still problems with rear cylinder carb ?????

[jerry]

Well i rode the bike yesterday after spending much time mm reseting the carbs idle screws and balancing at TICKOVER when the bike was warmed up with choke off,, so thought I had solved it as Vacuum guages were both perfectly equal at idle and 4000rpm ,, BUT rode off and immediately realised that it would hang on left carb until 2500+ rpm when all was smooths as silk up to 100mph ,, but coming to slow speeds or stopping at traffic light it still stall or refuses to idle on left hand carb,, set the idle screw highr but something still not right ???Im gonna pay up give it to alf to look at ????

The bellyf fi bre glass belly pan arrived ,, Thanks Nick and will be painted to match the bike ASAP the Ohlins rear shock giveds the bike a silky great rear end very happy with that ,,

Photos will come soon I promise

[jerry]

Alf does not have time to do it for several weeks he is so busy with his mega Kwak MV dealership but I was put in touch with a chap named Malcom who dynos speed record bikes ,, and builds custom turbos ,, he sorted the CV carbs with exactly the same problem on a mates Vmax ,,I rode over to see him on the MHR Monster ,not the bike with bad carbs , before Id even stopped he came out and said that bikes not idling right on the front cylinder ??? I was confused it seems ok ,, we whipped off the plug lead on front and sure enuf the vert cylinder was easy to tune on the airscrew until it was smooth idle but when we did the horizontal he was right it was idling rough and air screw had no effect .. I was amazed .. so I will have to clean the pilot jets in that one soon but the bike is usable .just a bit boggy of idle

He told me to bring the carbs of the other M750 over I told him the saga that its fine above 2500rpm but he said Ultrasonic is a waste of time with some carbs he has a £3000 system and he rate it as a big waste of money ,, sure it makes carbs shiney but most of the time it wont clean out crap in deep pilot galleries ,neither will carb clean and high pressure air , he said tiny drills and files and pilot probes are best ,, thats what he did to Steves old VMAX and it runs sweet ,, Carbs going to him asap ,,

[Tim88]

Very interesting thread so far, I have a feeling you may have found the right man for the job. Can't wait for the outcome! Good luck with a most frustrating problem.

[jerry]

Originally Posted by Tim88

Very interesting thread so far, I have a feeling you may have found the right man for the job. Can't wait for the outcome! Good luck with a most frustrating problem.

I live in hope ha ha

[vince53]

Yep waiting to hear outcome ,sounds like this guy knows his stuff keep us posted , gota be a good sign when you ride up and he pins up a flag that quick .. * )

[jerry]

Yes Vince ,, but now i gotta clean the pilot jets on the 1997 bike too ,, im getting good at removing carbs fast, the worst bit is the return cable getting it on and off very fiddly

[jerry]

I cant get anyone to sort the bike out Alf cant get it in until October ,Malcolm says September ??? I have tried everything Protwins are too busy there is no one who is able to help me sort this problem looks likr the bike will have just sit

[jerry]

OK update 24/08/21

ITS NOT THE CARBS !!!!!!!! put the supposed dodgy carbs from the 2000 M750 onto the 1997 Mike Hailwood M750 and heyho they work fine ..... and the bike seems ok .

So now the yellow 2000 model has the good carbs from the 1997 bike and its still not running well , will not tick over bangs and farts from rear cylinder ,,, so the problem must be something else ,, its not coils or ignighters ,, they have been swopped over ,, its not compression or air leaks at the head or exhaust ??????

could it be the crank pickup on rear cylinder ????? Im baffled but relieved its not the carbs

any ideas ,, im very frustrated was away for work for 4 weeks and im not feeling the love for these bikes just now ,,

[Nasher]

Have you checked the rear belt timing marks?

But I'm not sure how it could have jumped a tooth, maybe during the crash.

[jerry]

Originally Posted by Nasher

Have you checked the rear belt timing marks?

Not sure how it could have jumped a tooth, maybe during the crash.

They are spot on and new belts recently could crank pickup cause this issue ???

[Mr Gazza]

Posted Febuary..

Originally Posted by Pedro

You’ve changed most of the electrical elements but could it be the flywheel pick ups misbehaving?

Originally Posted by Kato

Firstly are you sure its carb related, given the symptoms you describe I would be looking at the pickup's & Kokusans as Ped says.

Posted March..

Originally Posted by Martin C

Pardon me for asking, but are you absolutely certain it’s a carb problem? My M900 once had a very similar problem that was caused by a poor coil wiring connection, almost no copper strands were intact inside apparently good insulation at the connector. At higher revs normal vibration was evidently enough to cause a better contact path.

[jerry]

Yes it could well be one pickup out of synch or knackered ,, everything else is ok ???????

will have to get a strobe now

[jerry]

Hmm.......... static timing spot on , airgaps both 0.7mm and pickups register 98ohms so im still baffled , the kokusan ignighters are fine as are the coils, plug leads and sparks plugs , all cables and earths are fine , the compression test is ok and leak down test shows no loss of PSI , the valve clearances are spot on as are timing belts marks ,, Carbs are perfect , all items tested on another 750 Ducati ... so yes now totally stumped ,,,,

oh and to cap it all my only working 750 has also died 5 pin relay and starter solenoid died ???maybe age ???

maybe time to consider a new bike ,, add in my health is poor at the moment and its all getting frustrating ,,, Petes old 77 1200 HD superglide is more reliable ha ha and more comfy

[slob]

just because a coil/pickup shows x ‘static’ resistance, doesn’t mean that it’s behaving correctly at 50-100c with current flowing through it.

[jerry]

yeah might get a spare pair on order ??? along with solenoid and relay