QuestionQUESTION: After replacing many parts of my HIF carbs I have problems to adjust them right.
I expected that the fuel level is wrong and took them several times apart and checked the float level.
In one of your answers you wrote: "The jet is just an L-shaped tube with the bottom sitting in fuel. The level of the fuel should be about 1/8 of an inch down from the top of the tube, maybe a bit less than that."
My fuel level is much lower, almost not visible.
I don't know what could be wrong. It started when I replaced the old floats an adjusted them to the gicen measures from the manual. I tried different types of float valves as well with the same result.
Have you ever heared that new replacement floats weight less than they used to?
Thanks for your advice.
ANSWER: Hi Ron. You might possibly have a problem with modern fuel containing Ethanol, because Ethanol is denser than gasoline. I have not heard of a problem with heavy floats. Anyway, a heavy float would result in too high a fuel level, not too low.
My visibility test is very reliable. You can double check by blowing on the top of the jet. The fuel level should go down, and when you stop blowing it should bounce back up again until it almost overflows.
I would guess that you have adjusted your float levels incorrectly.
The wording in the workshop manual is very misleading. It says the float should sit about 1mm below the level of the float chamber face (but that is with the carburetter inverted).
So, turn the carburetter upside down, put a metal ruler across the chamber, and WITH THE CARB INVERTED make sure there is a gap of about 1mm between the ruler and the depression in the middle of the float. If the gap is wrong, carefully bend the metal tab until it is about right. That should fix it.
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QUESTION: Hi Barrie
Sorry for my late reply. I wanted to check everything over again.
I'm pretty sure that I adjusted the float levels right.
http://www.youtube.com/watch?v=vPCfwkIdWpc
Also I haven't mixed up the floats.
Float LZX1601 rear carb and LZX1600 front carb.
The weight of one new (Original S.U. Burlen?) float is only 7.0 grams.
(I don't have the old ones anymore to compare)
Ethanol content is less than 5% here in Switzerland.
Now I adjusted the gap with inverted carbs and measured in the middle of the horseshoe to 5 mm, but carbs are still not (over-)flooding and fuel level is still far from 1/8 of an inch.
I don't know any further.
Best regards
Ron
ANSWER: Hi Ron. 5mm is MUCH too big a gap. I think you have over-adjusted the jet on the mixture screw so it is much too high. The jet should be visibly BELOW the surrounding bridge. Either that or you have not fitted the L-shaped interconnecting plate correctly. Something is wrong here.
By the way, I just weighed some HIF floats and they vary between 7 and 8 grams so yours is fine.
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SU HIF4 Float 
Assambled HIF4 Float
QUESTION: Hi Barry, thank you so much for your help and advise!
I totally agree with you. I just talked to a professional well known carb rebuilder in Germany.
First he was sure that the visible fuel level in the jet tube should be about 3 mm below the top. (As it is with HS and H type carbs.) But after explaining my problem he was not so sure anymore that it is the same with the HIF type carb. He has never taken the measure from an well working HIF carburetor.
I made some pictures, but I can't see what's wrong.
Safety fast!
Ron
AnswerI have seen the pictures, and they confirm that you have done everything correctly. However, it is still possible that you have adjusted the jet so it is too high. Can you show me the top of the jet? The best way to photograph it is with the dashpot and piston removed.
