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Has any one ever used a jake brake on a dirt bike:crazy: . If so where do you get one

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Jakes are only used on diesel engines (and only ones that haul large amounts of weight). I don't think anyone makes one for a gasoline engine. Most people are trying to eliminate engine braking with their bikes, why do you want more?

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Jakes are only used on diesel engines (and only ones that haul large amounts of weight). I don't think anyone makes one for a gasoline engine. Most people are trying to eliminate engine braking with their bikes, why do you want more?

Well my dads 1978 Suzuki PE250(2 stroke) has a jake brake

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Well my dads 1978 Suzuki PE250(2 stroke) has a jake brake

I highly doubt it since a two stroke doesn't have valves. Are you talking about the same thing I am? A jake brake is and engine brake (popularized by the Jacobs Corp.) that increases engine braking significantly so that trucks don't use their brakes too much. I have one on sale on ebay at the moment.

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Back in the 60s&70s,I had compression releases on my 2 strokes. It emptied the cylinder same as a Jake brake.There was a second hole in the head,and the release went in it. There was a lever on the bars(I put mine under the clutch lever)that you pulled when you wanted to slow down.It made a funny Phhhhhhhhhhhhht sound,and actually worked. Trouble was,you would get LOTS of dirt & dust back in the cylinder.

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Alright, a manual compression release. Yes, that has been used on a dirtbike as stated previously. That is different from a jake brake though, as it does not utilize the engine's compression to create retarding power.

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Back in the 60s&70s,I had compression releases on my 2 strokes. It emptied the cylinder same as a Jake brake.There was a second hole in the head,and the release went in it. There was a lever on the bars(I put mine under the clutch lever)that you pulled when you wanted to slow down.It made a funny Phhhhhhhhhhhhht sound,and actually worked. Trouble was,you would get LOTS of dirt & dust back in the cylinder.

Yeah sorry about the mix up i ment compression realeses. So are they crap. Can you still get them

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Back in the 60s&70s,I had compression releases on my 2 strokes. It emptied the cylinder same as a Jake brake.There was a second hole in the head,and the release went in it. There was a lever on the bars(I put mine under the clutch lever)that you pulled when you wanted to slow down.It made a funny Phhhhhhhhhhhhht sound,and actually worked. Trouble was,you would get LOTS of dirt & dust back in the cylinder.

Ah yes! The good old days! :thumbsup: I had an Ossa that had a compression release on it. Good thing to as the brakes sucked.

The only way you can put one on a bikes is if it has two spark plug holes. No modern bike does.

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Even though this misunderstanding about Jake brakes and compression releases has been cleared up I'll add this. Gas engines don't need Jake brake because they have a throttle. It does what a Jake does on a diesel.

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Has any one ever used a jake brake on a dirt bike:crazy: . If so where do you get one

ebay or some of the vintage suppliers sell them 25.00-30.00 bucks

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Even though this misunderstanding about Jake brakes and compression releases has been cleared up I'll add this. Gas engines don't need Jake brake because they have a throttle. It does what a Jake does on a diesel.

How does the throttle on a gas motor equal what a jake does on a diesel.:thumbsup:

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Decompression levers are really meant for bigger 4 stroke bikes, like a 250 and up. Any smaller than that, you dont need one because there is not enough compression built up in the cylinder

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Even though this misunderstanding about Jake brakes and compression releases has been cleared up I'll add this. Gas engines don't need Jake brake because they have a throttle. It does what a Jake does on a diesel.

This makes no sense, a diesel has a throttle also. You could make a jake for a gas engine, it would require some more electronics as you would need sensors to shut off the ignition when the jake is activated. I don't think anyone has made one for a gas engine as anything with a gas engine can't haul loads heavy enough to warrant having a jake.

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Where is the throttle on a diesel?

When the throttle on a gas engine is closed you get vacuum between it and the cylinder. That's where the "compression" braking comes from. Pumping air at about 25 inches of vacuum up to atmospheric.

Diesels have no throttle thus no "compression" braking and the need for a Jake brake. Or a throttle on the exhaust system like the aftermarket ad ons for light trucks.

The story I heard was that Jacobs invented it after loosing his brakes going down the Conejo grade.

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A Jake Brake DOES NOT do anything to the compression. All it is, is a simple butterfly valve similiar to the throttle of a 4 stroke. Only it's in the exhaust, and when it closes it restricts exhaust flow.

That's it.

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Wrong. Exhaust throttles are an easy way to add "compression" braking to diesels that don't have Jake brakes.

A jake brake opens the exhaust valve or an additional exhaust valve to release the compression at the top of the compression stroke causing the piston to pull vacuum on what would have been the power stroke.

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Wrong. Exhaust throttles are an easy way to add "compression" braking to diesels that don't have Jake brakes.

A jake brake opens the exhaust valve or an additional exhaust valve to release the compression at the top of the compression stroke causing the piston to pull vacuum on what would have been the power stroke.

You need to learn how to read and how to do simple internet searches before you call someone wrong.

http://www.jakebrake.com/products/ld-exhaust.php

http://www.jakebrake.com/technology/exhaust.php

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Where is the throttle on a diesel?

When the throttle on a gas engine is closed you get vacuum between it and the cylinder. That's where the "compression" braking comes from. Pumping air at about 25 inches of vacuum up to atmospheric.

Diesels have no throttle thus no "compression" braking and the need for a Jake brake. Or a throttle on the exhaust system like the aftermarket ad ons for light trucks.

The story I heard was that Jacobs invented it after loosing his brakes going down the Conejo grade.

Technically, very few fuel injected engines have throttles. All engines produce engine braking, a jake brake just amplifies it. The normal gas engine on a car has retarding power. When you let off the accelerator, the injectors stop firing and the fuel pump actually will shut off. Now your engine has no powerstroke and the compression stroke holds the car back. The only power produced during the power stroke in this situation is the copressed air in the cylinder trying to push the piston back down. A Jake brake opens the exhaust valve just as the piston reaches TDC on the compression stroke to release the compressed air. Then the exhaust valve closes and the piston starts down on what should be the power stoke. Now a vacuum is created in the cylinder. Thus, this gives it retarding power on two out of four strokes instead of just one. The throttle has nothing to do with it. Exhaust brakes are the flapper doors in the exhaust that produce back pressure.

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