Date: 18-11-17  Time: 14:01 PM

Author Topic: Performance issue( missing at 5,000 RPM)  (Read 202 times)

Mr Juju

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Performance issue( missing at 5,000 RPM)
« on: 21 October 2017, 02:21:10 PM »
Hi All, I have a very irritating misfire or carb issue most evident at about 5,000 RPM in top gear (around 60 mph) . If I try and change down to blast past it it doesn't work. It's like riding a restricted bike!! Please help. So far I have tried replacing the fuel tank breather hoses and changed the plugs but no good. Oh and I seem to be down around 50 miles on a tank of fuel. Please can anyone suggest what my next best move could be? Many thanks! :)

darrsi

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Re: Performance issue( missing at 5,000 RPM)
« Reply #1 on: 21 October 2017, 02:38:15 PM »
When did you last change or clean your air filter?
More people are born because of alcohol than will ever die from it.

Disorderlypunk

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Re: Performance issue( missing at 5,000 RPM)
« Reply #2 on: 21 October 2017, 03:15:27 PM »
i think darrsi has hit nail on the head there
if you have a clogged air filter you increase negative pressure in the carb and you will pull more fuel through (pressure has to equilise somehow)
you are effectively running rich and using more fuel per mile and not enough air to give you the power when you need it as the stoichiometric efficiency is well off
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slappy

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Re: Performance issue( missing at 5,000 RPM)
« Reply #3 on: 21 October 2017, 07:03:13 PM »
i think darrsi has hit nail on the head there
if you have a clogged air filter you increase negative pressure in the carb and you will pull more fuel through (pressure has to equilise somehow)
you are effectively running rich and using more fuel per mile and not enough air to give you the power when you need it as the stoichiometric efficiency is well off


Stoichiometric, I had to google it to see what it meant, after reading what it means I still don't know what it means :o

Disorderlypunk

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Re: Performance issue( missing at 5,000 RPM)
« Reply #4 on: 21 October 2017, 08:28:55 PM »
i used it on purpose
air : fuel ratio basically
-i never heard of the word untill i started watching Mythbusters
if i remember about 14.5 parts air to 1 part petrol makes bangs best but with every fuel it is different which is where things get interesting running methanol
riding this that and the other
modifing everything...
vloggin some bits - http://www.youtube.com/channel/UCvWtJO9iyS8XsR9RNHx72UQ

Mr Juju

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Re: Performance issue( missing at 5,000 RPM)
« Reply #5 on: 22 October 2017, 03:46:18 PM »
Hey Guys, thanks for that filter looks dirty so have ordered another. Will update when it is fitted.