Carb inlet rubbers and other stuff

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arthur
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Joined: Wed Jun 17, 2020 8:55 pm

Carb inlet rubbers and other stuff

Post by arthur »

OK first off are the inlet rubbers "HANDED" I ask because fitting the carbs the right hand carb is in very close proximity to the oil pump adjuster and the bottom of the other two carbs are very close to the top of the crank cases it dosn't seem right!
And trying to start her I need a dose of the Undertones "Teenage Kicks " my old crash damaged right leg can;t take the hammer now a days :lol:
Every now and then she will cough but most of the petrol seem to be in the exhausts although the plugs don't seem to be to wet
And taking out the drain bolts from the crank cases there is little fuel oil mix
I;m pretty sure the timing is right and the points gapped ok turning her over with the plugs out the plugs spark as they should in time with the points although it sometimes ignites the fuel in the exhaust
Is it me or have I cocked something up ?
barney01
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Location: Prestatyn.Wales

Re: Carb inlet rubbers and other stuff

Post by barney01 »

Hi, firstly the carb rubbers are not handed. Next we have to find out if the problem is electric or carb related. Try removing the airbox and spraying easy start into the carb intakes. Is the fuel fresh and carb jets clean?
Electrucs. Are the plugs sparking? Take plug out and lay it in cylinder head tou should have a big fat blue spark. The battery should be fully charged. The timing plate can be adjusted by loosening the screws and sliding the plate left or right. The timing is vital.
Its possible the fluid that is leaking from the exhaust is moisture being pushed out by engine compression. If the plugs are not wet after lots of kicking then petrol is not getting through to the cylinders
NO SMOKE .......NO POKE
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Alan H
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Re: Carb inlet rubbers and other stuff

Post by Alan H »

What type of plugs are in there and how new are they? I always fit non resistor plug caps too as they allow a better spark.
Have the carbs been serviced any time recently? I would recommend that you let Baz do them, that'll be one thing that you know is ok then.
Has the bike actually run since you've had it?
Proof that four strokes are over complicated
arthur
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Joined: Wed Jun 17, 2020 8:55 pm

Re: Carb inlet rubbers and other stuff

Post by arthur »

Hi All in reply
The carbs have been cleaned and new jets etc fitted ,
The points are new and I think properly set and gapped
The plugs all have a nice spark although they are old prehaps new ones will help
All cylinders have compression 115 -120
It seems that the petrol is bypassing the motor going down the pipes and every now and then igniting, a "flame /spark " will exit the drain hole
She has not run for many years but I live in hope
Its a long time since I have played with a 2 stroke or a carbed motor. Petrol injection and electronic ignition spoils us :D
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Alan H
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Location: Wombwell, Republic of South Yorkshire

Re: Carb inlet rubbers and other stuff

Post by Alan H »

I've never understood why people fit new (usually non genuine) jets when they 'maintain' carbs. Were the old ones worn out? Were they keyster? There could be your problem.
The only things that need doing are - clean the jets and passages thoroughly, same wuth float valves, and make sure fuel levels are right in the float chambers.
If fuel is bypassing the valves, they need sorting, and so does the tank tap. Easiest way to sort the tap is an in line shut off valve.
Proof that four strokes are over complicated
barney01
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Joined: Wed Sep 26, 2012 7:33 pm
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Re: Carb inlet rubbers and other stuff

Post by barney01 »

You say a flame/spark is coming out of the drain holes. Do you mean the SRIS valves on the front of the engine? If so if you try to start it without the valves in all the mixture for combustion will be pushed out. Hence no firing
NO SMOKE .......NO POKE
arthur
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Joined: Wed Jun 17, 2020 8:55 pm

Re: Carb inlet rubbers and other stuff

Post by arthur »

Hi all the jets were green and beyond salvage 20 years sitting in a barn is not good for anything, melted bellows sludge running down inside the carbs did not help either
Although the Honda CB400T I rescued from a field was a lot less fussy when it came to carb refurbishment.
Barney when I say from the exhaust I mean the tiny drain holes underneath where excess moisture is meant to escape from
Any road up I am off out to the workshop to have another go, I have taken the carbs off and blown them through with the air line s
and got some new plugs FINGERS CROSSED
arthur
Posts: 128
Joined: Wed Jun 17, 2020 8:55 pm

Re: Carb inlet rubbers and other stuff

Post by arthur »

Wahhhha hooo She lives !!! Clean carbs re-timed and new plug caps started 2nd kick :D Next question
How do I balance the carbs ?
They are the single cable pull type I assume the adjustment is from the top, lock nut on the rod.
But how do I get all three in sync?
The old Haynes is no use
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BAZ
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Re: Carb inlet rubbers and other stuff

Post by BAZ »

Use a flow meter allways works best...
barney01
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Joined: Wed Sep 26, 2012 7:33 pm
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Re: Carb inlet rubbers and other stuff

Post by barney01 »

NO SMOKE .......NO POKE
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