TOPIC:

got to the point with my restore where first starts were this morning, cannot get #3 to fire ? ....my Keihin CR smoothbores are fully rebuilt & internally glowing clean, floats are operating perfect, Dyna coils sparking up hot, all new ignitor & rectifier, brand new plugs, etc, etc, etc .....pulled the #3 plug to check for spark (wire connected, grounded, hit start button): sparking away good, and even pulled #4 to check its spark comparatively and same exact spark (running NGK Iridium) .....also, swapped the #3 plug with the #4 plug to make sure it was not plug, #3 again will not fire, #4 fires perfectly .....what I did notice is when I pulled the #3 plug initially, it was not wet nor even damp with fuel, and I'm thinking it should get wet or damp from fuel when starting but not firing .....all jets are new, everything new for the CRs, full rebuild kit and an ultra meticulous internal cleaning .....question: can I pull the air filter (K&N separate pod) for the #3 and spray something into the carb while the bike is idling on the other 3 cylinders to get some level of fire happening for #3 ? just enough to hear the Supertrapp go to all 4 cylinders, just to deduce fuel / carb issue for #3 ?? if yes, what do I use ? and I'm assuming it would be sprayed thru the lower opening below the throttle body of the #3 carb from the air cleaner side, again, at idle .....all comments & guidance appreciated, thanks -

How about your spark plug wires. The inner core of your spark plug wire could be burned or disentegrated on the connectors, (coil or spark plugs)

thanks for the reply ....my wires are aftermarket hi-performance, and as I mentioned, with the plug for #3 pulled and spark checked, that #3 NGK iridium plug is sparking away so the spark is there ....shot of starter fluid or carb cleaner into the #3 smoothbore from the air cleaner side before I hit the start button ?? ....I would hate to have to pull the rack of carbs again ....

nothing wrong to use starter fluid on carbs. if #3 is firing with starter fluid you did somthing wrong on your carb rebuild.

no-go on getting #3 to fire using starter fluid: 2 second shot into carb, 1 second shot into spark plug hole, still only getting 1, 2 & 4 ....??? question, to help deduce it IS something in the #3 carb: after I crank up the bike, which starts in less than a second, while running / idling on the 3 cylinders, if the #3 carb was spraying fuel, when I pull that plug, it should be wet or damp - correct ?? it is not, there is no wet or damp fuel on it .....looks like I have to pull the rack of carbs and go at #3 to see if there is a jet obstruction or something blocking / preventing fuel to spray on the #3 plug on ignition .....

also: could valves be stuck for #3 ?? ....it has been close to 10 years since she has started, ran & was ridden ....but she was mothballed as a VERY good runner before the 6 month restore she just went thru now .....if valves could be stuck, how do I unstick them ?? ......throwing everything out there because once I have the rack of carbs off (again, 5th time!) and I go thru the #3 carb and find nothing obstructing fuel flow (what I am anticipating), I need to know what else can be preventing the #3 from firing when I have excellent spark at the #3 plug .....???? .....thanks again

I am not a KZ 650 owner, but an internal combustion engine is an internal combustion engine. Before I would do anything else I would do a compression check on all cylinders and see what you have for readings. If that cylinder isn't sucking in air/fuel there isn't much gonna happen and your plug will not be wet. Next step for me would be to check the valve adjustments and double check that #3 carb is getting fuel.

Rick H.

great advice ....I still think valves may be sticking, but I'll grab compression tester this morning and ck all 4 before I press on troubleshooting.....carbs are fully rebuilt and spotlessly glowing clean inside, all new jets, floats, seats, needles, clips, etc ....and when I pull the bowl plug for the #3 carb, fuel pours out until I shut off at the petcock, so #3 carb getting fuel ....I'll report back, will be rather large bummer if I have to re'ring the engine, but if not proper compression in #3 compared to #1, #2 & #4, looks like I may have to ....thanks again

have you swapped the leads around? no2 to no3 that will eliminate a faulty lead or suppressor cap

Uncle Freddy wrote: ....it has been close to 10 years since she has started, ran & was ridden ....

All engines require three things to start and run: spark, fuel and compression. Why don't you do a compression test with a leak down tester?

OK, compression check done: engine warmed up to temp, cranking starter with throttle wide open, choke open and all spark plugs removed, the results: #1 = 125, #2 = #130, #3 = 115 and #4 = 115 ....my shop manual says 1982 and/on KZ650 engines are to have 100 to 156 psi ....so, I'd prefer higher readings (higher compression, better fuel suck) but these readings are within the spec range, albeit a bit low on the two cylinders reading 115 psi ....I last went thru the top end in 1992, she got new pistons & rings at that time, but there are only 62,000 miles total on the bike, as she is, and always has been, a fair weather rider only .....so, the question: are these readings OK to move on with my troubleshooting ?? or do these readings mitigate taking the top end apart and doing new rings ?? .... (to note: to the guy who asked about flipping the spark plug leads, I'm planning to flip my Dyna coils to see if, by chance, the #3 not firing moves to different cylinder, as the coils are from 1985 and although they should last lifetime, one may be throwing diminished spark to the plug on the cylinder not firing) ....also to note: the #3 not firing DOES fire when I shoot some starter fluid into the #3 carb so that alone tells me #3 not firing = fuel delivery problem

Realistically I think anyone would want the compression numbers up around 125 straight across the board, but 115 PSI should still be more than adequate for an engine that isn't going to be run in competition. At this point I would begin looking towards an ignition problem and still consider a valve adjustment check just to be safe and sure. So to answer your question, no, I wouldn't go tearing into the top end yet. Something else is amiss and you have other options.

Rick H.