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Spooge Again, But With Suggested Plan

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Would like to hear your opinions on this, especially as they’re much more educated than mine.

Situation:

1.  2013 YZ250.

2.  Bike seems to run well; no sputtering, bogging, etc. Throws me on the ground every so often.

3.  Burning C-12 and Maxima K2 at 32:1.

4.  Stock plug BR8EG. Plug is dry and black, not wet or brown.

5.  Noticed a small bit of spooge sitting inside the silencer – but not enough to run out. A week later spooge leaked out of the exhaust pipe/silencer joint. Took silencer apart and the packing is soaked.

6.  Air screw is out 2 1/8 turns. Manual recommends 1 ¼ turns.

7.  I live mostly with the throttle between closed and ½ open.

The assessment:

1. Running a bit rich, but not extremely rich.

The fix:

1.  Replace muffler packing.

2.  Put air screw at 1 ¼ turns out, then adjust as indicated.

3.  Ensure needle jet clip is in the second groove per manual.

4.  Install one size smaller pilot jet if #3 is per manual.

5.  If it’s still a bit rich at that point I’ll move the needle jet clip up one slot.

What does confuse me a bit is the fact it runs so well, I’ve never fouled a plug, etc. yet spooges the heck out of the muffler packing.

Am I thinking right here?

And FWIW, 2 of the silencer bolts were seized. I used some PB Blaster and that stuff worked great.

Thanks, Don.

A bit about me as I'm the new guy:

56yo, been off the dirt bike 27+ years.  Couldn't stand it any more and bought the YZ in April.

Nice Forum here - I've been reading for a month or so.

Edited by SpunBearing

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Sometimes we can go around in circles with the air screw and pilot jet and needle and never get it right.

 

The motor running too cool causes spooge, I suspect you might be a YZ250 owner who could be very happy with the leaner #8 slide.

 

After reading advice here, I'm using the #8 (from JD with their cable holder), and I find it's excellent. Much less spooge and no more 1/8 throttle sputtering.

 

I suspect that ideal jetting is slightly dependent upon rider preference and habit.  If you tend to suddenly snap the throttle open a lot in some throttle pos range, the jetting at that throttle range needs to be slightly richer to avoid hesitation.   eg.  On my YZ going into turns I like to be driving the rear wheel early, so I'm typically rolling open throttle gradually to 1/4, then I quickly open it to 3/4 or more. So I'm setup a little rich around 1/2 throttle with the needle, but leaner (and more crisp) on the slide and pilot settings.

 

Since the #8 works so well for some of us, ​I've often wondered why Yam sells the #7 slide as the stock part. Maybe someone more knowledgeable on this topic can comment. I have two guesses:

1. 2 strokes are sensitive to tune state. So small diffs in porting, fuel, engine temp, reeds, carb parts can mean different needs.

2. Many YZ250 riders, or at least Yamaha's testers, like/need the rich air/fuel in the 1/8th to 1/4 range. For example the type of rider who brakes deep into turns, slides the rear, pivots, points and shoots, never rolls past 1/8th throttle but snaps quickly from closed to 3/4 or open. For that kind of rider a #8 slide might cause some hesitation.

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I hadn't considered fuel burning temps.  Thanks moto, and I'll do some reading on that.

 

Thanks numroe, a different slide is on my list of things to consider and/or try.  And you kind of touched on my predicament:  I really like the way the bike responds now, and I'd rather not change it.

 

Maybe I'm trying to fix something that can't be fixed:  stop/mitigate the spooge yet keep the same running characteristics.

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If your packing was soaked, then I'd fix it. You'll probably have a lot of oil in your pipe too. Things will get worse.  It might pull ok as is, but it can be better. A lot better.

 

You'd probably find that if you changed nothing else but rode the bike harder, you'd have a thick spooge drip right down the silencer body dripping onto your swing arm.

 

That leaner #8 slide is worth a try. It allows you to go one clip richer on the stock W needle, and get clean crisp roll-on power from idle to 1/2 open and to wide open if you have the required main jet size.   The motor will sound great too, if you're a 2 stroke lover.

 

After you adjust the carb, and before re-testing, you should repack the silencer and try clean out the pipe. That built up oil will keep coming out forever.

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You're welcome.

 

I'd don't think it's difficult to know when you're motor is feed the right mix of oil, fuel and air. It'll pull smoothly at any throttle position.  It will have some nice heat in it, but not too much. There will be a little bit of oil smoke at times, and lot when the bike has sat for a few days or more. A little bit of spooge is I think a good sign because it suggests your piston is not too hot. Experts can maybe comment on that.

 

Here is an article explaining ways to seize your motor. It'll encourage you to go rich:

http://www.off-road.com/dirtbike/tech/dirt-bike-tech-twostroke-seizure-52428.html

 

Here is a popular old TT post on mix ratios for fuel:oil and air:fuel

It'll encourage you to go lean:

http://www.thumpertalk.com/topic/636371-premix-ratio/

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The yz250 head is a joke in stock form the squish is stupid huge around .070 inch.  A smaller squish of .040-.050 is best. Spooge is a big side effect with an inefficient head. Send the head to rbdesigns  for .045 inch squish and whatever type of fuel you want. it is the best money you can spend on your yz250

 

K2 is decent i found amsoil dominator burned cleaner, For what you are doing I would switch to amsoil interceptor. it is even cleaner than the dominator.

 

the leaner slide and leaner pilot circuit will help, but honestly just get your head setup and your problems will go away.

