Magny-Cours Aftermath

Spent yesterday evening stripping the bike down to once again try and find my problem. Troubleshooting was helped by a trail of small pieces of metal, both in the crankcase and in the rotary valve cover..... leading eventually to the culprit, which was a completely destroyed small end bearing! The bearing was sucked around the crankshaft and partly spat out through the rotary valve, damaging the disk, and covers on the way, and also taking a trip up and down with the piston a few thousand times.... Pictures speak louder than words.

So was this the cause or another symptom.... I'll have to spend some time to think about that one.

I have sent the barrel and head back to Performance Fabrications to have a hone, and fix up the head which had been "bead blasted" by loads of little bits.... A new piston and rotary disk are ordered.

Mixed fortunes at Magny-Cours

The RG 500 was running badly again, with a miss fire, and low on power at low revs. I changed the CDI which is really the last electrical component I haven't touched, and in timed practise, things started to come together, the bike worked fine at high revs, giving strong power between 8K and 11K. I had received my high volume radiator on the Thursday morning, before leaving and with this fitted the temperature never got above 84 degrees (a good investment!).

In timed practise I managed a 2:09 which put me middle of the grid on the 6th line.

As I lined up for the start of Race 1, I could hear the bike miss firing and blowing back through carb nr. 3, so I knew my problems were not over. I managed a couple of laps, but the problem got worse so I stopped! A brief session with the spanners confirmed that this can not possibly be an electrical issue - The fault was easily reproducible, and with a new plug, and swapping over the high tension leads, I could not get the problem to move - it definately has to be related to the carb or cylinder. Off with the carb, and no visible problems, so it must be an air leak somewhere.... The action plan is to look at the rotary valves (again), and potentially swap rotary disks between cylinders, and then if that doesn't work, I will have to assume leaky crankshaft seals, which will require a complete strip down and rebuild.

Luckily the RD 350 was running OK, although I had difficulty getting to the red line in 6th along the long straight to Adelaide. Everything was blasting past me on the straights, but I managed to have fun fighting with a group of guys, on am mixture or Ducati's, GSXR's, VFR's etc... so I was relatively pleased with the race. Magny-Cours is so fast, there are loads of places where on the 350 I didn't need to brake, and I am sure with more practise I could knock another 5 seconds of my lap time on the 350 - I could only manage 2mins 15secs. Anyway glad to have tried out the 350 with the new rad (swapped for a 4l0 radiator), which controlled the temperature nicely although, was pretty high, maybe unsurprisingly as the air temp was about 35 degrees centigrade.

Photos, and video to follow!

The extra power of the 500 (even running badly) was worth at least 6 secs per lap!

Last minute preparations

Well Magny Cours this weekend! The circuit is fast, and I of course expect to be on the RG500. I haven't received my new radiater yet, but hopefully I'll get it before the weekend. Looking at the weather forecast it could be hot and humid or cold and stormy, so we'll have to wait and see what jetting to use.

I have managed to start both bikes and run them up the road over the last few days. The Yamaha doesn't leak and seems to run cooler (with the 4L0 radiater installed). The RG ran OK, moving the needles up has made a significant difference, much richer and I didn't perceive the big hole in the power, so I think I have gone the right way with the jetting. While I was testing the RG (without the fairing on), I lost the right hand side carb trunk, which bounced off into the countryside in a bid for freedom. It was only after mobilising the whole family along the 1.5 kms section of road that we managed to find it hidden in some long grass (thanks Libby!).

So fairings on this evening, and pack the trailer for the trip up on Friday morning.

Speak to you after the weekend (come on England - last pool match this evening!)

Preparation for Magny Cours

So, I took the cylinder off the RG500 at the weekend, to look at the damage from my seize. Not too much damage and nothing above the rings, so a little TLC with some fine emery cloth, on the piston and the cylinder, and she is as good as new (almost). I also took the needles up 2 grooves, so I am running them one above the lowest groove. I am hoping this should improve my carburation hole at around 6K rpm. From reading various articles on carb tuning it would seem that I may be running lean at partial throttle - I will try this out tomorrow (up and down the road!). Apparently lean mid-throttle jetting can be characterized by a lack of power (hole), and a loud induction sound (wouououououou) noise, which fits pretty much what I was perceiving. Hmmm technical stuff.....

Annyway had troubles with one of the needle screws as it was completely solid and the top had been mullered by the previous owner, so I had to get the drill out, and drill down the throttle slide (5 cm hole) into the screw head. I actually managed a pretty straight line hole going out the other end of the throttle slide, to which I added a new thread and found a screw that would fit, so it all ended happily.

