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Discussion Starter #1
This is my first post and would like to start off by saying "hello" to everyone on the forums.

I recently aquired a CB500T that is in great original condition, but she needs her starter replaced. The previous owner told me the starter motors are notorious for going bad on these bikes. So here are my questions:

Will a starter motor for a 500F work on a 1975 CB500T?

Are the starter rebuild kits sold on Ebay worth getting?

Should I look at other areas besides just the motor (selenoid sounds like it is clicking over but I don't know what else to look at)?

I am planning on making a gradual conversion over to a cafe racer in the coming months. Carpy's cb750cafe isn't too far for me so I am sure that I will be picking up parts from him over the coming months.

I have seen some bikes with a "bobbed exhaust" that is shortened, flared towards the ends, and flat black. Are these something that you can buy or are they a custom piece?
 

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Hi and welcome

The starter for the 550 is probably different, although the insides might work. I don't know if the kit from e-bay will have all the parts you might need or not. The first thing you need to do is a little diagnostics. If you jump 12V straight to the starter does it work? if not then the starter itself is the problem. Take it off and take it apart and see if the brushes are bad. If not then is the commutator on the armature worn, pitted or corroded. You might be able to clean it up and use it some more. I have made lots of starters work again although I believe it is a temporary fix at best unless you totally rebuild using all new parts as needed. If this explanation is too complicated then a starter rebuild probably is also. I believe the starter from a Cb/CL 450 will possibly work. Good luck on the exhaust you may be able to find what you want on E-bay, and flat back is cheap.
Ken

AHRMA 412
Vintage racing - old guys on old bikes
 

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Yep, kicker's the way to go. Best option as I see it is to lose the electric starter entirely and block the hole... starters are too damn heavy for something that doesn't make you go faster.

Link below is for a company that makes block-off plugs for the starter hole (the one you want is the CB450 plug).

http://mginproducts.com/electrical.htm

A
 

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Discussion Starter #6
I have been going over the starting components and they seem to be in good order and receiving/sending out a electricity. This may seem like a real basic question, but how do I jump directly to the starter? I am assuming I bridge a wire directly from the Positive battery terminal directly to the wire leading from the starter? I figure it is better to ask before I blow something up.

The starter plug is a great idea and I may go that route if I can't get the starter to work. When I think of old school bikes (cafe racers, bobbers, etc) I think of kickstart. It says it will work on bikes up to 1974, do you think it will fit on a 1975?
 

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Yep, no question. I pulled the block-off plug from of a '72 450 and mounted in a '75 500T. They don't specify probably because there aren't many folks turning 500T's into racers. There are a few reasons, but most of it comes down to this: the 500T wasn't pretty.

As for parts swapping, you can use just about anything made for the 450 except pistons, connecting rods and crankshaft (and perhaps you can swap those with rods and pistons as a group - don't know, haven't tried). And perhaps exhaust valves - I understand that early 450s have a smaller exhaust valve diameter, but haven't verified myself. Intakes swap.

The frame is nearly identical. The motor is almost identical, and tops/bottoms swap interchangeably, provided you use the piston/ring/barrel combination that corresponds to the BOTTOM rather than top. I've had better luck with 450 heads on 500T's than the converse - both will run fine, but the increased stroke of the 500T combined with the more aggressive camshafts on a 450 is a better deal. Additionally, head parts are interchangeable - camshafts, rocker arms, etc. can all be swapped (though you'd do well to remount in their original locations and pairings).

I don't have a wiring diagram in front of me so can't be of much use to you on that. You could check the hot wire with a voltmeter and see if you're getting power when you hit the button - if you are and it doesn't turn you've got your answer.

A
 

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Discussion Starter #8
IIn what appears to be my genius move for 2007 I accidently touched the negative battery cable instead of the positive battery cable when I hooked up the hotwire. Not exactly what I was hoping to do.

The selonoid still seems to be clicking just fine. The turn signals, rear light, and break light are all in good working order. The only thing that now doesn't work is the headlight and the highbeam indicator (damn haste). I checked the fuse box and it looks like all the fuses are in one piece (although one is a little bent if that helps). Any ideas?

