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Old 01-31-2011, 08:47 PM   #1
Metrotexual OP
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Sherco Gas Mix. 80:1???

Guys. or er.. ladies...

I just picked up an 02 2.9. Thing is, the manual that I have states the mix should be 80:1. That seems really lean to me. Any reason why this is so? i was hoping to pour the same mix I'm using in the KTM 300, which is a 50:1 Motul 710 mix.

Thanks.
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Old 02-01-2011, 12:02 AM   #2
BorisTas
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Quote:
Originally Posted by Teufelshunde View Post
Guys. or er.. ladies...

I just picked up an 02 2.9. Thing is, the manual that I have states the mix should be 80:1. That seems really lean to me. Any reason why this is so? i was hoping to pour the same mix I'm using in the KTM 300, which is a 50:1 Motul 710 mix.

Thanks.
Howdy Teulfel,

Have had 3 290's , an 00 an 07 and my current 09, various ones have recomended 50:1 on the sticker but I've always run 'em at 80:1 and they still drip oil out the pipe, some I know use 100:1 so presuming you are TRIALS 'ing them and not MX racing pick a fig between 50and 100 and go for it !!
Motul is agood'un so why not tip in 2ltrs of your Katey mix and 1ltr of fuel and you've got 75:1

BT
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Old 02-01-2011, 05:48 AM   #3
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Take Boris' word for it. 80:1 is more than OK for trials use.
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Old 02-01-2011, 11:52 AM   #4
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Awesome Gents. Thank you!

I've rewarded your kind reply with a photo of my scoot. It's an 02, and i paid two thousand for it a while back. Now i have made the time for trials and some training.

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Old 02-01-2011, 02:09 PM   #5
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Sweet scoot. Very nice!
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Old 02-02-2011, 01:21 AM   #6
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Thumb

Always liked the chrome frame models . very nice !!

Since we're doing the picture thing

2000




2007




2009 R




Hope you have as much fun with yours as I have

BT
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Old 02-02-2011, 06:03 AM   #7
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If I must.....






All three of my Montesas, the 314, 315, and the 4RT. Enjoy!
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Old 02-02-2011, 02:00 PM   #8
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PLEASE BE CLEAR! on oil ratio vs usage!

Teufelshunde: and anyone else getting a trials bike! Please note this about oil ratios...

80:1 If you use what most of us state & do ourselves, you MUST agree the following is true.
{ALL}

A: this is for water cooled, newer TRIALS bikes!
B: EVERYONE assumes you are riding trials! or practicing trials, not anything else.
C: Using good quality oils, I recommend fully synthetic.

If you do something we cant forsee, like enter some "last man standing" or
enduro cross, or decide to race to town some 45 miles away, running your
Trials bike that way, and "if" somehow stuff goes bad, Don't come back
and yell at all of us here.

In trials, if you think about what the engine is doing for "every minute"
while you "ride it" you would notice that MOST trials activities are done at
idle. I'd venture to say less experienced riders it might be more than 80%
of the time. & that is a low conservative estimate. On the other hand your
MX/enduro/street rocket is the opposite, it is allowed to idle probably less
than 20% of the time you are riding. If you "race" on a trials bike, & mix at
80:1, nobody here is going to be shocked that it burns something up, I
would be suprised but still, you are now warned, and YMMV,
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Old 02-05-2011, 09:00 PM   #9
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The 80:1 premix ratio is actually RICHER than what you'd imagined - say 40:1 or 50:1. Keep in mind that the engine runs on gasoline - not oil, so a ratio of 80:1 means more gas (richer) for every drop of fuel it ingests.
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Old 02-06-2011, 08:51 AM   #10
Sting32
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Quote:
Originally Posted by BarkSlayer View Post
The 80:1 premix ratio is actually RICHER than what you'd imagined - say 40:1 or 50:1. Keep in mind that the engine runs on gasoline - not oil, so a ratio of 80:1 means more gas (richer) for every drop of fuel it ingests.
Bark, please...
in this whole context, the richness is oil to gas, not gas to air, PERIOD.

We're exclusively talking about the ratio between gas and oil, a product you have to concoct to operate 2 stroke engines in our trials motorcycles with 2 stroke combustion engines.

What you are refering to is jetting and carb functions at some engineering level which was done before the bike's carb was picked and used in production.

FWIW, there was a study done in the 70's or 80's published and is or was on the internet, and I dont have the link anymore, but the gist was except the too extremes (no oil and way too much oil) differences only acounted for infitessimal changes on an engine running wide open, IE: racing or weed eating. the study showed and the engineers figured the rich oil mixture helps ring to bore sealing over the gains and losses due to friction on same engine when less oil was use and the engine got more "fuel per atomised droplet" or the "richer" mixture you are refering to.

as far as 50:1 through 100:1 there is hardly any affect what so ever on a trials engine, that "oil to gas mixture not specific" carb tuning as suggested for your altitude, on engines which see wide open for bursts lasting well under a minute at most, in any type of trials competition mode of use.