Other work at the weekend was fitting a new radiator to the RD 350, I learnt from a guy at Nogaro that the 4l0 (an earlier model 350) has a larger double core rad, so I ordered a second hand one from RDLCCRAZY, and received it during the week. It took me a couple of hours to make some brackets to hold it, and I am realtively pleased with the results. Hopefully the 350 at least will run cooler at Magny Cours. The only issue I had was the original water circuit has a thermostat bypass pipe that allow water back into the top of the original rad. this was not present on the new rad, so I have removed the thermostat allowing full water circulation the whole time, and I have closed up the bypass pipe with a bolt screwed into the rubber pipe (I hope it holds...).

Little left to do now except decide on initial gearing for Magny Cours (I'll go with 15/39 to start with), and await my high capacity radiator for the 500, hopefully it will arrive before race weekend.

Speak to you soon.

Nogaro Video and C-en-T Photos

and some photos from Croix-en-Ternois:-

Nogaro

Just FYI, the rear tyre was changed on the RD350, the guy didn't balance the wheel.

I raced at Nogaro in the South West of France this weekend. We arrived Friday afternoon as the free practice was scheduled for the end of the afternoon.

The RG started fine, the re-found power band (with the exhaust valve working!), was incredible, but really accentuated by the fact the clutch was slipping freely, so every time the bike hit the power, the clutch would slip, and let the engine run up to 12K. I tried adjusting the clutch on the run, but couldn't get my gloved hands around the cable adjuster - should have come in really. Anyway I kept going but the bike was running dangerously hot - around 94 degrees celsius - too hot!!

As you may remember Nogaro has a long straight along which the clutch was slipping most of the way, at the end of the straight, I have already suffered from a "shut throttle" seize..... well it happened on the RG! On previous laps I had been holding the choke in to give some more fuel as the throttle is shut for braking, well on this particular lap, I was more concerned with other things so I forgot, and well, I got my punishment - leaving a 20 metre darky as the wheel locked, grabbed the clutch and cruised to a halt at the end of the straight - bummer!

Back at the pits, I let the bike cool off, and I could then freely move the engine, removed the plugs - all nice and chocolate coloured, removed the exhausts, and piston nr. 1 was the guilty culprit - unusual I was expecting nr. 3! The piston had touched on the exhaust port side, below the rings, I could see some shiny aluminium on the piston, which actually rubbed off with my finger!

All the other pistons looked OK, and no damage to the cylinders.

On Saturday morning, and after receiving the advice from most of the paddock, I decided to increase my main jets to help (up to 230's with the carb trunks on) with cooling the engine, and raise my idle speed to about 3K to ensure that even with the throttle closed, there would be some fuel going through - plus use the choke every lap!

The Saturday was as hot as the Friday, but the RG ran at the hottest of 84 degrees - hot but not as hot.... I shared the timed practice between the RG and RD as the game plan was to use the RD if the weather was really hot and use the RG if it cooled down. Well in the end we started for the first race Saturday evening at 18:00 and the air temperature was around 35 degrees, so the RD took the punishment. I got a reasonable start, but I was totally under geared for the long straight, which meant the RD was up at around 10K for most of the straight and people came whizzing past. Never mind, I had a few good scraps around the twisties, and finished a somewhat lowly (scratch) 29th place, but a fairly respectable fastest lap of 1:52.

Sunday was forecast rain! We awoke to a misty day, with moisture in the air - a great day for a hot bike! I lined up on the pre-grid (8th line), and slowly the heavens opened up on us! Really big blobs of rain, getting steadily faster. A few of the guys abandoned without even going out, but I was determined to give the RG an outing. The warm up lap was incredibly slow, and when the start was given, I must have got the worst start of my life, Libby said the lap car was nearly pushing me up the backside to get me going! Anyway throughout the deluge, I was opening the bike up only when I was in a straight line and vertical, the Michelin Power Ones, are OK, but they need to be up to temperature!

So the bike goes OK fairly linearly up to 6K, then a huge hole, and then the full beans as the valves open at around 7.5K - lovely to feel the bike really accelerating cleanly to the red line again, although the big hole made things interesting in the wet.

As the race continued, I got past a few guys, for the fun, but I wasn't risking anything, I was having to change lines as the puddles were getting bigger near the rumble strips!

Anyway I finished at 18th (scratch), with a fastest time of 2:23, even the fast guys were well over 2 minutes for a track that at it's best is around 1:35 for the promosport 1000's.

Now I have to find a big radiator, and clean up piston/cylinder nr. 1, before Magny-Cours in 3 weeks. Plus I need to move the needles either up or down - take your pick!