UK Monster Owners Club Forum .: Technical :. Engines, Clutch, Gears » still problems with rear cylinder carb ?????

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Old 06-09-2021, 02:49 PM   #76
hh93
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I read somewhere that some models use the Air Screws to set the final tick over speed - might not be applicable on your model, though.
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Old 06-09-2021, 06:08 PM   #77
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well another dissapointing day .. almost thought I had solved it but NO the bike still will not tickover even with NO throttle cables and no throttle stop screw ,, its also rough again and im completely peeed off and wish its was gone ..... very tired of this bike now also the tiny spring from the balancing screw took a leap for freedom and cant be found .......the timing is spot on even though the pickups are reversed ,, and the bike revs all the way to 8000rpm smooth as silk , i know the carbs are good when fitted on the other bike so Im flummoxed ,, and all the electrical parts work fine on the other bike ,,, what now ????
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Old 07-09-2021, 10:37 AM   #78
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its almost as if its running full advance all the time .. ???? nothing logical about this ,,

1.... The carbs are fine they work ok on other bike ,

2....the coils, HT leads , spark plugs , kokkusans all tested OK on other bike

3....pickup timing all set perfectly ..... I have now reveresed the pickups to standard condition ,, red white 1 & 2 and yellow Black 3&4 bike runs ok abover 2000rpm but not below ,,,

4.... new cables fitted to throttle

if everything is fine when tested on other M750 why does it not work on this bike ???

My faith in this bike is severely dented seriously thinking of breaking it for spares ,, I would make more money doing that ,,, also dented my faith in Ducatis ,, seriously considering selling all of them if i dont understand or cant fix something I cant trust it at all.. 6 months this saga has been going on ,
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Old 07-09-2021, 10:50 AM   #79
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Possible air leak somewhere?

Carbs to Intake manifolds.
Intake manifolds to Cylinder head.
Vacuum gauge take-off blanking screws in intake manifolds.
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Old 07-09-2021, 01:02 PM   #80
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Possible air leak somewhere?

Carbs to Intake manifolds.
Intake manifolds to Cylinder head.
Vacuum gauge take-off blanking screws in intake manifolds.
All checked OK Nasher that was one of my first thoughts weeks ago ,all are in perfect nick , i have relegated the bike to back of garage while I consider my options ,,,I am totally peeed of with it and its also making me hate my other bikes too ,,especially the S4 as I cant even get bck to Thailand and the exact nature of why it would not run still eludes me although I have parts now for several suspects ,, so peeed off with Ducatis that recently I have prefered to use Petes 50 year old HD at least it makes me smile and It can be ridden hooligan style too.....and its simple to diagnose issues ...which it does not have .
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Old 17-09-2021, 03:49 PM   #81
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JERRY. Im having similar issues on an M900.
When you say Pick up timing all set perfectly- is that just statically or did you strobe it to confirm your suspicion that "its almost as if its running full advance all the time ".
Ive tried to show graphically what I have and what you are saying from your posts. Have I understood correctly? I dont quite follow your numbering, I thought the numbers were fixed to the colours.

Anyway I am just about to dynamically test mine now the strobe has arrived and that should confirm the timing at both idle and whether it is indeed incorrectly fully advanced at idle.

If I find that mine is now right (and I have interpreted your posts correctly) then maybe swopping your red and white as line 2 is whats required.

Anyway I will report my findings

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Old 17-09-2021, 04:23 PM   #82
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Well, not today I wont. Bloody strobe doesnt work on motorcycles for some reason. So needto order another one!
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Old 17-09-2021, 05:51 PM   #83
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Yes PPUXLEY your diagram is perfect ,,both my other 750s SS and monster have wiring as your M900

thing is I have tried every possible combination and only the one I have lets the bike start ??? but noit run right ?? I have a strobe coming too for a bike I hope ?? but im back offshore in Denmark until 25th ish so will try again then ?????
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Old 17-09-2021, 06:00 PM   #84
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Yes PPUXLEY your diagram is perfect ,,both my other 750s SS and monster have wiring as your M900

thing is I have tried every possible combination and only the one I have lets the bike start ??? but noit run right ?? I have a strobe coming too for a bike I hope ??
You have tried line two then 1 white,2 red 3 yellow 4 black. Even though, I havent dynamically tested that, it definitely starts and idles like that, so maybe you have that horrible scenario in fault finding-two seperate and unrelated issues.
Well at least the strobe is going to confirm beyond doubt what the timing is both at idle and speed.

