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| The Honda VFR750 posing next to a shiny new can of Classic Racing Fuel. |
Intro
You may have noticed Classic Fuel Solutions in the CRMC
paddocks this year. With some fancy chrome jerry cans and a friendly staff, it didnt take us long to wonder over for a chat. Once we had established; we don't get free AVGAS from the RAF and no aviation turbine fuel (AVTUR) doesn't work in motorcycle, we soon got into the benefits of running their fuel. Suddenly we had a fully jerry can in hand and were just asked to try it out!
We wanted to go one better than that and opted to use the team Fuchs dyno to see what performance differnece running this fuel makes.
Classic Fuel Solutions have created a
105 octane, ethanol free, leaded race fuel with the aim of getting maximum performance from classic race motorcycles.
The RAFMSA classic racing team currently run their two strokes on a 50/50 blend of 100LL (blue) AVGAS and super unleaded with Motuls 800 road racing 2 stroke oil added mixed in. The four strokes all run on pump super unleaded.
We had decided to test the fuel on Symon Woodwards Yamaha RD250 (Little Al) and Gavin Heggs' Honda VFR750 RC24 to test it out on a two and four stroke respectively. Running the Fuchs dyno were Andy Green and Dave Bond.
We all had our own ideas on how the fuel would compare and what bikes would like it more but it was now time to see what it actually did.
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| Little Al piloted by Symon Woodward |
The 2 stroke
Yamaha RD250
With years of race proven development behind it and a Mick Abbey built engine, Little Al already puts out respectable power. This bike is designed to compete in the CRMC's post classic 250 air cooled class which allows for a fair bit of modification and tuning to both the engine and chassis.
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| Woodward gets his hands dirty |
The first order of business with the RD was get the ignition fine setup after a recent rebuild by Woodward running his normal mix of race fuel. After much adjustment and many, many runs; we came to the conclusion that the bike was pretty much happy with whatever, putting out consistant runs in the 44bhp range peaking at about 10,700rpm. In the end our best run had a peak of 44.6bhp and a smoothe (for a two stroke) power curve getting us up there.
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| Woodward supervising Bond |
This would be a good base line so we left Woodward to drain his fuel tank whilst we mixed up Classic Racin Fuels 105 octane race fuel with some motul 800 road racing 2 stroke oil.
With time short we let the bike run for a good while to get warm and to clear out any residual old fuel that might have been hiding in a line.
Once this was done we completed 5 power runs to see what would happen.
We were expecting the two stroke machine to perform worse on this fuel as the RON of AVGAS is effectively higher than the classic race fuel (road vehicle RON and aviation fuel RON is different pretty much just to confuse you) but were pleasantly surprised to find the figures coming back were very similar to what our own fuel mix was producing.
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| Poor Audio but you get the gist. |
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| Sorry no screen shot. |
In the end, our best result was 44.5bhp peak power with a prety much identical curve coming on a fraction earlier throughout the curve. Any differences would probably be atributed to conditions like temperature of the day and the bike. Little Al has cylinder head temperature probes which were all happily sat at the correct temperatures still.
So we could basically conclude from this that this fuel perfomed the same which was more than we expected.
We didn't have the time to play any further with the ignition and we were missing important information like exhaust gas temperature (EGT) which Little Al didnt have so we left it there so Woodward to get on to another appointment and we could roll out the VFR750. |
| Gavin Heggs on the Honda VFR750 |
The Four Stroke
Honda VFR750 RC24
From factory these bikes were supposed to put out 110bhp. This is more than the later RC36 which could be down to the RC24 being a higher speck sports bike in its day or just some fanciful thinking by Honda and the use of smaller horses. As for this machine; we werent expecting anthing mind blowing as she seems to put down similar power to the rest of the middle of the road VFR's in the class.
This was the first time the VFR had been on the dyno since being built. The exhaust was leaking less than usual so pops and bangs on the over run suggested things might be a bit lean. The dyno lambda sensor was playing up so whilst Green worked to fix that we pressed on with the initial runs on super unleaded. Again we were able to get consistent runs with the bikes cooling working nicely ( A long running problem for the bike) with the power output finishing up at an average of 85.7bhp with a 60ft.lb of torque.
We then drained the fuel, gassed back up with the classic racing fuel and went again for another five runs. The bike ran fine and again was consistent throughout the runs.
As you can see from the right the thicker red and blue lines show the power and torque using the race fuel which almost consistently performed worse than the super unleaded. This was a little disappointing but not surprising.
The Honda VFR was never designed with leaded fuel in mind and as such, this fuel is not realy designed for this machine. But that is not the only answer and if we had the time we could well have eliminated some of these.
Interestingly, just when we were done the Lambda sensor was fixed (one loose wire hidden in a block connector, typical) so we got a 6th run with the lambda sensor active which is the white line.
By now the bike was hot and figures were starting to drop. Regardless the Lambda sensor shows the bike was too lean initially The bike rapidly mchanged to about right intil that power dip where it goes too rich. Things then gradually lean off a bit but still on the rich side.
By now the bike was hot and figures were starting to drop. Regardless the Lambda sensor shows the bike was too lean initially The bike rapidly mchanged to about right intil that power dip where it goes too rich. Things then gradually lean off a bit but still on the rich side.
Bizzarly the leaded fuel perfored better when running a bit rich so it will be interesting to see what it does when the fueling has been ironed out.  |
| We need a better mic so you can hear her roar. |
Conclusion Two Stroke
With what we have seen so far we can say with some confidence that running the Classic Fuel Solutions race fuel is similar to running an AVGAS and unleaded mix. It has the added benefit of convinience and consistancy compared to the various sources you may well have got your fuel from.
We are going to run more tests with the race fuel on a machine with more sensors to push it a bit harder. We think there are some more gains to be had here.
Check back here for more updates during the winter break.
Conclusion Four Stroke
The VFR was initially a disappointment on this fuel but with a bit of hindsight we could well see a better outcome with a little fettling of the fuel system. We will always be at the whim of CV carbs but some fresh yets and needles might tidy things up a bit. The VFR is notoriously hard to make engine perfomance gains with. So simply changing fuel and some carbouration could be a very appealing posibility if a tiny fraction is what seperates you from the man in front.
It is a shame we didn't have the kit to go further here but this has been an eye opening initial test and we look forward to exploring further. First though we need to replace some very worn parts on the VFR's fueling.
If you want to give Classic Racin Fuels 105 octane race fuel a go, you can pre-book your collection from trackside on 0800 0371254 or just pop along on the day and meet one of their sales representatives, who will be more than happy to help you.
Classic Fuel Solutions will be present at every track meeting throughout 2019.
Visit the Classic Fuel Solutions website for more information: https://classicfuelsolutions.co.uk
The Classic Racing Motorcycle Club (CRMC) offer live timing and have race results going back years so if you can’t make it to come watch the action you can still stay up to date with the help of
We race under the banner of the Royal Air Force Motorsports Association (RAFMSA). If you are serving and wish to get involved with motorsports you can find all the contact details you will need on the RAFMSA website.
Finally special thanks go to the companies who continue to support us:
and individual sponsors:
Andy Green: New Era Restorations
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| Packed up and ready to go home after a long evenings testing. |
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