Building a race bike

[redax5]

This is a very interesting and informative thread, much more so than the ' is it a jota or not thread', blah.
My question is what bikes can run in the Phillip Island Classic specifically the International Challenge, 1970-80s era bikes. I read an article on a bike that raced there, 83 FJ1100 in a Harris-built Suzuki? XR69 chassis, it sounds like it is more in the vein of a "Run what you brung" class as long as it is '70s-'80s. What classes does the Redax Laverda run in?

We run in BEARs Formula 4 class here which is supposed to be the Heritage Class
But the way the rules are written you can run any British, Italian or American bike in that class if it is based and looks like a bike from that period
So our main competition is a guy riding a modern Thruxton 1200 R which we can still beat if our bikes don't break

Island Classic is supposed to run under PCRA rules but they relax the rules a fair bit for the feature class, hence you get to see the Irving Vincents come out to play for example

I have looked at the NZ BEARs rules as we gave some thought to shipping the bikes over to have a play in their BEARs series that is on early in the year, but I don't believe they would let my bikes run under their rules which are more inline with the Aussie PCRA rules
PCRA for example don't like the Showa upside down forks and modern Brembo braking systems we are using and would probably have a heart flutter when they spot the thumb brakes

So we stay in BEARs and keep modifying the bikes just so we can see if we can beat our track records each year

 

[GregT]

Over here you would have to run in F1. Against moderns with the same level of suspension but slipper clutches and wider rims.

i think you have been looking at the rules for the Heritage or historic class which as you say are very like PCRA or our post classic rules.

I suspect you would still be up the pointy end. Most of the big F1's at BEARS meetings have the riders who can afford them - older, slower...

 

[julian]

All this is very interesting, I do like hearing of other ideas and experiences.
The cam chain tensioner is one thing I am seriously thinking about, my thoughts are simply to use the std nylon "gear" but fit a needle roller inside, as I will be doing post race strip-down after every meeting I think I should be able to catch a problem before it causes damage if one is going to happen. Thoughts?

I think we need a race tech thread where people post ideas and attempts at improvements, (I say attempts not in a contemptuous way but as with my work for example, it's not proven so it's not necessarily an improvement until it's proven to be so other than in theory)
I think it would make a nice discussion thread as long as it does not get side tracked too much. What do others think? I don't mind it being discussed here either but it may be more permanent if we had a dedicated Tech thread.
J

 

[sideshow]

All this is very interesting, I do like hearing of other ideas and experiences.
The cam chain tensioner is one thing I am seriously thinking about, my thoughts are simply to use the std nylon "gear" but fit a needle roller inside, as I will be doing post race strip-down after every meeting I think I should be able to catch a problem before it causes damage if one is going to happen. Thoughts?

I think we need a race tech thread where people post ideas and attempts at improvements, (I say attempts not in a contemptuous way but as with my work for example, it's not proven so it's not necessarily an improvement until it's proven to be so other than in theory)
I think it would make a nice discussion thread as long as it does not get side tracked too much. What do others think? I don't mind it being discussed here either but it may be more permanent if we had a dedicated Tech thread.
J

I think that would be a great resource
start it up sir!

 

[Vince]

Yes please. Great idea. There is plenty of practical experience here. One thing that used to be talked about heaps but not so much now is data logging. Maybe they dialled it down when they reduced electronic aids in the big boy events. I haven't seen anything on it in the press in years. If you cannot measure it how can you improve?

 

[julian]

PS. Started the oil pump last night, I sure hope this thing works like I want as this is one hell of a lot of work for a Lemon
Adding it to the right hand side directly on the end of the crank, so need to make a complete housing bolt on and off including oil pickup ports etc. Oil feed will be to the oil cooler and then directly into the end of the crank and ends of the cams and no oil filter, simply a strainer and magnets.
Lots of work planned for tomorrow. Hopefully I don't get too many customers
J

 

[julian]

I see data logging as more of a rider / driver aid but it can be useful.
For example at Goodwood this year we were pulling 6k in top on the back straight where we were just hitting 5k last time, but lap times were a lot slower. Only after the race did the driver tell me he was "shopping" because he had stalled on the start (which I knew of course) and had to start from the pit 3/4 of a lap down he just stayed out of the way of the leaders and enjoyed himself as well as he could. However the data sheet showed that the engine was a lot more powerful than before (as also noted by the driver) but rather than just "it feels faster" we actually knew it was a lot faster. We had not dynoed it as time was a premium and the car won't go on the rolling road due to it's special gearbox, 1st is an on off device and you use the tyre spin as a clutch. Very exciting

Interesting but I would not like to see period Classic bikes with big electrics, in fact in the UK you are not allowed. You even have to tuck modern ignitions out of sight etc.


Greg, out of interest, how do you police slipper clutches? surely this is not easy to police? I for one am pretty sure I could design an undetectable slipper if I really needed to. is it worth the trouble to ban them? after all the good guys used to moderate the lever before slippers were invented, same thing but needs more skill, surely allowing a slipper would even the field and not hurt racing? Just a question.

 

[Andy J]

Interesting question, but it is a can of worms again. I suppose it’s really down to what you want from your racing. Evenly matched races that anyone could win, or races where the best riders and machines (generally) always win.

 

[Tippie]

SFC had the nylon wheel with needle roller bearing inside, I have always used them in my SFs. Needle rollers in the gb output shaft on SFC also iirc - you mentioned doing that too.
Engineering mod thread could be good.