On the strobe thing. I was slightly concerned that the Gunson G4113 Timestrobe Xenon Timing Light I have now ordered and says it WILL do motorcycles looks, absolutely identical to the Draper I have just sent back, that says it DOESNT and didnt.
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Old 10-10-2021, 07:09 AM   #85
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I had a Chat with Alf of Alfs who is a Ducati expert,,, mentioned the dodgy pickups , he said he has seen a few over the years that measure 100ohms and look perfect but are toast , probably some internal issue ????, the symptoms Patrick and I are having are also common ,, no tickover on one cylinder or poor running above tickover , missfires , etc etc ,, so as Patrick has seemingly cured his 900 with one new pickup , it looks like I will be getting a single pickup this week for the 750 ,, ''when one has eliminated all the possible , the clearly only the impossible is the answer ''
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Old 17-10-2021, 10:44 AM   #86
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OK new pickups fitted ,, bike now runs on both cylinders at 3000rpm BUT will not run below 3000 rpm on both cylinders it spits back ,, I know the carbs are fine its a timing issue but static timing is spot on and air gap is 0.7mm , I have a Draper strobe but it wont work on Ducati , but does on my car and a Yamaha 600??? also the pickup cables are still back to front to make the bike run

Interserting fact is that official Ducati wiring diagram for my bike based on VIN number and wiring colours is for fuel injection model year 2000,, but my bike is year 2000 carby model,, Ducati say that I should use model year 1998-1999 wiring diagram in that case but its missing the carb heaters of my years bike and the colour codes are different for the igniters and coils ????

weirder and weirder

Im sure the timing is not right but I cant see how , I have set it up same as my other 2 750 bikes

and without a strobe I cant tell if its advanced or retarded ..
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Old 17-10-2021, 02:53 PM   #87
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OK new pickups fitted ,, bike now runs on both cylinders at 3000rpm BUT will not run below 3000 rpm on both cylinders it spits back ,, I know the carbs are fine its a timing issue but static timing is spot on and air gap is 0.7mm , I have a Draper strobe but it wont work on Ducati , but does on my car and a Yamaha 600??? also the pickup cables are still back to front to make the bike run

Interserting fact is that official Ducati wiring diagram for my bike based on VIN number and wiring colours is for fuel injection model year 2000,, but my bike is year 2000 carby model,, Ducati say that I should use model year 1998-1999 wiring diagram in that case but its missing the carb heaters of my years bike and the colour codes are different for the igniters and coils ????

weirder and weirder

Im sure the timing is not right but I cant see how , I have set it up same as my other 2 750 bikes

and without a strobe I cant tell if its advanced or retarded ..
It really sounds like the issue is the same as mine in reverse.
My strobe would not fire at high revs but would at low. Have you run your strobe when taking the revs above 3000rpm.
As we discussed when we chatted on the phone....if I had the bike and didnt know its history I would definitely be trying with the forward pick up coil (the one at 7 oclock with Yellow and Black) feeding the ignition unit and coil for the Vertical cylinder and the rear pick up coil ( the one at 4 oclock with red and white) feeding the horizontal cylinder.

If it then ran, but didnt run "right" then I would reverse the wiring in each pick up plug to the ignition boxes first one then the other.- (NB NOT SWOP them from one igntion box to another)
If the strobe works AND you do have the wires reversed in the plug it will show it running at full advance 32 degrees? when idling when it should be running at 6 degrees advance.
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Old 20-10-2021, 07:42 AM   #88
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I have tried all the swops suggested by Patrick ,, no improvements ,, and have borrowed a Snap on Strobe which also does not work ,,, bike only runs at above 3000 rpm now on both cyclinder which is worse than before when it ran fine on Horizontal but would no run below 3000 on rear ,,

put the old pickups back on bike made no difference

now hit a complete dead end ????
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Old 20-10-2021, 07:59 AM   #89
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Replace the cables and connectors between pickups and igniters.
Even if you just pull the old connectors apart and leave the cables in place, but jump with temporary new cables and connectors.

It's easy to assume that something should work because it's connected, but often not the case.
I cured my Monster, bought as a non-runner, by replacing the connectors to the injectors. No signal was passing through the joints!
On my old NVT flipper switches on the Norton, no current passes through some of the contacts, nor bullet connectors, due to tarnish and Verdigris on various bits. You have to go in and check that every part makes proper contact.
I often check continuity and resistance either side of a connection now, to make sure juice is getting through.
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Old 20-10-2021, 08:13 AM   #90
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Replace the cables and connectors between pickups and igniters.
Jerry bought the set from Electrex that had all new wiring, I think
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