UK Monster Owners Club Forum .: Technical :. Mods & How To's » Timing Strobe Help!

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Old 18-09-2021, 03:16 PM   #1
PPuxley
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Timing Strobe Help!

I have now tried two different new timing strobes on my 1995 M900....neither work
First the Draper 29
and Second the Gunson 44

Incidentally they are completely identical, made by the same people, absolute proof that you pay for a name!!!

On the Gunson I did try it on the Laverda and it worked perfectly.

Do these Monsters have special shielded HT leads or something??? Mine has what I think are the standard factory MTA Plug caps and leads

So, can somebody give me a specific make and model of strobe that they have and that is known to work on early Monsters.
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Old 18-09-2021, 05:05 PM   #2
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Having never even got my strobe out of the drawer for well over 20 years I was curious about this.
So I just tried it on the Monster and yes it does flash.
The little widget that goes between spark plug and cap was a ropey fit and was clearly meant to fit with the nipple on the plug, which mine doesn't have, so it fell out after a few seconds but did flash whilst connected.
I bought it from a shop (remember those?) in the 80's and all it says is that there were two models available 12V and 240V. Mine is the mains version.

All I can suggest is that the connection between spark plug and cap needs looking at, even if that means making up something that will guarantee a connection.

Probably not that much help to you as mine is an ie model so perhaps not a direct comparison to yours?

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Old 18-09-2021, 05:52 PM   #3
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patrick’s is inductive, it clips round the ht lead rather than inline, hence the shielding question. dunno, sorry
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Old 18-09-2021, 06:11 PM   #4
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Ah! too clever to work eh!

In that case I would be tempted to see if I could get the bike to run with a bit of heavy copper wire rigged between spark plug and cap somehow, and induct from that.

No idea if that would work as I'm talking out of my arse.

You'd be welcome to borrow my quaint old strobe Patrick, but I do know the bulbs don't travel well, as we found out when we used to loan them out years ago.
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Old 18-09-2021, 08:47 PM   #5
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Thanks, guys. Just come back to read this. I did get it working on the horizontal cylinder but it was a bit hit and miss with me holding the clip thing twisted against the lead. But not on the vertical.
I did try a piece of plain copper wire interposed into the lead, the bike ran fine but it still didn't get the strobe to flash.
Interestingly the Gunson generic instructions say , if you can't get the strobe to flash , turn up the sensitivity. This model has no sensitivity control.
So I think its all just a bit marginal in this application.
Thanks for the offer of a lend, but im going to persevere and try and find a model that will work
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Old 21-09-2021, 04:24 PM   #6
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Never had a problem with the inductive pick up on a strobe even when the lead is flopping about in the inductive clip. What can cause problems is using the bike's battery to power the strobe, had inconsistent and inaccurate performance on both Triumph's and Honda's using the bike battery as the power source for the strobe, must be some sort of interference,so alway now use a separate battery to power the strobe, doesn't seem to matter on cars.
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Old 21-09-2021, 04:48 PM   #7
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No, I was using a seperate fully charged battery. The Jota is sat right next to the Monster and worked the strobe with no problem, moreover it worked on the horizontal cylinder just not the vertical. Very strange. I'm waiting to get hold of one of the old style ones that actually puts the sensor into the HT circuit.
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Old 27-09-2021, 08:16 AM   #8
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I was rummaging in a not often visited cupboard yesterday and I found myself with a strobe gun in my hand that I didn't know I had! I don't even know where it came from, so I hope I haven't borrowed it and forgotten who it belongs to.

It's a yellow Gunson, the same shape as the one I pictured above but a 12 volt with an inductive sensor. The thing is that it has the adjustable sensitivity that you mentioned might make it work on your Monster Patrick.

I know that you have another type coming to you, but if that fails, then you are welcome to try this one. Obviously I will make sure it's working first.
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Old 27-09-2021, 09:03 AM   #9
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Quote:
Originally Posted by Mr Gazza View Post
I was rummaging in a not often visited cupboard yesterday and I found myself with a strobe gun in my hand that I didn't know I had! I don't even know where it came from, so I hope I haven't borrowed it and forgotten who it belongs to.

It's a yellow Gunson, the same shape as the one I pictured above but a 12 volt with an inductive sensor. The thing is that it has the adjustable sensitivity that you mentioned might make it work on your Monster Patrick.

