Slow Monster rebuild

[350TSS]

^^^ Good suggestion unfortunately the indicator lights in the instrument are LEDs and are sealed inside the unit - no means of taking it apart that I can see

[350TSS]

A good couple of days and hopefully making some progress.
To ensure I had a working rear brake light I had to bleed the brakes (re-wiring the hydraulic switch meant it had to be taken off the master cylinder). Always a pain bleeding the back brake but when I worked out that the pipe union was drawing air and nipped it up it only took about 20 minutes (having spent an hour getting lots and lots of bubbles but hardly any draw through from the master cylinder).
The rear brake return spring is an unsatisfactorily home bent spring and coupled with a slightly notchy feel to the pedal, I decided to rework the arrangement.
The notchiness was due to the push rod not being perfectly aligned with the axis of the MC. Originally I had the MC on 12mm spacers off the footrest hanger(and as such was a bit intrusive on footrest space) and with the original standard slotted end fitting it needed to be a further 1mm outboard of the footrest plate to alleviate the notchiness in the lever. I decided to go with a spherical bearing mounted inboard of the pedal. The spherical bearing is more tolerant of any misalignment. The spring was re-bent to actually exert some return pressure. I had to machine up some narrower spacers and the mechanism is now really sweet in operation.

Today I spent my time trying to get a viable spark. Given that I had power at the coils I started there, swapping the wires to the coils - no result, running an earth lead from the coil bodies I did not expect to have any effect and I wasn't disappointed, similarly the removal of the plug caps and trying to track to the cylinder head studs.
I now knew I had a more serious issue, but where to start? I am as sure as I can be that I wired the Ignitech unit correctly but all the wires were wrapped in tape and incorporated into the loom and that would be a long and arduous task to remove it.
The FastBikegear hall effect triggers were my first port of call. This comprises an aluminium rotor bolted to the belt drive sprocket in the centre of the Vee with two rare earth magnets pressed into the the outer portion of the rotor. The sensors are mounted on a 3D printed nylon plate that bolts on the outside of the belt covers. You have to cut a 50mm hole in the belt cover to allow the rotor to project through.
I fitted CF belt covers and always had a concern that this cover was not correctly positioned.
After a lot of measuring I believe I may have found my spark problem. On the basis of my calculations I currently have a 5.2 mm air gap between the rotor and the sensors. I have no idea what it should be but I have a feeling it should be between 0.2 and 0.1mm. Tomorrow we shall try to obtain that gap and try again, fingers crossed.
fried chicken wilmington nc

[Luddite]

Originally Posted by 350TSS

On the basis of my calculations I currently have a 5.2 mm air gap between the rotor and the sensors. I have no idea what it should be but I have a feeling it should be between 0.2 and 0.1mm. Tomorrow we shall try to obtain that gap and try again, fingers crossed.

Sounds like a good piece of detective work there! For what it's worth, the recommended air gap between the pickup and the flywheel on the early 900 was 0.7mm ± 0.1mm.

Hopefully, you'll have some good news to report tomorrow.

[PPuxley]

Interesting stuff. I would think youre on the right track with the air gap- 5 mil sounds way too much.
I like the rear brake light pressure switch idea, a good cheap reliable modifiocation

[slob]

Surely you don’t need to get at the LEDs themselves? Can’t you just reroute the wiring that goes to and from them?

[350TSS]

^^^^ The instrument cluster has c15 wires going into it (3 x speedo, 2 x rev counter, 1 each for LH and RH turn, 1 x panel light, 1 x neutral, 1 x charge warning light, 1 x main beam warning, 1 x oil pressure, 1 x temp warning (unused), I x positive 12V and an earth). Because some warning lights have only 1 lead I assume that there is a PCB inside that provides a common earth path. I do not think I can reverse the polarity of one LED without disabling the others or worse possibly permanently disabling the rev counter or speedometer electronics.

[hh93]

I found this thread a few days ago and it's a fascinating read. Just at P37

Are all the earlier pictures or links to them lost now ???

[350TSS]

I cannot answer as to what happens to pictures posted on the forum.
All my earlier pictures were stored on my PC (not backed up) which spectacularly blew up taking the hard drive and all the pictures with it, so those are irretrievably lost.
All the pictures were taken first on an iPhone which was destroyed when a water bottle in the car leaked into the phone resting place on the centre console of the car and latterly on a Huawei so the earliest pictures I can lay hands on are from 19/12/2019.

[slob]

no pictures are actually hosted on the forum, they’re linked to imgbb or postimg etc.

