Sport 1100 - Twin-Plugging + Ignition Upgrades?

[Kristian]

Fellas,

Research comes out 50/50 for whether twin-plugging works on these bikes. It is nearly impossible to find comparative dyno runs confirming anything. Also, inability to alter the stock Digiplex ignition is also cited for why twin-plugging isn't all that for Sports.

Has anyone twin-plugged their Sport, or other big-valve big blocks, either with or without ignition upgrade? Dyno runs?

It seems to me the optimal is to upgrade the ignition first--Silent Hektik or Sachse--before twin-plugging, so timing can be optimized for twin-plug operation. For example, German Guzzi tuner extraordinaire HMB is big on doing this to Sports, but, ignition upgrade seems to be key. Has anyone done this?

Mike Rich's very valuable opinion seems to be to not bother with twin-plugging with the stock ignition; and that makes sense.

The ignition issue seems to be at the heart of the stubborn 2.5-3.5K RPM stumble and torque dip from which Sports suffer.

Thanks-

Kristian

[yogidozer]

try using a digiplex from a Strada. that helps with the stumble. proper jetting first

[dxhall]

Twin plugging may give some horsepower or mileage increase, but it's not a matter of simply sending the heads out to be drilled for another plug hole, and bolting the heads back on.  Because the flame front on a dual-plugged head starts in two places, the time necessary for compete combustion is much shorter than it would be with a single-plugged head.  That means that, to make the dual-plug head work correctly, the ignition must be seriously retarded.  How much - well, you'd have to run dyno tests to find out.   

I have a Sport 1100 in my shop which was dual-plugged, and then abandoned by the owner-plugger because he couldn't figure out how to fire the plugs. 

[John A]

 On a Bassa I use a pair of Dyna dual outlet 5 ohm coils. to power them I use a pair of relays that are switched from the original  leads for the original coils. The trigger signal from the ecu goes to the coil negative. I used a program from FIM- fuel injected motorcycles, I think they are not in business anymore. with their program you could adjust the timing which was done on a dyno. Dual plugging was done by Mike Rich along with porting. very nice work. I use throttle bodies from a Sport I . Id do it again, been over 100K miles. You already have a 10 spring clutch which I put in mine. It would burn down an 8 spring in short order.

[Kristian]

On a Bassa I use a pair of Dyna dual outlet 5 ohm coils. to power them I use a pair of relays that are switched from the original  leads for the original coils. The trigger signal from the ecu goes to the coil negative. I used a program from FIM- fuel injected motorcycles, I think they are not in business anymore. with their program you could adjust the timing which was done on a dyno. Dual plugging was done by Mike Rich along with porting. very nice work. I use throttle bodies from a Sport I . Id do it again, been over 100K miles. You already have a 10 spring clutch which I put in mine. It would burn down an 8 spring in short order.

Thanks; looks like it's been a while, but, did you do before and after dyno runs?

[LowRyter]

I just wonder if weak spark is a cause of the stumble, whether a stronger coil might help?

I've ridden one of those bikes and it did have a bad stumble too.  One of the graybeard posters here, Carl Allison, said that the timing chain (or adjuster) was the culprit on his bike after going through almost everything. 

[Kristian]

I just wonder if weak spark is a cause of the stumble, whether a stronger coil might help?

I've ridden one of those bikes and it did have a bad stumble too.  One of the graybeard posters here, Carl Allison, said that the timing chain (or adjuster) was the culprit on his bike after going through almost everything.

I don't think it's a weak spark. Having done extensive research on this – I think I've seen every post on the Internet regarding Sport 1100's and ignition - it seems to be ignition related. There is little empirical data – Dyno runs – on the effects of swapping out the DigiPlex ignition with something better and without vacuum advance designed for fuel economy. As Yogidozer notes above, and is reflected in Guzziology, there was an indication that swapping in a Spada Digiplex for the Sport 1100 cured the stumble. I spent all sorts of dyno time in 1996 or so when I had my first Sport trying to kill the problem, to no avail. It seems the Sport Digiplex advances the ignition curve very rapidly, with full advance happening rapidly and well before 3000 RPM, and which doesn't work well with the cams.

The umbrella fact to this is that it must've been pure hell for Moto Guzzi to try to get the ancient, air cooled, pushrod, big-valve, carbureted, 1100 cc lump through the EPA, or anywhere, hence its desire to get the things to run as lean as possible. Even Porsche, with orders of magnitude greater engineering talent and money, had to abandon the beloved air-cooled flat six by 1997.

