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Author Topic: 2 stroke fuel mixture  (Read 30473 times)

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huskyrider78

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Re: 2 stroke fuel mixture
« Reply #60 on: June 27, 2008, 12:00:34 pm »
Article (and PDF download) is on http://www.classicscramble.org.au/CSC_Workshop.htm (article near the bottom of the page)
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Offline Freakshow

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Re: 2 stroke fuel mixture
« Reply #61 on: June 27, 2008, 01:05:38 pm »
Yep thats the same 1978 article.  could have saved myself all that scanning.

what would have been nice would have been if he elaborated on jets he ended up with when he recalibrated to get the same air/fuel ratio's   he says they rejetting all night but it would have been interesting to see the jet movement from one ratio to the next.   IHMO
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cxs58

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Re: 2 stroke fuel mixture
« Reply #62 on: January 22, 2009, 11:16:53 am »
I know this topic is dead and almost buried but I want to thank y'all for the advice and the great reading - all problems sorted and the mixture is around 30-1.
The Husky goes like a f#@ken rocket - scares the sh!t out of me.
Thanks
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Offline Freakshow

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Re: 2 stroke fuel mixture
« Reply #63 on: January 22, 2009, 04:28:31 pm »
It may have been a dead topic, but thatnks for reposting it, i just went back over the thread and remebered how good it was.

 i think this was probally one of THE best topic/ Discussion on this forum.
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For sale -  PRE 75 Yamaha MX stuff, frame, motors and parts also some YAM DT1,2,A and Suzi TS bikes and stuff

Offline utsman

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Re: 2 stroke fuel mixture
« Reply #64 on: January 31, 2009, 08:26:12 am »
Hey here's one for ya

The factory recommendation for my ktm300 is 60:1 :o
Guy at the shop said 50:1, dont use anymore you will foul plugs. I precedeed to tell him that I would certainly be running it with more oil than that and would re - jet if needed. I ran it all dAY at 40:1 with no problems. Next tank will be 32:1.

Are Ktm trying to make money selling rods and pistons??

STU
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Offline Hoony

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Re: 2 stroke fuel mixture
« Reply #65 on: January 31, 2009, 09:07:36 am »
G'day Stu,

This is my experience.

i run my KTM300 on Motorex cross power 2T at 50:1 no problems in the 4 years i have had it (got it new), i was old school till then and used to run Castrol TTS at 40:1 in all my bikes. i now run Motorex in the others as well ever since 2005. no issues at all.

i will check the spring colors for the power valve for you. its a 30 second job mate, piece a piss.  i'll scan that section of the manual when i get some time today.

sounds like you have the light spring in yours if its peaky.
« Last Edit: January 31, 2009, 09:13:52 am by Hoony »
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Long time Honda Fan, but all bike nut in general, Big Bore 2 stroke fan.    http://www.youtube.com/watch?v=XJoKP6MawYI
1985 Honda CR500RF "Big Red"
1986 Honda CR250RG
2005 KTM 300EXC "The GruntMeister" ( I love that engine)

Offline Lozza

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Re: 2 stroke fuel mixture
« Reply #66 on: January 31, 2009, 09:15:08 am »
Plugs foul because of jetting and heat ranges.They recommend those crazy ratios more for emissions and their own feel good factor.
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Jesus only loves two strokes

360DUDE

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Re: 2 stroke fuel mixture
« Reply #67 on: January 31, 2009, 09:50:00 am »
Running rich/ lean can mean 2 ways
Either your oil and petrol mix is to rich/lean meaning oil to petrol ratio when you mix your fuel
or your jetting and needle is either rich/lean

50 to 1  =  5 litres of fuel to 100mls of oil                      Lean
40 to 1  =  4 litres of fuel to 100mls of oil
35 to 1  =  3.5 litres of fuel to 100mls of oil                     to
30 to 1  =  3 litres of fuel to 100mls of oil                       rich  fuel mixes

Your pilot jet will mostly effect starting and idle and the first 1/8 of throttle
The clip setting on the needle will mostly effect 1/4 to 3/4 throttle ( top clip settng is the leanest and bottom is the richest)
and the main jet moslty effects 3/4 to fully open thottle
and then you have your air screw which you have to balance with the 3 above

If you don't know what you are doing find a mate that does, if you set your bike up to lean with fuel or jetting you can blow your engine big time!!!!

Hope this helps someone
Luke


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Offline utsman

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Re: 2 stroke fuel mixture
« Reply #68 on: January 31, 2009, 06:35:11 pm »
Wicked,

Hey hoons are you running a Br7es (recommended) or Br8es (in my bike) plug. appreciate the powervalve info if ya can. I SHOULD HAVE A MANUAL IN A COUPLE OF WEEKS TOO.(BLOODY CAPS BUTTON!!! 50:1 is obviously OK with a good oil hey Hoony. I just can't seem to be able to do it. When it comes to mix time I seem to just go nup, it needs at least 40:1 .

Thanks for the info guys. I am pretty up to speed with jetting. Just shocks me the amount of people at bike shops who think if plugs are fouling use less oil in your premix ???. I was trying to explain to shop guy but he didin't get it. Nice dude though.
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Offline Hoony

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Re: 2 stroke fuel mixture
« Reply #69 on: January 31, 2009, 07:06:31 pm »
Ok, here we go.

Mid (Standard) power valve spring is part # 546.37.072.300 and is Yellow in color

Soft power valve spring is part # 548.37.072.000 and is Red in color
(peaky aggressive performance)

Hard power valve spring is part # 548.37.072.000 and is Green in color
(smooth power)

I noticed a big difference between standard (yellow) and Red spring when I did back to back testing, there was a bit of difference with the green but not as much over standard.




« Last Edit: January 31, 2009, 07:31:50 pm by Hoony »
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Long time Honda Fan, but all bike nut in general, Big Bore 2 stroke fan.    http://www.youtube.com/watch?v=XJoKP6MawYI
1985 Honda CR500RF "Big Red"
1986 Honda CR250RG
2005 KTM 300EXC "The GruntMeister" ( I love that engine)

Offline Hoony

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Re: 2 stroke fuel mixture
« Reply #70 on: January 31, 2009, 07:31:23 pm »
.
« Last Edit: January 31, 2009, 07:36:38 pm by Hoony »
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Long time Honda Fan, but all bike nut in general, Big Bore 2 stroke fan.    http://www.youtube.com/watch?v=XJoKP6MawYI
1985 Honda CR500RF "Big Red"
1986 Honda CR250RG
2005 KTM 300EXC "The GruntMeister" ( I love that engine)

Offline BJJ

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Re: 2 stroke fuel mixture
« Reply #71 on: January 31, 2009, 07:42:48 pm »
BR8ES, 40:1, Mobil 2 Stroke Racing Oil from BigW and Unleaded Prem.  Works a treat.
Mind you,   for $2.50-$4.50 for a new plug (non gold),  you should change every race.
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Offline utsman

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Re: 2 stroke fuel mixture
« Reply #72 on: January 31, 2009, 08:14:48 pm »
Hoony,


YOU ROCK!!!!
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