engine braking
- Thread starter blue 48
- Start date
Yeah, Blue, I do the same-thing to help slow down some of my weight. See, the bike is 29" at 60lbs, and I am 255lbs. So, at 315+, V-brakes really aren't the best to keep it 100% safe. (I cruise at 25ish, tops lower 30's)
motorpsycho
Active Member
why would you want to do this, it's not good for the engine in my opinion.
you'd be allowing the piston rings to scrape the cylinder walls with no oil, and the bearings to possibly run dry.
since the engine would not be running, there would be fresh no gas/oil entering the crankcase.
I understand that there would be residual oil on the rings and bearings, but it can't be all that much.
I would think that doing this a lot over time would just prematurley wear out the rings and bearings due to short times of no oil.
I wouldn't do it.
you'd be allowing the piston rings to scrape the cylinder walls with no oil, and the bearings to possibly run dry.
since the engine would not be running, there would be fresh no gas/oil entering the crankcase.
I understand that there would be residual oil on the rings and bearings, but it can't be all that much.
I would think that doing this a lot over time would just prematurley wear out the rings and bearings due to short times of no oil.
I wouldn't do it.
Just shutting off the ignition doesn't stop A/F mix from entering engine.As long as the engine is turning its still getting oil and gas but only a lean mix with the throttle shut.I wouldn't do it for long periods but briefly shouldn't be an issue.
cloud_2901
Member
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- Jun 30, 2011
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I hold my throttle half-open while engine braking with the killswitch.
That way it's not going to run out of fuel, it will in fact get too much fuel in there if you don't ease off the throttle after 30 seconds or so.
That way it's not going to run out of fuel, it will in fact get too much fuel in there if you don't ease off the throttle after 30 seconds or so.
motorpsycho
Active Member
I still wouldn't do it.
Braking
Well, I have done the kill-switch thing to help slow down, but I never have enough real speed to cause problems when going there.
I've got it! I'll just ease this missle down, and then I wont have to worry about slowing down this beast.
Well, I have done the kill-switch thing to help slow down, but I never have enough real speed to cause problems when going there.
I've got it! I'll just ease this missle down, and then I wont have to worry about slowing down this beast.
Barnfresh
Active Member
Sounds like what you really need is a decompression valve (compression release) like the old 2-stroke flat track racing motorcycles used to slow down, back in the days when they weren't allowed to have brakes.
The comp release normally threaded into the combustion chamber with a 14mm thread (like a 2nd sparkplug) and had a single valve controlled by way of a cable attached to small one fingered lever which hung under the clutch lever on the handlebars. Squeeze the lever and the valve would open allowing air to escape from the combustion chamber slowing the engine down, much like a jake brake on a diesel engine. They were effective to the point that if actuated while in too low of a gear the rear wheel could lock or skid.
The only problem with installing one on the little HT is it's size in relation to the small combustion chamber. You would need to locate a compression release that is more in "scale" to a 50cc engine. Maybe start with a decomp valve off of an old moped (Sachs?) or small chainsaw. Figure a suitable location, cut fin, drill and tap head. Install comp release valve assy making sure there is adaquate clearance so valve can't contact piston crown at TDC when fully open. Run cable to a 2 finger BMX lever on handlebar.
The comp release normally threaded into the combustion chamber with a 14mm thread (like a 2nd sparkplug) and had a single valve controlled by way of a cable attached to small one fingered lever which hung under the clutch lever on the handlebars. Squeeze the lever and the valve would open allowing air to escape from the combustion chamber slowing the engine down, much like a jake brake on a diesel engine. They were effective to the point that if actuated while in too low of a gear the rear wheel could lock or skid.
The only problem with installing one on the little HT is it's size in relation to the small combustion chamber. You would need to locate a compression release that is more in "scale" to a 50cc engine. Maybe start with a decomp valve off of an old moped (Sachs?) or small chainsaw. Figure a suitable location, cut fin, drill and tap head. Install comp release valve assy making sure there is adaquate clearance so valve can't contact piston crown at TDC when fully open. Run cable to a 2 finger BMX lever on handlebar.
Cavi Mike
Member
Just because the engine isn't firing doesn't mean fuel isn't still being drawn into the engine. These aren't fuel-injected engines. Carburetors work on vacuum so as long as the engine is spinning, it will be creating vacuum and fuel will be drawn in. It doesn't matter if the plug is igniting the mixture or not, the mixture will still be there lubricating the engine.
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