CRMC Honda Capacity Limit GOING GOING Almost GONE

[kew]

Absolutely correct, Imps were in the main 875, I believe the Sunbeam Stilletto was 990 and its impossible to get a 750 BM engine out to 1200

Peter, Using an R75/5 crank you can get a BMW out to above 1170cc i am told also it is reputed that someone in Germany has them to 1220cc with this crank.

What engine would you have to put the R75/5 crank into to get the 1220 cc?

[petercaughlin]

666,
you may well be correct, the point is you can get a 750 to 1200 now because there`s a lot of later stuff to enable you, but I`m willing to bet you couldn't do it in the period,which is why it wasn't done

[tonybsa2008]

Ian,you may have a piont about the TZ,but I did do a Post classic meeting at Carnaby 2 on my A65,I only race a TZ,because I specifically want to race one,I also want to race a period correct Classic Norton,but I am not interested in turning up to be lapped by sidecars that remind me of the Modsports saloon car class of the 70s(Ie anything goes,as long as it looks right from 10 feet away(sorry metres),and I feel,I am probably not alone in that view.

[ianw]

Ian,you may have a piont about the TZ,I also want to race a period correct Classic Norton,but I am not interested in turning up to be lapped by sidecars that remind me of the Modsports saloon car class of the 70s(Ie anything goes,as long as it looks right from 10 feet away(sorry metres),and I feel,I am probably not alone in that view.

Tony, that is the exact reason for the demise of Forgotten Era & Post Classic classes, how would you feel turning out with your Norton only to be lapped maybe twice in a race by a blooodily TZ750?
When the Forgotten Era Club (sidecar class) was concieved, the class had a specific ban on the Jap 4 cylinder 2 strokes because of the damage they did to sidecar racing. The class ran perfectly with full grids but then some racers wanted the Jap 4 cylinder 4 stoke multis allowed in the class. They were allowed in with a limit of 1mm oversize bore. That didn't last long, as with any class, there were those that thought rules were there to be ignored. I saw it first hand, I could keep up with the GS1000's but then the next season, away they went, blatantly obvious they were running big motors. So the TZ700/750's were allowed in, the rest is, sorry to say history.
In the early days of Forgotten Era when we had the full grids, a lot of the outfits were Classic Club bikes, we actually took bikes way from the Classic class which was due to the fact that some classic racers wanted to race against something different. That changed when the GS's & the TZ's were allowed in.
With hind sight, the Forgotten Era class should have had a cut off date as the Classic Club have & the specific ban on the Jap multi 4 & 2 strokes should have been enforced, the class would probably still have been going today.

[tonybsa2008]

Ian,you are probably right,but dont make it personal.I came in AFTER the rules had already been changed.
If they had not of been changed,I would have raced a TZ elsewhere,as we do now in modern openclass racing.
You may not like the big TZs,and they are not to evryone liking,but a lot of people get a lot of pleasure out of seeing and hearing ours,racing.
I am merely trying to dispell some of the myths about how expensive they are to run.
The first 4 meetings I ever did,were with a Windrick Triumph with the CRMC,and all we did was get lapped! Obviously I was a novice and that was a large part of the problem,so you can see,I am no stranger to being lapped!
What I would like to see,and be a part of in the CRMC,is a large variety of competive machinery,at affordable prices,rather than 2 or possibly 3 makes of engine capable of winning,its not only boring for the competiters,its boring for the paying spectators.

[ianw]

Tony, there is nothing personal. Your views seem to contradict themselves.

[666]

Absolutely correct, Imps were in the main 875, I believe the Sunbeam Stilletto was 990 and its impossible to get a 750 BM engine out to 1200

Peter, Using an R75/5 crank you can get a BMW out to above 1170cc i am told also it is reputed that someone in Germany has them to 1220cc with this crank.

What engine would you have to put the R75/5 crank into to get the 1220 cc?

Keith, Any of the early air cooled crankcases, the germans are making 100 and 102mm pistons and boring and fitting liners in std barrels. I have seen pictures of both, the pistons have teflon buttons in the gudgeon pin holes which carry the oil control rings as the pin has to be high in the piston and the barrel looks equally suspect as the bore comes dangerously close to hold down bolts which i think would cause major distortion and head gasket issues. I have not worked out the capacity using a std R75/5 crank.The use of a longer stroke makes other problems with the bottom of rods hitting the camshaft, i most certainly would not care to run such an engine for obvious reasons. But as with all of the BM's the difficulty is spotting these power units as the differences are difficult to spot although the sound should easy to hear.

[steve-e]

That there. The pistons have teflon buttons in the gudgeon pin holes.
John please explain further I'm enjoying this education

[sidecarracing]

Peter, Using an R75/5 crank you can get a BMW out to above 1170cc i am told also it is reputed that someone in Germany has them to 1220cc with this crank.

What engine would you have to put the R75/5 crank into to get the 1220 cc?

Keith, Any of the early air cooled crankcases, the germans are making 100 and 102mm pistons and boring and fitting liners in std barrels. I have seen pictures of both, the pistons have teflon buttons in the gudgeon pin holes which carry the oil control rings as the pin has to be high in the piston and the barrel looks equally suspect as the bore comes dangerously close to hold down bolts which i think would cause major distortion and head gasket issues. I have not worked out the capacity using a std R75/5 crank.The use of a longer stroke makes other problems with the bottom of rods hitting the camshaft, i most certainly would not care to run such an engine for obvious reasons. But as with all of the BM's the difficulty is spotting these power units as the differences are difficult to spot although the sound should easy to hear.

To clear things up a little: Beemers with prefixes R75, R80, R90 and R100 all use the same stroke, being 70.6mm to be precise.
Bore sizes being 82, 84.8, 90 and 94 for these models.

