Author Topic: problem with engine petering out  (Read 1377 times)

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Offline oldtimer

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problem with engine petering out
« on: 03 Jul 2023 at 14:56 »
My 1947 T35 starts usualy first kick but it will not run at a steady tickover , all the bits in the carb ie needle, jets , slide are as should be
it always wants to peter out and stop but it always starts again strait away it,s as if its lowon fuel but as the float needle has only one position you cannot raise the float . any ideas please .

Offline eddie

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Re: problem with engine petering out
« Reply #1 on: 03 Jul 2023 at 17:35 »
In the bottom of the float chamber there is a guide hole for the float needle - make sure that has not become choked with muck - thus hindering the movement of the float.

  Regards,
               Eddie.

Offline oldtimer

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Re: problem with engine petering out
« Reply #2 on: 04 Jul 2023 at 15:03 »
I have had the float chambers off and they seem clean . This all started some time ago when I filled the tank localy and the name of the station was harvest Fuel and i am wondering if it had alot of ethanol in it as it melted the petseal in the tank and gummed everything up
it stuck the carb slides and you couldn't open the throtle it even stuck a valve open in the quide as it was unused for some time . it seams like lack of fuel but the tanks full .

Offline EW-Ron

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Re: problem with engine petering out
« Reply #3 on: 04 Jul 2023 at 23:22 »
and gummed everything up

We think there is your answer.

Can take a LOT of ungumming from there.
Triple cleaned every jet and passageway ??

Offline oldtimer

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Re: problem with engine petering out
« Reply #4 on: 06 Jul 2023 at 07:09 »
Thanks , i think oltrasonic cleaning is the way forward then .

Offline Hamwic

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Re: problem with engine petering out
« Reply #5 on: 10 Jul 2023 at 08:56 »
Another favourite for petering out is a blocked air hole in the fuel cap. By the time you have checked the fuel level - by taking the cap off - the fuel flows again, but only for a while!

I've recently had the taps off my MK5, and found that the reserve passages on both were blocked with fine rust particles that had got through the gauze. Although there was a good gallon in the tank, it wouldn't come out once I went on to reserve. I guess a bit was splashing into the main passage while under way, but it faltered when stationary. They blew through once dried out, but draining the tank was not an option by the side of the road.

Cheers for now
Doug

Offline oldtimer

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Re: problem with engine petering out
« Reply #6 on: 29 Jul 2023 at 15:15 »
Iv'e had the carbs ultrasonic cleaned and still will not run it reves  but as soon as I shut the throtle it it stops , theres plenty of petrol coming though and new plugs some times it runs on one cylinder and then it starts up on the other / Very fed up trying to sort it .also the either the bendix or the kick start gear is worn and it misses the pawl , what sort of job is it to get in the gearbox and replace it if i can get one .

Offline eddie

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Re: problem with engine petering out
« Reply #7 on: 29 Jul 2023 at 15:56 »
Have another look at the carb. Take out the choke block, and inspect it very carefully. On the cylinderhead side of the block (in line with the pilot air screw) there is a very shallow drilling. In that drilling, there are 3 holes - one very small vertical drilling up to the main choke, another drilling almost vertically down - and a third small drilling right in the bottom of the shallow drilling. This one often gets overlooked because it looks as if it is the flat in the centre of the larger drilling.

  Regards,
               Eddie.

Offline oldtimer

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Re: problem with engine petering out
« Reply #8 on: 31 Jul 2023 at 13:15 »
Thanks for all the sugestions , i will have another look at it I did think is lack of compression but in testing it with tester it shows just over 100 psi . is that about right , but am I doing it ok the other plug out and i gave it 3 kicks . I restored this bike about 27 years ago and it was fine till i filled up with fuel from petrol station called Harvest energy .

Offline EW-Ron

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Re: problem with engine petering out
« Reply #9 on: 31 Jul 2023 at 21:48 »
Compression should always be tested HOT, throttle wide open.
Testing cold is a little less consistent.
100 psi doesn't sound too bad. Its best if both cyls are within 10 psi of each other.

Getting the carbs fully ungummed can be quite an adventure.
Good advice on removing/inspecting/cleaning  the jet block.
Are you sure its all gone from the tank ?
Last thing you want is more coming into the carbs.

Offline graeme

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Re: problem with engine petering out
« Reply #10 on: 06 Aug 2023 at 10:55 »
Indeed, make sure there is no rubbish coming out of the tank. As far as cleaning out the carby, I have had good success in cleaning gummed up drillings by boiling up a pot of  water with a tablespoon full of dishwashing powder dissolved in it, and let it boil away for a good couple of hours with the carby in it. Then wash it thoroughly with clean water

Cheers, Graeme