Not so Bright Spark

Hi All

Ive done a couple of roller conversions, one on my GRiSO and another on a friends 8v 1200 sport

Both went well , everything done as it should + remapped with marks handiwork, however the sport has an issue when it heats up of what I believe is dropping a cylinder . Hesitation but only when over  70c and only at idle
Apart from that its pulling like it should

Can anyone tell me the significant purpose of   this item . Is it an earthing Tang  

Many thanks in advance from a very wet Halloween in  Ireland

These didnt go into the Sport when converted. Could this be my issue?[You must be registered and logged in to see this image.]

Yes, that should be it. I put them in all I have done w/no spark issue.
I'd say you found your problem.
I arranged them so it would touch cover when closed up. Like stock

so if Finger Photo is in the 5 o clock position .... what time or where is the correct Stock position for these things


Off now to source them ...

Also ...
anyone know the part number for same

Thanks

They can happily be discarded. There is a new and better earthing tang that goes not the two bolts that hold the centre of the rocker retainer plate to the cambox that touches the underside of the rocker cover without gouging it like the previous plates do.

The reason they are there at all is so if the spark plug caps are damaged and the spark tries to arc to earth it can do so easily. The rocker cover is isolated by the neoprene cover gasket and either the plug tube o-ring or, on later models, the circular neoprene gasket between cover and plug tube. If the spark tries to arc to earth and there is no earthing tang it will try to take the path of least resistance which may be through your knee! Needless to say this would be a bit disconcerting. It's also the primary function of the black plastic covers on the back of the rocker covers. A second line of defence against knee-shocks!

Oh, and the poor running won't be related to the absence of plates.

ok Cheers Pete
So Ive been trying to eliminate the cause of this issue , Ive swapped the HT leads over from my GRiSO that I know are good and gave it new plugs but will have to wait for a for it to stop pissing rain to run it properly
Another factor may be That the owner decided to take the slack off the throttle cables before he reset the TPS on Guzzidiag ... Not sure what he did ?
When I got it It was Idling at 1000 rpm so I readjusted the cables until it read 4.7 engine off and It ran spot on 1250 rpm then reset the TPS
CO trim was at 2 but still rough ... only evens out at 8 ... Is this too high to run it ?

Also the new earthing tangs you described are definitely installed

Are all the drains on the airbox and plugged? Commonest problem I've found is that when the TB's are damaged due to dirt ingress as soon as you clear the trims and reset the TPS everything goes to hell in a handbasket as it will of trimmed itself as the damage occurs but as soon as the trims are cleared the baseline fueling is all wrong. The 50mm TB's are stupidly sensitive to wear.

Sorry, and an edit on this. If the CO is at +8 to get it to behave at idle it's probably down to wear in the TB's assuming an open loop map. The wear in bushes, throttle plate and choke of the TB mean more air than should be is getting past the plate at idle. Does it tend to spit back or 'Chuff' into the airbox when at operating temperature? If so this is further evidence that points at TB wear.

When you add fuel using the CO trim it adds, (From memory. Mark will jump on me if I've got it wrong.) 300 microseconds of pulse width to each squirt. Thing is it does thei across the whole map. So at idle, when the throttle plates are closed, it makes a big difference as little air is being passed. At wider throttle openings and higher RPM the additional fuel is proportionally smaller so the effect is less pronounced. It will though affect fuel consumption.

We have had bikes through with quite badly worn/damaged TB's that we've had to go up to high twenties-low thirties on the CO to get them to idle acceptably. I hasten to add that these were generally fairly munty, poorly cared for 8V's but the common thread with them was missing drain hoses or plugs in same or the installation of a K&N/DNA/Whatever type labyrinth air filter in the interest of 'Improving performance'. It improves it ok, straight into the trash can!

Bumped for the edit included above.