I know that you have another type coming to you, but if that fails, then you are welcome to try this one. Obviously I will make sure it's working first.
Thank You, Gazza! The other one should be with me tomorrow., but if that fails, I will take you up on your offer.
Im out there again atm (just popped in to check a wiring diagram), Checking everything again. Ive just looked at the belts - I dont know whether its even possible to get them a couple of teeth out and it still not crash the valves......but anyway they were spot on.
I havent actually swopped coils yet, so Ill do that now and see if the fault moves with the coil. Ive already swopped CDIs and the fault stayed put. Im really running out of ideas.
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Old 27-09-2021, 10:21 AM   #10
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I think you can play a higher game with your strobe?
The fact that you're not getting a signal from the vertical pot is probably indicative of a poor current in the lead, which would follow if that cylinder is wetting it's plug.

So you could use the strobe as a diagnostic when you swap the coils and the same swapping the leads.

It might not be a strobe problem at all? Once you have a nice fat spark and good current running through the leads I expect the strobe will work okay?
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Old 27-09-2021, 10:35 AM   #11
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Quote:
Originally Posted by Mr Gazza View Post
I think you can play a higher game with your strobe?
The fact that you're not getting a signal from the vertical pot is probably indicative of a poor current in the lead, which would follow if that cylinder is wetting it's plug.

So you could use the strobe as a diagnostic when you swap the coils and the same swapping the leads.

It might not be a strobe problem at all? Once you have a nice fat spark and good current running through the leads I expect the strobe will work okay?
Yes someone else has suggested its the coil/ lead. Im swopping them now
I have just run resistance tests on all the coils and pick ups

Coil Primary 5 Ohms both, (spec 3.8-5.2)
Secondaries both a bit high at 18Kohm, but both the same ( spec 10.8 - 16.2)
Pick ups both 101ohms (spec 95-105)
Caps both 5 kohms
Leads without caps 0.5ohms, although I acknowledge that under load all sorts of things can happen

So nothing jumping out of the page at me there.
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Old 30-09-2021, 10:54 AM   #12
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Originally Posted by Mr Gazza View Post
So you could use the strobe as a diagnostic when you swap the coils and the same swapping the leads.

It might not be a strobe problem at all? Once you have a nice fat spark and good current running through the leads I expect the strobe will work okay?
Still not sorted.
  • I swopped the coils WITH THEIR LEADS, and the problem stayed on the vertical.
  • I have had the alternator casing off and checked the pick ups for air gaps and the ignition timing, statically, I made a very slight adjustment. No change to fault, it stays on the vertical (wet plug )
  • I have now deployed the new (old) strobe that arrived yesterday. It works on the horizontal cylinder at idle and mid range and demonstrates that the ignition is slightly over advanced
  • On the vertical it only flashes at idle , again showing slight over-advance. Then fails to flash at mid range revs.
  • For good measure swopped the plugs, no change. Have also tried the old plugs and a set of new ones -no change

WTF??
The only thing I havent swopped from horizontal to vertical are the ignition pick ups and the carbs. And the wet plug fault remains resolutely on the vertical.

PICK UPS
Can a pick up really lead to a fault like that- its a trigger, it either triggers or doesnt and all the resistance readings are good.

CARBS
So, is it back to the carb? The choke plunger not seating properly when choke is "closed"?
Could an over rich mixture then lead to a supressed spark at rising revs that wouldnt give enough inductive power to fire a strobe????
Im clutching at straws here, now
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Old 30-09-2021, 01:17 PM   #13
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Just emailed you what instructions I have as requested. I hope a 10MB email is okay?

My thoughts are that if the carb was capable of wetting the plug enough on its own, then it could possibly short the plug out and considerably reduce the resistance in the HT lead, reducing the current enough to fall off the scale of what the strobe can read.. I don't know if it works like that though?

Looking at it from the pick up end, again I don't exactly know how they work, but if one is getting weak, or less sensitive, then would it have less time to read the magnet as it whizzed past at higher revs? I know they will fail with heat, but that's not the problem here.

I think the logical way forward is now to swap the pick ups if they are interchangeable, If the fault still remains on the vertical pot then it kind of has to be the carb.
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Old 30-09-2021, 04:59 PM   #14
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Thanks for the reply, and the instructions....I now understand how it reads/indicates the revs, quite ingenious, really.

I'm in there again now and have the alternator cover off again now to move the pick ups to correct the slightly out ignition timing.
What a PIA system...you cant actually dial in the ignition timing dynamically with the motor running..........or am I missing something. I assume racing versions have an after market ignition system that you can programme externally.

I was all ready to swop pick ups but it isnt really very straight forward without rewiring them. The front one (vertical) and nearest the casing cable exit would never reach the position of the back one without chopping and extending the wiring, which is a bit drastic.

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Old 30-09-2021, 06:30 PM   #15
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I see you have an original pattern slave cylinder with ‘Hydraulic Clutch” on it. They are getting a bit rare now.
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