Tuesday 30 August 2011

RD 350 Brake pistons seals

So I received my seals for the rear brake of the 350, the problem I am trying to solve is that the brake squeals and rubs. Anyway removing one piston is relatively easy. You just remove the pads, and keep one piston completely in, and pump the brake, the pistons are about 3cms long, and a single piston should come out no problem. The first side I removed and then used a hook to remove the seals, the outside "dust" seal was slightly damaged, but the inner seal was in good condition.

While I was waiting for my seals to arrive (purchased at at WEMOTO cost 12 quid for the two sets), I wanted to remove the second piston, the only way I could think of was to put back the first one and pump it out, which is what I did. The second piston was in good condition as well as the seals.

Both pistons had small pitting in the chrome surface, which I (very lightly) sanded down so that there was nothing proud.I received the new seals, but they did not come with any red rubber grease - apparently this is the stuff to use to lubricate, the seals and pistons, anyway I didn't have any, and it doesn't seem to exist in my local shops, so I tried putting some teflon grease in some brake fluid and also some "Judy butter" grease in the brake fluid, I just wanted to see if the grease would dissolve or not.

The teflon grease dissolved. The judy butter (which is a mountain bike fork grease) didn't dissolve and remained greasy, so this is what I used to put the seals in.

Putting the pistons back in was hard work! Initially there was not enough space to get any kind of tool in there, but after much sweating and swearing I could get a bar of metal in to lever with. Again you have to be careful not to damage the pistons, and the technique that worked best was really to "walk" the pistons in, not pushing against the piston equally across its surface. Don't ask me why, but it definitely worked better by pushing and rocking the pistons in. Once the pistons are sufficiently in (about 1cm showing), you can just push and the piston will go in relatively easily. For the second piston I used the same technique.

The brake bled quite easily, I kept the bleed nipple in a high position to enable the air to escape easily.

I have managed to enter the VMA Postclassic 350 series for Ledenon with the 350, so I will be running the 350 and the RG500 the whole weekend! Should keep us busy esepcially as I will be doing some back to back races. I changed the gearbox sprocket back to a 16 on the 350, as Ledenon is a longer circuit than the planned Croix-en-Ternois. Hopefully as this is my "home" race, I should have some support, although the racing starts early - first race on Sunday morning at 8:30 - still it will be cooler at that time in the morning!

The only thing left to do this weekend is check the cab synchro of the RG and take a quick look at the plugs on the RD.

Speak to you soon.

Monday 22 August 2011

Rear wheel bearings

Rear wheel bearings for the RG/GSXR rear are 47 OD, 17 ID, and 14 wide.
The SKF reference is 6303-2RSH for the sealed bearings.

Replace the gear shaft oil seal on the RD 350 YPVS, a relatively simple job, remove the engine cover, I removed the gearbox sprocket although you could probably do without, remove the nylon chain roller thingy, and then I used a small hook to get inside the seal and pull it out, after a few minutes of huffing and puffing it came out. I pushed the new one in and then bashed it in the remaining distance with a box spanner fitted over the gear shaft.

Hopefully no more leaks from there.

I have also renewed all the pilot jets on the RG500 and moved all carb needles to the top slot, hopefully this will help my hole in the middle issue. We'll see.

Tuesday 16 August 2011

Ledenon

Was at Ledenon this weekend to try a few things on the RG, but also to let my friends have their first experience of the track on the 350! Only Pierre-Luc was up for it, as others were either too busy (scared) or on holiday.

Traveled down on the Friday evening and setup in the pit car park, the weekend was open with sessions alternating between cars and bikes. We pitched the barnum, had a few beers and went to bed.

For a change the weather was fantastic, if anything too hot on the Saturday, and just a small breeze to take the bite out of the heat.

You purchase 20 minute sessions at Ledenon for 20 Euros each, which is great coz if you break down you don't waste your money on a whole weekend. The only trouble is you have to queue extensively first thing in order to buy your places for the day. For the Saturday we bought 4 sessions each 2 in the morning and 2 in the afternoon.

Pierre-Luc was a little nervous, firstly about the bike, and secondly about going onto the circuit for the first time. He certainly looked the part, with his old road boots, and borrowed leathers - a real 70's continental circus racer! He had never ridden a 2 stroke previously a part from a teenage moped, so it was sure the 350 would be a surprise. Would he become a 2-stroke convert?

As we drove up through the pit lane, you could tell he was loving every minute of it. After a couple of minutes they let us loose, and we were away, he stayed behind for the first lap, and then when the tyres were up to temperature I picked up the pace and left PL, to his own devices.

The 500 was running bigger pilot jets (up to 30 from 25)and I had also added back the rubber tubes connecting the carb snorkels to the air box - the idea here, was to try and get cooler air from the air box instead of taking hot air from behind the radiator - anyway the combination of the two modifications had made the bike way too rich, so it wasn't pulling at all well, although interestingly at about 9K rpm it took off with loads of power all the way through 12K... a bit high for my liking.

