Author Topic: mk5 carb question  (Read 5757 times)

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Offline varagaz

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mk5 carb question
« on: 15 Feb 2015 at 19:25 »
On the mk5 amal 274 carb how do you check the float heights  thanks in advance gaz

Offline douglas1947

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Re: mk5 carb question
« Reply #1 on: 16 Feb 2015 at 11:35 »
Do you have the small type of floatchambers?
What is the special problem?

Michael

Offline varagaz

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Re: mk5 carb question
« Reply #2 on: 16 Feb 2015 at 11:47 »
I have the brass floats. wanted to check float height . has my bike running rough  carb been cleaned out  trying to set up ...engine has full rebuild

Offline frankclock

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Re: mk5 carb question
« Reply #3 on: 16 Feb 2015 at 20:58 »
Hello from Australia
you say the bike is running rough
I went to the Douglas rally in Bathurst here last year & had a fair amount of trouble with the bike running rough, it seemed to be very rich puffing out back smoke & in the end it was put on a trailer when it failed to keep running
in the end it turned out to be the fuel I was using, over here we have 97, 95 & 91unleaded as well as ethanol based
I had put in 97 whilst filling up my car & this proved to be the problem, after replacing with unleaded 91 all my problems were cured!!!!
maybe this could be your problem, its an easy fix if thats what it is
good luck

Offline douglas1947

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Re: mk5 carb question
« Reply #4 on: 18 Feb 2015 at 05:57 »
I think there is only one position in fixing the Float needle to the float.

Do you have changed any patrs of the carburettor?

Michael

Offline eddie

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Re: mk5 carb question
« Reply #5 on: 18 Feb 2015 at 07:15 »
Hi,
     On the 274 carbs fitted to postwar machines there is no provision for altering the fuel level. Any wear that has taken place will raise the fuel level. Should this level become excessively high, fuel will seep out of the bleed hole in the slot in the body just above the cap nut that secures the choke block. Up to this point, any discrepancy in the mixture strength should be adjustable on the slow running screw. It is unlikely that the slight increase in fuel level will drastically affect the mixture in the higher throttle ranges. If the mixture strength is erratic, check that the float and it's needle are free to move in the float chamber body - there is a hole about 3mm dia in the bottom of the float chamber that can get clogged up with dirt, making the float stick in the chamber. Also, check that you have the correct cap nut and washers between the carb body and float chamber - Amal made 2 depths of cap nut!
  Hope this helps,
    Regards,
                  Eddie.

Offline varagaz

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Re: mk5 carb question
« Reply #6 on: 18 Feb 2015 at 14:17 »
Thanks for replies i will check that 3mm  hole bought new jets .floats. neddles  . Will try at the weekend . Also which furl is best super unleaded or unleaded

Offline eddie

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Re: mk5 carb question
« Reply #7 on: 18 Feb 2015 at 17:05 »
Hi,
     I use ordinary unleaded in my Dragonfly without any of the problems that were forecast with the introduction of lead free petrol. You may find it advantageous to fit slides with a slightly smaller cutaway, and increase the main jet by 5. The smaller cutaway will give a better pickup from tickover, and the increase in main jet will make the engine run a little cooler on full throttle. From what I understand, some owners have had problems with super unleaded - something to do with engines running weak due to it having a higher viscosity than the ordinary unleaded.
   When I first started using unleaded, I used to lace it with Valvemaster to prevent valve seat damage , but found the petrol soon went stale, so have reverted to plain unleaded without any problems.
   Regards,
                 Eddie.

Offline douglas1947

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Re: mk5 carb question
« Reply #8 on: 19 Feb 2015 at 11:57 »
I can agree, what Eddie has posted.

I will just tell:
A friend of mine has same troubles (with a bloody Cossak Twin).
Bad starting + no idling.

The reson was too old petrol! He refilled the tank and all was okay.

The modern petrols donīt last long (and the "bio sprit" ethanol makes tanks rosty).
When I donīt use bikes not often (for example in winter or TOO MUCH BIKES!?):
I use only the "best" quality "Super Plus".
I has a guarantee of 12 month, E10 only 3 month for full ower!!!

Michael


Offline hvirtanen

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Re: mk5 carb question
« Reply #9 on: 20 Feb 2015 at 07:07 »
'On the 274 carbs fitted to postwar machines there is no provision for altering the fuel level. Any wear that has taken place will raise the fuel level. Should this level become excessively high, fuel will seep out of the bleed hole in the slot in the body just above the cap nut that secures the choke block.' 
    wrote Eddie.

Do you think that it would help to file a new slot on the float needle to adjust the float level? Or to make a new float needle altogether using a pattern from another carb?

with best,

-hv

Offline eddie

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Re: mk5 carb question
« Reply #10 on: 20 Feb 2015 at 11:46 »
In a word - no, don't mess about with the height of the float. Lowering it may restrict the fuel flow and cause the engine to run weak. Raising the float may result in it contacting the tickler button - in which case, the carb will just flood. Wear on the float needle wont drastically affect the fuel level, but it may result in erratic control of the level if there is a significant ridge on the taper. Incorrect fuel height is more likely to be caused by either a punctured float, or one that is being weighed down by solder if it has suffered a previous repair. If you think your fuel level is too high, try fitting a second fibre washer between the float chamber and bottom cap nut on the carb body. This is an easy mod to do - and more importantly, easy to undo if there is no improvement.
  Regards,
               Eddie

Offline varagaz

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Re: mk5 carb question
« Reply #11 on: 20 Feb 2015 at 20:08 »
Got my new  carb bits  no 4 slide,  needles ,floats  assembly , main jet  ,repair kit   that lot should re furb the carbs hopefully  it will  be  happy days

Offline varagaz

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Re: mk5 carb question
« Reply #12 on: 22 Feb 2015 at 17:27 »
Bike now running sweet has a nut  super unleaded branded fuel not supermarket  4 slide 107 needle+ needle  jet   2nd clip down 90 main jet  new fibre seals  carb cleaned  eddie thanks for the tip

Offline douglas1947

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Re: mk5 carb question
« Reply #13 on: 23 Feb 2015 at 16:25 »
Nice to read thatīs all okay!

Michael

 

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