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PostPosted: Mon Jul 07, 2008 9:36 pm 
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Joined: Sun Mar 30, 2008 2:54 pm
Posts: 29
Me personally for my '79 CR250 i am using a 25:1 ratio using Stihl 2-Stroke mix oil. I find it a little boggy in the very top end but that also could of been because i was a bit higher in altitude then i normally would be.

SO.... I was just wondering what everyone uses for their two stroke bikes?? and if they have found any added benefits to some oils compared to others and such. What octane gas is everyone using? Do any of these older engines actually have a high enough compression ratio to benefit from the extra octane??


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PostPosted: Tue Jul 08, 2008 8:20 am 
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Joined: Fri Jul 14, 2006 8:12 am
Posts: 323
Location: Wuppertal/Germany
i use 98 octane and synthetic 2t oil in 1:50 mix.

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78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
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73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
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PostPosted: Tue Jul 08, 2008 8:01 pm 
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Joined: Thu Jan 05, 2006 1:35 pm
Posts: 344
I use Maxima 927 oil and mix it 32:1 in winter and 28:1 in summer.


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PostPosted: Wed Jul 09, 2008 10:56 am 
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Joined: Sat Dec 23, 2006 10:00 pm
Posts: 313
Location: CA
High octane pump gas with a quality 2 stroke oil will work fine for play rides. Good pre-mix ratios can be determined
by plug reading - looking for a light brown/tan coloring. I would start with 32:1 and go from there.

If you are looking to race your bike, I recommend a 50:50 mixture of race and pump gas with a name brand synthetic
2-stroke oil. This will help cut cost while eliminating or at least reducing some of the inconsistencies inherit in using
pump gas.

Personally, I use VP Ultimate 4.2 in my four strokes and VP MRX01 with Redline oil at 32:1 in my two strokes. Other than
AMA Pro racing events, both of these oxygenated fuels are legal for competition and worth a few extra ponies. The main
thing you get with race fuel is repeatability, meaning each gallon is the exact same - that can't be said about pump gas.

Another misconception is that all race gas is high octane. The best running, most expensive, nastiest brew that VP
concocted for 2-strokes was MR-2. It had an octane rating in the low 90's but the additives caused it to burn more rapidly
and efficiently and thus make more power. I remember it cost about $110 for a five gallon can and it would make your eyes
and nose burn when you mixed it. VP stopped producing it when the AMA adopted the FIM's unleaded fuel restriction.

dogger

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1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R


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PostPosted: Wed Jul 09, 2008 5:44 pm 
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Joined: Fri Feb 27, 2004 10:20 pm
Posts: 906
Location: San Clemente, CA
Good synthetic oil - like Maxima. Mix at 32:1. Use 91 pump gas from the same station. Use a repeatable measuring system - same gas can and a Ratio Rite jug. Get the pre-mix ratio consistent and out of the jetting equation. Your big variables are a) worn jets in the carb, b) rich stock jetting c) altitude and d) temperature. Get some jets and test - change one jet at a time. Worry about race gas later.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF


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