After our first session, PL was already half ways converted certainly to the track, but also I believe he already had a small taste for 2-strokes. He had kept the revs. down, so hadn't completely experienced the manic acceleration of a 350 coming on pipe. He was a very happy chappy, very impressed with the speed of some of the bigger 4 strokes shooting past him in all places on the track.

I didn't have time to alter anything for the second session, with only one hour between them. On a good day it takes me one hour to change jets, so it wasn't worth the stress, plus I had a group of guys around the bike asking questions, so I knew I wouldn't be able to concentrate on the job on hand.

The second session (11:00am) I only did a few laps, the bike still not pulling right, and I didn't want to damage anything. I pulled off, and started to pull the fairing off. Suddenly there was no noise from the circuit, and I guessed that the session had been red flagged, and a couple of minutes later I was surprised to see PL back at base? Oh dear..... he had been involved in the accident. Apparently a guy had come through under him on a left hander, and promptly lost it sliding into PL's trajectory, he managed to avoid the bike, and pulled off to the exterior edge of the track with another guy, and then he felt a dull impact from behind, and another guy had come through fast, and must have panic braked when he saw the accident and promptly lost it, and threw himself at the back of the 350, he ended up with his leg up and under the rear mudguard. PL was sitting on the bike, and trying to get this guys leg out from behind him.... Anyway it all sorted itself out, the second faller broke his leg, a couple of ribs, and collarbone.....

The damage to the bike was minor, one of the silencers had been bent up, and a weld had been cracked along the silencer, we bent the thing straight put on a new spring, and it held for the rest of the weekend.

PL was pretty nervous about going out in the afternoon, but soon got over it and had a great time for the rest of the day. I, in the meantime, and replaced the pilot jets with 27.5's, and to be honest It was potentially worse, so the third session of the day stopped before it started. I did notice that I had not fully tightened one of the carbs (nr. 3) so maybe this was why it seemed worse, anyway for good measure I changed all the plugs (first time running with Denso Iridium plugs - apparently they contain much more Iridium that other brands, and are therefore much more hard wearing - we shall see!).



For the 4th session, I reduced the pilot's back to original size (25's), and still the big had a huge hole in the power literally nothing between 6-8K, but making good power again up top. I had no idea that the pilot jets could make so much difference to the midrange - previously I had thought this area of the carburation was pretty much 90% the needles.

On Sunday, I was back to my original (Magny Cours) setup. I had removed the rubber connectors, and was running 25 pilot jets. The bike still seemed to be running a little rich on the rear cylinders (remember I am are using 10 points bigger main jets at the back (240's)).

With the bike in this config. the hole is much smaller, and manageable, and the low down power made the bike drivable. The two last sessions on Sunday were a real pleasure, and I managed to concentrate on getting my lap times down, eventually seeing a 1:44.9 which would put me roughly in the top ten if I managed to do it regularly during a race. So this is the setting I will probably use, although I may try tweaking the needles to run one position higher, thus hopefully leaning off the mid range slightly.

Anyway a great weekend's testing for me, and a great experience for PL, who was thoroughly converted to the track, although he was eyeing up those Triumph Daytona 675's, so I am not sure he is completely 2-stroke crazy - yet!

Monday 8 August 2011

Technical Update

Finished the 350 over the weekend - refitted exhaust, and tested powervalve - everything seems OK. So got to work on the 500, I wanted to check the clutch operation, and fit bigger pilot jets going up from the standard 25's to 30's - may be a little excessive but according to people on the gamma list that's what I should be running with all the other mods to the bike - maybe it will make it easier to get off the line. I also refitted the connecting tubes to the carb trunks, in order to ensure I am getting cooler air into the carbs instead of picking up hot air from behind the radiator. I removed one exhaust, in order to get a clear view of the oil drain plug, drained the oil, and removed the clutch cover, nothing interesting in the clutch, my washers were still in place, and everything seems OK, I did however notice that one of the power valve covers was loose, which could have been causing the rattling noise I was hearing after Magny-Cours. Anyway put the clutch back, then changed all the pilot jets in the carbs, changed Nr. 1 o-ring aswell as it was looking a bit knackered. I opened the mixture screw to 1.5 turns in order to compensate for the bigger pilot jets.

In order to mess with the carb trunks, I needed to remove the petrol tank and seat unit, and when I did this, I noticed that my battery eliminator (a big capacitor) was broken, the positive connector was snapped off, unfortunately it had snapped off right at the base, so impossible to get some solder on it to fix it, so that one went in the bin, and luckily I still had a spare, so that went on. I have since ordered a couple of capacitors with a screw fixing to the terminals, which should be more solid.

Fresh oil in the gearbox, and now all is ready, we should be doing a track day at Ledenon next weekend. A couple of mates are interested in coming down, and will be trying the 350, while I will be trying to improve my times on the 500!

Tuesday 2 August 2011

Photos of broken bits



You can see the broken bush which comes pushed into the right hand Power valve covers, and also you can see a new joining part, compared to the old one which has been worn significantly giving a kind of step in it between the two valves.... Anyway these parts are now replaced, my only hope is that the valve hasn't been damaged in the process.