[Chriswilly]

Sorry - I don't wish to blitz this link BUT would like to contact ZIMBO (Stonehouse) at some time to possibly view his 'Dukes' and perhaps learn something for the future -
have spent hours on the site to find his e mail address without sucess.

Sorry.

[walkingpictures]

Originally Posted by Chriswilly

Sorry - I don't wish to blitz this link BUT would like to contact ZIMBO (Stonehouse) at some time to possibly view his 'Dukes' and perhaps learn something for the future -
have spent hours on the site to find his e mail address without sucess.

Sorry.

He was on here yesterday,have you tried sending him a Private Message?

[350TSS]

The project grinds on.........slowly.
I have tried a number of ways to obtain a 0.7mm air gap between the rotor attached to the camshaft drive pulley and the 3D printed plastic housing holding the pick up sensors. Plasticine was attached to the sensors and the 3D plastic part bolted on, unfortunately the plasticine was more resilient than the the 3D part resulting in the part bowing and the plasticine not really giving a clear indication of the air gap. The problem really is in the use of CF belt covers which are not the same dimensions at the three attachment bolt holes as the original moulded plastic belt covers.
Measuring with the depth gauge provides a range of results with a variability greater than the required air gap.
I have toyed with the idea of manufacturing a new sensor holding plate in 6mm aluminium but this will not get over the problem of variability of the depth of the CF belt cover and also I cannot work out how to attach the plastic encased sensors to the inside of the 6mm plate without infringing the air gap to the rotor. I will eventually find a way around it but "Lonely" my solitary brain cell is sorely taxed at the moment.
To resolve my electrical problem with the oil pressure switch I decided to go mechanical.
I purchased a pressure gauge from Aliexpress for about £6, it has a 40mm dial and a range 0 to 200 PSI. Ideally I would have liked one with a range 0 to 100 PSI but could not find one although the larger range means that the gauge will be operating well below its design tolerance and should therefore not be over-stressed by a M900 oil pump (max pressure at a guess would be about 80PSI).
It was advertised as suitable for pneumatic and hydraulic applications.
The thread on the input to the gauge is 1/8" NPT which I'd never heard of before (apparently an American thread, tapered and 27 TPI - wierd). Anyway, I bought a suitable tap and the required 21/64" drill. This is now not such a cheap fix.
I had some 10mm scrap plate to make a connection to the oil pressure switch hole but a 21/64" (8.33mm) hole with a tapered thread would not leave enough meat as it would almost certainly lozenge when the gauge was screwed in tight enough to be oil tight (and then it wouldn't be at all).
So I bought some 12mm x 25mm alloy flat bar, making the economic case slightly worserer.
I drilled a blind hole and taped it to take the gauge, cross drilled the plate to take a banjo bolt to thread into the oil pressure switch housing and then through drilled 3mm to connect the banjo bolt hole to the threaded gauge hole. The part was then shaped on my linisher (a belt sander inverted on my knees with the on switch locked on) put in the ultrasonic parts washer and blown dry and free of swarf with an air line. Here it is installed.

I turned the engine over on the starter (no sparks yet so I cannot actually start it) and the gauge quickly sprang to 40 PSI which either shows that the gauge is wildly inaccurate (entirely possible with cheap Chinese products) or I have very good oil pressure. I much prefer the second option.
Two issues with this installation, first a standard banjo union is between 8 and 10mm deep and a banjo bolt is sized accordingly so I now have between 2 and 4mm less thread engaging in the oil pressure switch hole thread. I will buy a longer M10 x 1.0mm stainless set bolt and turn it into banjo bolt and second the installation masks the oil filler cap, not really a huge problem as the bike rarely needed topping up between oil changes any way, it would just be a matter of cracking the banjo bolt and swivelling the gauge to get at the filler cap.

[350TSS]