Kristian

[John A]

Thanks; looks like it's been a while, but, did you do before and after dyno runs?

No before, the one after showed close to 90 hp with a great bump in torque. no more missing and popping on trailing throttle, no flat spots. no stumbles. itll ping on 87 octane and its hot outside if that's all I can find. like I said, it'll drive right thru a 8 spring clutch on a hard pull even before I put a heavy sidecar on it. When he flowed it, Mike Rich said he got numbers almost as good as their race bike.

[Fnq1000]

Hi Kristan

Here's some dyno information and discussion, scroll down to Guzzi

http://www.bikeboy.org/performance.html

Cheers
Jason

[Tom]

Kristian.  Does your bike have carbs? and is the stumble at 2500K rpm's?  If so the problem is from the lean nature of the oem carb settings.  Different jets would help.

[Kristian]

No before, the one after showed close to 90 hp with a great bump in torque. no more missing and popping on trailing throttle, no flat spots. no stumbles. itll ping on 87 octane and its hot outside if that's all I can find. like I said, it'll drive right thru a 8 spring clutch on a hard pull even before I put a heavy sidecar on it. When he flowed it, Mike Rich said he got numbers almost as good as their race bike.

Wow, that is very impressive indeed and exactly what I am after. Apart from dual plugging and porting, and probably exhaust, what else did you do? You probably have the world's fastest Bassa!

[Kristian]

Hi Kristan

Here's some dyno information and discussion, scroll down to Guzzi

http://www.bikeboy.org/performance.html

Cheers
Jason

Thanks, yes, I know bikeboy's blog very well; that gentleman does it right. His jetting prescription for the PHM 40s sounds bang on.

[Kristian]

Kristian.  Does your bike have carbs? and is the stumble at 2500K rpm's?  If so the problem is from the lean nature of the oem carb settings.  Different jets would help.

Well, that's the thing. Jetting can't solve the problem on Sport 1100s; that much has been proven time and again, with the problem being particularly exacerbated by getting rid of the airbox. I never got rid of the stumble myself back in the day, not even when I switched to Mikuni HSR 42s from RaceCo.

Bikeboy, Italian bike tuner extraordinary in Australia, recently showed this again; he has a great blog post from last year about chasing correct jetting for a Sport 1100 on a Dyno with AFR analysis, and the stumble never goes away. I am betting that if you were to put a manometer on the intakes to establish intake pressure when setting timing, which is a common way of doing it on race cars and bikes, there would be a big drop in pressure right around the RPMs at which the stumble occurs, indicating a bad mismatch between ignition timing, camshafts, cam timing, and intakes.

The other piece of conventional wisdom destroyed by this research is that it's a mistake to remove the air boxes on Sports and V11s, and replace them with small, individual pod filters clamped directly to the throttle bodies and carburetors. In every case I've seen, that gives the poorest running.

[Tom]

The other piece of conventional wisdom destroyed by this research is that it's a mistake to remove the air boxes on Sports and V11s, and replace them with small, individual pod filters clamped directly to the throttle bodies and carburetors. In every case I've seen, that gives the poorest running.

 :1:

[Tusayan]

On the carb Sport, the intake pressure waves created by the aggressive Crane cam, the short effective header pipe length and the airbox suppress carb function and make the engine go lean in the mid-range area of concern.   According to John Wittner, who was there, Guzzi knew this but ran out of time.  As a result, they anticipated that the carb Sports would be entirely retuned by the owners and that the air box would come off in the process, which in my experience helps if the inlet horns are the right length.  Wittner used the phrase "intentional kit bike"

The injected Sporti engine, developed over the subsequent two year period, has high pressure fuel delivery through a small orifice, instead of light manifold vacuum pulling fuel through a relatively large jet, so aberrant pressure waves in the inlet tract don't have as much effect on fuel delivery.  As a result, when the fuel map is corrected the injected bikes don't have the same mid-range stumble.  Still a kit bike but an easier kit bike   

This situation was one reason Guzzi went with EFI in '97 instead of using Japanese carbs like Ducati's budget bikes: at the same power level, Guzzi had a more challenging situation with pushrod engine cam timing versus desmo cam timing, and Japanese carbs would not have solved it completely.

