68C

I think I agree with Craig, I have heard that using loads of heavy braking and then parking up outside the pub can mean the section of the stationary disc under the pads will stay hot for a lot longer than the section exposed to the air and can affect its hardness. The thinking is you should move the bike a little a few minutes after parking under these circumstances to even the disc cooling. Some aircraft turbine engines suffer a similar heat effect except in this case the heat in a recently stopped engine moves upwards so the upper section of the shaft is hotter than the lower half. The shaft then 'bows' often to the extent that attempting a start will damage the engine. If you know you will have to start the engine in the timescale that shaft bowing may occour you have to cool the engine immediately after shutdown by dry motoring it or with some engines winding the prop by hand. Judging by his name HelicopterJim can probably explain this better than me. Put simply, don't park and walk off if the discs are hot.

One of the problems with the later bikes is the adoption of the wider tyre and six-speed box. The LH side is much the same as earlier bikes but they moved the shaft over more to the right and so the pork chop and footrest are also further to the right, so your right foot is already further out than your left. The LH rest can be lowered easily by relocating onto the frame bolt below and aft - although this does give rise to problems setting the gearlever low enough depending on what boots you wear. The RH side footrest can be mounted on a longer bolt through the brake pedal assy but moves the foot even further to the right. Ideally the brake lever needs to be mounted further back and further in allowing the footrest to take the old brake pedal position - this would need a redesigned brake pedal , a new brake pedal mount plate and possible remounting of the master cylinder ........ have fun.

I suppose your going to tell us its warm and sunny where you are as well. Ever wondered why British politicians always visit America in the winter?

I was beginning to think the same myself, a 100bhp/litre engine it ain't. Thanks all.

I personally think this falls into the picking the fly sh*t out of the pepper area.. I doubt that these ditch pumps notice a miniscule difference in back pressure from one cylinder to the other. Of course, YMMV, and I've been wrong before.

Your faith in engineers is commendable. I have the MyEcu fitted which can accept two O2 inputs, I am using the standard narrow band Guzzi O2 sensor at the moment fitted into the factory port on the x-over. Of course the MyEcu map needs to be set up for each bike and this is where my worries about the difference in the available pipe cross section between the LH and RH side arose. The problem - if it is a problem - was posted by someone else on the MyEcu forum and as with all doubts has started to worm into my mind. I think I will get two extended bosses and weld them on and blank the original port. I hope to be able to fit them to the input pipes of the x-over under the gearbox. I did see the two ports on the downtubes and wondered about using them with smaller O2 sensors but am mindful of a comment by Luhbo that the bike may start to look a little 'experimental'. So, has anyone practically addressed this matter?

The standard fitment for the O2 sensor is into a factory fitted threaded insert welded into the LH side of the x-over. It seems the sensor probe protrudes a long way into the exhaust pipe. This must act as a restriction to the gas flow, a restriction that is only present on one side. One would think having different restrictions between the LH and RH exhaust ducts would affect the back pressures and so the fuel required for each cylinder. Does this mean that only the cylinder that has the O2 probe is effectively running closed loop, the other cylinder just being a probably innacurate 'guess'. 1. Does this restriction matter? 2. Would it be better to arrange for the probe to have only the tip protruding into the gas flow. This would mean using some kind of extension threaded into the standard port. 3. Is the factory bung position in the ideal spot? 4. If running two probes (for the MyEcu) would it be best to weld the second boss into the RH side similar to the LH side or is there a better position. I should perhaps mention I have the later exhaust system with the front crossover as well as the perhaps more efficient centre x-over (don't know if it has a name - I hear the earlier version is described as the 'colostomy bag').

Can anyone explain that graph for me? I assume the highest blue line is the Horse Power following modifications and the red line as before and that the two lower lines are the before and after Air Fuel Ratios. What is the significance of the dip in the AFR around 4100pm? Is it usual for engines to slowly runner leaner at the higher revs as in this grah? Why does he HP remain constant at the top end? This not a criticsm of the work done to your bike, just me trying to understand things. If I had been given this gaph for my bike I would have added fuel round the 4100 point, but I suspect that is too simplistic.

Hi Felix420, Don't understand your last post. Surely there is only one TPS sensor, how can you swop it over?

Best set the 530Mv (or whatever setting you want) with the engine running/idling , it will change from a static engine due to the vacuum pulling on the butterfly, about 10Mv higher in my case.

Is there any risk of the fuel stabiliser affecting the plastic fuel tank, I appreciate you stated no methanol fuel but wondered what is in the fuel stabiliser. I have only used it in lawn mowers to ensure an easy start at the next mowing season.

Hi mznyc, Sorry for delay in replying - summer suddenly arrived so went camping. As several folk have posted anything that fits the thread would do. With the old 1970's two strokes we used a Dial Test Indicator screwed into the plughole to set the ignition timing as most had spark plugs in the middle of the head. You could either find TDC by rocking a measured distance either side of TDC and making two marks on the flywheel and again halving it or if you were lucky the manuacturer gave timing in both degrees advance and piston distance from TDC. Perhaps an aside, I have just made a Cliff Jefferies MyEcu kit (second attempt!) and having great fun starting the tuning process, it is already crisper than the OEM ECU although a bit hesistant at low throttle openings. Even us older buzzards try and keep up with the times.

