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Discussion Starter · #1 ·
Hi all,
Am quite new here. I have a 1972 CB 250. Changed battery and started a treat.
To get the bike to start with a full charge i need to be riding for an hour.
Today, I can only kick start the bike to get it running with no issues. When i press the starter button I hear a tick like its trying to start.
What are peoples immediate thoughts.
John

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Probably something wrong with the charging system. These older bikes did not have that great a system to begin with, and riding in low RPM will slowly drain the battery any way. I'd test the voltage on the battery with a voltmeter, while the bike is working. You want it to show over 12V, with everything on. It will be under 12V at idle, but it should go up to about 13V in higher RPM. Anything over 14.5V is too much, and that means you need a new regulator. If the bike does not charge enough, I'd first try checking if all the connections are good. Otherwise you may need a new winding (modern ones may also give a bit more output). Replacing the bulbs with modern LEDs can also help.
 

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I would suspect the Starter Solenoid is NOT passing the FULL Current to the starter.

The Solenoid is ONLY an Electrically activated SWITCH.
It allows a LOW Current Switch (the Push Button at the handle bar) to energize a coil which pull a contact Into place to Bridge the (2) High Current side contacts and allow full Battery current to flow to the starter.

To CHECK. Open the Seat to expose the Battery. the solenoid is the Small Round part near the battery that has a Large Cable coming from the Battery and a 2nd large cable that goes to the starter.
There are (2) Smaller Cable that come from the Handle Bar Switch.

Listen to see if the TICK you hear is coming from that part when you press the starter button.

If it is then with the BIKE in NEUTRAL Bridge the (2) large Cable Connections with a Screw Driver.
That will simulate the internal Switching process. If the Starter turns then you have found your problem.

Solenoids can be re-built the FSM shows how but they are cheap enough to simply replace.

To explain what has happened:
When you bridged the (2) High Current Connections and the Starter Turned you saw a SPARK. and it left a small arc burn on the screwdriver.
The same thing happens when the internal contact is pull into position to bridge the terminals on the inside of the solenoid.
Over time the arc burns build up carbon deposits and insolate the contacts from making a good connection.
The TICK you hear is the Coils Energizing and pulling the internal contact into position.
 
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Discussion Starter · #4 ·
I would suspect the Starter Solenoid is NOT passing the FULL Current to the starter.

The Solenoid is ONLY an Electrically activated SWITCH.
It allows a LOW Current Switch (the Push Button at the handle bar) to energize a coil which pull a contact Into place to Bridge the (2) High Current side contacts and allow full Battery current to flow to the starter.

To CHECK. Open the Seat to expose the Battery. the solenoid is the Small Round part near the battery that has a Large Cable coming from the Battery and a 2nd large cable that goes to the starter.
There are (2) Smaller Cable that come from the Handle Bar Switch.

Listen to see if the TICK you hear is coming from that part when you press the starter button.

If it is then with the BIKE in NEUTRAL Bridge the (2) large Cable Connections with a Screw Driver.
That will simulate the internal Switching process. If the Starter turns then you have found your problem.

Solenoids can be re-built the FSM shows how but they are cheap enough to simply replace.

To explain what has happened:
When you bridged the (2) High Current Connections and the Starter Turned you saw a SPARK. and it left a small arc burn on the screwdriver.
The same thing happens when the internal contact is pull into position to bridge the terminals on the inside of the solenoid.
Over time the arc burns build up carbon deposits and insolate the contacts from making a good connection.
The TICK you hear is the Coils Energizing and pulling the internal contact into position.
Hi Yendor,
Many thanks for your insightful and knowledable response.
I actually did have a look at the solenoid the other day, but will take another look following your instructions. Let you know how I go. Bike has remained idle since 1998 so am sure there are some items that need attention.
John

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Discussion Starter · #5 ·
Hi Yendor,
Many thanks for your insightful and knowledable response.
I actually did have a look at the solenoid the other day, but will take another look following your instructions. Let you know how I go. Bike has remained idle since 1998 so am sure there are some items that need attention.
John

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Hi Yendor,
Thanks for your info.
Got the bike to start but...

I pulled the advance and points off. I have done everything as per manual
Put the advance on LT when pufting back in
Checked gap for static ignition
Checked ignition timimg with light.
Charged battery to full charge
The bike starta but i does not run...sigb


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If it ran before you took the Points assembly apart, and you removed the advance double check you did not install the advance assembly 180 deg out of sync.

It is either that or your Points Gaps/Timing are not correct.
 

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Discussion Starter · #7 ·
If it ran before you took the Points assembly apart, and you removed the advance double check you did not install the advance assembly 180 deg out of sync.

It is either that or your Points Gaps/Timing are not correct.
Thanks for the advice. Appreciate it

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