Hi All,
SO the left hand piston had definately touched the barrel! In four places, I can't feel any damage with my fingers, but you can certainly see it clearly. On the piston you can feel some scratching, but I think I will remove this with fine emery, and ignore this! A rebore at this stage is probably not worth it.
After looking around the web and various forums, I still don't understand what is happening. I found a really good website which describes different types of seize on two stroke engines here : http://www.pwab.org/PISTONDIAGNOSTICGUIDE.htm
My piston looked perfect from the top, as in image one, but had 4 corner seized! The guy's web site says : The main causes for this problem are too quick warm-up, too lean carb jetting (main jet), or too hot of a spark plug range.
The plugs were perfect colour throughout the weekend, a lovely "cafe au lait", the warm-up was OK, and the jetting on the carbs is normally measured by looking at the plus - so I am no farther forward... anyone any ideas?
I will ask the bloke at the rebore shop, what he thinks.........
Still the bike is in pieces again, the fairing is ready to be painted, Pete Mockler is helping out with the number plates, we just need to get the engine going again.
Speak to you soon.
Thursday, 26 April 2007
Monday, 23 April 2007
Issoire - Track Day
Just a quick update after my track day at Issoire. In preparation to this day (Sunday 22nd April), I had put on my new racing tyres, and my first impressions of the bike were transformed. The tyres offer amazing grip, with confidence inspiring performance, even though I was "running in" the bike after the rebore, I enjoyed myself trying to get a maximum lean angle with the tyres. I felt like my elbows would touch the ground, however from the photos, I can see that I still have room for improvement (don't even touch my knees!). The engine felt fairly rough to start, and my rev. counter was playing up which made staying under 6K pretty difficult, however the first session (20 minutes) went off pretty well. Of course I am getting overtaken by pretty much everything, but considering I was almost the smallest bike, plus running in, this is hardly surprising. Half way through my second session, the engine started making a strange blowing sound, and I thought I had lost an exhaust baffle, however after a quick stop to inspect things, the right hand power valve cover had made an escape, oh dear!
I managed a slow return to the pits, and luckily for me, lunch was called, and I managed to walk around the circuit and find the missing cover, with that installed, I inspected for other loose bits, and tightened up all over, a good thing, as I had also lost a small clip from the same powervalve, not important but I need to replace it - must have been drunk when I put this thing together.
The first session after lunch went well, and then after 5 minutes into the second session I thought I felt the engine tighten up. I went straight for the clutch and rolled into the pits. After removing the exhausts, no signs of a seize, but something is not quite right.... I had been reving to about 7K and even 8K in some places. Perhaps I need to cool it a bit.
The bike started fine, although the next session I kept my hand over the clutch lever in readiness.... Nothing uptoward happened, and I had a good session bringing my slow lap times down, as I grew in confidence, although I once again stuck to around 6K.
The last session of the day was great, I lifted the rev limit a little, and had a scrap with a junior on a 125 (I think) - he was going great and my bike managed to keep up. Still if I want to be competitive I will seriously need more power, and above all a different riding technique! In the slow bends I was definately quicker than some of the "big guys", however I have difficulty moving on the bike, which gives me much more of a Mike Hailwood technique than Barry Sheene (if I can be so bold as to compare!). I have to work on this. I think maybe my rearsets are too high which cramps my legs and makes it difficult to move - I will try lowering them to give a bit more comfort. I say that, but moving about on the bike creates a good deal of shake, which I do not get when sitting relatively still, however given that most GP riders move about, this must be the direction to go! I was finding the bends really easy (to go fast) when I was completely off the brakes, so I really needed to get well setup for each bend and get some speed off BEFORE entering the bend to get maximum corner speed. If I kept the brakes on too long (through late braking) it pushed me much further into the bend with the corresponding edges coming up a little too quickly. The bike and overall the tyres really worked well even with the front brake partially on, although this is a habit, I should try to avoid!
Overall the days impressions were good, although still some uncertitude about the engine, I will restrip and get the stud fixed on the barrel, and have a closer look at the pistons to see if any damage occurred - I hope not! Take a look at the circuit on their web site - http://www.ceerta.com/ it was pretty in amongst the rape seed fields - fortunately I am not allergic to rape seed! There were however loads of flying insects - one guy got stung 3 times by an errant wasp.
I will try and post a couple of short video clips in a few days, however I now only have a few weeks before first race, so I need to concentrate on the remaining jobs :-
Painting fairing, make some numberplates for the sides of the bike etc... Plus stripping the head and cylinders down (one more time!).
I managed a slow return to the pits, and luckily for me, lunch was called, and I managed to walk around the circuit and find the missing cover, with that installed, I inspected for other loose bits, and tightened up all over, a good thing, as I had also lost a small clip from the same powervalve, not important but I need to replace it - must have been drunk when I put this thing together.
