this is a compilation of backfire videos from around youtube. i do not own
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How to diagnose carburetor vacuum leaks on your motorcycle
This is a simple video demonstrating the best method to detect vacuum leaks
around your carb boots. Vacuum leaks are a fairly common problem in older
bikes, and luckily they can usually be remedied quickly and easily, the
first step however is diagnosis.
If your bike is running rough, won't rev up or has an irregular idle,
before you take off the carbs and open them up, check for vacuum leaks. A
vacuum leak occurs when too much air is introduced into the combustion
chamber via a failure in one or more of the carburetor boots or other
rubber mating surface. When too much air is sucked in, then the bike cannot
combust the gasoline efficiently; there must be an optimal ratio. Therefore
it is up to you to detect these leaks, and either plug them up or replace
the carb boots.
In this particular bike, the engine was running VERY lean. Not only did we
have vacuum leaks, but the baffles were taken out of the engine, and the
previous owner had removed the air filter and neglected to install a new
one. This is not only dangerous by allowing foreign material to enter the
engine, but it also makes the engine run much hotter, as lean explosions
create more heat than regular ones (think about blowing on a fire in your
fire place: more air, hotter fire). This can be detrimental to a variety of
parts in the engine, and it is a good thing we didn't ride this bike around
too much before finding the problem.
If anyone has any questions as to why this is important or how to
find/repair these leaks, leave a comment and I will respond.