Topic: Honda Cb 500 Four, Supercharged "BigBang" Chopper

[SOHC4 Cafe Racer Fan]

I ran a Big Bang cam on a CB750 chopper years ago. It added some low end torque. The sound was not at all what I expected, kinda sounded like a big cb350t.


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seperate exhost lines vill probely give a nice big banging..if you mix it all in a 4-1 it vill be more boring.

 

What kind of exhaust did you have on that 750?
Did that big bang cam create much more vibrations compared to stock?

I was planning 4-2 pipes or 4-4. Have to see which one looks better.

As far as I can see in the thread, the engine is still apart.

[Medyo Bastos]

I ran a Big Bang cam on a CB750 chopper years ago. It added some low end torque. The sound was not at all what I expected, kinda sounded like a big cb350t.


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seperate exhost lines vill probely give a nice big banging..if you mix it all in a 4-1 it vill be more boring.

 

What kind of exhaust did you have on that 750?
Did that big bang cam create much more vibrations compared to stock?

I was planning 4-2 pipes or 4-4. Have to see which one looks better.

As far as I can see in the thread, the engine is still apart.

are you talking to me?  i been riding cb750's a hell of a lot longer than you been posting on this board! i made reference to the said cam here ~> http://forums.sohc4.net/index.php/topic,82842.msg1542706.html#msg1542706

[Lostboy Steve]

I had a cm400 with slightly baffled pipes and it sounded pretty good.probably similar to how this will sound.

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[spotty]

was talking to a mate of mine who works for a cam grinding place here in oz and mentioned that i'd like to do this big bang cam thing and he was somewhat scornful..."why not just grind a normal cam that gives you more bottom end" , honestly, some people have no imagination

also unfortunately all the machinery they've got there is too big to work on m/cycle sized cams, poo, but he does know of people who are capable of such activities at hopefully a reasonable cost so maybe the Honda and the Vmax will get some camshaft silliness inflicted on them. unfortunately the Vmax has 4 of the bloody things so that won't be cheap

[754]

Sound advice, but lost on the chopper guys... they go to great lengths to look or sound different..
Ask your buddy if he heard if Luther cams I had one.. had to be made somewhere.. mystery cam.

[Terry in Australia]

was talking to a mate of mine who works for a cam grinding place here in oz and mentioned that i'd like to do this big bang cam thing and he was somewhat scornful..."why not just grind a normal cam that gives you more bottom end" , honestly, some people have no imagination

also unfortunately all the machinery they've got there is too big to work on m/cycle sized cams, poo, but he does know of people who are capable of such activities at hopefully a reasonable cost so maybe the Honda and the Vmax will get some camshaft silliness inflicted on them. unfortunately the Vmax has 4 of the bloody things so that won't be cheap

I had a pair of wild Yoshi race cams out of a Suzy GS1000 drag bike engine re-profiled by Wade camshafts in North Melbourne back in the 90's Spotty, they were fantastic, back then they'd re-grind a cam for 10 bucks per lobe. I had to laugh when I noticed a heap of boxes marked with the "Sig Erson" logo, when I asked them what the story was he told me that they manufactured the cams, then sent them to the US, and many were then imported back into Oz for guys who wanted an "American" cam....   

Sadly the owner died a few years ago and they sold the business, but the new buyer bought much of the machinery and cam profile info, and I believe that they're still going, here's their details:

Clive Cams.
4/35 Clyde St, Ferntree Gully VIC 3156
(03) 9758 5977

If they'll do a "Big Bang" cam for a CB750, I want one too!

[rb550four]

The frame, the cam, the turbo........ I've seen allot of nice projects come and go around here but this one... this one is going well beyond the norm in both design and execution.
 Hats off to you and your refined abilities... continue to dazzle us ,please.

[Keskine]

Okay, it has been pretty quiet here for a while but it doesn't mean that nothing has happened.
I was waiting for some parts so i could continue the build. But it took a while, so in the mean time i decided to try making a girder front end for this bike.



I also got the custom made rear shocks for the bike so i was able to make brackets for those. Then i visited one guy who made me dust caps for the rear wheel.


Then my pulleys and belts arrived for the supercharger and the alternator so i started to line those. Intake manifold is also under construction.