The first session after lunch went well, and then after 5 minutes into the second session I thought I felt the engine tighten up. I went straight for the clutch and rolled into the pits. After removing the exhausts, no signs of a seize, but something is not quite right.... I had been reving to about 7K and even 8K in some places. Perhaps I need to cool it a bit.
The bike started fine, although the next session I kept my hand over the clutch lever in readiness.... Nothing uptoward happened, and I had a good session bringing my slow lap times down, as I grew in confidence, although I once again stuck to around 6K.
The last session of the day was great, I lifted the rev limit a little, and had a scrap with a junior on a 125 (I think) - he was going great and my bike managed to keep up. Still if I want to be competitive I will seriously need more power, and above all a different riding technique! In the slow bends I was definately quicker than some of the "big guys", however I have difficulty moving on the bike, which gives me much more of a Mike Hailwood technique than Barry Sheene (if I can be so bold as to compare!). I have to work on this. I think maybe my rearsets are too high which cramps my legs and makes it difficult to move - I will try lowering them to give a bit more comfort. I say that, but moving about on the bike creates a good deal of shake, which I do not get when sitting relatively still, however given that most GP riders move about, this must be the direction to go! I was finding the bends really easy (to go fast) when I was completely off the brakes, so I really needed to get well setup for each bend and get some speed off BEFORE entering the bend to get maximum corner speed. If I kept the brakes on too long (through late braking) it pushed me much further into the bend with the corresponding edges coming up a little too quickly. The bike and overall the tyres really worked well even with the front brake partially on, although this is a habit, I should try to avoid!
Overall the days impressions were good, although still some uncertitude about the engine, I will restrip and get the stud fixed on the barrel, and have a closer look at the pistons to see if any damage occurred - I hope not! Take a look at the circuit on their web site - http://www.ceerta.com/ it was pretty in amongst the rape seed fields - fortunately I am not allergic to rape seed! There were however loads of flying insects - one guy got stung 3 times by an errant wasp.
I will try and post a couple of short video clips in a few days, however I now only have a few weeks before first race, so I need to concentrate on the remaining jobs :-
Painting fairing, make some numberplates for the sides of the bike etc... Plus stripping the head and cylinders down (one more time!).
Tuesday, 17 April 2007
Ledenon - Photos
A quick update, after the rebore had a real problem with a pattern head gasket, which leaked water no matter how tight the head was on. After changing for the real YAMAHA part, everything works fine and no leakage. After all the tightening of the head, I may have loosened one of the cylinder studs (no.9). It appears to tighten but I can not reach the required torque without getting that sensation that something is about to break, slip... Anyway I have a track day planned as Issoire this weekend (22 April), and we will see if it holds until the engine is run in completely again. It will be interesting running in the bike at a track day but I don't really have an alternative, as I can not put it on the road. In preparation for this weekend, I have put on my "real" racing tyres AVON AM20 and AM23 (I think), these are much narrower than the previousl Dunlops but should bring back the very sharp handling I remember of old. I have also short circuited the oil pump, in order to run a petrol/oil mixture directly from the fuel tank. This meant, cutting the oil supply to the pump, draining the oil tank, and connecting the carburetor oil feeds connections together, to avoid them sucking in air. We will see how this performs!
In principal the bike starts and runs well with these modifications in place. I am now using the empty oil tank (saved at least one kilogram of weight of the oil here!), as a catch bottle for the crankcase breather, battery overflow, and carb overflow pipes. I routed all of these into the hole left after removing the oil level indication sensor from the tank.
The next challenge after this weekends outing, will be get the fairing painted... some thought required here. I will probably go for a boring white, which matches the tank, and the old seat unit, however if I get imaginative, I may add some speed blocks in a true Yam tradition!
I received my track stand in the mean time, so I should be alright without the centre stand this time around. I am just praying for fine weather this weekend!! It is forecast!
A couple of piccies of me on the bike at Ledenon.
Thursday, 12 April 2007
Current Dates for Proclassic
CAROLE 12 May (Saturday only) - Unlimited, Post Unlimited 750.-
CROIX 9 & 10 June - Classic 500 et 750, Unlimited.-
CAROLE 30 June (Saturday only) - Classic 500 & 750, Post Unlimited 750.-
LE MANS 21 & 22 July - all classes-
LE VIGEANT 11 & 12 August - all classes-
LEDENON 1 & 2 September - all classes-
CROIX 22 & 23 September - classes to be confirmed
CROIX 9 & 10 June - Classic 500 et 750, Unlimited.-
CAROLE 30 June (Saturday only) - Classic 500 & 750, Post Unlimited 750.-
LE MANS 21 & 22 July - all classes-
LE VIGEANT 11 & 12 August - all classes-
LEDENON 1 & 2 September - all classes-
CROIX 22 & 23 September - classes to be confirmed
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