[kew]

To be honest I don't care what size engines anyone buys, I'm happy racing my Honda which I will put together myself.
I'll be happy if I can only get it up to 1300cc, the size I used to race it at in 1965.
Obviously I will have to use cb360 pistons, cb900 head, Hyabusa gear box, etc. just as back in the day.

[David Stewart]

Well............. That all seems to have got very emotional.

Looking at it from a dispassionate point of view:-

Point 1 - You have a group of racers that have read the rules - as they are currently written - and built their bikes to comply with that specification. These racers are quite normal in that they wish to race to win within a championship that currently exists and has other competitors making use of exactly those rules.
Nothing wrong with that and all quite legit.

Point 2 - You have a different group of racers (and a few ex-racers) who wish to race their historic bikes in a manner that was not only possible, but actually done "within the rules" back in the correct period. The championship that currently exists does not actually appear to sufficiently cater for this - and even if it technically does, it means scrapping for 10th, 11th, 12th places against the bikes in category 1 that have taken advantage of the current rules.

Point 3 - The problem actually seems to be clouded a little by the assumption that the CRMC is "Dedicated to the preservation and racing of motorcycles from the pre-1972 period" - which used to be on a lot of their literature (but I can't currently find on their website).

You are not the first to come up against this conundrum. There was a similar group who wanted to do exactly the same thing with real Classic GP500 single cylinder bikes and who were also frustrated with the brand new bikes (replicas) that purported to be Manx Nortons etc.
They went off and organised the Lansdowne Cup series and took guest slots at various clubs. That was actually very successful for a while and when I first saw the Camathias Cup for sidecars, I assumed that was what it was all about.
If it wasn't, what is it about?

If there aren't enough of you out there who actually possess and actively intend to race those "Real Classics" this whole 5 page thread is really just so much hot air. If there are enough of you, you simply need to put your money down and get on with it.

The crux of the matter is that you can't put the Genie back in the bottle. If you allow within the rules a £50 note (for want of a better example) to be fitted to the handlebars and that £50 note makes the bike 1 second per lap faster. As soon as 1 person fits the £50 note, everyone else has to do it too or they are instantly at a 1 second disadvantage.
Therefore, you haven't changed the result in any way, all you have done is make the price of competing go up by £50 for everyone.

If you keep on doing that you will find that people get disillusioned and quit, because a hobby that used to cost £5,000 a year and looked like really good value for the amount of fun you got out of it, suddenly costs £10,000 and your not having any more fun than you were for half the price.
I think that is the point you have reached about now.

As I said at the start - just a dispassionate view from outside, but if you don't DO something about it now whilst people still care enough to argue about it, your opportunity will be gone.

[666]

That there. The pistons have teflon buttons in the gudgeon pin holes.
John please explain further I'm enjoying this education

Steve, As you can see the oil control ring run across the pin hole with support from a teflon button, also notice how close the stud holes in the barrel are, highly possible distortion and head gasket problems.

[666]

To be honest I don't care what size engines anyone buys, I'm happy racing my Honda which I will put together myself.
I'll be happy if I can only get it up to 1300cc, the size I used to race it at in 1965.
Obviously I will have to use cb360 pistons, cb900 head, Hyabusa gear box, etc. just as back in the day.

[oldbelly]

I would be a bit worried about pistons as short as they are , without having the control ring like that and that bore is just too big for that barrel ?

[ianw]

That there. The pistons have teflon buttons in the gudgeon pin holes.
John please explain further I'm enjoying this education

Steve, As you can see the oil control ring run across the pin hole with support from a teflon button, also notice how close the stud holes in the barrel are, highly possible distortion and head gasket problems.

Hi John, back in 1975 our friend Pete Davis at Puma Engineering took my Weslake out to 960cc, all the Weslake runners, including Bill Currie said it couldn't be done. Pete did it, 960cc. He'd done a few for the grass but mine was the first for road racing.
He used Ford pistons to get the bore size, problem was that the gudgeon pin to piston crown height was bigger than than the pistons which Weslake supplied. To get a round this he shrunk a new fin spiggott onto the top of the cylinder & then fitted larger diameter liners ( before the days of when Nicasil became readilly available.) It worked perfectly.
Looking at your pic of the BM piston,is that a liner or nicasil bore? That gudgeon pin looks scarilly close to the crown.
Would it be possible to shrink a new fin on the top of the BM cylinder as Pete did for me? There are numerous companies in the USA who will make pistons & rings to suit your pattern( I think minimum batches of 6 pistons) That way the gudgeon pin in the piston could be dropped further away from the crown.
For steve e. John will tell you, top fuel bike dragster engines ran pistons with PTFE buttons in the piston skirts for years then when the piston coating proccess's were developed useing PTFE & other slippery chemicals, the dragsters used a combination of both.
My Puma Weslake engine in the 80's & 90's ran an "oil injection" system that Pete made me. The cylinder had 2 small holes drilled into the bore just below the position of the bottom piston ring on bottom dead centre. The hole was fed with engine oil from the high pressure side of the oil pump via a restricted orifice so there would be a continuous sqwirting of oil front & back. The piston would then come down & be coated with oil before going back up the bore. Again, it worked perfectly.
Pete Davis, the best Engineer (self taught) I have had the pleasure of knowing, he made the fastest Top Fuel Dragster engines in the world and was finally inducted into the Dragster Hall of Fame. All done from the prefabricate garage & shed at the side of his house. As John has said, if you can't afford it, with a bit of knowledge, make it yourself, or get someone to make it for you,something different that works doesn't need to cost a fortune.