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Can anyone tell me if I'm running to lean or to rich? I just rebuilt this motor on my yz250 and don't want to again. Its 35 currently turning into winter and I domt want to blow my bike up. 

The first picture I just took the spark plug out it's not fouled but I was just running it.

The second picture is a picture of the out plug that fouled out I'm not sure if it was in my 02 thought will still help me. I have 2 yz250s and just would like to hear a comment. I would hate to blow my bike up.

And is messing with the air fuel screw going to help me lean/richen it out? I run 30:1 on break in then will do 40:1 possibly

20181108_175206.jpg

15417213562176400277656489697094.jpg

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Can anyone tell me if I'm running to lean or to rich? I just rebuilt this motor on my yz250 and don't want to again. Its 35 currently turning into winter and I domt want to blow my bike up. 

The first picture I just took the spark plug out it's not fouled but I was just running it.

The second picture is a picture of the out plug that fouled out I'm not sure if it was in my 02 thought will still help me. I have 2 yz250s and just would like to hear a comment. I would hate to blow my bike up.

And is messing with the air fuel screw going to help me lean/richen it out? I run 30:1 on break in then will do 40:1 possibly

 

20181108_173202.jpeg20181108_175206.jpeg

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You don’t need to run more oil when running in motor, just mix up you normal ratio and oil 

search for “jetting with zook needle “ and you should get some answers for your elevation and temps 

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You don’t need to run more oil when running in motor, just mix up you normal ratio and oil 
search for “jetting with zook needle “ and you should get some answers for your elevation and temps 
Is that the type of needle I should get your saying?

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The correct needle is the NECJ for all around clean jetting.

As far as oil ratio, i ran 40:1 with AMSOIL Dominator year round, never fouled a plug.

There are enough jetting guides here to choke a horse, but the NECJ needle (suzuki RM needle) is key to a happy life.

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Looks lean on the main, or perhaps it just wasn't run long enough to color the insulator.
Yeah I wasnt sure that's why I wanted to see. I have picture of the fouled plug I thought I posted it but I didnt1541784919231.jpeg

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It won't hurt anything. It'll just run like garbage and foul plugs. You could jet much crisper and still be safe.

20181028_142851.jpg

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It won't hurt anything. It'll just run like garbage and foul plugs. You could jet much crisper and still be safe.
20181028_142851.thumb.jpg.b6ab9f3df1130c4e50939de8e12ffb9d.jpg
I just wanted to get it threw winter and after putting 1800 in the motor I dont wanna blow it yo maybe. Thank you

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12 hours ago, WILLY THE WORT said:

It's a Suzuki (zook) needle.

You can't read a plug that way. You read the BOTTOM of the insulator, not the tip of the plug.

http://www.braigasen.com/howtoread.htm

Cecil, you really need to read that webpage WILLY quoted and do a plug chop to know for sure. 

This graphic is one of the best guides out there:

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Cecil, you really need to read that webpage WILLY quoted and do a plug chop to know for sure. 



This graphic is one of the best guides out there:



image.png.26ed5eb5d12206665a97b4293b998f26.png
Yeah I did i screen shotted it to I dont have a saw to do that right now but i really need to

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Hi Cecil, you need to remember the more oil you premix in makes the mixture leaner (there's less gas in it but more oil) for instance 25:1 has less gas in the mix than 30:1, rich and lean is about the fuel not the oil content, mix your oil to gas ratio exactly as the manufacturer of the oil recommends on the bottle, less fuel in the ratio weakens the octane and increases likelihood of detonation and pinging, essentially the crappier the oil the more you need to put in, e.g. Motul, Amsol (very good oils) routinely run at 50:1 versus lawn mower mix at 25:1 (cheap oil) in motors that don't have tight tolerances and don't rev as hard as a bike.

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On 11/9/2018 at 8:12 PM, sbest said:

Cecil, you really need to read that webpage WILLY quoted and do a plug chop to know for sure. 

This graphic is one of the best guides out there:

image.png.26ed5eb5d12206665a97b4293b998f26.png

Questionable graphic in some regards.

