Kawasaki Sportsbike Riders Club - Australia - Online Forum

I am not 100% know how to describe this situation, but trying now hehe
ok

will using the engine to slow the speed before braking damage the engine or increase it's workload? does it depend on the speed as well? if going say hum......100km/hr and coming out of freeway and use the engine to slow down the bike before braking before the traffic lights....is it ok? or preferably disengage the clutch and just let the bike roll?

Thanks Guys

hidepenny wrote: or preferably disengage the clutch and just let the bike roll?

Thanks Guys

hell no!!
as u said...use the "engine braking" by down changing...hell i can pull my bike up with hardly any brake at all (just downchanging to 1st, then a bit of front to woo me up...)...
just like driving a manual car...

hidepenny wrote:I am not 100% know how to describe this situation, but trying now hehe
ok

will using the engine to slow the speed before braking damage the engine or increase it's workload? does it depend on the speed as well? if going say hum......100km/hr and coming out of freeway and use the engine to slow down the bike before braking before the traffic lights....is it ok? or preferably disengage the clutch and just let the bike roll?

Thanks Guys

nope

and thats one reason why 'slipper' clutches were invented
using engine braking (but no locking up the back wheel)


cheers

Use the engine braking, gives you far more control, reduces braking distance and puts you in a position where you should be in the right gear should something go wrong and you need to accelerate or take evasive action, and apart from that makes a ride a lot more fun.

Regards
RonnieG

However, do not let the engine revs be too high. My instruction manual says down changes should be done below 5,000 rpm. This is ok for around town, but when racing thru the mountains you have to be a bit harsher.

There's very little chance that this will damage the engine, and is certainly not as 'stressful' as revving the engine out on wide open throttle.

Some high km engines will get a little bit of oil smoke on over-run, usually due to the extremely high vacuum in the combustion chamber and the lack of ring or valve stem sealing, but that's not really going to hurt the engine unless you never do oil changes/top ups.

I'd be more worried about being harsh to the clutch/gears than anything else.

stevew_zzr wrote:There's very little chance that this will damage the engine, and is certainly not as 'stressful' as revving the engine out on wide open throttle.

Hmmm, you sure about that? I'd've thought that the greater density of the air-fuel mixture a piston has to compress when then engine's running at big throttle openings acts as a cushion, helping the conrod slow the piston down on the way to TDC...

You can exceed your rev limiter when down shifting too...

Actually the good book by keith code and most the other racing stuff i read says you should use you brakes to stop and your engine to go ans slipper clutches are to prevent rear wheekl lockup and chatter thats why you dont see the big racing bikes as sideways as much as you used to.

Changing down gears and letting the clutch out wont hurt but you should try to mathch the revs as well with a bit of a throttle blip and dont over rev the engine either, wouldnt want to see much more than 8000rpms on the tacho on the road and probably 10000rpms at the track but then again who looks at the tacho on the track.

No wont hurt it but dont over rev it onthe downchange either.

I-K wrote:

stevew_zzr wrote:There's very little chance that this will damage the engine, and is certainly not as 'stressful' as revving the engine out on wide open throttle.

Hmmm, you sure about that? I'd've thought that the greater density of the air-fuel mixture a piston has to compress when then engine's running at big throttle openings acts as a cushion, helping the conrod slow the piston down on the way to TDC...

Well, i can sort of see what you are saying, conrod failure is usually more related to force on the conrod. The conrod's/piston's mean acceleration will be lower when there is nothing to force it (ie nothing to compress, or nothing expanding), although the vacuum will apply some force it's really nothing compared to the force that the whole assembly is under when you are actually pumping air/fuel through there and igniting it

But if you *do* downchange and over-rev it (ie past redline), then yes you could eff up the conrod.

yeah Thanks guys for the technical info, greatly appreciated, also i heard with the high rev engines, r we meant to ride it high rev? or just like cars let it run at 3000rpm or so in order to keep the engine in good shape? coz i heard one guy was doing that for long time ( running low rpm) and blew the engine? is that related somehow? or it's just not a good idea to run these kinds of high rev engine on low rpm? i ususally change gears at 6k - 8k rpm, coz anything lower than than is very slow.

zx9r king wrote:However, do not let the engine revs be too high. My instruction manual says down changes should be done below 5,000 rpm. This is ok for around town, but when racing thru the mountains you have to be a bit harsher.

If blipping the throttle this theory goes out the window real quick....