Racing 2021

Hi Ralph
I cant believe your rings are so shot. But then it does get welly. The classic club had a bit of a reputation for holding you in the paddock back in the day. Never an option to turn it off as I knew we could never restart it. My 8 valve used to steam like a kettle. All my bikes have large oil tanks. I run 7 pints in the big girl. Cadwell it is then. Hope you get sorted.

I think that waiting in the warm up area is responsible for at least as much engine damage as ‘throttle to the stop’ race use.

My 900 NRE / Triumph once melted the solder on the earth eyelet bolted to the head steady FFS. Heat would make it run horribly, the ‘warm up’ lap usually cooled it down though when it got some air flowing over it.
I went to oil in frame (extra capacity and cooling surface area) and an oil cooler. Also ceramic coated the ex pipes to reduce ‘under faring’ temps. That all made a huge difference. I also worked at making it easier to bump start, racers can often be a tad guilty of not perfecting pilot settings etc, and practiced bumping it till I had the confidence to switch it off at will.

I’ve never seen rings do that though Ralph. I wonder if it was wear or heat damage ?

Are you running Royal Purple?

Let me know what you need Ralph. I have some 920 JS piston rings ‘in stock’ used and new, that you can use if needed.

acotrel said:

When you race in the rain - if it is bad for you, it is bad for everybody else. Racing in the rain is safer. If you drop, you don't usually get grabbed by the track and rolled. So you are less likely to break bones. Since the late 1960s we have had tyres with lots of grip. Riders become dependent on them, so riding in the rain is a bigger problem for many. A lot depends on your mindset. Riding in the rain never worries me, because I know the guys with the big horsepower motors are stuffed.

Click to expand...

I agree it can be a mind thing to a certain extent, but that isn't always because of the fear of being hurt. I was a London courier for a few years and riding in the wet was a way of life. I can ride in the wet but I do realise that things can go wrong very quickly, I don't have an endless supply of money or time and as a lot of the parts on my bike have been made by me, the time issue can get out of hand very quickly.

I don't push too hard in the wet because at my age I am not looking forwards to a career in racing, it is supposed to be fun.

Tyres have changed again since the 60s, this past few years most of the manufacturers seem to be making more focused tyres, the Continentals I use are defiantly better in the dry than the Avons but the Avons are a better all rounder, there are tyres made now that are practically slicks and are a lot faster in the dry, I noticed my times are closer to some of the top guys in the wet but they are using more dry focused tyres, the ones that seem to bugger off no matter what, are changing wheels.

I think the tyres are being moved forwards by the SuperMono guys, the tyre companies have identified a market.

Fast Eddie said:

Ralph, exactly what do you need for the motor?

Click to expand...

I was going to change the pistons and take the opportunely to have them coated, the but Jim has them on back order, I have put an order in for rings and a few other bits which are in transit from Philadelphia and should be here by Wednesday. Now the next race has been cancelled, I have a bit more measuring to do and may have time to wait for the pistons. The motor has been together 3 years so it's time for a bit of a refresh.

There was another strange problem, I noticed a small chunk had been taken out of the top/side of the left piston, this corresponded with what looked like a bump in the liner where the rear through bolt is. The machining for the through bolt in the barrel breaks through and exposes the liner, it looks like this is where the gasket was blowing, where the bolts are the gasket bulges down into the hole and I think this creates a week spot in the gasket (stretching and thinning the gasket) once the gas was escaping I think the top of the liner that doesn't have direct contact with the barrel gets hot and attracts a carbon build up. What looked like a bump turned out to be carbon.

I am going to machine some top hats to fit in the top of the bolts and make the top of the barrels flat, I am going to make them a interference fit to the barrel which will mean drilling them out each time but hopefully that will be the lesser of 2 evils.

worntorn said:

Ralph said "This is what happens when an old air cooled twin is held on the line."

If I remember correctly, yours is a full race spec 920 with Maney cases and crank + JS components, not much Norton remaining?

That should be a really durable engine, hopefully it will work out for you yet.
This tells me to stay away from the track with my mostly Norton 920 engine. Not much chance of survival for it in track use.



Glen

Click to expand...

I think the engine is durable but it has been together 3 years, the rest of the engine is in very good condition. It does make me cringe a bit calling it a Norton, the timing gears, oil pump, head and timing cover are the only bits that have been anywhere near Norton, all in the design though.

Schwany said:

Good tuner tip about raising the needle to soften the hit reapplying throttle. Race 1 Darley Moor first paragraph for those that missed it.

Click to expand...

It did make a slight difference, but clutching at straws springs to mind.

Bernhard said:

Over the last few years the tyre manufacturers have stopped making race compound tyres for the clubmen racing, ie you cannot get for love or money new Dunlop KR 125 tyres anymore.
I used to race with Metezeler's tyres with their race compound road tyres - but no longer available.

Click to expand...