I would not judge heat range by the color change on the ground strap.  Heat range will blacken the first few threads of the plug if the heat range is appropriate, but really you can run any heat range that doesn't foul or cause detonation.  The stock plug is usually the correct one unless you're doing unusual stuff with the motor.

The insulator color is a very good indication of mixture at WOT.  No need to cut plugs apart.  When the 1/2-full throttle jetting is good the insulator develops a carmel/rust orange color.  Det will not necessarily leave deposits on the plug.  You can burn a motor down from det and the plug may come out looking great.

I feel the jetting process is best done by riding the bike.  Start down low, get the pilot and needle clip position dialed in so the bike runs crisp up to about 1/4 throttle.  Four stroking, blue smoke and spooge indicate a rich condition.  Lean will cause a hanging idle and surging.  You want to be just on the crisp side of rich.  The main is pretty easy, lean will feel weak in the midrange and pull hard on top.  Lean may also cause detonation especially under high loads like deep sand.  Rich will cause smoking and may cause the motor to break up at high revs.  Rich on the main will leave the plug looking black.

I like to look at the plug on a well jetted bike to admire the beauty of a well seasoned insulator.  You can't jet the low throttle circuits by looking at the plug though.  Once you're close, the bike is running strong and crisply at low throttle, you can check your work by looking at the plug once you have some time on it.

 

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2 hours ago, parttimerider said:

Hi Cecil, you need to remember the more oil you premix in makes the mixture leaner (there's less gas in it but more oil) for instance 25:1 has less gas in the mix than 30:1, rich and lean is about the fuel not the oil content, mix your oil to gas ratio exactly as the manufacturer of the oil recommends on the bottle, less fuel in the ratio weakens the octane and increases likelihood of detonation and pinging, essentially the crappier the oil the more you need to put in, e.g. Motul, Amsol (very good oils) routinely run at 50:1 versus lawn mower mix at 25:1 (cheap oil) in motors that don't have tight tolerances and don't rev as hard as a bike.

This is true but the jetting is not significantly affected in practice.  32:1 is 96.875% fuel, 50:1 is 98% fuel.  You wouldn't be able to tell a difference between the two ratios on the same jetting.

32:1 with a good oil like Maxima Super M will work for all types of riding.  Less oil is not desirable or beneficial, more oil is unnecessary. 

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29 minutes ago, turbo dan said:

This is true but the jetting is not significantly affected in practice.  32:1 is 96.875% fuel, 50:1 is 98% fuel.  You wouldn't be able to tell a difference between the two ratios on the same jetting.

32:1 with a good oil like Maxima Super M will work for all types of riding.  Less oil is not desirable or beneficial, more oil is unnecessary. 

Hi Dan I agree more oil fowls plugs and exhausts, less oil is asking for trouble, the happy spot is a motor builder (on the type of oil) and oil companies recommendation.

32:1 vs 50:1 (96.875% vs 98% fuel) would be comparable to a RON difference like std unleaded vs premium, 32:1 mix vs 50:1 is also thicker (more oil in it) meaning the jets would run less volume as the fluid is (slightly) thicker and would be like going down a jet size or two, I realise these are small differences but it adds up and if it ends up as much as comparing 91 octane vs 98 octane then detonation could occur, further fuel in a two stroke does a lot of piston/chamber cooling as does the plug through the head, on a new and tight piston to sleave this heads towards a seize.

My point is run the mix as the oil manufacturer or the motor builder intended it to be then jet, on the safe side, for plug colour and adjust mix screw for altitude.

Apart from jets or a worn needle (Cecil mentioned the bike motor has been rebuilt are these worn too? he has 2 YZ250's should he be trying the others carb on this one) the other major issue is float level, a while back a guy gave me a tip, take your float bowl off and put a plastic container in the float bowls place, turn the fuel on and you can see exactly where the float level is and measure it as float level plays a big part in main jets and needle jets without changing the jet size.

 

anyway just my thoughts.

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