My Track bike project

A lot of people have told me to put up a thread on my track bike project, so here it is  
A few pictures to show how far I have got so far.





So far it is a CB500 s frame modified to take a CBR400RR (NC29) swingarm and suspension. The rear wheel is a CBR900RR fireblade one (£1.20 on fleabay), running a 180/55/17 tyre. I'm using a cb500 sprocket carrier machined down to align the chain run, with a CBF500 output shaft to space out the front sprocket.
The front end is from a CBR600RR4 with a front wheel from a SP1 and a 120/60/17 tyre. The brake discs will be Brembo 310mm when funds become available. The clip-ons are only on for ease of moving it about, it will have a set of renthal bars on it once I have the top yoke conversion done. The lower yoke is from a CBR900rr (98 model) the pinch bolts on the RR4 fouled the radiator at full lock.
The observant ones will notice that the rear upper engine mount has been removed to allow the monoshock to be aligned properly.
I have made one to be fitted just under the shock mount, but ran out of argon, so welding that in will have to wait.
The engine cases/head have just been vapour blasted and will be painted once I have finished using it to position everything correctly. They are currently empty apart from the gearbox output shaft. (I saw no need for lifting a complete engine about unless necessary)
I shall endeavor to post pictures and any progress as they occur

Looking forward to reading through this thread as your project progresses! 

Wow good work, just shows what u can do if you put your mind to it. Lot of work just to get it to this stage  keep up good work☺

Looking good so far. You planning on keeping the tail section or converting to something more strealined with a single seat?

I'm still not sure about the bodywork, although it will be a single seat unit. Probably a one piece race unit.
My preference is to keep the standard style of the 500 'S'.
That's why I went to the trouble of keeping the same style wheels rather than take the easy route and use the 600rr 3 spoke wheels. I did try them but they just didn't seem right for this bike. I guess it's down to personal taste.

Now sporting a radiator originally meant to grace a CBR400rr (NC29)
As I won't be running a cooling fan, thermostat and all the hoses that go with them a larger radiator would be required.
The CB500 does run quite cool unless you're stuck in traffic.
Although how a tuned engine will behave is yet to be discovered.  

Hi Andy

Really interesting stuff. I look forward to reading the updates to this thread as and when they arrive.

All the best with the future works.

Scott

looking really good....... is this destined for the Thundersport? I thought they were pretty strict about mods?

Thundersport are indeed very prescriptive about the modifications you can make whilst still allowing you to compete. 

In fact, you can't even use a K&N air filter as this is a "Performance upgrade", so unfortunately, I shouldn't think we have much chance of seeing this machine in that particular series anytime soon.

This is destined for trackdays. I'm building it how I want it and not down to regulations.
And for no other reason than because I can
Even my work bike (CB500S) is too modified to fit into a race class.
I'm also a bit too old to start being a conformist now.  

At last a little progress has been made.
The rear upper engine mount has now been welded in, as has the lower suspension mount.
I'm pleased to announce that the bike can now stand on it's own wheels.
This is quite a milestone as I can now determine the ride height and position the other things such as seat, bars, footpegs etc.

Finally got around to getting a Dyno run done for my work bike.
As this will be used as a 'mule' for testing my project engine I needed a base line to work with.
I didn't think it was too bad for a courier bike that's done well over 150k, it also runs a higher gearing (15/39 and a 160/60 rear tyre)
The larger capacity alternator didn't seem to cause any great losses either.

I got around to fitting the 4 degree ignition advancer to see if it made any difference.
And the answer is yes it certainly did  
There seems to be a much crisper throttle response and more bottom and midrange power.
Of course all this was judged by a test ride, and a spirited one at that! So until it goes back on the dyno next month I can't say for sure.
Tuning the CB500 doesn't list high on the tuning companies 'must do' list so I have to do a lot of research to find parts. This gem came from a VTR1000.


As far as mods go, this had to be the easiest to do. The hardest part was cleaning the gasket faces to fit the new cover gasket.

Nice little  mod to know about keep it up

Really interested in the ignition mod as I race but not with thundersport. Any more details appreciated.

Any more updates on this Andy?

