Carb? Stuttering after a while

Discuss mechanical problems here.
MOGGIEMOS1@
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Re: Carb? Stuttering after a while

Postby MOGGIEMOS1@ » Fri Jun 26, 2020 7:37 pm

Ye it starts no problem first turn of the key...pump works very well. I drained the tank and refilled and pump performed as it should..I have no knocking whilst revving..obviously I can't take it for a good run due to lack of power but on last inspection..yesterday the plugs looked like new after letting it tick over for 15 minutes...I will try your suggestion of loosening the dizzy..advance..and retard and see how I go..ive tried everything else so fingers crossed...I will update you on progress thanks for your assistance

MOGGIEMOS1@
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Re: Carb? Stuttering after a while

Postby MOGGIEMOS1@ » Fri Jun 26, 2020 7:50 pm

Would the fact that I put a 45D dizzy in affect how the timing should be set despite what the manual says which I assume covers the original 25D thanks myoldjolopy

Bornfree
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Re: Carb? Stuttering after a while

Postby Bornfree » Fri Jun 26, 2020 10:13 pm

newagetraveller wrote:
Fri Jun 26, 2020 1:35 pm
Dirt in the float chamber?

Ignition coil breaking down in the hot weather?
Not the second option as I've tried replacing the coil with a new one I had. (Unless I'm supremely unlucky!)

So tomorrow I'll have a look at the float chamber, think there's a spare gasket in the spares box!!

myoldjalopy
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Re: Carb? Stuttering after a while

Postby myoldjalopy » Sat Jun 27, 2020 1:12 am

MOGGIEMOS1@ wrote:
Fri Jun 26, 2020 7:50 pm
Would the fact that I put a 45D dizzy in affect how the timing should be set despite what the manual says which I assume covers the original 25D thanks myoldjolopy
No, the principle is the same for both. If the engine runs (and assuming the fuel and ignition systems are adjusted and working properly) then you will have to adjust the timing by rotating the dizzy in the clamp. For finer adjustments during road testing use the dizzy's advance-retard knurled nut. But we don't know when your engine was last run/rebuilt and if there are other factors at play....

MOGGIEMOS1@
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Re: Carb? Stuttering after a while

Postby MOGGIEMOS1@ » Sat Jun 27, 2020 7:02 am

Thanks again myjalopy I will have another tinker today starting with checking for binding of the wheels (brakes).
The dizzy doesn't have the knurled nut like the 25D did..the engine was rebuilt about 3years ago I am led to believe..thanks again much appreciated

shoebone
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Re: Carb? Stuttering after a while

Postby shoebone » Sat Jun 27, 2020 10:20 am

Well, this is fun, what have we got .. three different problems on one post? So .. to MOGGIEMOS1@ .... Some new parts are bad straight out the package these days .. I am suspecting your condenser, if you have the original one try fitting that.

myoldjalopy
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Re: Carb? Stuttering after a while

Postby myoldjalopy » Sat Jun 27, 2020 11:19 am

Yes, a new post should be started for each new topic really.
But, for 'MOGGIEMOS1@' it is possible the new condensor or coil is faulty - so you could re-fit the old ones (one at a time) and see if that makes a difference. Best to use 'Distributor Doctor' ignition components to be sure they are good quality. If pulling the choke improves things as you say, and you have Haynes, try the mixture test described in the section about setting up and tuning the carb. It might be worth checking the valve settings are correct as well. Problem is, lack of power can be any number of things and we don't know if the engine was running well before this problem arose. Is this the first time trying to run the engine after the re-build, or has it been running since and only recently playing up?

Bornfree
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Re: Carb? Stuttering after a while

Postby Bornfree » Sat Jun 27, 2020 8:37 pm

Yes as OP I nearly got totally sidetracked!!
Last edited by Bornfree on Sat Jun 27, 2020 8:39 pm, edited 1 time in total.

Bornfree
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Re: Carb? Stuttering after a while

Postby Bornfree » Sat Jun 27, 2020 8:37 pm

My progress to date:

Fuel pipe to carb tightened
Filler cap loosened
Coil replaced
New air filter (because I could!)
Pump filter cleaned and reshaped (see picture above)
Float chamber cleaned (some black gunge at bottom), refitted with new gasket. (Needle valve appears clear, so did not replace.

Just been out for a 16 mile run in it, and previous occasional stuttering behaviour not presenting itself. So now I've an excuse for a longer run out tomorrow if its not raining, to see if the problem is there.

MOGGIEMOS1@
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Re: Carb? Stuttering after a while

Postby MOGGIEMOS1@ » Sun Jun 28, 2020 11:50 am

Hi again
Apologies for invading someone else's post as I'm new to posting on this forum and not exactly sure how to place new posts but I will have a look around and it won't happen again..a quick update on my progress...its running and pulling 100% better thanks to myjalopy advising me to check for brakes binding well believe it or not 1 wheel was binding and quite hard to turn (I fitted new brakes last year and probably didn't adjust them properly) but I freed and adjusted and hey presto problem loads better...I never gave it a thought because I thought it was timing or fuel problems...thanks everyone for advice especially myjalopy
Much appreciated

myoldjalopy
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Re: Carb? Stuttering after a while

Postby myoldjalopy » Sun Jun 28, 2020 1:23 pm

Phew! Well done! Good thing I mentioned the brakes then and you didn't spend days messing about with timing, ignition and carb settings, possibly making things worse! And.......a nice easy fix - we like them! 8)

Bornfree
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Re: Carb? Stuttering after a while

Postby Bornfree » Fri Jul 03, 2020 5:20 pm

Ref. OP and stuttering
Should have also added toy list of actions done that whilst checking the fuel filter I blew back down fuel feed to clear anything lurking.

Anyway, sunny day today so just been for a 20 mile return run to the river and back and all was good, running nice and smoothly.

So far so good!!

Bornfree
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Re: Carb? Stuttering after a while

Postby Bornfree » Mon Jul 27, 2020 9:43 pm

Well I don’t think it’s sorted yet..

The run mentioned above was fabulous. So a couple of runs have been ok, but latest one was not good, lots of stuttering!

Checked the float chamber again, and a very very small amount of muck at the bottom.
Checked the fuel filter in the fuel pump again, and struggled to see any muck.

So now I’m wondering if I should drain the fuel tank and clean it. My thinking is that as I pick up speed maybe muck is being sucked up in the tank, and the faster the pumping the more muck. Then when I stop after it’s started stuttering all the muck falls away and off we can go again smoothly. Does that sound logical?

So is draining the tank by using the nut underneath sufficient to drain, and see what comes out? And then wash it through with some clean petrol. Or do I need to remove the tank and put some tank cleaner in and shake it around?

What are your thoughts, please?

kennatt
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Re: Carb? Stuttering after a while

Postby kennatt » Tue Jul 28, 2020 6:46 am

before doing anything else,take it out on a quiet road and as soon as the stuttering starts ,into neutral and switch off so engine and pump are not doing anything.Coast to a stop and remove the top of the carb so that you can see the fuel level.If low then you have found the cause ,and then you can trace the fault in one direction,eliminating others.


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