Ducati Sporting Club UK > DesmoDue Race Series > DesmoDue - General Questions and Chat > decision on big bore ???

[ali]

Originally posted by mw
infact the feeling is that the big bore 583 with correct carbs and set up would beat a 620 on power and torque

... hence having the big bore 620 option is important as this would (if you wanted to spend the money) allow one to get even ... it's all v close thou' so the extra expence probably wouldn't be worth it unless running v close to winning the championship ...

Right. *rolls up sleeves*.... where do you want me to start????

I will happily pay for ANY 620 to be dyno'd with ANY 675 carbed bike on the same dyno, but you'll have to promise to re-imburse me if there isn't at least 7bhp difference. That's a modest 13% difference.

To give you an idea that has the equivalent effect on power/weight as removing 22kg from the bike!

the expected power outputs of a sorted big bore 583, standard 620 and big bore 620 are all around 62 -65 bhp

********. Try 51.5, 59 and 62.

however all this about different dyno figures is also very misleading as each dyno has a different reading to the other ...

but three different dynos delivered bhp figures within 0.5 bhp for three 675 bikes? "Very misleading"????

for what it is worth i believe changing the rules so quickly as a knee jerk reaction would be wrong ... it's just too soon ...

Couldn't disagree more. Sort it out now or you'll have an entire field of 675ie checkbook racers.

we need to see how it goes at the next race at the v least before looking at any changes...

No we don't.

riders also need to look at their riding and not their machines for the fact that they were slower than the bike infront ... alan johnson on a 583 came 5th and 6th.

Andrew produced the ride of the weekend as far as I was concerned. I hardly think this thread has anything to do with rider ability. I'm sure CK & AK are biting their tongues on the whole BB issue. Where would Andrew have ranked with a 680ie???

I had an enormous amount of fun on the weekend, I have huge appreciation for the race committee, but that needs to be reciprocated back to those that have invested a huge portion of their savings/loans/time on getting on to the grid.

Cheers,

ali

[fil2]

Originally posted by ali

Right. *rolls up sleeves*.... where do you want me to start????

I will happily pay for ANY 620 to be dyno'd with ANY 675 carbed bike on the same dyno, but you'll have to promise to re-imburse me if there isn't at least 7bhp difference. That's a modest 13% difference.

To give you an idea that has the equivalent effect on power/weight as removing 22kg from the bike!

********. Try 51.5, 59 and 62.

but three different dynos delivered bhp figures within 0.5 bhp for three 675 bikes? "Very misleading"????

Couldn't disagree more. Sort it out now or you'll have an entire field of 675ie checkbook racers.

No we don't.

Andrew produced the ride of the weekend as far as I was concerned. I hardly think this thread has anything to do with rider ability. I'm sure CK & AK are biting their tongues on the whole BB issue. Where would Andrew have ranked with a 680ie???

I had an enormous amount of fun on the weekend, I have huge appreciation for the race committee, but that needs to be reciprocated back to those that have invested a huge portion of their savings/loans/time on getting on to the grid.

Cheers,

ali

Excellent post Ali..........

Phil

[dickieducati]

i still dont understand .

everyone had the opportunity to buy whatever eligible bike they wanted for the series.

whats the issue?

[Monty]

Originally posted by mw
i believe all this histeria about a big big bore kit is rider perception not fact ...

the 620 big bore kit gives only v v slight power increase but it does give a wider power band and slightly more torque ... all to keep it on a par with a v well set up big bore 583 (it is not just about fitting a big bore kit and instantly getting the power to be on a par with the 620's you have got to sort the carburation (shorter inlets and flat slide carbs) and set it all up correctly ).

