Ken Posted February 28, 2022 Report Share Posted February 28, 2022 Okay, so I am in Rotax class. One test question is Must you remove the comp tube to synch carbs. possible answers are 1)yes 2) No,if you set the stop to full closed on one of the carbs. 3) No, just block off the air flow between the 2 if the engine is fitted with the long hose on cylinder 2&4 side There can be more than one answer and we were told to use any source available so this is not cheating Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted February 28, 2022 Report Share Posted February 28, 2022 The carbs must be isolated from each other for balancing. This means disconnecting the compensation tube from one side or the other and connecting the gauges, or blocking the flow between them and using the taps on the intake manifold. The engine would run like crap. if at all with #2. Quote Link to comment Share on other sites More sharing options...
Roger Lee Posted March 1, 2022 Report Share Posted March 1, 2022 Answers 1 & 3 are correct. You can remove one tube off one car or both and hook up a syncing device. This is aimed at engines that are a few years old that do not have the longer rubber hose on the comp tube. #3 is also correct because Rotax does have a longer rubber tube on NEWER engines that aren't on older ones and this can be clamped off. There is a picture of this in the manual. Either way separates the carbs so they can be synced independent of each other. Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted March 1, 2022 Report Share Posted March 1, 2022 I'm just jealous you are in Rotax class! Quote Link to comment Share on other sites More sharing options...
Anticept Posted March 2, 2022 Report Share Posted March 2, 2022 Hoses should be kept reasonably short, but it's not going to be too big of a factor because it averages out the pulses. Pnematic gauges with a restriction will dampen to the correct readings as well. The main concern is the hoses themselves stretching and compressing with the pulses, which is why you can't put 50 foot hoses on, that may be significant enough to skew readings. Maybe. Quote Link to comment Share on other sites More sharing options...
Roger Lee Posted March 2, 2022 Report Share Posted March 2, 2022 Most hose are close to the same length, but need to be. Quote Link to comment Share on other sites More sharing options...
Bulldog Posted November 15, 2023 Report Share Posted November 15, 2023 Does anyone know of a good trick to easily remove one of the rubber hoses? Mine are on very tight and the 2/4 side doesn’t have much spare room to slide either way. Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted November 15, 2023 Report Share Posted November 15, 2023 I usually push the end of the hose with a screwdriver and pull on the compensation tube. Just don't poke yourself with the screwdriver. Quote Link to comment Share on other sites More sharing options...
opticsguy Posted November 16, 2023 Report Share Posted November 16, 2023 I'm making a new set of sync hoses. Since the connection is done on the left side, shouldn't I mike the hose for the left gauge shorter by about a foot. The right carb has to go through the metal tube before the sync hoses are connected. Quote Link to comment Share on other sites More sharing options...
Roger Lee Posted November 17, 2023 Report Share Posted November 17, 2023 Length has nothing to do with it. Just make your hoses equal length. Quote Link to comment Share on other sites More sharing options...
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