 

The smaller the squish i run the cleaner and more crisp my bikes run. the rm250 is one of the snappiest cleanest running motors out there and stock is has about .045 squish. this is not a coincidence!  My varner built race fuel only rm250 motor had a squish of about 1mm or .039 and it was the cleanest crisp responsive running bike i have ever owned.

 

 

set squish to 1-1.2 mm aka .040-.045 inch

repack silencer

if you already like running c12 i suggest you get the head setup for it and take advantage of all that glorious octane.

 

I guarantee the problem goes away if you do this.

 

read this

http://www.thumpertalk.com/topic/492565-yz250-squish-clearance/

 

than do this

http://www.rb-designs.com/squish-band-test.htm

 

and send it to him for proper setup

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lower flash point oil or a 450F

 

Wouldnt you want a higher flash point (so the oil can actually lubricate instead of burn) and a lesser ratio (closer to 50-60:1 for slower riding?)

 

This is how I do it and have had excellent results, the most oil I ever use is around 48:1 when a lot of WOT is expected.

 

Why a LOWER flash point? 

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Wouldnt you want a higher flash point (so the oil can actually lubricate instead of burn) and a lesser ratio (closer to 50-60:1 for slower riding?)

This is how I do it and have had excellent results, the most oil I ever use is around 48:1 when a lot of WOT is expected.

Why a LOWER flash point?

For low temperature applications like slow single track riding where you can't get bike up to operating range. You want to encourage burning because the heat is absent at 0- 3/8th throttle range. Lubrication typically not a high concern with this throttle range.

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I had a similar problem when i first switched to race fuel and 32:1 royal purple (not quite as bad as soaking the packing but running rich), dropped down to 50/50 104 octane. And adjusted my air screw and never had a problem since.

Though my throttle range is either wide open or not at all.

Edited by LAYZ71

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Thanks for the fuel burning temp information.

At the advice of some folks I ride with I removed the 178 main and installed a 175. That didn’t make sense to me, but since I’m the newb I ran with it.

And I didn’t like it at all. In the ½ to WOT range the bike seemed to be starving, didn’t have as much power, sounded lean rather than the previous fat, etc. The spark plug looked the same as before I started these mods, and still had a small bit of spooge at the silencer. Air screw was fastest at 2 ½ turns out.

Today I re-installed the 178 main, removed the 50 pilot and installed a 48 pilot. I’ll try it from this direction. Air screw was fastest at 1 ½ turns out. I’ll have to final adjust it when I can get to the trails.

Thing I forgot to mention in my original post was when the bike was idling and I blipped, there was just a tiny tiny bit of hesitation. Never noticed it while riding as I never was in that situation. After swapping the pilot, I think it's gone. Will confirm when I get to the trails.

Truth of the matter is I really liked the way it ran before. Now I'm just experimening to see if I can clean up the spooge. If I can't keep the same running characteristics, I'll return the entire thing to stock...and just repack my silencer as needed.

What I found really interesting was how much things changed just by swapping out that main.

Does anyone have any numbers detailing exactly how that (178 to 175 main) affected the air/fuel ratio?

Edited by SpunBearing

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In the back of your manual under the tuning section there is a chart that shows how much percentage 1 jet change makes.

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My 295 I have a 168/42 pilot . Run yamaha lube 50 to 1. I have chased jetting from too big now to leaner setting, plan a 40 pilot as the idle side could be slightly cleaner with the air jet,8 slide. Raced a enduro this weekend and that thing motored clean, just had brake problems.

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My 295 I have a 168/42 pilot . Run yamaha lube 50 to 1. I have chased jetting from too big now to leaner setting, plan a 40 pilot as the idle side could be slightly cleaner with the air jet,8 slide. Raced a enduro this weekend and that thing motored clean, just had brake problems.

With those small jets, what altitude, typical air temp and approximate humidity are you riding at/in?  Also which needle and clip position?  I need to try a 45 pilot. Currently using a 48. This will be my first summer with this motor. 

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around 600 ft, 60 degrees or so, middle clip on a stock needle.

i have not even unloaded my bike yet, really slacking ............ going to pull the plug and see what it looks like, beside just a enduro there was a good grass track and on it i was able to open it all the way up, almost scary fast ! lol . 

just about talked myself into getting a new lectron and try it out, going to try this one size smaller pilot and see what happens and after that i'm going to update.

as it sets it motors perfect, just don't like the start up off choke as i have fouled a few plugs, wanting to put a ty davis oversized tank on also and don't want any plug issues. 

our enduros here are mainly single track stuff that is not high speed.  this jetting might not work out where you in the upper power band, me i'm using the lower part and that is where it needs to run clean.

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bobby, Is your 295 kit on a 1999+ YZ250 motor or something else?  I just noticed your TT garage shows a 1992 WR250, which makes our jetting incomparable.

 

If you do have the current YZ250 motor and 295 kit, then to make your leaner jets work I can only guess you have a lower float bowl level, different reed valve, restrictive air filter or exhaust, or something else that makes you carb mix rich without smaller jets. Not being critical! Just curious. If it works it works.

 

I must try a leaner 45 pilot jet, but so far I've not felt any need except for my motor's reluctance to idle low and consistently. If I have to choose between a little bit of spooge (rich) or else some hesitation to throttle opening, I'll choose the richer setup with spooge any day. Hesitation is too annoying.  Luckily I've never fouled a plug yet in this bike after about 40 hrs. 

 

 

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Its a 04, too many bikes.. I over service my bikes. Ram valve, fmf pipe, stealth q muffler. Pulled my plug and it clearly wasn't lean after the race. My idle isn't good like my 92 wr by any meaning. Minor jetting on the 92 and done. This 04 I have been all over the map on jetting and still chasing. Zero spooge on my muffler.

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