Rev limiter?

[Lars]

Big fat shims over the buckets that like to squirt out like bullets are a big one too...

Has that ever happened to anyone ?  

It has to happen when the valves are floating or something. normally they are held in place by the cams.

[pizzleboy]

So, then, wouldn't you want a VTEC engine on a bike?  2 medium valves at lower RPM then open up the other 2 about a certain RPM?

[KevinC]

Yep, which is why they made the VTEC. Only $1000US for the first valve adjustment, what a deal! And for no real advantage over the older version except to make it harder to ride in the rain.

The GS will tolerate a lot of over-reving valve float - I've tested it! After very serious abuse, it does seem to wear the cam a bit weird, but I wouldn't worry about the occasional indiscretion in stock trim.

I now have a Dyna electronic, adjustable rev limiter. It works very well.

For maximum performance, you definitely don't want to shift at peak power. It depends on a bunch of factors how far you want to rev past peak hp, including the width of the power band, gear spacing, power on the over-rev, etc. The optimum shift rpm will likely be different in each gear.

Given the GS's power band, it is quickest to go almost to redline. This is particularly true if you have pods and an aftermarket exhaust.

[KevinC]

Actually, poppet valves (either spring driven or actively closed like Ducati desmodromic valves) are, basically, crap.  What you need is sleeve valves that run concentric to the piston inside the cylinder.  Search the web for the Napier Sabre, an aero piston engine with the best specific power (hp/lb) ever acheived in a production engine.

Hmmm. First, I'd argue whether a war time aircraft engine with major overhaul times of 30 hours (OK it did go up to 300 once they got the sleeves sorted) is really a "production" engine. Second, it would be interesting to know what they included in the quoted weight numbers - is that all the ancillaries: water pumps, radiators, oil pumps, supercharger, ignitions system, etc.?

In any case, I think any modern motorcycle engine has a better bhp per pound. If you don't count the tranny and all the ancillaries of a GSXR, R1/R6, or any of the other sport bikes, they have to be over 1.5 hp per lb. The whole bikes only weigh 350 lbs.

And they go more than 300 hours between majors too.

[JamesG]

Has that ever happened to anyone ?  

Yeah...



It happens when the vavles start "floating" up high enough that the cam can catch a shim on the side instead of the face and launches it out the bucket...

[KevinC]

Cool!

[Blueknyt]

alittle JB weld take care o that......would love to have adjustable tappets like on the TSCC engines

[dgyver]

....Basically the valves go spastic and the engine stops internal combustioning.  Its real obvious by the rapid metalic clatter, so it acts sort of like a rev limiter, but there is very real threat of causing damage to the motor that way ( and I have done so several times.   )....

Oh...so that's the reason I lost power around 12K. Well it's tough trying to read a tach with a broken needle.  

What is the redline on a GS anyway?

[JohNLA]

Yea, cool pic, James
I did that to my Radian

[glenn9171]

Redline on the GS is 11k.