What is hot start

[07250ex]

as said above please tell me anything and everything you know about hot start?

[procircuit406ex]

Its on the clutch perch lol and from what I know it dumps the carb full of gas

[trx450jason]

I might be wrong but from what I understand it leans out the bike for easy starting when its hot. After its stalled or shut off hot the bike is full of gas so using the hot start just leans it back out.

[klay_911]

yea, like when u flip in race and it fluds the bike or w/e u use it to start the bike quicker

[GPracer2500]

It's basically the opposite of a choke or enrichener. A choke cuts off ("chokes") the air supply. In the case of an enrichener, extra fuel gets added. Either way, the purpose is to richen the mixture. Usually we use the term choke to describe both of these things even though many of them are actually enricheners, not chokes.

A hot start mechanism does the opposite. It pipes fresh, cool air that is not mixed with fuel directly into the intake manifold.

When a bike gets stalled or tipped over it often loads up the engine with a rich air/fuel mixture. This makes them hard to start. The hot start helps correct that by adding fresh air that doesn't have any fuel mixed in. Also, when the engine is really hot the mixture can go rich. The engine heats up the intake air as it gets sucked into the engine. Hot air expands and gets less dense so the mixture goes rich. When you're starting the bike the engine isn't sucking the air in very fast so the heat of the engine has plenty of time to heat up and expand the air it gets sucked in. When the bike is already running this doesn't happen to nearly the same degree. That's where the name "hot start" comes from.

The 1998 YZ400F was the first bike I'm aware of that used a hot start mechanism (also the first common bike to use an FCR). Its hot start was a little valve attached to the intake boot between the air filter and the carb. A hose plummed air around the carburetor (completely bypassing it) and straight into a small fitting on the intake manifold.

By the time the YZ426F came out in 2000 the FCR carb had evolved to where the hotstart mechanism was integrated into the carb itself. That's how they all are today. A little valve inside the carb is opened with a lever and cable or with a button right on the carb body. When opened it lets the engine such in fresh air that doesn't have any fuel mixed in.

[LRD450R]

IT HELPS WHEN ITS COLD AND IT IS ON A 450R IF DONT KNOW

[250xridamatt]

Originally posted by GPracer2500
It's basically the opposite of a choke or enrichener. A choke cuts off ("chokes") the air supply. In the case of an enrichener, extra fuel gets added. Either way, the purpose is to richen the mixture. Usually we use the term choke to describe both of these things even though many of them are actually enricheners, not chokes.

A hot start mechanism does the opposite. It pipes fresh, cool air that is not mixed with fuel directly into the intake manifold.

When a bike gets stalled or tipped over it often loads up the engine with a rich air/fuel mixture. This makes them hard to start. The hot start helps correct that by adding fresh air that doesn't have any fuel mixed in. Also, when the engine is really hot the mixture can go rich. The engine heats up the intake air as it gets sucked into the engine. Hot air expands and gets less dense so the mixture goes rich. When you're starting the bike the engine isn't sucking the air in very fast so the heat of the engine has plenty of time to heat up and expand the air it gets sucked in. When the bike is already running this doesn't happen to nearly the same degree. That's where the name "hot start" comes from.

The 1998 YZ400F was the first bike I'm aware of that used a hot start mechanism (also the first common bike to use an FCR). Its hot start was a little valve attached to the intake boot between the air filter and the carb. A hose plummed air around the carburetor (completely bypassing it) and straight into a small fitting on the intake manifold.

By the time the YZ426F came out in 2000 the FCR carb had evolved to where the hotstart mechanism was integrated into the carb itself. That's how they all are today. A little valve inside the carb is opened with a lever and cable or with a button right on the carb body. When opened it lets the engine such in fresh air that doesn't have any fuel mixed in.

Thanks for all the info. It's really great to be messing around on here and learn something new from an educated post for a change.

[SGA]

Originally posted by 250xridamatt
Thanks for all the info. It's really great to be messing around on here and learn something new from an educated post for a change.
I agree. That was a good, informative post.

[07250ex]

Originally posted by SGA
I agree. That was a good, informative post.

GP is by far the smartest most informative person i have came across on this website that man is like a google or howstuffworks.com, I look forward to when he answers mine and others questions because i know it will be a good clean answer and im sure to learn something.