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What the battery can put out is illrelevent, the total circuit resistance is the important consideration. If the fuse has 0.3Ω, the relay 0.8Ω, the button 0.4Ω and the horn 0.1Ω, what happens in that fused circuit.

Sounds like a horn driver that is stuck. When it gets stick it causes a direct short ( or near that) and pulls the voltage on the circuit low.

I little side project I was involved in. It has been neglected unfortunately. The main page has a few other articles if you are curious. https://www.yamaha-motor-university.com/ymu/motorsports/advertising/YMU%20Service%20Limit/index.html

Here is three relevant articles. https://www.yamaha-motor-university.com/ymu/motorsports/advertising/YMU%20Service%20Limit/docs/Three%20Ignition%20System%20Types%20September%202012.pdf https://www.yamaha-motor-university.com/ymu/motorsports/advertising/YMU%20Service%20Limit/docs/Troubleshooting%20TCI%20Ignition%20Systems%20October%202012.pdf https://www.yamaha-motor-university.com/ymu/motorsports/advertising/YMU%20Service%20Limit/docs/Ignition%20Coils%20July%202013.pdf

Transistor Controlled Ignition. Works just like points but is controlled electronically instead of mechanically.

Coils do come in two distinct varieties when it come to the primary resistance and I agree the problem is with too much current through the primary side. TCI (Points fall into this) or CDI. TCI coils have a few Ohms of resistance and induce voltage into the secondary through a collapsing field, this is why dwell is important. CDI coils have very little resistance, normally a few tenths of an ohm, and work off a rising field to induce voltage in the secondary. Using a CDI type coil on a TCI bike will allow it to run, until either the coil or the ECU cook due to the extra current. Using a TCI coil on a CDI unit will cause a very weak spark and normally cause the CDI to find an alternate path internally for current, which then fails. The original coil could have just partially shorted out some of its winding til it smoked. If a CDI style coil was then used as a replacement, it could have quickly have gotten cooked. I originally learned this lesson in the 80's with GPz900, I just had to have those high-output Accel coils.... Went through 4 TCI units, and 3 coils before I figured it out.

Correct, the Ducati and most full wave units are series. Their downside is exactly what you state. They cut half the driven current and half the charging at that point. They work good from a cost stand point but suffer in the charging stand point. In regards to three phase units, the output is limited by the regulator, not the diodes, the diodes only drop a half volt so the wattage they have to dissipate is minimal. The majority of the heat is generated in the scr or mosfet during regulation. Every unit I have seen is rated at 14v, which is common charging for lead acid batteries. The silicon isn't the problem, it is the units ability to dissipate the heat created during the regulation. Lack or airflow and low mass are an issue. Some units use a water cooling because of this, such as commonly found on marine products. Using a newer 3 phase unit on a Guzzi is an easy way to provide more stable charging. Overheating isn't an issue.

The 35 amp is the max rating of the regulators output, normally at 14v. This doesn't change if something on the rectification side changes, like running off of two legs. Of course the output will. Some modern race bikes will actually overheat the regulator til it shuts down and then the battery goes flat, just not enough system draw at 14,000 rpm and the stator is totally kicking ass at that point. So much current gets shunted the reg/rec casing can't disperse the heat. Simple fix is to remove a single stator leg which drops the stator output by 1/3 and then the rec/reg can handle the heat. The only stators that don't produce full output all the time are the ones that have a field coil, anything with magnets is always working. Also fully operational 35 amp system working at full capacity is only taking about 0.6hp to power, so not much to gain.

I have ridden my Scura at a track day. I have both an 2003 R6 (SBK) and 2006 R1 (SBK), race only. To be honest, the Scura wasn't even fun. While it didn't try and kill me like the R1 always does the amount of effort and work that it took really took the pleasure out riding on the track. But some people prefer the bike being the challenge and not the track, so...

I won't quote to keep this simple. Phil, I actually meant it. Your description of how a narrow band works was solid. No sarcasm was implied. Gstallons, DI = direct injection GuzziMoto, quite right, in addition modern ECU's that still use a narrow band measure also measure the time it take for a "switch" (cross of the 0.45v) to happen. This works better on multi cylinders than twins. If the switch was quick, then the change in injector pulse was close, if it was very slow then the injector pulse was way off and will be corrected by a larger margin on the next cycle. 68C, fuel pressure is important but it is an area of diminishing returns. 13% of idle injector pulse is about nothing in the real world, math is important but due to the other variable involved with a running production engine it ends up being the difference between "good" motor and "weak" motor. At WOT that can make a bigger difference. Quality control and accuracy vs. production cost quickly become a fight, cost wins every time. KiwiRoy, systems that use a manifold vacuum referenced pressure regulator are still common, particularity on multi-cylinder models. Large twins intake pressure generally vary to much to be useful and are accounted for digitally for this reason. There are 4 cylinder models that reference 3 cylinders to fuel pressure and then only the 4th only to the ECU, this is used for both D-electronic fueling, finding TDCC, and acceleration compensation. Needless to say the response of modern air pressure sensors is very good. In the scheme of things the response of a fluid system is pretty slow to react to changes to intake pressure, there is lots of mass involved in proportion, so it ends up working pretty well even when on a theoretical level it doesn't.

