TOPIC:

Still having nightmares with my 13
She fired up straight away but won’t tick over and pops & farts below 2K. 
I’m 99.9% certain the carbs are scrupulously clean and as I’ve got two sets and the bike shows the same symptoms on either set I’m starting to think it’s ignition related. The really weird thing is the bike was running perfectly one day and the next it was playing up? I’ve put a new set of plugs in with no improvement, I’ve tried pulling the plug leads off one at a time but she just misses no matter which lead I pull off. I’m really at a loss with this bike. So guys and girls is it possible it’s ignition related? I’ve got a set of new coils that come with the bike so that’s my next port of call unless anyone can point me in the right direction. I’m in Warrington Cheshire and I’m willing to pay someone if they could sort it out for me.

Hi Paul , I do not want to head You the wrong way , but , I had similar many Years back , tried everything , even took it to a shop [ First time that I ever took one of my Motorcycles in for repair ] , it came back , still the same , last resort , I removed the Cam Cover , and found the Cam had jumped a tooth or two . P.S. It took awhile [ No Computers  to search ] , but ,  In my defence , it was my First [ and only ] Overhead Cam Motorcycle I have owned  .

Thanks, someone else said it had happened to them so I’ll lift the cam cover and check 

We don't have enough history here to really help you out as far as I'm concerned. It's a real struggle to arm chair diagnose performance issues without as much information as possible.  I don't mean to beat down on you here but rather to take this opportunity to remind everyone to please include as much information as possible so we can have a meaningful dialog.

English CW suggests a timing chain jumping issue may be the problem-  Possible but most reports of a chain that had jumped has led to bent valves. There is an interference angle between the intake and exhaust valve and if they are not timed to each other it's possible for the valves to hang up on each other. Also, if the valves are not timed to the piston, it's possible for the valves to get bent by the piston. I'm only aware of one occasion where someone found a jumped chain and no mechanical damage. Paul mentions that once the bike gets to 2K rpm, it runs fine, so in my mind that would rule out a jumped timing chain, but at this point inspecting the timing chain for proper timing and also inspecting the tensioner roller and sprocket would be prudent, so since we have no history on the last time these parts had been looked at or mileage on the bike, yes, check this out.

I still want to put my money on blocked idle circuits/ transition ports. What you describe is exactly what would happen with blocked idle circuit since this circuit operates from idle up to around 2K rpm where the Main circuit takes over. I've rebuilt hundreds of carbs over the past  50 years and I have had 4 or 5 that I just could clear the idle circuit on , and it's only since understanding how Scotch's Cleaning Tool clears the idle circuit, that I had a ah-ha moment realizing that for years, I had paid no attention to the direction I blew out carb passages and on a few carbs, managed to further block those transition ports, blocking the idle circuit. It's critical that when clearing the idle transition ports, that the object is to reverse flow air or cleaning fluid from the transition ports back towards the pilot jets. What happens is that the smallest part of the idle circuit is the transition ports themselves and blowing out the ports in the direction of flow will jam up debris at the transition port. The larger open parts of the idle circuit are the air port which has an entrance point on the front of the intake throat ( the bell of the inlet of the carb) and the pilot jet where the fuel is picked up in the carb bowl.
You say you have meticulously cleaned this set of carbs and you also have a second set of carbs and that the bike runs the same on both sets of carbs, so now you suspect an ignition problem -  Possible. Battery voltage below 2K rpm ???We don't know this and it could affect the output of the coils. Grounding issues could have similar issues but if it was a ground problem, other problems would show up. Pulser coils which signal the Igniter might be a problem if the 6 pin connector is corroded but for all 3 pulser coils to act up at the same time.... not likely.

I feel your pain here and throwing out thoughts for you to consider. I know you believe your carbs are clean but the diagnoses points to the idle circuit. I've had carbs off and on engines that are problematic 5 times or more until finally, got them to run right. Operability issues can be troubling to diagnose but thinking/talking it through usually leads you to the answer. I'm still going to stick to blocked idle circuits. You may prove me wrong, but I doubt it.

good Luck !!
KB

I also thought blocked idle jets as being the problem  , it is possible both sets of carbs have the same problem [ think we have all been there ] , and still do . I just offered the cam chain jump  scenario because it happened to me , and I went through everything before I happened upon on it . Bike was running great , stopped for Petrol , pulled away , and the misfire started . Of course first thought was shite Petrol . Arrived Home , Tank off , emptied the tank into a container , and There it was , so I thought , about the size of a Tennis Ball , just floating there , something not Petrol . With the Carbs cleaned , and Petrol without the other substance , I thought '' away we go '' , turns out problem was still there . Another carb clean , Electrics and timing checked , pulling my Hair out , off to the local Bike shop . And still the same . It was then I had the Epithany , and checked the Can Timing , and I got off lightly , just one Tooth out [ from Memory ] . New chain installed [ I have a funny story about that ] , and all good .

Englishcw - I ‘m curious to know - since the 1300 is normally a mechanically quiet engine,  I would have thought you’d be aware of some unusual noise prior to the cam chain jumping a tooth?