It looks like it is going to be kickstart from here on out. I would rather spend $20 on the plug than $150 on a new/refurbished starter. That is money that can be better spent on an electric ignition.
 

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Ideas? Yeah. Get out a voltmeter and a wiring diagram.

Test for voltage at the headlight connector and continuity on either side of the switch. Trace the headlight wire at every connector back until you get to the one that has power. Clean that connection.

A
 

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Yep, no question. I pulled the block-off plug from of a '72 450 and mounted in a '75 500T. They don't specify probably because there aren't many folks turning 500T's into racers. There are a few reasons, but most of it comes down to this: the 500T wasn't pretty.

As for parts swapping, you can use just about anything made for the 450 except pistons, connecting rods and crankshaft (and perhaps you can swap those with rods and pistons as a group - don't know, haven't tried). And perhaps exhaust valves - I understand that early 450s have a smaller exhaust valve diameter, but haven't verified myself. Intakes swap.

The frame is nearly identical. The motor is almost identical, and tops/bottoms swap interchangeably, provided you use the piston/ring/barrel combination that corresponds to the BOTTOM rather than top. I've had better luck with 450 heads on 500T's than the converse - both will run fine, but the increased stroke of the 500T combined with the more aggressive camshafts on a 450 is a better deal. Additionally, head parts are interchangeable - camshafts, rocker arms, etc. can all be swapped (though you'd do well to remount in their original locations and pairings).

I don't have a wiring diagram in front of me so can't be of much use to you on that. You could check the hot wire with a voltmeter and see if you're getting power when you hit the button - if you are and it doesn't turn you've got your answer.

A
So I have a 500t engine with a bad top end and a 450 engine with a bad bottom end, can I combine the two into a working engine. The bottom baring on the 450 is messed, I'm not sure what the problem with the 500 is yet. Could I for example, put the entire cylinder and head with pistons and rods from 450 onto 500 bottom end?
 

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Here's the deal: if memory serves me right, they changed the stroke to make the 450 into a 500...that means that the cylinder may be slightly taller on the 500, but I could be wrong...best way to make sure is to get the vernier calipers out and start measuring.
 

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I don't remember all the details but the short answer to your question, yes, you can run a 450 Head on the 500T Bottom end. It does require some work, its not a straight bolt on affair.

I believe you keep the 500T crank and rods, it should bring displacement to around 550cc? I could easily be incorrect on those numbers as its been about 4 years since I looked into it.

This is really testing my memory though I think it was Swagger who is a member here was using the 450 / 500t combination.

It is also discussed on the HondaTwins.net Forum somewhere. Try searching both this and the Honda Twins forums.
 

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Stock cb450 bore and stroke is 70mm by 57.8, 500t is 70mm by 64.8. So there is a significant difference in the stroke. You would have to swap the rods, cylinder, piston, head, and timing chain. iIRC the 500t head is different also so the whole setup needs to travel as a set.
 

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and if you are stupid and want to turbo or supercharge one like I did at one point, you use a 450 bottom end, rods, and piston, with a 500 cylinder, head, and cam chain. It drops the compression pretty low.. I think somewhere around 6:1 so you need a metric fuckton of boost to make the thing haul the mail again.
 

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and if you are stupid and want to turbo or supercharge one like I did at one point, you use a 450 bottom end, rods, and piston, with a 500 cylinder, head, and cam chain. It drops the compression pretty low.. I think somewhere around 6:1 so you need a metric fuckton of boost to make the thing haul the mail again.
Sounds like a nice opportunity to juice it and compress it @ 6:1. Maybe N2O to get it moving til the boost kicks in. Sounds fun anyway.
 

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Sounds like a nice opportunity to juice it and compress it @ 6:1. Maybe N2O to get it moving til the boost kicks in. Sounds fun anyway.
It sounds fun until you realize your oiling system cannot support a turbo, and your charging system cannot support the e-pumps needed to oil the turbo, and then one of your partners goes to rehab and finds jesus and the other loses the turbo manifold he was making for you when he gets fired from his job.
 
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