They are starting to make them again now days, not the Dunlops but most of the others, I heard Avon are about to release a new race tyre soon. Even Pirelli have a race compound of the Phantom.

Chris said:

Hi Ralph
I cant believe your rings are so shot. But then it does get welly. The classic club had a bit of a reputation for holding you in the paddock back in the day. Never an option to turn it off as I knew we could never restart it. My 8 valve used to steam like a kettle. All my bikes have large oil tanks. I run 7 pints in the big girl. Cadwell it is then. Hope you get sorted.

Click to expand...

That is the problem, not being able to turn it off, I need to come up with a solution. The ring are 3 years old so I must take some responsibility but it is still anoying being held on the line with no info about how long we may be there.

Fast Eddie said:

I’ve never seen rings do that though Ralph. I wonder if it was wear or heat damage ?

Are you running Royal Purple?

Let me know what you need Ralph. I have some 920 JS piston rings ‘in stock’ used and new, that you can use if needed.

Click to expand...

Both probably, yes royal purple.

Thanks for the offer, hopefully I should be sorted.

Schwany said:
Good tuner tip about raising the needle to soften the hit reapplying throttle. Race 1 Darley Moor first paragraph for those that missed it.

storm42 said:

It did make a slight difference, but clutching at straws springs to mind.

Click to expand...

It does work though, as long as the carburetion is close to or spot on to begin with. I've done it inadvertently trying to get a little more color and fuel around a hotter plug at cruise, and that was the result. Softer transition when getting back on the throttle. I moved the clip back up to a leaner setting for a street bike only driven on clear weather days. I like the hit. It's really all I have to look forward to putt putting around on a little 750.

I'd be clutching at everything trying to go fast in the rain. I don't care much for rain on a road bike. Too much clean up, and too much pucker factor.

Nice race write ups BTW. I'm no racer, but a good read just the same.

Hi Ralph
I took up my chain adjustment as I thought it was too much slack giving me an on off throttle movement of the bike. Ok in the dry (but not great) in the damp It takes the edge off my riding. I followed Al's advice & brought my tick over up, this smoothed things up a lot. It's the drive on opening the throttle that moves the bike around in the wet. I really need to sort a smoother lighter throttle & try not to roll on & of the throttle so much. Amal MK2 smoothbores 960 TTi box

Nigel, I hope the pics below better explain post 24. this is the damage to the piston caused by the carbon.



I think the hot gases getting past the gasket and down the backside of the liner caused enough localised heat for the carbon buildup on the liner.



Tracking through, it had been going down the bolt hole too.



I am hoping this will help.

Chris said:

Hi Ralph
I took up my chain adjustment as I thought it was too much slack giving me an on off throttle movement of the bike. Ok in the dry (but not great) in the damp It takes the edge off my riding. I followed Al's advice & brought my tick over up, this smoothed things up a lot. It's the drive on opening the throttle that moves the bike around in the wet. I really need to sort a smoother lighter throttle & try not to roll on & of the throttle so much. Amal MK2 smoothbores 960 TTi box

Click to expand...

I also lifted the tick over which helped. I have also thought about altering the throttle so the initial pull needs more twist but I think the play in the box is the main problem, the vid shows how far the clutch move before the chain in second gear, this would be the best part of half an engine rotation, a fair old swing of the hammer.

I use the clutch to take out some of the hit, I need to get better at it though.

That looks like perfect logic Ralph. The alloy bungs will fill the void on the top & should help the gasket. Looks like a good plan.

Most of it is down to the grunt of the big engine Ralph. It's what makes it such a joy to ride. The 750 was much smoother in the wet.
I dont have that level of "feel" that the top riders have for easing the bike into the throttle!
Looking at your video reminds me I have not changed the cush drive rubbers in the K4 rear wheel for a while!

Chris said:

That looks like perfect logic Ralph. The alloy bungs will fill the void on the top & should help the gasket. Looks like a good plan.

Click to expand...

We will see. I have just put my entry in for Cadwell, are you entering? the entries opened at 6 tonight, I am guessing they will fill up quickly.

Chris said:

Most of it is down to the grunt of the big engine Ralph. It's what makes it such a joy to ride. The 750 was much smoother in the wet.
I dont have that level of "feel" that the top riders have for easing the bike into the throttle!

Click to expand...

Me neither, and I have probably made it worse with the twin pipe hike in torque, we need to be careful what we ask for

Yes I am going to enter 1300 classic & F750 as I havnt run the 8 valve or the Rickman yet. I'm going to switch bikes over the weekend. Should do my head in completely. If a big if I get to a track day I will change that.

Chris said:

Yes I am going to enter 1300 classic & F750 as I havnt run the 8 valve or the Rickman yet. I'm going to switch bikes over the weekend. Should do my head in completely. If a big if I get to a track day I will change that.

Click to expand...

I am in the 1300 classic.

Are the meetings still run behind closed doors?