1985 big red 250es running lean....how do i fix this?

[dylanisaacs]

my 1985 big red 250 is running lean because i pulled the plug today and the bottom-inside of the plug was white. how do i fix this? and can this cause overheating?

[dougspcs]

Can definitely cause engine damage..

Remove your carb and look for dirt or restriction in you main jet, if none then move the main up to the next size number jet to richen the mixture.

But double check you are running the correct plug..too hot a plug will also give the appearance of running lean..

Either us bad..the stock NGK # DR8ESL

[TxPowderCoater]

like said, check for crap in carb, take the time to unscrew the low speed jet and the main jet and get them clean with #bits and air pressure. also check emulsion tube to make sure the holes are open and happy as well.

[dougspcs]

like said, check for crap in carb, take the time to unscrew the low speed jet and the main jet and get them clean with #bits and air pressure. also check emulsion tube to make sure the holes are open and happy as well.

What's the emulsion tube? Your BR got parts on it mine doesn't?

[tri again]

emulsion tube?
as I recall there some tube under on of the carb jets full of holes and usually muck.
may have been called an emulsion tube. and yes, mr Tx, I missed that sucker 3x.
Good call.

Reminds me, I never replaced the external venting tubes on
my 87 es after a 2 week carb fiasco that ended with it on the kitchen stove and some marriage counselling. Those are the only other tubes that come to mind that may make a difference.

do you have:
factory exhaust?
un messed airbox?
stock air filter?
as doug said, the correct plug?

When my 100 runs lean the exhaust gets cherryred and see through.
Can't be good.

[dougspcs]

Emulsion tube..googled it. Hey yeah I got one of those. Starting to feel jealous cuz everyone had one but me!

Handled it like a hundred times..no idea it had a name.

Always good to learn new stuff!!

[barnett468]

Hello Dougspcs



check emulsion tube to make sure the holes are open


What's the emulsion tube? Your BR got parts on it mine doesn't?

This is an item that people who are not thoroughly familiar with how some features of a particular carburetor work either don’t know their carburetor has and/or don’t know how it works.

There are many good books on carburetors that explain what effects different parts/circuits etc, have.

The “emulsion” tubes in question are actually misnamed, because they quite simply do not emulsify anything. They are simply tubes with holes called “aerator” or “aeration” holes [in this application].

Their primary function in this application is to partially “regulate” or “control” the amount of fuel that can flow through them up the maximum amount the main jet can flow at different atmospheric pressure levels inside the tube when used in a “siphon” [not forced like fuel injection] type system.

The amount of atmospheric pressure inside the tube is relative to the atmospheric pressure immediately above the open end of the tube which is relative to the velocity of the air passing immediately past the open end of the tube.


See links below for photos of “emulsion” tubes.


NEEDLE JET/EMULSION TUBE COMBO

http://www.ebay.com/itm/Emulsion-Tubes-needle-jets-36-Mikuni-CV-carbs-/290294228981


NEEDLE JET/CHOKE WITHOUT AERATION HOLES (NON EMULSION TUBE TYPE)

http://www.ebay.com/itm/Mikuni-Needle-Jet-VM30-VM32-VM34-VM36-VM34-05-159-P6-/150847544454


PILOT JET/EMULSION TUBE COMBO

http://www.ebay.com/bhp/honda-pilot-jet

[dougspcs]

Hello Dougspcs

This is an item that people who are not thoroughly familiar with how some features of a particular carburetor work either don’t know their carburetor has and/or don’t know how it works.

There are many good books on carburetors that explain what effects different parts/circuits etc, have.

The “emulsion” tubes in question are actually misnamed, because they quite simply do not emulsify anything. They are simply tubes with holes called “aerator” or “aeration” holes [in this application].

Their primary function in this application is to partially “regulate” or “control” the amount of fuel that can flow through them up the maximum amount the main jet can flow at different atmospheric pressure levels inside the tube when used in a “siphon” [not forced like fuel injection] type system.

The amount of atmospheric pressure inside the tube is relative to the atmospheric pressure immediately above the open end of the tube which is relative to the velocity of the air passing immediately past the open end of the tube.



Barnett, you're doing it again!!

I just hadn't heard that term before and was having fun with it. I've always called it the primary nozzle!

Please don't megapost me! I didn't ask to be schooled..

But thank you for putting the big words in quotes for me to look up.

Quit being so "patronizing" and "condescending", it's not winning you any friends!

[TxPowderCoater]

What's the emulsion tube? Your BR got parts on it mine doesn't?
dunno what BR is, but my 200 has a keihn carb with an emulsion tube on the end of the mainjet, its what the needle drops into.
I guess the 250 has a different carb and if so, still clean it no matter what type it is, sounds plugged.

[dougspcs]

dunno what BR is, but my 200 has a keihn carb with an emulsion tube on the end of the mainjet, its what the needle drops into.
I guess the 250 has a different carb and if so, still clean it no matter what type it is, sounds plugged.

BR = BigRed

[dylanisaacs]

do you know how many turns to adjust it when i put it back in?

[TxPowderCoater]

do you know how many turns to adjust it when i put it back in?
there is no adjustment on the emulsion tube, snug it down and then snug down the jet into it. The air fuel screw is adjustable and it is usually 1.5-1.75 turns out is a good starting point and then fine tune from there but only when the engine is up to operating temp.


wooot 10!