 

[GregT]

Greg, out of interest, how do you police slipper clutches? surely this is not easy to police? I for one am pretty sure I could design an undetectable slipper if I really needed to. is it worth the trouble to ban them? after all the good guys used to moderate the lever before slippers were invented, same thing but needs more skill, surely allowing a slipper would even the field and not hurt racing? Just a question.

And a good one too.
Watching and listening is the starting point. Both how the bike is ridden and activity on forums like this one. I know for instance that there are slipper clutches being developed for the 16V Hondas. Progress is being reported on a US based forum. There is one main kiwi contributing to performance areas on that forum - and he's well aware it would be illegal here. Suzuki's I'm pretty well tapped in to and I haven't heard anything coming. Kawasakis have always had one available. The shaft drive models of the time had it and the clutch interchanges - which is how the factory did it.
i suspect it will be like Formula Ford. The cheaters are those in the midfield trying to bridge the gap to the front runners.
Protests here are relatively cheap. It would take less than 15 minutes to check.

Someone mentioned the rule-bending XR69's with Yamaha engines used at PI in the International. They'll probably be the first to run slippers as they aren't looked at as closely. One of them turned up here. It got pushed up a class to pre 89 much to the owner's indignation.

A dedicated performance mods thread would be a good idea. It'd stop your build thread being derailed anyway.

 

[julian]

Nice answers all.
I don’t mind the thread derailing sometimes as it’s also interesting but will start a tech thread on Monday. General or Tech forum?

Have new pics on Monday also, oil pump getting progress.
J

 

[sideshow]

Nice answers all.
I don’t mind the thread derailing sometimes as it’s also interesting but will start a tech thread on Monday. General or Tech forum?

Have new pics on Monday also, oil pump getting progress.
J

It would be nice to keep this one going too , with less derailment

 

[Andy J]

Nice answers all.
I don’t mind the thread derailing sometimes as it’s also interesting but will start a tech thread on Monday. General or Tech forum?

Have new pics on Monday also, oil pump getting progress.
J

I guess in the tech forum?

 

[julian]

Update time,
Spent a little time last night sorting the oil pump design,
*Machined the outer bearing housing down to just longer than the bearing (for a little skimming room after welding)
*Cut the oil pump housing to size, then made a plug to position the oil pump on centre with the crank, now figured out how the oil pickup will be routed, this needs to be very large compared to the old one as I am going to use a lot of oil.

What I had not mentioned before due to me not completely making my mind up on that point previously was that the engine will be Air cooled AND Oil cooled a bit like the old GSXR Slingshot Suzuki, Oil fed in copious quantities to the right places to bring the local temperatures down. Ceramic coatings will also be used in heavy amounts but I think I said that before. There are some serious mods needed to the head especially to manage this but I think if I don't then I may run into cooling issues later if I manage to achieve the power that I want. Pistons will also be sprayed with an oil jet from underneath, I have done this before and it solved some problems and it's not supper hard to do. I just hope this crankcase never gets destroyed as there's a massive amount of work in it.

*Made a big hole in the side of the crankcase
*Made a nice big oil pipe from ally tube for the pickup pipe, Bent with gas and a lot of care.
*Fitted it into the relevant holes and fettled it a bit.
*Oil sump is going to have a "Sub sump" bellow the engine to both increase sump capacity and to stop oil surge and pickup problems.

More to follow after another evening session tomorrow.

Regards,
Jules

 

[chrisk]

Now you are just hurting my brain.

 

[chrisk]

One of the Slabside curiosities is that if they are run without the breather hose to the airbox they expel globs of oil out of the cam cover gaskets.
Once the breather is reconnected to the airbox they are oil tight.

I spose, if they are sloshing around bucket loads of oil it has to go somewhere, and the partial vacuum evens things out a bit. Just thought I'd mention it Julian.

 

[piranha-bro2]

Loving this stuff, Julian!!

 

[martymoose]

Had to ride across town Monday, in 40 degress, in peak hour to get my booster jab, the air/oil cooled Suzuki bandit 1200 never batted an eyelid. SF2 got a bit rattly on the way home Friday night, heavy traffic, very hot. No oil cooler......

 

[julian]

One of the Slabside curiosities is that if they are run without the breather hose to the airbox they expel globs of oil out of the cam cover gaskets.
Once the breather is reconnected to the airbox they are oil tight.

I spose, if they are sloshing around bucket loads of oil it has to go somewhere, and the partial vacuum evens things out a bit. Just thought I'd mention it Julian.

Hi Chris,
They had early problems with the race bikes due to returning the head oil down the centre cam chain tunnel, at sustained high revs the chain whipped the oil into a froth and threw it out of the gaskets and starved the oil pump. This was cured by changing the oil drain and later on the race bikes having a sub sump like I am planning. We did the same on some of the pre-war race engines we tuned and had/solved the same problem.
You also have a phenomena that is concerning internal air movement.
Imagine 4 cylinders, two up two down, the two going down move a lot of air into the crankcase, the two moving up allow it to go up, however this is a lot of air movement, 750cc x 12000 = 9000 litres of air movement per minute inside the crankcase. The Muzzy ZXR Kawasakis actually modified their crank cases internally to make them more aerodynamic for less power sapping and it gave them a couple of hp apparently. I am trying to consider all of this in my build. Especially with the twisted crank it will be a more violent air movement, we will see.
I may also use an air box, I am considering this as air box resonance can be worth good HP.

Regards,
J

 

[julian]

Had to ride across town Monday, in 40 degress, in peak hour to get my booster jab, the air/oil cooled Suzuki bandit 1200 never batted an eyelid. SF2 got a bit rattly on the way home Friday night, heavy traffic, very hot. No oil cooler......

That's what I am hoping Marty, It will surely be better than nothing.
J