Now my machinist is on a vacation, so i started to build gas tank and the rear fender. I'm still thinking if i should extend the gas tank a little bit. For the rear fender i will make completely new sides that go with the same curve as the wheel.

[budman]

Very cool.

[Stev-o]

Big Bang bike, and I thought that was a bad thing?! [was for my K4]  Subscribed...

[Terry in Australia]

Nice work!

[SOHC4 Cafe Racer Fan]

Big Bang bike, and I thought that was a bad thing?! [was for my K4]  Subscribed...

I was thinking of the Big Bang Theory and the new Twin Pulse V4 from Ducati.

[Keskine]

What do you guys think about the barnett clutch for cb500. Is that any good? Or should i think about changing the whole clutch from 550 or 650 and then buy the barnett clutch kit for that.?
I´m speaking about these kits http://dynoman.net/engine/clutch/barnett.html

Other thing is that does any one know if there is engine differences in Cb500 Four models. This one is K3 if im right. So this one is from between -77 and -79?

I have also been reading that the gearbox in cb500 is not that good compared to 550 gearbox. What is the difference? Can i just swap the 550 gear box for this one?

[Stev-o]

Barnett clutches are very good.

The weak link in the 500 gearbox is the clutch rod, they have been know to break.  Honda eliminated it on the 550.

If you want to upgrade, slap an entire 550 [or 650!] motor in that frame.

[754]

 Barnett, some swear by them, some swear at them.
 I swear by them, they can be a bit graunchy when cold.
 Bike is looking good..

[Keskine]

Barnett clutches are very good.

The weak link in the 500 gearbox is the clutch rod, they have been know to break.  Honda eliminated it on the 550.

If you want to upgrade, slap an entire 550 [or 650!] motor in that frame.

Problem is that we dont have those 550 engines that much here in finland. If we did, i would have used one those, or at least the parts from it. There is one 550 gearbox for sale in Uk, thats why i was thinking about changing it.

[Stev-o]

Barnett clutches are very good.

The weak link in the 500 gearbox is the clutch rod, they have been know to break.  Honda eliminated it on the 550.

If you want to upgrade, slap an entire 550 [or 650!] motor in that frame.

Problem is that we dont have those 550 engines that much here in finland. If we did, i would have used one those, or at least the parts from it. There is one 550 gearbox for sale in Uk, thats why i was thinking about changing it.

Sorry, I forget that you Europeans and not as lucky as us when it comes to spare parts.
I have spare 550, 750 and 900 [Kaw] engines that may get used one day.

[Terry in Australia]

Send him a Z1 engine Steve, that'll make that puppy bark!

[754]

Your girder looks similar to one I have, will you run a shock ?

[Keskine]

Your girder looks similar to one I have, will you run a shock ?

Yeah, looks quite similar. I will run a shock with it, now i have one shock that i'm going to try if it works. It is a mono shock from a scooter.

[SF]

That thing is long, low and looking mean! Friggn love it man


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[Keskine]

Been a while since last post to this project but it is still going on. Moved the bike to another garage and built a lift table to have a little bit better working positions. I also managed to finally buy a lathe to help making all the custom parts. Here's a few updates what have been done to the bike.

Intake for the keihin fcr carburetor and self made velocity stack for mock up.


Trigger wheel for megasquirt based ignition system and handlebars bracket


Gas tank tunnel with places for ignition coils.


Stainless steel intake manifold with connectors for ignition pressure sensor and analog pressure gauge. I made the end caps a little bit round with planishing hammer.



Bracket for gas tank and fuel line connection done. Also modified the rear fender a bit to have more room for the rear tire.


New rear brake bracket to allow the wider tire.

 
Electronics fitted and external oil lines finished.


This is how the bike looks at the moment.

[Keskine]

Few more pictures..

I 3d printed new base for this old bicycle/moped light to allow led lights. It is going to be my front light.


Made this aluminium bracket for belt tensioner. It replaces the old dust cap.


Then I made the exhaust from stainless steel. I'm going to make small mufflers, also from stainless steel. Pipes are going to be 4to4.

[SOHC4 Cafe Racer Fan]

Nice job on the pipes.  Are you going to use Cone Engineering style tips or something different?

[Keskine]

 

Nice job on the pipes.  Are you going to use Cone Engineering style tips or something different?

Yes something similar but a bit smaller.