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| What gas : oil ratio do you use?? and gas https://vintagedirtbikeforums.alp-sys.com/viewtopic.php?f=21&t=1930 |
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| Author: | digitalbrad [ Mon Jul 07, 2008 9:36 pm ] |
| Post subject: | What gas : oil ratio do you use?? and gas |
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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| Author: | b-joe [ Tue Jul 08, 2008 8:20 am ] |
| Post subject: | Re: What gas : oil ratio do you use?? and gas |
i use 98 octane and synthetic 2t oil in 1:50 mix. |
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| Author: | mitchie [ Tue Jul 08, 2008 8:01 pm ] |
| Post subject: | Re: What gas : oil ratio do you use?? and gas |
I use Maxima 927 oil and mix it 32:1 in winter and 28:1 in summer. |
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| Author: | dogger315 [ Wed Jul 09, 2008 10:56 am ] |
| Post subject: | Re: What gas : oil ratio do you use?? and gas |
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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| Author: | redrocket190 [ Wed Jul 09, 2008 5:44 pm ] |
| Post subject: | Re: What gas : oil ratio do you use?? and gas |
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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