Today was mostly spent measuring so that I could ensure that the air gap to the Hall effect ignition triggers/sensors was 0.7mm and not 5.2mm.
The problem was finding a constant datum; the front face of the rotor containing the magnets was a good place to start, but the problem was that the 3 bolts that hold the sensor plate have origins in different planes. I tried measuring to the base of the threaded holes and there was about a 1.5mm difference across the 3 bolts. Also measuring to the base of a blind hole resulted in 3 different answers on the same hole, probably thread swarf from 25 years ago when it was made. Every measurement was taken at least 3 times, obviously rogue answers were discounted and the three closest were averaged. Even so the range was up to 0.25mm.
I worked out that the outer face of the 3D printed part had to be level with the outer face of the rotor retaining boss and at that point the air gap would be 0.65mm (close enough for me).
The 3D printed part that holds the sensors has three hollow legs that aligned with the three belt cover retaining bolt holes.
With some trepidation I attacked each of these with a file until the legs were the calculated correct length so that the front face of the part was flush with the rotor retaining boss.
I checked the result with plasticine and it looks about correct.
I then turned it over on the starter and it definitely isn't touching, BUT I still do not have any sparks at the plugs. I swapped the coil leads over and still no joy.
I did notice that the rev counter was not registering when the engine turned over so tomorrow I will disconnect the rev counter lead in case that is causing the issue. (I still have 12v on both sides of the coils with the ignition ON and the run switch ON).
If the rev counter lead is not the culprit and personally I doubt it then the loom will have to come apart to check the power leads to the sensors and the Ignitech unit. Fingers crossed it is the rev counter lead.

[350TSS]

Tomorrow took a bit longer than next day as a dose of diarrhea kept me close to the bog rather than in the garage. It was not a case of the bottom falling out of my world but rather..........................................?? ??
Today was I hope constructive, I found the reason for the rev counter not working, the female connector in the 20 way connector to the Ignitech unit was not engaged properly and when the male bit was pressed home the female bit retreated. Operator error as I fitted the female bit.
I decided to test all the connections/ inputs and outputs to the Ignitech unit, this involved making up multiple jumper leads between the two parts of the connector so that I could actually get a test meter onto the various input/ output posts. With a 20 way connector the posts are too close together to just push a female onto the male as there is a danger of shorting when trying to attach crocodile clips or put probes on. This took a fair while but the good news was that each terminal post on the Ignitech unit seemed to react the way it should.
The only thing left was the supply voltage. The circuit is battery - ignition switch - fuse box - terminal box - ignitech unit. The battery was showing 13.2v as was either side of the ignition switch, the output terminal from the fuse box and from the terminal box. The wire leading into the Ignitech unit was showing only 8 to 9 volts. This input cable is new, has one soldered join, mechanically supported by heat shrink and whilst thin wall insulated is rated at 11 amps. It is about 300mm long. I suspect a dry joint at the join is the culprit. A further operator error - doh!!!!
At this point I had two options, dismantle about 40% of all the wiring running around the head stock to take out the offending wire or just try to run another (slightly heavier duty) cable through the sheathing around the headstock, which is what I did.
I now have battery voltage at the Ignitech input terminal post but ran out of time to test whether or not I now have sparks at the plugs.
I bet you cannot wait for the next exciting episode in this long running saga

[350TSS]

Well I'm back on the project after almost exactly a year.
I have not been idle and every couple of weeks I would spend some time checking one or other aspect of the wiring and each time I was disappointed with the same result - no sparks. It was very disheartening and every day I went in the garage I looked at the "ornament" on the workbench and had a ponder as to what to do next but ideas eventually dried up. It had defeated me.
I am a member of the Morini Riders Club and a certain Benjy Straw advertises in the club magazine operating an electrical repair service for anything Italian (brave man - but obviously mainly Morini focused) from a "secret location near Tonbridge" which turned out to be about 6 miles from me.
The Morini had a broken kick starter spring which I was unable to source anywhere and he had one so both bikes were packed into a van and sent off to him. It took a lot longer than anticipated as first he went on holiday, then I went on holiday then he got Covid.
He spent 5 days on the Monster and returned it to me with great big fat sparks on both cylinders. Hurrah!!!
It turns out my wiring would have worked but there were a few things that together contributed to no sparks
1. I had high performance coils designed for a carbie Monster from Exact (imported California Cycleworks components) and the impedance on these coils is 4 ohms - the Ignitech recommendation is for lower impedance coils 2 to 3 ohms
2. I was using the leads and plug caps supplied with the coils - why wouldn't you? The standard plug for a Monster is a resistor plug and these plug caps were also resistor caps - apparently a poor combination for a good spark
3. I had wired a common earth from the Ignitech unit and the Hall effect sensors - apparently separate earths would improve the chances of the signal from the sensors not being corrupted
4. I had wired the Hall effect sensors (6 wires) into a single 7 core cable for neatness of the loom, Benjy felt that two separate 3 core leads was a better solution.
5. I had wired the coil power lead with 1 x 1mm cable split close to the coils into 2 x 1mm cables he recommended 2 x 2.5mm cables from the fuse box.
He said that probably none of these issues alone would have prevented a spark but in combination it they overwhelmed the possibility of it working.
I still have a few things to do but that will follow on later posts