Slow G3
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Slow G3
Hi all
I have a 1958 G3LS
I've only had her for a couple of weeks, and we are getting to know each other.
I know the performance is not earth shattering, but 45mph on the flat and level is not great.
Climbing a moderate hill means dropping down to 2nd and only 20mph
I thought that perhaps the automatic advance/retard mechanism is stuck.
Is there any easy way of checking this?
Any other pointers would be gratefully received.
Cheers
Mike
I have a 1958 G3LS
I've only had her for a couple of weeks, and we are getting to know each other.
I know the performance is not earth shattering, but 45mph on the flat and level is not great.
Climbing a moderate hill means dropping down to 2nd and only 20mph
I thought that perhaps the automatic advance/retard mechanism is stuck.
Is there any easy way of checking this?
Any other pointers would be gratefully received.
Cheers
Mike
Mike Croudson
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Re: Slow G3
No that's no good. Presumably it has always been like that?
Does it rev freely when in neutral?
Assuming that the ignition is correctly timed you can rotate the points plate by hand to check that it operates freely and the bobweights move outwards against their springs. The A/R unit is well known to stick.
You can also check the points gap as over time the points tend to develop pips which reduces the gap which will retard the ignition timing.
Also check that the main jet (assuming it has the right one) isn't blocked/obstructed.
Is the engine note 'flat'? Does the engine get very hot and/or is the zorst pipe blueing badly at the exit from the cyl head? Both are indications of retarded timing.
As an aside, a common mistake with a new bike is to ride with the choke on. The choke is off when the cable is pulled tight by the h/bar lever.
If you don't have them the manuals are available under 'Books' in the link below:
http://archives.jampot.dk/
Does it rev freely when in neutral?
Assuming that the ignition is correctly timed you can rotate the points plate by hand to check that it operates freely and the bobweights move outwards against their springs. The A/R unit is well known to stick.
You can also check the points gap as over time the points tend to develop pips which reduces the gap which will retard the ignition timing.
Also check that the main jet (assuming it has the right one) isn't blocked/obstructed.
Is the engine note 'flat'? Does the engine get very hot and/or is the zorst pipe blueing badly at the exit from the cyl head? Both are indications of retarded timing.
As an aside, a common mistake with a new bike is to ride with the choke on. The choke is off when the cable is pulled tight by the h/bar lever.
If you don't have them the manuals are available under 'Books' in the link below:
http://archives.jampot.dk/
Last edited by SPRIDDLER on Sun Sep 11, 2022 10:05 am, edited 1 time in total.
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- clive
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Re: Slow G3
You are right that you should get better performance and it does sound like a retarded engine. The auto advance can be checked with the engine off. Take the timing cover off and turn the advance b hand. It should snap back when released. If it does not the cause can be wear in the stud that the weights hinge on, weak springs or the chain being too tight. So worth slackening the chain to see if it improves things. Also if it stood for a while before you got it try giving the mechanism a thorough squirt with WD 40 to see if it eases up.
clive
if it ain't broke don't fix
if it ain't broke don't fix
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Re: Slow G3
Thank you for your repies.
A few things to check.
Thanks for you time and input.
Cheers
Mike
A few things to check.
Thanks for you time and input.
Cheers
Mike
Mike Croudson
- jackstringer
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Re: Slow G3
For the fun of it it's worth giving the carb a bit of a clean. Check there is plenty of flow from the tank while you are at it.
If you can get to a local group meet you might find it worth letting another member have a quick go on yours or vice a verse versa as its handy way to judge if it's just you or your bike that has a issue.
Not that it's common but check the sprockets.
If you can get to a local group meet you might find it worth letting another member have a quick go on yours or vice a verse versa as its handy way to judge if it's just you or your bike that has a issue.
Not that it's common but check the sprockets.
- Pharisee
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Re: Slow G3
That's 10-15mph slower than I cruise my '54 G3/LS and I would still have a little in hand.
Fair enough, mine has a manual A/R but you do seem to have a problem. As has already been suggested, ignition timing and carburation should be checked. Do you have plenty of compression or can your machine be started easily without using the exhaust valve lifter?
Fair enough, mine has a manual A/R but you do seem to have a problem. As has already been suggested, ignition timing and carburation should be checked. Do you have plenty of compression or can your machine be started easily without using the exhaust valve lifter?
I'm from the Fens.... Gimme six.
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Re: Slow G3
Hmmm, lots to think about.
Compression seems OK, I can start it without the valve lifter, but it takes some effort.
It's obvious that the bike has been rebuilt, but has been standing for some time.
I put new fuel into the tank, but still a lot of brown sludge came out when I tickled the carb.
Next job, clean carb and flush out the tank.
When I look at the points, and turn over the engine, only the cam moves, and opens the points.
I would have expected to be able to rotate the A/R bobweights by hand, but I can't.
I'll take some photos later today, and post here.
Cheers
Mike
Compression seems OK, I can start it without the valve lifter, but it takes some effort.
It's obvious that the bike has been rebuilt, but has been standing for some time.
I put new fuel into the tank, but still a lot of brown sludge came out when I tickled the carb.
Next job, clean carb and flush out the tank.
When I look at the points, and turn over the engine, only the cam moves, and opens the points.
I would have expected to be able to rotate the A/R bobweights by hand, but I can't.
I'll take some photos later today, and post here.
Cheers
Mike
Mike Croudson
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Re: Slow G3
Hi all
I have now taken on board your comments and suggestions.
I've cleaned the carb, seems OK.
I've also dismantled the timing cover and points plate.
The issue I have (I think) is that the A/R weights are very loose.
I can move them a few degrees before the springs take up the slack.
Is this right?
Can I move the springs to the second hole on the mounting plates, so making them a but tighter?
Please see the attached photos
Thanks for any suggestions
I have now taken on board your comments and suggestions.
I've cleaned the carb, seems OK.
I've also dismantled the timing cover and points plate.
The issue I have (I think) is that the A/R weights are very loose.
I can move them a few degrees before the springs take up the slack.
Is this right?
Can I move the springs to the second hole on the mounting plates, so making them a but tighter?
Please see the attached photos
Thanks for any suggestions
You do not have the required permissions to view the files attached to this post.
Mike Croudson
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Re: Slow G3
I wouldn,t move the spring to the 2nd hole as this will probably cause the spring to tighten and prevent the timing from advancing as it should with engine speed. This would make the bike less responsive and slower. I don,t think the a/r is the problem. It sounds more like carburation.
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Re: Slow G3
just makes sure the timing is set with the bob weights wedged fully advanced , it should not take much effort to moved and should return easily under spring tension