What you will find though, when you have more oil in a trials bike than it can use and "burn" you fill the exhaust system with oil, see more "smoke" out the exhaust, than you really need to. take that $200 muffler on any trials bike, that someone engineered to be as light as possible, yet durable enough to last (gasgas will get there someday, lol) and then fill it with 3-5 lbs of extra oils, seems senseless to me, but that is just me maybe.
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Old 02-07-2011, 07:13 AM   #11
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Quote:
Originally Posted by Sting32 View Post
Bark, please...

What you are refering to is jetting and carb functions at some engineering level which was done before the bike's carb was picked and used in production.


All I'm referring to is the simple fact that the whole "rich/lean discussion" as it pertains to two-stroke premix ratios and carburetion is one of the most widely misunderstood concepts in motorcycling.
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Old 02-07-2011, 10:50 AM   #12
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Quote:
Originally Posted by BarkSlayer View Post


All I'm referring to is the simple fact that the whole "rich/lean discussion" as it pertains to two-stroke premix ratios and carburetion is one of the most widely misunderstood concepts in motorcycling.
I think you are making this more complicated than it needs to be. Just so I understand you correctly. You are saying 50:1 is 98% fuel and 2% oil. So 80:1 is 98.75% fuel to 1.25% oil. So in essence you are correct, there is more fuel and you might be able to call it richer when refrenced to the Fuel air mixture.
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Old 02-07-2011, 10:53 AM   #13
Sting32
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Quote:
Originally Posted by BarkSlayer View Post


All I'm referring to is the simple fact that the whole "rich/lean discussion" as it pertains to two-stroke premix ratios and carburetion is one of the most widely misunderstood concepts in motorcycling.

Again,
I hate to see NEW trials riders get confused about rich or lean oil mixture becuase
you want to theorize on the rich/lean fuel_with_oil_ droplet_size to air Mixtures theory,
which is NOT what this thread is about. (did you read the subject line?)

We BOTH know dang well, that a dirty air filter is a bigger concern and effect on
lean/rich Air to Fuel ratios, than droplet sizes of premmixed gas and how it could affect FUEL to air ratios...

Most of us change jets, and move the needles to fix "lean/rich combustion" conditions.
In this thread about OIL TO GAS MIXTURES RATIOS we use and RECOMMEND,...

You are going to have to accept 2 things to be virtually true:

1, 99 out of 100 riders will NEVER adjust rich/lean combustion setting by changing fuel to OIL ratios

2, that trials MFG's have already pretty much tackled the rich/lean
combustion settings by picking the carb, then recommending the correct
jetting, needle and screw settings, all based on a fair range of
recomended oil/gas ratio's for MOST RIDERS, for your altitude through a
fair amount of testing. Yes there is flexibility, jets, needles, adjusting
screws etc.

We accept it, and know in some aspects there are alternatives, like
different carb MFG that do slightly better or Worse in giving AIR/FUEL
mixtures at different Velocities of demand through the carbs. (some carbs
work better off idle, some better at high to highest RPM, as well as jetting
I know, can affect it through all different ranges.

So, lets leave those thoughs you added above, in your "lean/rich air
mixture biases effects from oil/fuel mixtures... (a Physics & engineering study)."
Which of course is a thread that you have not started YET

In such thread, I would argue that the amount of oil per droplet of air fuel
mixture delivered via carb, in a TRIALS engine {AND operated and Dyno'd
as a trials engine} has 1/100th of the already infinitesimal affect on rich/lean fuel to air mixture.

I might be wrong with that arguement, it has been a while since I last stayed in a Holiday Inn Express... :>
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Old 02-07-2011, 12:47 PM   #14
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Sting, my friend...lighten up. There's nothing going on here that warrants a tirade. But in all fairness, if a rider is new to two-stroke tuning, wouldn't you agree that he has a much better base to learn from with good information going in? 80:1 is a richer premix ratio than 50:1. If your reality differs...I can't help you. It's all good.
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Old 02-07-2011, 01:15 PM   #15
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Quote:
Originally Posted by trailer Rails View Post
Just so I understand you correctly. You are saying 50:1 is 98% fuel and 2% oil. So 80:1 is 98.75% fuel to 1.25% oil. So in essence you are correct, there is more fuel and you might be able to call it richer when refrenced to the Fuel air mixture.
Yes, exactly...80:1 is richer than 50:1. That's all there was to it.
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