the rules were formulated to allow people 2 choices either don't fiddle and fettle and buy a 620 or buy a 583 and work to get it on a par ... infact the feeling is that the big bore 583 with correct carbs and set up would beat a 620 on power and torque ... hence having the big bore 620 option is important as this would (if you wanted to spend the money) allow one to get even ... it's all v close thou' so the extra expence probably wouldn't be worth it unless running v close to winning the championship ...
the expected power outputs of a sorted big bore 583, standard 620 and big bore 620 are all around 62 -65 bhp however all this about different dyno figures is also very misleading as each dyno has a different reading to the other ... they are useful in evaluating dif engines run on the same dyno as a comparison but not worth it between dif dynos.

also look at sigma's article on the desmo due rules to see the background.

i was overtaken by geoff at the old hairpin near the end of the 2nd race and i was overtaken by the dls/dlc bikes at barn ... eg all within a short distance. geoff has a lot of local knowledge which i suspect the others haven't ... in qualification he was 0.6 secs a lap faster, at end of race 1 he was 7.12 secs clear (about 0.6 a lap faster) and at the end of the 2nd race he was only 3.35 secs clear which means a less than 0.3 sec a lap advantage ...i don't believe that's a power advantage .. that's local knowledge ... and what everyone seems to have forgotten ... rider ability (he is a v good rider who used to race against the baines's and beat them!) it all seems to me a great shame that everyone is concentrating on the hardwear issues and taking away from geoff what was a well earned and deserved win in both races.

for what it is worth i believe changing the rules so quickly as a knee jerk reaction would be wrong ... it's just too soon ... we need to see how it goes at the next race at the v least before looking at any changes...

riders also need to look at their riding and not their machines for the fact that they were slower than the bike infront ... alan johnson on a 583 came 5th and 6th.

I have to agree with most of what Michael has said(there has to be a first time for everything mate ) Both Neil and John Hackett, engine builders who KNOW about Ducati's have stated that a big bored 583 when set up properly with short manifolds and flat slides will MORE than live with a 620. In fact John's reasoning behind his initial development of a the '620' big bore kit was because he felt the 675's would have an advantage! Having watched all of the racing at the weekend I have to say that Geof Spencer was VERY smooth and fast everywhere I could see him, noticeably faster than most into and over the mountain-which is just race and track experience. Don't forget that Dave Riley riding a standard-eg not specially dynoed and set up-620 monster with only 1 disk- was leading race 2 for the first 2 laps-and he is a novice rider, and Andrew Johnson finished 5th on a 583!

John

[Edited on 3-5-2005 by Monty]

[Jools]

Originally posted by Monty

I have to agree with most of what Michael has said(there has to be a first time for everything mate ) Both Neil and John Hackett, engine builders who KNOW about Ducati's have stated that a big bored 583 when set up properly with short manifolds and flat slides will MORE than live with a 620. In fact John's reasoning behind his initial development of a the '620' big bore kit was because he felt the 675's would have an advantage! Having watched all of the racing at the weekend I have to say that Geof Spencer was VERY smooth and fast everywhere I could see him, noticeably faster than most into and over the mountain-which is just race and track experience. Don't forget that Dave Riley riding a standard-eg not specially dynoed and set up-620 monster with only 1 disk- was leading race 2 for the first 2 laps-and he is a novice rider, and Andrew Johnson finished 5th on a 583!

John

[Edited on 3-5-2005 by Monty]

Is it just me or does it seem to be just the people who have 620's or the rule setters who seem to be in denial about the 620's advantage?

I'm sorry Monty, but I think you've spent too long hanging around in the rarified atmosphere surrounding top engine builders like Neil Spalding and John Hackett.

I'm sure that it is possible to build a flat slide carbed 674 cc bike that is quicker than a 620. If you happen to have the budget and the renowned engine building skills of Mr Hackett or Mr Spalding to do it.

By the time you've done that it's going to cost you more money than it would've done to buy a 620 in the first place.

Meanwhile, back in the real world, guys who thought that the series was started as the antidote to 'cheque book racing' are spending untold hours in unheated lockups with a few spanners and a socket set doing everything themselves. The knowledge that John Hackett or Neil Spalding could build them a race winning engine is about as relevant to guys on a budget as walking to the moon and back. Fine in theory but it's never gonna happen.

