Tunster
It's a good idea to measure the bores if you get the head off. My CB72 had a full 350 kit so the numbers cast on the barrel are not a good guide when the bike has been used for racing.
Also - a racer will have been used with a range of sprockets for different circuits. Depending on the power / torque output you may want to try non-standard sprockets. It will be interesting to know if you have a 4 or 5 speed transmission in there.
G
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Sprocket question
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GORDON BROWN
- honda305.com Member
- Posts: 154
- Joined: Wed Oct 27, 2010 12:36 pm
- Location: edinburgh scotland
gearing etc.
Hello Tunster
Looking at your carbs. on the resto. thread, they are 30mm which are a large for a 250. I would think its probably bigger. Also the lower gearing might be because it has a close ratio box, the first gears in these are very high and it makes them difficult to get away ( this is all relative of course) this obviously also lowers top speed but the race engines are often tuned to rev. higher.
As G-man said different sprockets for different tracks (or even the road) is not that unusual so it might be better to see what you have before you worry too much about them.
Of course all this might be nonsense and a lot of guessing! By the way did you get the ign. sparking at all ?. Another thing to check is if it has a kick starter shaft ?
Better let you get on with your bikes instead of answering all these questions now.
Regards
Gordon
Looking at your carbs. on the resto. thread, they are 30mm which are a large for a 250. I would think its probably bigger. Also the lower gearing might be because it has a close ratio box, the first gears in these are very high and it makes them difficult to get away ( this is all relative of course) this obviously also lowers top speed but the race engines are often tuned to rev. higher.
As G-man said different sprockets for different tracks (or even the road) is not that unusual so it might be better to see what you have before you worry too much about them.
Of course all this might be nonsense and a lot of guessing! By the way did you get the ign. sparking at all ?. Another thing to check is if it has a kick starter shaft ?
Better let you get on with your bikes instead of answering all these questions now.
Regards
Gordon
Re: gearing etc.
Gordon
Just to hijack the thread briefly. What route did people take to get a close-ratio 4-speed 'box?
Can it be done with a combination of CA and CB internals. I must admit that I am being lazy and haven't checked out the gears I have.... :-)
G
Just to hijack the thread briefly. What route did people take to get a close-ratio 4-speed 'box?
Can it be done with a combination of CA and CB internals. I must admit that I am being lazy and haven't checked out the gears I have.... :-)
G
GORDON BROWN wrote:Hello Tunster
Looking at your carbs. on the resto. thread, they are 30mm which are a large for a 250. I would think its probably bigger. Also the lower gearing might be because it has a close ratio box, the first gears in these are very high and it makes them difficult to get away ( this is all relative of course) this obviously also lowers top speed but the race engines are often tuned to rev. higher.
As G-man said different sprockets for different tracks (or even the road) is not that unusual so it might be better to see what you have before you worry too much about them.
Of course all this might be nonsense and a lot of guessing! By the way did you get the ign. sparking at all ?. Another thing to check is if it has a kick starter shaft ?
Better let you get on with your bikes instead of answering all these questions now.
Regards
Gordon
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F
Cb72
I think it's 4 speed but not 100% it's impossible to turn the motor over by hand though I can get 1st and 2nd. I've removed the wheels for a refurb,new tyres etc and as there's no kickstart I will have to wait until I get them back. As for the ignition, i fitted a new battery and the amps drop when I flick the switch so I think that's a good sign? I want to get it running before I remove and strip the motor and I'm itching to see what she sound like.
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GORDON BROWN
- honda305.com Member
- Posts: 154
- Joined: Wed Oct 27, 2010 12:36 pm
- Location: edinburgh scotland
gearing etc.
Hello Tunster
Yes I know what you mean its hard to go through the gears until you get the wheel back in, chain connected etc. and get the gearbox turning. Oh, and regarding what it will sound like, I think LOUD probably if it has open megaphones !
G-Man, there were factory close ratio 4 & 5 speed boxes available in the 60's and as far as I have read also some conversions (possibly just high first gears ) made in the UK, back in the day as they say. Also a lot of the classic / vintage racers from the 80s & 90s used Nova boxes based on the original ratios, I think the main difference between now and then is that nearly all races were push start and so you could get away with the higher gear.
As for modifying the std. box I am not sure ( the Xing. of 2nd / 3rd still keeps bottom to top ratio the same ) but I think I read that Teazer tried CA ? top gears which might be lower, so closing it up a bit, perhaps he could confirm this.
Sorry Tunster now I have really hijacked your thread.
Gordon
SAFOJ
Yes I know what you mean its hard to go through the gears until you get the wheel back in, chain connected etc. and get the gearbox turning. Oh, and regarding what it will sound like, I think LOUD probably if it has open megaphones !
G-Man, there were factory close ratio 4 & 5 speed boxes available in the 60's and as far as I have read also some conversions (possibly just high first gears ) made in the UK, back in the day as they say. Also a lot of the classic / vintage racers from the 80s & 90s used Nova boxes based on the original ratios, I think the main difference between now and then is that nearly all races were push start and so you could get away with the higher gear.
As for modifying the std. box I am not sure ( the Xing. of 2nd / 3rd still keeps bottom to top ratio the same ) but I think I read that Teazer tried CA ? top gears which might be lower, so closing it up a bit, perhaps he could confirm this.
Sorry Tunster now I have really hijacked your thread.
Gordon
SAFOJ