While many automotive system use a pwm fuel pump with a fuel pressure sensor most motorsport products don't (none come to mind at least); even with a return-less fuel system. Instead the regulator is incorporated inside the tank and only fuel maintained at the correct pressure flows to the rail. The intake pressure sensor is used by the ECU to compensate for differences in pressure between idle and WOT by changing the injector on-time. Been standard on many Yamaha's since 2006. I have yet to see an OEM motorsport or automotive application that operates in a choked flow condition. Maybe a DI unit (haven't really studied them to be honest), but those are still a few years away for mainstream motorsports usage. Modifying fuel pressure at the regulator is a very common method for supplying additional fuel in aftermarket boosted applications, normally the regulator is just referenced to manifold pressure at a 1:1 ratio. Nice quick summary of narrow band Phil!

Another alternative is zinc brazing. While some base material grinding is required it does work quite well in an area like this. It is a common procedure in the sail boat industry. I wouldn't even try epoxy, in an area that is stressed it will pull off and fail again, you will never get it to bond correctly, then any other repair is that much more difficult. Silicone would work as well. TIG would be the best but is also the most expensive and labor intensive. As others have said, some shims should be used.

Somewhere in history there was the cross reference to a Yamaha part number for the seals, double lip if I recall. . They lasted much longer than the performance oriented Ohlins seals... The Ohlins oil (RT43) is the same as Yamaha M1 which was spec'ed when Yamaha owned the majority share of Ohlins back in this era. Suspension guys love the "spec" grease and it is really nice. But oil will work just fine. Any lube is better than none.

Clutch? The Mandello does use the now infamous single plate.

Scura #269, 13k miles. Original clutch. Crack tested a few times, so far so good. I swear there is/was a German site that was registering Scura's way back and had some world results for the exploding syndrome. I don't think I was dreaming...

I think you are looking at this wrong. The slave piston was not fully extended out of the bore, it was fully pushed in to where it could not push into the bore any further. As the clutch wears on a Guzzi with a hydro clutch the slave piston retracts to allow the clutch to engage. As the clutch wears the slave piston goes further into the slave cylinder. His sounds like the slave piston had retracted as far as it could but when the clutch wore further and the piston could not retract any further the clutch started slipping. Buy spacing the slave out away from the clutch it allows more travel in the required direction and thus the clutch has stopped slipping (for now). The only real fear is that if the clutch is allowed to wear down to far it could cause damage to the rest of the parts, but my guess is that the clutch is OK and it is really just an issue with the pushrod being slightly too long. It could be an issue with fluid not being able to move back up into the master cylinder, but it does not quite sound like it to me. Perhaps I am wrong, Durrr. I wasn't quite thinking correctly. Sorry and thanks for the correction. Carry on as usual. Nothing to see here.

Hey Moscow, Hydraulic systems like our brake and clutch will function until the slave cylinder piston is physically pushed out of the bore. They are self adjusting to a point of failure due to fluid leakage. The piston in the slave is retracted by the seal (assuming the return port in the MC is not obstructed). Some pressure is balanced from the clutch diaphragm and the resistance of the clutch slave seal, this is very small. When removing the clutch slave you should have been able to press the slave piston back into the clutch slave. If you could not this is a failure of the MC or lines not allowing fluid to return to the reservoir.Very often aftermarket levers cause this, they do not allow the MC piston to return enough to allow for fluid to pass through the return port. But as clutches wear they can slip, that is why they are a replaceable part. The MC and the slave cylinder (barring modification) are not a replaceable part, for a reason.

Two comments here. A) test rig should simulate the environment that the components work in. Substituting air for oil is a no go. Air just removes the oil that is part of the system. Use air to pressure an oil tank that feeds the test rig, your results might change. 2) Lapping? While I haven't had this system out this is a piston in a tube with radial holes at a determined depth. The piston balances oil pressure (low side + spring pre-load) vs the high side (mechanical oil pump pressure.). What was "lapped" the piston to the bore?

This has to be the best forum thread I have read in an eon. This is really the way forum's should operate. Everyone admits to drinking and impaired judgment (not that this is the case here... just in forums in general. But at least here we are honest about the booze!) and then sitting down to work on a motorcycle. Awesome, simply awesome. Good taste in beer too! I'm going to have another martini and then go finish framing in a bathroom addition. Cheers!

Yep. everything but the shoe phone. But back to the original complaint. My 02 does not like to downshift more than 1 gear at time.Clutch, throttle matching... nope.. It just doesn't like it. Same with my 70 Guzzi. My other 4 motorcycles (all Japanese brands) no issue, even the ones with no slipper clutch. But out of 6 motorcycles and countless others I get to ride the Guzzi's still get the biggest grin out of me. Welcome to the club. Just remember it is different, you may have to re-learn a few riding habits to adjust.

"Guzzitech ECU map to match Stucchi crossover and Mistral mufflers." Via a PC? I couldn't ever get my Scura to idle for shit. MyECU fixed that. I spent years F#%KING with that nonsense. It would seem the range that Guzzi's work with-in is very wide. Some people have no issues, others have never ending. The OEM ECU sucks, or at least its programming does. If you use it as a base, your case is lost before it even began to my experience. Which, the bike ran great for almost 3 years, then it when to hell. Can't imagine that the ECU changed.... But it did.... POS.

The protective plastic that is used to keep the sheet steel from getting scratched would be my guess. Probably cut with the sheet still present then peeled off afterwords.

Tread patterns are not what they seem. The old force water out theory is just a wives tale. It really is more about finding somewhere for the water to go. Hydrodynamics of a tire at speed is very different from what most people would expect it to be. Run it in the direction of the arrow if you can. But to be honest, the arrow is a usually decided by the marketing department, not engineering.

This has to be the best forum statement I have read in years. Simply awesome.