These are the guys that I believe the race series was conceived around and I think the rules have stitched them up. They've spent thousands only to find that they are outclassed by people with bigger pockets. You only had to look at the 3-4 lengths that the 620's were putting on 674's along the very short start finish straight after being neck and neck at Barn to see the advantage they've got. It's clear from the stands, never mind the view from the saddle. The difference on circuits with longer straights is going to be huge.

Here's a thought. Instead of trying to level the series (albeit too late) with talk of how the 583/674 people should spend another thousand or so to get flat slides and some serious engine building done, how about asking John Hackett and Neil Spalding to work out the size of inlet restrictor that would be needed to restrict 620's or 680's to 52 bhp.

Shouldn't be hard for top engine builders to work out and would cost the 620/680 boys about £20

[dickieducati]

i still dont understand .

everyone had the opportunity to buy whatever eligible bike they wanted for the series.

whats the issue?

[antonye]

Originally posted by dickieducati
i still dont understand .

everyone had the opportunity to buy whatever eligible bike they wanted for the series.

whats the issue?

I didn't

I couldn't afford a 620 but was told that a big-bored 600 would create equal power. Re-reading Neil Spalding's Rules Guide on his website also suggests this too, taking it one step further by saying that changing the manifolds and carbs would *increase* the power over a 620 - not make it level.

Based on this, I did the sums and still couldn't afford a 620, but could afford the 600 with the big-bore.

At least Jools is seeing the bigger picture too.

[fil2]

"""I have to agree with most of what Michael has said(there has to be a first time for everything mate ) Both Neil and John Hackett, engine builders who KNOW about Ducati's have stated that a big bored 583 when set up properly with short manifolds and flat slides will MORE than live with a 620. In fact John's reasoning behind his initial development of a the '620' big bore kit was because he felt the 675's would have an advantage! Having watched all of the racing at the weekend I have to say that Geof Spencer was VERY smooth and fast everywhere I could see him, noticeably faster than most into and over the mountain-which is just race and track experience. Don't forget that Dave Riley riding a standard-eg not specially dynoed and set up-620 monster with only 1 disk- was leading race 2 for the first 2 laps-and he is a novice rider, and Andrew Johnson finished 5th on a 583!

John"""""



U can hardly call dave Riley a novice Monty or Andrew johnson...

Im sure i have the wrong perspective on this monty but you always fall on the side of the JHP Simga " known " riders side.?!?!?!........there should be no sides in this..

The issue is not about the standard 620 its about the BIG BORED 620 that we all voted against....

im so tired of all this bullsh*it and for me and others its detracting from what was gonna be a top series.........

Phil

[Edited on 3-5-2005 by fil2]

[Jools]

Originally posted by dickieducati
i still dont understand .

everyone had the opportunity to buy whatever eligible bike they wanted for the series.

whats the issue?

everyone had the opportunity to buy whatever eligible bike they could afford for the series.

When I investigated it to see if I could even afford to go racing at all (I obviously couldn't) you could pick up a carbed 600 for £1000 if you got lucky on eBay (more typically £1500). The cheapest 620 I saw (being a much newer model) was in the £3500 region.

£2000 cheaper! so in theory I could get a 583 and have £2000 for race preparation for the same price as the cheapest unprepared 620, after all, the rules are set up to provide a level playing field.

What part of "some people can't afford a 620" don't you understand?

What part of

[dickieducati]

sorry i dont.

if people are that bothered about winning trophies rather than having fun then they should have got a better bike to start with. i dont know much about bike tuning but it seems fairly obvious to me that if you want to get the best performance you start at the highest level possiible ie a 620.

to use cash as an excuse is i think poor.

if anyone wanted to borrow a grand to get a better bike it would cost them 20 odd quid a month. big deal. one and a bit less beers a week.