Damping down a too aggressive throttle response (1998 750 Formula)

Flywheels were the same from start to end, Craig.

Only difference was the water pump drive/ignition journal.  Later cranks were even worse than the early ones in terms of shoddy workmanship!

There were (very) minor differences in the oil drillings in the crank pins, but all parts interchange without problems.  Only the LH web is specific to build date, but can also be swapped for later type but will need the later ancilleries.  The earliest would snap off the end where the ignition rotor is fitted.

Just as important is the balancer shaft, early ones also shit themselves big-time!

The cracking heads, etc, etc are signs of wear after 30+ years of use, the main bearing and skull-less heads issues were factory fumbles, have to admit that.  The Zane engines have a definite "use by" date, after that, who knows?? :D

chriskay said:
I have heard of people on Zanes popping wheelies, and not being able button off. (Aye Cosi)
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Usually a case of the throttle cable coming undone because of the shoddy factory routing... potentially lethal! :o

piet
 
sfcpiet said:
Flywheels were the same from start to end, Craig.
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Grazie mille, Piet.  (There, that's that rumour killed  ...  ;))

sfcpiet said:
The cracking heads, etc, etc are signs of wear after 30+ years of use, the main bearing and skull-less heads issues were factory fumbles, have to admit that.
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And I like to tease ...  :-*

Ciao

Craig
 
Ventodue said:
@ Andrew:  Again, good thought.  While I know of them, I really don?t know much about Power Commanders - no direct experience, no understanding of how exactly they work. (I can just about get my head around carburettors and stuff, but efi systems make my head hurt!  Where?s Steve B. when you need him?  ;))
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Hi Craig,

I've been away riding the Corsa, and after (sort of) recovering from that been busy with other stuff (and trying to avoid the handbag fights on here of late).

How are you getting on with you EFI conundrum?  I reckon the situation first needs to be clarified - is your nasty throttle response something specific to your bike or is it "the normal nasty throttle response"??  I've ridden maybe 6-8 Zanes ranging from Ghost to 2000 Formula and they've all exhibited a very abrupt pickup from a closed throttle.  Have you ridden other Zanes and other Formulas in particular?  Is it the same or is it worse?

Cheers
SteveB
 
Ta Steve -good to hear from you, and hope all is well with both yous guys  :).

Simple answer:  don't know.  I've only ever ridden this Formula, you see.  But interesting that you've found it to be fairly widespread.

The bike is due over at Peter's in a couple of weeks, so any thoughts in the meanwhile most appreciated ...

(Doesn't happen with a Corsa, of course  :D)

Ciao

Craig

 
breganzane said:
How are you getting on with you EFI conundrum?  I reckon the situation first needs to be clarified - is your nasty throttle response something specific to your bike or is it "the normal nasty throttle response"??  I've ridden maybe 6-8 Zanes ranging from Ghost to 2000 Formula and they've all exhibited a very abrupt pickup from a closed throttle.  Have you ridden other Zanes and other Formulas in particular?  Is it the same or is it worse?
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Wot I sed...

Ridden a few more :P, all more or less the same.

piet :D
 
Has anyone ever fitted a pair of flatslides to one of these, can't help feeling they could be made to work a lot better with them on if there is the room in there.


    Keith
 
laverdakeith said:
Has anyone ever fitted a pair of flatslides to one of these, can't help feeling they could be made to work a lot better with them on if there is the room in there.
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Very cramped, Keith.

Stock intakes are very downdraft, don't think normal carbs will handle the angle.  Would need to be something from quite late pre-injection jap fours and most of those are CV, perhaps the odd race kit or similar might yield something suitable.  Maybe those downdraft things from rubber band Ducrappis will work.  Will still need quite a bit of re-modelling of the tank and/or airbox.

Still got the lack of flywheel to cope with, could be fun though.

But once you get them running OK, it's still only a matter of time till the next self-destruction. :D

piet
 
Ventodue said:
Ta Steve -good to hear from you, and hope all is well with both yous guys  :).
Simple answer:  don't know.  I've only ever ridden this Formula, you see.  But interesting that you've found it to be fairly widespread.
The bike is due over at Peter's in a couple of weeks, so any thoughts in the meanwhile most appreciated ...
(Doesn't happen with a Corsa, of course  :D)
Ciao
Craig
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Hi Craig,

If there's something unusual about your bike then some of the suggestions posted earlier might bear fruit - TPS voltage etc etc.  As I said, my impression is that all the Zanes - and many of the early EFI bikes in fact - have an abrupt transition when just picking up from a closed throttle.  You can get used to it, but hopping from something like the Corsa to the Formula will always require YOU to recalibrate YOUR TPS! :-)

I believe it is a limitation of the ECU, which is fairly crude by modern standards.  As far as I know, that Marelli ECU does not employ a MAP (manifold absolute pressure) sensor and as such all engine management is based on RPM vs TPS.  My initial tune of the EFI RGA was done using this method and resulted in a very snatchy transition not at all unlike a Zane in fact.

I reconfigured a bunch of sensors and changed the base fuelling algorithm to be RPM vs LOAD.  The ECU samples TPS and MAP, along with other engine variables like crank phase/angle, temps and RPM, then does a bunch of sums and comes up with with a LOAD figure (20,000 times a second).  This figure inherently contains a lot more information than a simple TPS number.  The end result is a crisp pickup way better than any carburettor but without the unpredictable snatchiness.  Both maps delivered the same peak hp within 0.5hp but were chalk and cheese in the riding experience.

Rather than taking the troglodyte approach and fitting FCR's  :P it would be far better to use most of the original EFI equipment and upgrade to a more advanced ECU.  I'd be happy to come and fit and program it for you if you pay my travel expenses! ;-)  I wouldn't waste money trying to chip-tune the original ECU, accept it for what it is or replace.

My $0.02.

Cheers
SteveB
 
Seems to be a problem across the board with EFI bikes. I had the same with the Yamaharley - all or nothing from throttle off to on. Somewhat disconcerting throttling on through a tight bend, especially in the wet.

I bought and fitted a Throttle Tamer which dampened the response from nil to on quite a bit. Has a cammed throttle reel. May be worth a look prior to looking at the electronics as it isn't all that expensive

www.g2ergo.com/g2-tamer-throttle-tubes-1.html
 
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