Rev Limiters

[brianbuck]

Have just noticed that the SCB have issued a notice to the effect that Rev Limiters will be mandatory on all speedway bikes from the start of the 2020 season.

As a supporter with no mechanical knowledge whatsoever,  I'd be grateful if someone who has, would explain what these are, and what effect they will have on the bikes.

Thanks in anticipation!

[andout]

Beat ya to it......just posted under you SGB Today!

[dontforgetthefueltapsbruv]

I asked Chris Louis at a recent supporters night about these and his opinion was that they were close to pointless

[ch958]

Dean Felton? Tell us what you think

[ond]

A Rev limiter cutting in half way round a corner will suddenly give the bike grip!!! Result will be the rider falling off ,!!!!! 

A rev limiter cutting in at the end of the straight ..... results, rider falling off. 

Smart riders could incorporate it into a device which will be a traction control to cut in when needed. 

Loads of unburnt methanol at the start line because the limiters are cutting in....... result in blown and sneezed motors.

where is the testing for this ?..????

 

[dontforgetthefueltapsbruv]

The hard limit to be set at 13500 - cant see this being an issue anywhere other than the startline so any fears of it kicking in mid corner are surely unfounded

Presumably this is an attempt to reduce engine wear and therefore costs by removing the issue at the start where almost all the stress halpens

Even there the opinion of Chris Louis was that the benefit would be minimal

[f-s-p]

Dont see the point as the only time they have any use is at the startline. Current engines can rev up to 18k but is used in racing between 8-12k if I remember correct. But I guess savings are savings even if only for the 4 seconds before tapes up...

[SPEEDY69]

They will potentially get better starts - all those revs don't help.  RIders will adapt.  

[steve roberts]

Of course once upon a time riders used to twist the throttle back and forwards on the start line so as to gain maximum grip when the tapes rose...now of course it's just full revs with the throttle full on akin to rocket propulsion when the clutch is eventually released.

Edited January 6, 2019 by steve roberts

[Vince]

I like the idea of rev limiters being introduced, would like to see the limit dropped a bit each year as in the end it could phase out the super short stroke motors that are on such a knife edge for set up. In my opinion the long stroke motors worked more safely on a bigger variety of surfaces.

They recommend a soft limiter kicking in before the hard limit which should reduce the risk of the limiter picking up unwanted grip. In reality its no different to gearing the bike right now, under gear it and it over revs and loses power, you would just gear the bike to suit the limiter. None of it will apply unless the limit is reduced in the future anyway so the worst that can happen at the set limit is not over revving on the start (or in the pits!) which can only extend engine life.

Think you'll find there is quite a lot of throttle variation on the gate from decent riders to suit the conditions even if it doesn't look like it.

[martinmauger]

Think a cost effective way of reducing speed and therefore cost is limiting power.  Using standard & sealed F2, 2v JAWAs or even the Honda engines of decades would be a good idea, but this would render riders' current equipment as worthless junk.  So if the maximum permitted power, for league racing at least, was set to say 65BHP or 70BHP (I forget the power output of modern bikes) provided riders used 500cc engine of up to 4 valves with homologated carbs & silencers.  Riders could retain and use their existing engines without necessarily binning ignition systems and all the internal 'trick' parts and it would be up to them how they achieved a power limit.  Riders could get their engines tested at approved centres, like motorcycle MOT stations, and the SCB employ random 'rolling road' testing throughout the season to police the idea.    Just an idea....

Edited January 6, 2019 by martinmauger
spelling, sigh

[Tsunami]

17 hours ago, ch958 said:

Dean Felton? Tell us what you think

I think I remember Dean being in favour of them a short while ago.

Incidentally, I am told Josh Auty did tests on these limiters at Scunny last year.

Edited January 6, 2019 by Tsunami

[PHILIPRISING]

KELVIN Tatum is a big advocate of rev limiters... will be revealing why in Speedway Star shortly.

[adonis]

8 hours ago, dontforgetthefueltapsbruv said:

The hard limit to be set at 13500 - cant see this being an issue anywhere other than the startline so any fears of it kicking in mid corner are surely unfounded

Presumably this is an attempt to reduce engine wear and therefore costs by removing the issue at the start where almost all the stress halpens

Even there the opinion of Chris Louis was that the benefit would be minimal

if its not going to kick in other than the start , ( most are not even revving full out at the start anyway ) hows it going to save any engine wear ,. Unban titanium which gains extra power by allowing higher revs but costs the earth , then bring in a new untried piece of clobber (no doubt another expensive piece of junk )  to prevent what you assisted by un banning titanium .. somethings stinks here . can't wait to see who's behind this money maker

[PHILIPRISING]

PROBABLY bringing speedway into line with every other form of motorcycle racing under the FIM umbrella... many in favour after a comprehensive study by an FIM working party

[Sings4Speedway]

From my far from accurate mechanical knowledge i thought a standard short stroke gm revved to 12k rpm and the baby gm got to 13.5k rpm max. Unless there is a newer generation then the limiter is introduced to prevent the a selection of the engines going passed their very maximum revs which would only possibly be achieved on the start line when held by irritating referee's. Sounds like another load of unnecessary expense imposed upon every rider to me.

[adonis]

13 hours ago, PHILIPRISING said:

PROBABLY bringing speedway into line with every other form of motorcycle racing under the FIM umbrella... many in favour after a comprehensive study by an FIM working party

We'll see how many are in favour when they have to start using them , my guess is it will be the people who make or sell them  that will be all for them and nobody else , the FIMs knowledge of speedway could be written on a postage stamp , and the fact that you suggest the working party thinks that the operation of a speedway bikes engine can be lumped in with other forms of motorcycle sport  is a more than adeqaute demonstration of that .  imposing a potentially dangerous piece of equipment without proper testing or approval from the people who have to use it  is another one ,

Edited January 7, 2019 by adonis

[adonis]

23 hours ago, steve roberts said:

Of course once upon a time riders used to twist the throttle back and forwards on the start line so as to gain maximum grip when the tapes rose...now of course it's just full revs with the throttle full on akin to rocket propulsion when the clutch is eventually released.

not many hold them full on , half to 3/4  then let the clutch out and give it full throttle , when taters was the worlds best gater he used to say a fast start happens in the first 3 yards by feathering the clutch and throttle to make it grip , full throttle from the start will just help to dig a hole .

[Gambo]

1 hour ago, adonis said:

We'll see how many are in favour when they have to start using them , my guess is it will be the people who make or sell them  that will be all for them and nobody else , the FIMs knowledge of speedway could be written on a postage stamp , and the fact that you suggest the working party thinks that the operation of a speedway bikes engine can be lumped in with other forms of motorcycle sport  is a more than adeqaute demonstration of that .  imposing a potentially dangerous piece of equipment without proper testing or approval from the people who have to use it  is another one ,

GP Riders have had the opportunity to test rev-limiters for some time now, although I believe only a few have been bothered to test them.

[adonis]

42 minutes ago, Gambo said:

GP Riders have had the opportunity to test rev-limiters for some time now, although I believe only a few have been bothered to test them.

Just the same as the positive killswitch , solid block tyres , carb restrictors , foisted on the riders untested ,by people who don't have a clue about the effect , all things brought about with little or no thought , and all things that got dumped after somebody else had the expense of buying them , I forgot to say , the GP riders don't bother testing them because they have no intention of ever using them .

Edited January 7, 2019 by adonis