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Dhla 45s, front carb vacuum real high back carb fine. Solution ?? - Fuel System/Carbs - The Lotus Forums - Lotus Community Partner #ForTheOwners Jump to content


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Dhla 45s, front carb vacuum real high back carb fine. Solution ??


s1guy

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  • Gold FFM

If you're using a Carbtune, I'm assuming you know how to adjust the carbs to achieve balance.  Have you tried any adjustments?

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British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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  • Gold FFM

In that case, maybe a compression test to exclude the really bad stuff?

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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  • Gold FFM

I assume you've already checked what Fab suggested.  Did you have the shafts out?  Butterfly issue?

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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Ok checked mounting plates and manifold for leaks. No leaks. Rear carb vacuum is good. Nothing i do will bring the vacuum on the front carb down. When i give it some gas it comes down a bit but at idle the vacuum on the carbtune is pegged. Throttle plates ??

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Is it possible we've been looking at this from the wrong end? Perhaps the trouble is with the aft carb or cylinders, as I do not see how a high vacuum level is reflective of a defect. If, in fact, there is a sub-par vacuum level on the aft inlet tract would it not conform with the measurements seen in this case? 

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2 hours ago, s1guy said:

This is still what i got. Not good. 

I'm not familiar with carbtune, I use vacuum gauges, (on multi carb bikes not Lotus) balance is normally achieved at tickover, but I notice from your video on throttle your mercury is dropping where I would expect to see it rise.

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Sorry didn’t read your previous post, so have revised this post! To me it looks as if the balance is way off. Two cylinders appear to be doing all the work! Solution close the air corrector screws, adjust linkage screw between the carbs to reduce the vacuum on the left two channels. If its not the linkage are all the cylinders firing? Pull the plug leads off on at a time. You may find the engine is just running on one carb, which would explain the above. Don’t worry if your engine has been running ok up until now its probably just an adjustment issue. 

 

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Two cylinders may not fire if the mixture is wrong, one carb is blocked or the linkage adjustment is way off. Bring the idle down as slow as possible to reduce the vacuum and make finer adjustments. If its idling too fastbits very tricky to see the effect of changes.

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