I have been busy rebuilding my cylinder head, lapping in the standard valves and helicoiling the exhaust stud threads.
This head had 0.5mm skimmed from the face and was gasflowed. I'll be fitting it to my work bike in the next few weeks and get it run on the dyno to see what gains it gives.
I measured the bores to see if I can run 73mm forged pistons or if I would need to bore it out to 74mm.
I was very impressed to find that there was no wear at all on the bores so I can keep the standard size pistons, although they will be forged and higher compression.
Sorted out what code bearings I need for the crankshaft main bearings, having the crankcases vapour blasted almost removed the bearing size markings I do check them all using plastiguage anyway, but it's nice to have a starting point.
Just to confirm that I can multitask when I feel like it, I have decided to change the chain and sprockets to a 520 set-up. This reduces weight, friction and energy required to turn it. Which means that less power is wasted in between the engine and the back wheel.
Hopefully I should have a dyno run to show gains from the cylinder head, ignition advancer and the 520 chain in the next month or so.
Although Xmas is likely to reduce my available garage time I'm sure. Not to mention the annual dent in the finances. I'm dropping hints about the pistons that I want, wouldn't it be nice to find a pair under the tree

Loving reading about this project!

Spent this afternoon sorting out the shims and exhaust studs on the cylinder head. The stud threads I helicoiled, and used high tensile m6 x 35mm grub screws rather than the crap studs that are originally fitted.
All the shims are done and the head is ready to be fitted to my test mule, all I need now is time to do it.

I have finally got around to doing the 520 chain conversion  
It feels so much better, although this could just be down to the new chain and sprockets.
Losing 1.5 kilos from the chain and sprockets can't be a bad thing whichever way you look at it!
Hopefully it will show up on the next dyno run as a reduction in power lost before it reaches the rear wheel.
I was a bit hesitant about the strength issue, however my friend uses one on both his BMW S1000 and a gsxr750 with no problems so I feel safe.

A bit of an update, if only to show that I haven't given up  
The ignition advancer, although the bike felt much livelier on the road with a much crisper throttle response there was no significant gain showing on a dyno run. This could be due to a number of reasons, all of which I will explain.
My best guess would be the slipping clutch, which is self explanatory really. This is going to be replaced with an EBC kevlar one soon.
I took apart a spare airbox as I thought that it could be restrictive, and my findings were...........!
Whoever designs airboxes to enhance Honda's breathing ability must have been on holiday when this was designed! I was designed to fit in the frame and that's it.
The air intake has an area of 18.4cm/2  (40x46mm)
This is reduced to 16.62cm/2 by the 46mm diameter tube that the air filter sits on.
2x 34mm carbs have an area of 18.16cm/2 (not accounting for butterfly and spindles)
Whilst this looks just do-able in figures, lets take into account that this is trying to suck the air in through a 90 degree bend in the tube and the resistance of the air filter. Already I reckon that we are down to at least 70% efficiency, Then take into account that the initial intake is pointing backwards so that whatever speed you are doing at a given time must create a partial vacuum.
It seems reminiscent of running in a gas mask, anyone with military experience will not have forgotten that episode I'm sure.
Those who have not just imagine trying to breathe with a pillow over your face.
I have now set myself the task of building a more suitable airbox for my needs. The confined space between the carbs and the fuel tank mean that suitable individual pod filters are not an option.
Due to funds or more importantly the lack of funds, the fitting of FCR39 carbs has been shelved until I win the lottery.
Plan B is fitting a pair of 38mm CVK's from an early Fireblade. This in itself is no mean feat, but it can and will be done.
I have dismantled a set and sorted the spacing using a donor pair of CB500 carbs. There are a few as of yet unfinished minor issues such as the idle adjusting screw, the Fireblade one was just not accomadating. The inlet rubbers need to be bored out to 46mm to suit, The set of carbs I had were missing the alloy bellmouths so I need to source a pair of those. The spacer bars can be finished to the correct length once I'm confident that I won't need to strip them apart anymore. Here's a couple of pictures to show the differences.



I also decided to adapt a standard cam chain tensioner and convert it to a manual one, It has done 1600 miles so far and no problems at all, I'll explain all after a 10k trial period.

It seems like an age since I last had any time to press on with the project, but a little progress has been made.
I have now managed to successfully bore out the new inlet rubbers to suit the 38mm fireblade carbs.
This done I now know that the spacing is correct and I can tidy up the studs holding them together as well as other things like getting them ultrasonic cleaned and set up the jetting.
I will struggle with an airbox as there's very little clearance with the suspension mount, so I'll have to rethink that aspect of it.

The air filters arrived, so I got to checking them for clearance with a fuel tank.
And found that there isn't any  so I'll have to modify the tank to make some room.
This will probably mean disposing of the fuel tap too. Which isn't as bad as it sounds because this isn't a road bike and I can just use a 'dry break' self sealing hose connector.

It's a pity I can't use a high flow airbox that I made, but the upper suspension mount would mean that I would have to go back to a twin shock set-up. I haven't completely eliminated that idea yet, but will see how this route evolves first.

U done amazing work on your race bike  andy  well done