[dylanisaacs]

ok but where is the air screw? i caint seem to find it in the online manual or on the carb

[TxPowderCoater]

some are actually blocked off with a small disc, If so, I usually drill through with an 1/8 bit and then use an ease out to grab the disc and pop it out. but I havent a clue w/o seeing what ya have. Some are out in the open easy to get to on the neck area that mates to the engine intake, some are on the side of the carb and some are under the very bottom of the carb by the edge of the bowl. I dunno what ya got but usually there is 2 screws that are adjustable, one is idle and its usually on the slide neck and the other is usually the air/ fuel screw.
send me a link to your online manual and I'l see what ya have and possibly help you better.
Sorry I couldnt help more.

[dougspcs]

Some carbs have air mixture screws, some have fuel mixture screws..you're has the later.

The fuel mixture screw is behind the float bowl under the carb..it isn't plugged.

[barnett468]

Hello dylanisaacs


my 1985 big red 250 is running lean because i pulled the plug today and the bottom-inside of the plug was white. how do i fix this? and can this cause overheating?

I’m glad to see the plug “chart” I made for you along with the other plug color related information I posted for you on your other thread [part of which is pasted again below] is helping you determine your bikes running condition. It is a very useful tool you may use many times throughout your life however a slightly different description would be given to the first 3 numbers when applying the chart to a car, especially on cars produced AFTER 1973. For cars produced AFTER 1973 the chart would read 1-2 good and 3 would reflect some sort of problem. An overly lean condition would show up differently than just the plug being #1 white.

I see you currently have 3 separate threads [original posts] that contain information regarding your carburetor and/or plug color issue. I posted a reply to your “troubleshoot” thread but then saw this one and saw it was currently the most active so I thought it would be better to post my reply here for you.

I have included some information that shows part of the chronology of events regarding your running/plug color issue so others that might not be aware of these things can better assist you. Information is important, the more you give and more accurate it is the better the responses that you receive will be.

Even if your bike idles fine, based upon your bikes history and the fact that it sounds as though you might have had the carb off since a week ago I suggest you do an air leak test by gently spraying [using the long narrow nozzle] FLAMMABLE [not water base] brake cleaner around the intake boot at the head and carb mount while the bike is idling. If the idle goes up noticeably you have an intake air leak.


“Hello dylanisaacs


Glad your bike is still running. When we left off 6 days ago your dad put oil in your tank to stop the rust and added fuel stabilizer a week or so before. Your bike ran ok after cleaning some gunk out of your tank/gas valve [but you didn’t say if there was any carburetion issues after I asked] and your plug was dry and black. Now all of a sudden, a week later your new plug is white.

Based on your bikes history I suggest you do not ride it until you answer the following questions so we can try and see what’s going on. If it is super lean it might get damaged from running too hot. If your plug has only been in for 30 minutes or less it might not have been in long enough to get color on it, but your bike sounds like it is lean for some reason based solely upon your description of the plug color.

Out of the extensive amount of plug readings I have done over the years I never saw a bike have a plug that that had less than 20 hours on it and was totally black go to having a new plug that was totally white for no reason at all. If your jets got plugged that much between then and now your bike would not run so it seems reasonable to think that you must have done something in between then and now which would cause this and if so it would help me and possibly others to know what it was first.


If you answer ALL the following questions I or another can help you better.



Originally Posted by dylanisaacs

my pop has now put a small drop of oil and stabilizer in my gas tank to clean the jets out

xxxxx

Originally Posted by barnett468

Hello dylanisaacs How many hours does the plug have on it approximately?


Originally Posted by dylanisaacs

plug has less than 20 hours i think, i ride at a mix of high and low but mostly low rpms, it needs 1/4 choke to start, it starts with the first kick, its 2. pale yellow with no rust or sedlemient

xxxxx

Originally Posted by barnett468

Remove the plug and by picking a number please tell us EXACTLY what color the pointed white porcelain part is.

1. White

2, Lite tan

3. Dark tan?

4, Dry black?

5. Moist gooey black?


Originally Posted by dylanisaacs

its 4. Dry black

xxxxx

Originally Posted by barnett468

Hello dylanisaacs Let us know how it carburetes too if you want, ie, any flat spots or burbles/stutters?

xxxxx

Originally Posted by dylanisaacs

pulled my plug today and it was white how do i fix it?


Did you change or do ANYTHING besides your spark plug since the last time you posted?

Did you still have oil in your gas while you were running with the new plug?

What number was the old plug?

What number is the new plug?

Did it burble/stutter upon acceleration with the black plug?

Did it have any flat spots [no burble or stutter upon acceleration with the black plug?

Does it run the same now as it did with the black plug?

Does it idle the same as it did before and does it idle ok?

Does it still require the same amount of choke to start now as iot did when the plug was black?

Do you notice your motor running hotter than it did before?

Does your exhaust pipe glow red after a while?

How long has your new plug been in there?

Do you know what your main and pilot jet sizes are?”

[tri again]

Hi,
Not sure I read everything correctly but I remember a
thread about using brakleen to clean stuff that will be torched or welded.
I personally can't seem to live without it.

Apparently it turns into phosgene gas in the presence of flame which can cause permanent lung damage with the smallest of exposure.

I've heard that carb cleaner can work to check for intake leaks but not sure about that either.
I read the can after I read that article and the warning is very vague.

http://www.3wheelerworld.com/showthread.php/127373-Deadly-poison-gas-from-welding-something-you-cleaned-with-brakleen?highlight=phosgene