Get an old spark plug and a degree disc. Stick the degree disc to the front of the alternater with a blob of BluTack (used by kids to stick posters to their bedroom walls). Smash the ceramic out of the spark plug and weld in a bar pointing out the threaded end about one inch, round it off. Make sure the piston is not near top dead centre and screw in the plug. Slowly turn engine until the piston just touches the plug tool. Make a note of the degree disc angle. Slowly turn the engine the other way until the piston again contacts the tool. Make a note of the reading. Top Dead Centre will be exactly halfway between those two readings. Make a note of that angle. Remove plug tool and turn engine until the degree disc is at the angle noted in the previous step. That is TDC. Repeat for the other cylinder I leave it to your imagination the result should you use the starter motor to turn the engine during this procedure!

This thread (and the recent speedo threads) reminds me of how we used to determine the safe speed in each gear when you don’t have a rev counter, most medium sized Brit Bikes didn’t of course. As our old bikes tended to disintegrate above 6000rpm this was always taken as a safe limit – shock horror when the Commando was allowed to run out to 7000rpm! Conveniently 6000rpm is exactly 100 revs per second. So if we remove the spark plugs, put the bike in top gear and push it for exactly 100 engine revolutions and measure the distance travelled in feet we can say that at 6000rpm the bike will cover the measured distance in one second. You may remember from school that 100mph is about 147ft/second so be prepared for a long push. You could push for ten revs and multiply the distance by ten but it may not be so accurate. As one statute mile is 5280 feet and there are 3,600 seconds in an hour we can now calculate the speed in miles per hour at 6000rpm: distance travelled x 3600 ÷ 5280 = speed in mph @ 6000rpm This is even easier in Kilometres as of course there are 1000metres in a Kilometre. distance travelled x 3600 ÷ 1000= speed in kph @ 6000rpm Or more simply: distance travelled x 3.6 = speed in kilometres @ 6000rpm Repeat this in each gear and mark the edge of the speedometer to indicate the safe limit in that gear. Of course most speedometers are optimistic so there tends to be a built in 10% error on the safe side. If you draw a graph of ‘distance travelled’ against ‘speed in mph/kph’ ( try a vertical scale of 0 - 150mph and horizontal of 0 to 200 ft) and plot your data you can draw a straight line from zero to that point. Extend the line some distance then divide the line between zero and your point into six to indicate the thousand rpm jumps, carry on past your point for the higher revs. You can now move up your diagonal line to find the safe rpm for your bike, track across to the speed scale and you have your safe speed. You will need a different diagonal line for each gear. I have drawn the graph and saved it as a jpeg but could not figure out how to put it into this post. I don’t have a web page to upload it to.

Hi Jrt, are you saying noone uses this board or the two listed above?

Then I too am interested, I tried to make one of my own, was'nt pretty or very effective.

Are we talking workshop stands or permanent fit?

I agree with that, ideally the master cylinders would be changed as well, I mentioned the Yamaha to show a simple re-layout of the pipes did work in practise. One could get really clever, fit a front master cylinder for a single caliper set up and add a second master cylinder to be mechanically connected to the rear brake pedal - hey, with clever linkage we could even have it adjustable to alter the bias as they do with some racing cars. Perhaps the original rear master cylinder could drive a slave piston to operate this linkage so it could be tucked away somewhere and so keep it looking standard. A roll yaw rate gyro from a model helicopter could sense lean and adjust the brake input via a stepper motor - and reduce throttle a tad. Pressure sensers could drive a variable intensity rear light.......and......er.........uh, sorry.

Baldini kindly mentioned the thread I stated recently, I miss the linked system as well. I had a new 1977 Yamaha XS750, which was an excellent bike for it's day - shaft drive, three cycls, three discs etc. I saw the linked braking on a Guzzi and converted my Yamaha to the same system, it worked really well. My friend with the Guzzi demonstrated the safety of the system by braking on a gravel surface and pointing out that the rear wheel had locked first, I tried the same with my modified Yamaha with similar results. My local dealer was finishing as a Guzzi dealer in favour of Yamaha so I managed to get a good deal for the year old Yamaha and bought the last Guzzi T3 they had in the shop at a great price. I intend to convert my V11, immediate problems seem to be way the brake light switch holds the hose to the rear master cylinder, there wont be enough thread to connect the second hose. Using a longer standard brake hose bolt would mean no rear brake switch. May have to fit a mechanical switch. I will post when I get it done.

If you were asking about my MyECU, I built it although not without problems, as posted on the MyECU forum, had it running for a few days when it quit. Probably my assembly quality. Have just built another one and am now trying to get that to run. The TPS flying leads I added are certainly handy, for a instance - I rode around with the stock ECU and a multimeter reading the TPS voltage strapped to the tank, on the over run with a closed throttle it does not always go to the same setting as a cold stationary engine. I think it must be vacuum taking up the slack in the mechanical parts of the butterfly spindles etc. Perhaps this carefull setting is not really neccesary. For many years I was meticulous with ignition timing until I got an old kickstart sportster with manual advance and retard, once started it did'nt seem different wherever it was set!

Sorry, truly did not mean to be rude, I had heard of KL - as in Kuala Lumpur but not KY. Even I have heard of America, I think we used to sell a lot of tea there. Now on the search for brake pipe fittings to try out the linked system.

I guess I am, forgive me for being a bit thick but where is KY, which country?

So the main worry is the high wear rate of the rear pads. I will see if I can live with that, perhaps fit a different rear caliper?