Another Honda 400/4 for AC500

[Andy Jones]

Steve you are probably right.  I was somewhat re-assured by the photos of Mochek hondas that raced the production TT and appear to have standard exhausts.  Though I guess in reality the TT doesn't see the same lean angles as a short circuit (though with the bumps might show up ground clearance just as bad??)

[Iain Green]

Though I guess in reality the TT doesn't see the same lean angles as a short circuit

But modern tyres open up all sorts of new possibilities for grinding bits of your bike on the floor!

[Andy Guy]

Yep. Even clipons and levers. 😂

[Steve Adlem]

Steve you are probably right.  I was somewhat re-assured by the photos of Mochek hondas that raced the production TT and appear to have standard exhausts.  Though I guess in reality the TT doesn't see the same lean angles as a short circuit (though with the bumps might show up ground clearance just as bad??)

Classic case of period 'Production Racer Cheating'.  Exhausts were rerouted.

Compare photos of a standard bike and the Mocheck racers, that exhaust is giving more ground clearance than the ones that left the factory.....

You can even see the 'blueing' of the welds where 3 downpipes were shortened!  Might give you a clue what you could do.

[Andy Jones]

Steve "Eagle Eyes" Adlem 😄😄

I never spotted that before but you are absolutely right 3 welded downpipes!

[Andy Jones]

Well time for an update on this project. 

First I have to say to anyone planning to build their own race bike........don't bother just buy an existing race prepped bike!!  Seriously it has been so time consuming with every little job taking about 10 time more time and effort than you think and nearly everything you make up doesn't work first time. 

However, I am now at the stage where I have an eligibility cert and an entry for Brand Hatch this weekend.  I still have a list of jobs to do this week but here is the bike as it currently stands:




Aim for Brands Hatch = get 3 race finishes (and a s a bonus at least try to beat my Dad also racing in PC AC500 on his Pantah)

Aim for next season = try to finish mid-pack

Aim for 2019 = demolish the opposition 

I have had this on the dyno and it currently makes a heady 35bhp at the rear wheel.  I have a couple more ponies to come once I go up another jet size and modify my bellmouths.  But this is it for now and on paper at least will leave me well behind the competition.......so lets pray the thing bloody handles well 

Over the winter I will have the wheels rebuilt and a full paint job.  I am also looking into getting some head work done to get me at least over 40 bhp mark.  However the full development for power will probably be stretched over the next few years as time and money allow.

[Andy Wilson]

Looks nice Andy, well done!  Couple of points which you have probably already considered
1) Can't see your oil containment on the pictures, do you have a bellypan or  'tray' for it
2) I know some people swear by those original Honda swinging calipers, and I guess you have race pads in there , but I'd consider a Lockheed (or similar)  conversion at some stage before your "demolition of opposition" phase 

WHOOPS EDIT I SEE THE BRAKE ISSUE HAS ALREADY BEEN DISCUSSED ABOVE, SORRY!!!

Have a great time at Brands..................Oh! and respect your father, my lads never did that, they just went out and beat me 

[Nige Collier]

Andy , he wont need brakes with 35hp lol

[Colin Wilkinson]

Pic from Manx Grand Prix 1977, standard exhaust cut across four pipes in a vee and welded back up. Did it in 1975 to a brand new bike for the 1975 MGP.
http://www.motorcycle-usa.com/photogallerys/Honda-CB-400---Colin-Wilkin.jpg
 Colin

[ken platt]

Don`t be beastly Nigel .

[simon walsh]

Hi,
My dad took a 400/4 to 3rd in the Formula 3 TT (which was also 3rd in the World Championship) in the late 70s.  I remember he said that they rerouted the pipes due to excessive heat from the standard arrangement which used to cause the motor to overheat.

Don't worry about HP - if it handles and stops well you will be surprised how well you can do

Regards
Simon

[Andy Jones]

Thanks for the comments it really has been such hard work and I can’t wait to ride it.

Andy - There is belly pan mounted under there somewhere it is very snug.

Colin - although I only had the aftermarket copy from David Silver as it was brand new I couldn’t bring myself to cut and weld it.

Nige - I certainly hope that’s true but if not a front end conversion for 35mm forks and twin discs might be on my list to Santa

[Nige Collier]

Andy not that it matters at the moment as ime sure the bike will get developed over time but the issue you have is power to weight, 35hp & most likely 140 plus kg will be a killer , most of the 2 stroke opposition have around 55-60 hp and weigh 115kg, my own 500 Honda weighs in at 108kg & estimate 45hp which is very competitive in class

[Andy Wilson]

Andy - There is belly pan mounted under there somewhere it is very snug.

Very neat then, well hidden! 

[Andy Jones]

Andy not that it matters at the moment as ime sure the bike will get developed over time but the issue you have is power to weight, 35hp & most likely 140 plus kg will be a killer , most of the 2 stroke opposition have around 55-60 hp and weigh 115kg, my own 500 Honda weighs in at 108kg & estimate 45hp which is very competitive in class

Nige you have hit the nail on the head.  Despite my work on the frame with a hacksaw and angle grinder the bike weighs in at 162kg (wet weight with fuel).  Which is a good saving over standard but still heavier than I would like. 

This is not helped by still having a generator and starter on the bike.......but damn that push button start is so convenient and there's seems little point in trying to make the bike even lighter whilst I am going to be sitting on it (at 6ft and 14 stone I am no Dani Pedrosa).

Still some more tuning and a strict diet and exercise programme over winter should help a bit, but unless i get to at least 60bhp I won't be worrying the front runners.

But for now having fun on a bike I have built is more important than trophies (or so i tell myself  ).