9th August

Spent a day on the dyno on Saturday with the RS500 - cheers to Neil for helping out with the carb changes etc and to Mark Dent for his tiresome efforts and knowledge.

When we first run the bike many weeks ago we made 127hp, but the tempertaure was only 53F and very high pressure - a good day for power - not the best day to set up an RG500 for the first time. Since then I've had no end of problems with fouling plugs and the bike has remained unhappy in any situation other than flat out in a straight line through the gears. The 1st run confirmed my suspicions that things had gone pretty wrong -80hp - but given this was a duff battery screwing up the powervalves (SEAC chamber actually, but lets not split hairs), - and the subsequent run was 105bhp - exactly the same reading as I had on Camb M/Cs dyno!! Things could definately be better.

After finally getting the bike back to where it should be we set out to prove once and for all what the fuelling issues I have been having heading into a corner are - basically it feels like fuel starvation, but the bike feels very rich most of the time elsewhere, and has a tendency to foul the plugs. It suggest it's rich, but also may be having starvation issues. I'd run a pump but it when I tried that it resulted in the grose valves being unable to close as the pressure pushes them open and te fooats overfill and the fuel pisses out.

On the road, after you run through the gears flat out, when you change down the bike will not blip the throttle and jsut bogs, resulting in terrible fuelling as you get back on the gas. Not conducive to track riding and definitely confidence sapping. We suspected float heights, jetting, fairing closeness etc We also did some did some part throttle work trying to determine if the part throttle power curve had any holes that could also cause issues with getting back on the gas. BTW it made 120 actual horses with an ambient tempertaure of 90F on full throttle and 100bhp on 1/2 throttle and 60bhp at 1/4 throttle! Not bad ... hey!

We also tried the carb mods I mentioned a while ago - a splitter that attempts to reduce the carb size on part openings to help redress the awful behaviour of RG500s below 5K - well lets just say the jury is still out - certainly it gets off the line with far less revs, doesn't stumble below 4K like a normal RG500, but does richen things off in the mid range and we ran out of time to pull the carbs and adjust the needle again, and while I'm confident that the seat of the pants view is very positive we can't demonstrate it on the dyno at the moment ... A worthwhile mod to try on all flat sides? Probably! The dyno didn't show the results, but hey how do you validate a mod that gives better throttle response anyway!!

Anyhow ... the dyno day was superb .. Mark was his normal superlative self, and I left a happy person having finally ruled out a number of sources on my fuelling issues after running the bike about 45 times during the day. Now we know it's not float height, or electrical, or the fairing, but probably fuel flow or a vaccum forming in the tank. Also the part throttle dynos show some huge gaps in the power where the PV opens, and while we've set the powervalves for full throttle to maximise the curve and it's smoothness it isn't happy in the part throttle openings passing through the PV opening. On a track less of an issue coz you just stay in the PV open band, but on the road it's a pain in the arse because you get a stumble before the rush as you spend most of your time waiting for traffic to clear and rarely have space to hold her WFO!

The 3D programmable ignition offer the solution in this respect, but it will take some time to fill the holes part throttle produces by using the 3D mapping capability .... Mark and I have a strategy for this over time .. but it will take a long time! We have our full throttle map pretty much spot one now, and we intend to find a map for the 1/4 and 1/2 throttle at some point and fill the gaps in by hand on the throttle bands just averaging out, then just trial and error it from then on ... But before that I need working tacho so I can report the rev range that things are happening.

Most of all though the dyno helped confirm that I really do have a fuel delivery issue. We suspect either the float chambers being emptied or the tank pressurising, so some new bigger grose valves to try and a tank vent is on the cards - if that fails I'll put the pump on and find a way to stop my inclinded carbs pissing fuel everywhere at tick over! Oh and I'll be raising the clip on the needles also jsut to redress the mid bad richness caused by fitting the carb splitters ... I say again 120bhp at 90F ... fsck me how impressive is that - the ride home from Neils was spectacular and once again I've fallen in love - just had to knock off every mile or so to allow her to gather herself up for another full straight line hoon before the dreaded blurggggh blurgggh riiingggg situation! Things are definitely much improved, and we have a direction to take now - soon I shall be able to carve turns again!