overhaul!

[Auto_Demon]

Ya, sorry for all the posts guys but i just need it to run long enough so i can take it on our camping/quading trip on the weekend of september 6. After that i am doing a rebuild on the motor

[Mosh]

I am not scolding you at all and you have no need to appologize for the questions. I was just putting the puzzle pieces together to form the whole picture.

Now IMO, I have pulled 2 R engines apart this year, that were purchased as "runners" that had stock pistons that looked like yours. They both had cracks going up the exhaust and intake sides and were literally seconds from shattering into a crankshaft twisting, jug cracking mess. One actually chipped some of the piston off and wadded the crank bearing up. I would highly advise you do not run it anymore. I have a feeling you might have the same thing going on. The one engine, had so much piston slap it cracked the bottom of the jug sleeve. If yours grenades, you are taking a major gamble on crank and case damage that will take a 800$ overhaul and double that price possibly...Just looking out for you..

[Auto_Demon]

Well to be honest if it was gunna go it would have aleady, when i had it running good i ran the piss out of it and it was fine, but it is getting an overhaul

[El Camexican]

Well to be honest if it was gunna go it would have aleady, when i had it running good i ran the piss out of it and it was fine, but it is getting an overhaul

Your money Dude, but if you end up venting your cases it's gonna be an expensive weekend.

PS. About that Chinese carb. There are two things in life you should never buy knock-offs of: one is Vise-Grips, the other is carbs. Get a used 36 or 38mm Keihin off eBay and rebuild it, you'll have a much better carb.

[Auto_Demon]

Ya i never bought the carb, it came with it, when i rebuild it im going to get a 36mm keihin pj quadvent, found one for $250

[El Camexican]

Ya i never bought the carb, it came with it, when i rebuild it im going to get a 36mm keihin pj quadvent, found one for $250

Too much! You should be able to do better than that for a PJ. Heck I have a fully rebuilt one with a new choke assembly and it's polished to boot. $150 + shipping and it's yours, but I'd recomment something like this over the PJ.

http://www.ebay.com/itm/KEIHIN-36MM-PWK-QUAD-VENT-CARBURETOR-TRX-250R-ATC-TRX250R-BANSHEE-/310721915414?pt=Motors_ATV_Parts_Accessories&hash=item4858782a16&vxp=mtr#ht_533wt_1255

[Auto_Demon]

Well i have the majority of a 38mm keihin pj, just missing cap and slide but i dont hVe the main jet for it and i want to keep the airbox and the boot wont fit over

[yamaha225dr]

It's your machine but you are gonna really have a problem on your hands if that motor grenades. I can have my whole engine rebuilt for $600 but if it grenades and sends shrapnel down to the transmission the price can easily surpass $1,000. Which price would you rather pay? My motor is still pushing 180p.s.i but it's getting a full rebuild this winter just for the extra insurance.

[barnett468]

brand new fmf exhaust, put in a new plug when i put the jet in, it runs fine until wot then it sputters, but it smokes alot




plug is slightly wet and black all the way down inside with a slight brown hue



can you post a photo?

yes try around a 130 if 135 was the last.

what color is the smoke, lite gray or dark black?

does it linger or dissipate after a few seconds?

You plug should be bone dry when you remove it hot after 30 seconds because the heat will dry the gas up. if it is even barely moist 30 seconds after removal it is oil.

i suggest a leak down test. you might be sucking oil from the gear box due to a bad crank seal



Smoke is light greyish blue, and it lingers for a long time.It is positively burning oil.



I checked the chaincase oil and its at a good level, rode it around for a good 5-10 minutes and checked it again and it was fineUn fortunately it takes very little crank case oil to cause an engine to smoke so you might not notice a drop in your oil level in a short period of time.





plug is slightly wet and black all the way down inside with a slight brown hue



Simple, if you're sure it's rich get a smaller jet from the same vendor. some of the aftermarket jets are not equal in size to the oem ones.
Ya, sorry for all the posts guys but i just need it to run long enough so i can take it on our camping/quading trip on the weekend of september 6. After that i am doing a rebuild on the motor



My last post suggested a leak down test and mosh also recommended one. I also requested a photo of the plug and suggested you get the proper heat range if is not.

I suggest you simply follow my jetting post above until it runs clean or melts the piston, which ever comes first.

Even if you were running diesel oil with your gas it should not smoke at 50:1. that;s why i asked about the color and suggested it might be your crank seal...

[Auto_Demon]

Replaced the right side crank seal and its running better than ever now

[barnett468]

Replaced the right side crank seal and its running better than ever nowWow, that was fast, well glad to hear it.