Date: 28-03-24  Time: 08:39 am

Author Topic: carb inlet rubbers  (Read 2675 times)

king1

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carb inlet rubbers
« on: 12 September 2014, 06:57:09 pm »
Hi
I am after some help
My bike is running on kangaroo juice
I have cleaned out tank, cleaned carbs, oil and filter change.

The symptoms and motorway cruising speed it is stuttering, at fast acceleration there is no power and it even slows down.

I have been told it could be my carb rubbers that are leaking as they are cracked,

Could this be the problem, I was going to try sealing them and wrapping tape round them, alternatively new ones are £70.
I have been looking at other topics on the forum but still need help

Any advice

Thanks
Kelvin

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Re: carb inlet rubbers
« Reply #1 on: 12 September 2014, 07:32:23 pm »
Splash water on them see if they leak it sounds like its an air/fuel issue

noggythenog

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Re: carb inlet rubbers
« Reply #2 on: 12 September 2014, 07:49:56 pm »





What does the air filter look like???
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darrsi

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Re: carb inlet rubbers
« Reply #3 on: 12 September 2014, 08:15:22 pm »
I've had an air leak from the carb rubbers before when one of them was fitted incorrectly, and the symptoms are bogging down and the odd stutter on hard acceleration, very noticeable when trying to overtake.
It feels like there's not enough petrol, but in reality it is just too much air.
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king1

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Re: carb inlet rubbers
« Reply #4 on: 12 September 2014, 09:12:55 pm »
Fuel filter is ok
I will try the water to see if they are leaking.
A biker I met today said it might be the ignition coils

noggythenog

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Re: carb inlet rubbers
« Reply #5 on: 12 September 2014, 09:46:33 pm »
Fuel filter is ok
I will try the water to see if they are leaking.
A biker I met today said it might be the ignition coils


Maybe you did a typo but what about the air filter?


Plus if it's the coils/leads you need to diagnose then get out to your bike in the pitch dark and start it up and sit and look at the plug caps close to the top where the lead comes into the cap and look for electrical arcing...small lightening bolts etc......my bike was rough after winter and a foccer told me this and right enough one of the leads had a break and was arcing across.
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Re: carb inlet rubbers
« Reply #6 on: 12 September 2014, 09:58:23 pm »
Many people have the cracked carb rubbers but I dont think that anyone has had a problem from them, if you took them off and twisted them then you perhaps will generate a tear but in situ I dont think the cracks that you see go all the way through. Dont know for sure -- just sayin
Mine are cracked too and have no probs.
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greenman

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Re: carb inlet rubbers
« Reply #7 on: 12 September 2014, 10:09:12 pm »
Mine did similar, worse on acceleration, I tried all sorts, full service in the end, then I changed plugcaps and transformed the bike. Maybe worth a try, ngk at 5 quid a pop.
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darrsi

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Re: carb inlet rubbers
« Reply #8 on: 12 September 2014, 10:13:42 pm »
Not trying to state the obvious, but fuel tap switched fully on, and no fuel pipes kinked anywhere?
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king1

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Re: carb inlet rubbers
« Reply #9 on: 13 September 2014, 12:54:29 am »
fuel filter, air filter both ok
fuel tap ok
all pipes ok
I did look at 1 of the plugs and it was ok, could not get the second one out so gave up

I only started all this work cause it was running bad and it is still the same

So I will try to see if rubbers are leaking and if arcing from plug caps

Any more suggestions?

king1

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Re: carb inlet rubbers
« Reply #10 on: 13 September 2014, 03:18:38 am »
update
just tried running it in my break and no arcing from plug caps

His Dudeness

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Re: carb inlet rubbers
« Reply #11 on: 13 September 2014, 04:22:35 am »
I've had arcing and carbs running dry. Arcing has a juddering, lumpy feeling with a sudden loss of power at certain revs. Not getting enough petrol is more of a gradual loss of power.

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Re: carb inlet rubbers
« Reply #12 on: 13 September 2014, 07:11:01 am »
Does this only happen at higher speeds? Could be carb float level too low or fuel pump problem?

king1

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Re: carb inlet rubbers
« Reply #13 on: 13 September 2014, 08:05:55 am »
An update
this morning I noticed that when I rev the engine, black smoke comes from ghe exhaust

darrsi

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Re: carb inlet rubbers
« Reply #14 on: 13 September 2014, 09:05:29 am »
An update
this morning I noticed that when I rev the engine, black smoke comes from ghe exhaust


That's the total opposite, black smoke would generally indicate not enough air, or too much fuel.


It could also mean that a new Pope has not been elected yet.  :lol
« Last Edit: 13 September 2014, 10:28:12 am by darrsi »
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Re: carb inlet rubbers
« Reply #15 on: 13 September 2014, 10:13:11 am »
My carb inlets are cracked or so it appears. I'll try and take an image with my phone camera alas it had no flash so I need the day to light up a bit. Anyway, my engine runs fine. One test is to spray wd40 over the inlets, I did this with my tank unbolted , turned 180 degrees and sat on the seat. Improves access to the inlets. WD40 with the straw attachment and spray a little (1 second depress) over one of the inlets. See if the engine flutters. Repeat over the other inlets 1at a time. Flutters indicate a potential air leak. A vacuum gauge may also help diagnose but the carbs need to by syncd first ideally, mind you if there is an air leak then syncing would also be a challenge possibly.
For mixture tests I use a gunsons color tune. Great for pilot screw adjustments and diagnose fuel/air mixture dynamically through the rev ranges.
Hope this helps
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keno

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Re: carb inlet rubbers
« Reply #16 on: 13 September 2014, 05:00:19 pm »
have you had the tank raised?
if so check the tank breather pipes are not kinked when you lowered it.