[yogidozer]

Well, that's the thing. Jetting can't solve the problem on Sport 1100s; that much has been proven time and again, with the problem being particularly exacerbated by getting rid of the airbox. I never got rid of the stumble myself back in the day, not even when I switched to Mikuni HSR 42s from RaceCo.

Bikeboy, Italian bike tuner extraordinary in Australia, recently showed this again; he has a great blog post from last year about chasing correct jetting for a Sport 1100 on a Dyno with AFR analysis, and the stumble never goes away. I am betting that if you were to put a manometer on the intakes to establish intake pressure when setting timing, which is a common way of doing it on race cars and bikes, there would be a big drop in pressure right around the RPMs at which the stumble occurs, indicating a bad mismatch between ignition timing, camshafts, cam timing, and intakes.

The other piece of conventional wisdom destroyed by this research is that it's a mistake to remove the air boxes on Sports and V11s, and replace them with small, individual pod filters clamped directly to the throttle bodies and carburetors. In every case I've seen, that gives the poorest running.

I rejetted changing slides/needles/jets, along with the Strada digiplex to get rid of the stumble. Tried many combinations to get it to work properly, but that was quite a few years ago. I would have to pull a carb to tell you exactly what I used. Digiplex from a Strada made a big difference. Guzziology is a good place to get ideas about jetting suggestions to start trying.
edit, I still run the ram air box

[jacksonracingcomau]

Yes twin plugging needs ignition timing reset, many ways to skin that cat.
Not sport but I have 1100 cali motor, twin plugged, fiited old twin contact breaker housing and cam gear to suit.
Still low comp pistons but tightened squish
Restricted advance to 10 deg at cam 20 at crank
Set at 10/30 btdc
Will never pink even worst outback fuel
Carbs 40mm dellortos as 1100sport, jetted to suit, no stumbles or misses.

None of it rocket science, think cliff my ecu can sell box to adjust timing on digiplex, prob others too

[lazlokovacs]

+1 what jackson said


just chucking something into the mix....

the cali vintage 1100 engines (sharing many parts with the sport 1100) are twin plugged as standard -

however the ignition isn't retarded at all (from stock)

and the 2 calvins I've known have pinked horribly

YMMV!

[John A]

Wow, that is very impressive indeed and exactly what I am after. Apart from dual plugging and porting, and probably exhaust, what else did you do? You probably have the world's fastest Bassa!

cam,I think it was  Norris S grind. I degreed it in by making some eccentric bushings to get it where I wanted it. I retained the chain rather than gears, its been my experience that aluminum gears fill the sludge trap. also I wanted to take advantage of the cam being slightly retarded on trailing throttle from chain slack giving more torque when I go WOT, like on a corner exit. I used a Valtech tensioner and got good practice with trial and error fitting of the eccentric bushings. I retained the stock airbox with a stock paper filter but with an open top. Exhaust is From MG cycle with a crossover in front and a crossover under the trans. Mistral mufflers. A Roper plate for better oil control and it runs good. There is other stuff that I cant remember, just regular hop up hot rod tricks.

[jacksonracingcomau]

cam,I think it was  Norris S grind. I degreed it in by making some eccentric bushings to get it where I wanted it. I retained the chain rather than gears, its been my experience that aluminum gears fill the sludge trap. also I wanted to take advantage of the cam being slightly retarded on trailing throttle from chain slack giving more torque when I go WOT, like on a corner exit. I used a Valtech tensioner and got good practice with trial and error fitting of the eccentric bushings.

Offset dowel ?
I simply vernier drill cam gear, disproves myth of ergal alloy getting into sludge trap.
Ergal alloy work hardens, drilling cam gear like drilling stainless, prep for fight.
May be other gears not ergal, drill good test.

Quicker way is to ovalise the one hole, normal for modern bikes, tighten nut when valve timing correct

Your variable valve timing theory before it�s time but if it works for you :1:
Me, I like accurate, cest la vie

[rocker59]

Keihin FCR41 carbs on my Sport 1100.

Euro .10mm/.15mm valve clearances.

No stumble.

Sent from my SAMSUNG-SGH-I337 using Tapatalk

[Kristian]

Keihin FCR41 carbs on my Sport 1100.

Euro .10mm/.15mm valve clearances.

No stumble.

Well, it's not usually a stumble as much as it is a big torque dip, which will show up on a dyno run from 2K RPM. Some stumble, but if jetted OK, they don't. I'm certain though the FCRs fuel loads better than PHMs.

[Murray]

Fellas,


The ignition issue seems to be at the heart of the stubborn 2.5-3.5K RPM stumble and torque dip from which Sports suffer.

Thanks-

Kristian

Are you still running delorto's? BTW why are you lugging it?

[yogidozer]

still running delortos, no stumble after jetting/Strada digiplex change. added crossover, mistral mufflers

[Kiwi_Roy]

Hi Kristan

Here's some dyno information and discussion, scroll down to Guzzi

http://www.bikeboy.org/performance.html

Cheers
Jason

A very good Dyno explanation here
http://www.bikeboy.org/dyno.html

[Tusayan]

Well, it's not usually a stumble as much as it is a big torque dip, which will show up on a dyno run from 2K RPM. Some stumble, but if jetted OK, they don't. I'm certain though the FCRs fuel loads better than PHMs.

Japanese carbs are better than the Dellortos, and with those carbs richening it up helps, so that some fuel still makes it up the jet in the affected rpm range, regardless of funny things happening in the inlet tracts.  The latter would not allow the bike to comply with the emissions laws, hence fuel injection on the 97-98 models as explained above.

A tubular crossover also helps, usually better midrange at a minor cost in top end power.

[John A]

Offset dowel ?
I simply vernier drill cam gear, disproves myth of ergal alloy getting into sludge trap.
Ergal alloy work hardens, drilling cam gear like drilling stainless, prep for fight.
May be other gears not ergal, drill good test.

Quicker way is to ovalise the one hole, normal for modern bikes, tighten nut when valve timing correct

Your variable valve timing theory before it�s time but if it works for you :1:








I prefer gears, at the time I couldn't find a set that I trusted. I think that in North America there were some inferior gears made for Guzzis and BMW's so it became very hard to tell what you were getting.
I do not want to have a gear merit thread, I've had them go hundreds of thousand miles and have had them start coming apart in 20K. My point is there are merits to a chain so let's leave it there. I drilled the locating pin hole larger and made some eccentric bushings to time it. It's just the way I did it, not that it's the best or even easiest way.

[Orange Guzzi]

I would address the stock cam chain tensioner.  I recently pulled the front off my 2003 motor and found that it had about 4 ounces of pressure on the cam chain.  The spring is about the size of a small paper clip.  I could rock the crank and the came would not move because of the weak tensioner.  I replaced it with the Valtek. 

Tuning is not an absolute science.  A riders weight and gear can make a big difference on the amount of fuel needed to move the bike. 

With the higher duration cam in the Sport bikes, you get back flow due to the intake valve staying open longer.  Making the engine run much better at higher rpm's. Probably the reason for the pressurized stock airbox assembly.   The nature of the beast.  Giving up low rpm performance for high rpm performance. 

The higher domed piston reduces the size of the combustion chamber at tdc giving the engine and the higher compression ratio.  I put a set of V11 high dome pistons in my California engine with the smaller combustion chamber.  Cranking pressure was 225 psi.  Way to much as Pete R said.  The head was going to blow off.  I raised the cylinder with and extra base gasket and got the compression down to 185 psi.  The 8 spring clutch would not handle the extra h.p.  Replaced it with Ram.  I have not had a chance to test the Ram clutch.  Waiting on the 3m marine sealant to cure on the rear spoke wheel tubeless conversion.  Takes 7 days to cure.  And the weather sucks.  Went from 0 degrees F to Monsoon season.

My carbed 1996 Sport ran great with K&N pods and D&D exhaust.  Much better than my riding ability.  If I want more power and more speed, I have a FJ1200 that is scary fast.  If I want slow and fun, a Buell Blast.  And for the Old School Cool day's a KZ1000 LTD. 

[Tom]

I rev past the stumble at low rpm's and that's on a stock set-up. 

[Murray]

There is a wire you can shunt to ground on the ignition that will pull 3 degrees out of the advance, I assume this is so the unit could be fitted to other models, I'd be pretty reluctant to pull any advance out of one. As Orange Guzzi suggested looking at the cam chain tensioner would be worth while t 20 000kms I had something like 4-5mm slack the blade/ago tensioners seem to be the go unless you want to stump up for some steel gears.

The delortos didn't hold their tune/balance for any meaningful period of time either (possibly related tot he overly complicated cable throttle setup. 2500kms a good tuner could make a difference to how it ran 5000kms it needed doing, only ever seem to affect the midrange.