skinvandal Posted July 28, 2009 Share Posted July 28, 2009 hiya! right... i've just spent my evenings rebuilding an old fzr 600 (3he) it'd been down the road and i fancied a streetfighter so it got the treatment. Behold! i've got as far as the last 5% and i'm struggling... the bike will start and run, but has no power. after running it for a while it's apparent (by the temperature of the exhaust downpipes) that cylinders 1&3 ain't firing. the carbs have been off and cleaned spotless...jets blown out and diaphragms checked etc. there IS a spark on 1@3, i know i've had them out and seen a fat blue spark out of each plug, when you hold your palm over the carb inlets there's a sucking so they're drawing fuel. i've done a whole load of checks on the ignition system, but this bike came as a none-runner, me and a mate got the engine started before i restored it but didn't think to check each cylinder... so... firstly... anyone know the firing order? i'm trying to prove it's one of the coil packs, as they feed 1&3 and 2&4 respectively, but the electronical and resistance tests seem to be well within tolerances i'm just wondering if the previous owners swapped spark plug leads or something? i've got a manual (not haynes) and despite reading from cover to cover i can't find this info. also as your sat on the bike, your left is cylinder one, and your right 4. correct? i'm thinking cylinders 1@3 have the spark delivered at the wrong time, but if 2&4 are firing that further proves the fault to be in the wiring or a problem with coil pack one. they're cut to the right length And numbered, but the more i think about it the more i need to check what's going on. i'm aware the firing order is probably something like 1342 or 1243 but if that's the case are cylinders 2&4 firing at the same time? i.e they both go suck, squeeze, bang, blow together? they must, cos there's only 2 wires to each pack and they feed 2 cylinders.... hmm... any assistance would be gratefully received. i only wanted something to have a go at airbrushing with, and it's way too small for me so i need rid, and i don't want to sell it unless it's spot-on cheers jim Link to comment Share on other sites More sharing options...
jordanscycles Posted July 29, 2009 Share Posted July 29, 2009 You should check the valves, because I had that same problem and it ended up being that the exhaust valves were shimmed too much causing two of the four cylinders to not fire, but had spark and suction. You could rotate the engine to where the exhaust and intake should be closed and spray compressed air in to make sure it doesnt escape through the valve and valve seats. Link to comment Share on other sites More sharing options...
skinvandal Posted July 29, 2009 Author Share Posted July 29, 2009 You should check the valves, because I had that same problem and it ended up being that the exhaust valves were shimmed too much causing two of the four cylinders to not fire, but had spark and suction. You could rotate the engine to where the exhaust and intake should be closed and spray compressed air in to make sure it doesnt escape through the valve and valve seats. thanks buddy, i'll try that... Link to comment Share on other sites More sharing options...
skinvandal Posted July 29, 2009 Author Share Posted July 29, 2009 nah, all valves holding pressure, everything moving as it should, valve wise. i've done some more fault-finding and i'm getting confident one or both of the coil packs are faulty. i've checked, traced and proven every wire in the ignition system, and they're all fine, i've even had all the switches off, tested and cleaned to no avail. the primary resistance on both pack are spot on and balanced (across the common and trigger wires) and the secondary resistances (i.e up the ht lead to across the other) are within spec. one pack runs pots 1&3, the other 2&4, the bike's currently running on 2&4, but if you unplug the coil that provides these pots the engine still runs and pots 1&3 start to warm up. electricity is like water innit? it finds the easiest route to earth, i'm wondering if there's some sort of imbalance under load, and the 1&3 coil is shorting. this would explain why 2&3 warm up when 1&4 are disconnected, BUT... they're measuring the same readings and the manual says that's ok. what the blarney's going on??? anyone??? Link to comment Share on other sites More sharing options...
motofix Posted January 29, 2010 Share Posted January 29, 2010 nah, all valves holding pressure, everything moving as it should, valve wise. i've done some more fault-finding and i'm getting confident one or both of the coil packs are faulty. i've checked, traced and proven every wire in the ignition system, and they're all fine, i've even had all the switches off, tested and cleaned to no avail. the primary resistance on both pack are spot on and balanced (across the common and trigger wires) and the secondary resistances (i.e up the ht lead to across the other) are within spec. one pack runs pots 1&3, the other 2&4, the bike's currently running on 2&4, but if you unplug the coil that provides these pots the engine still runs and pots 1&3 start to warm up. electricity is like water innit? it finds the easiest route to earth, i'm wondering if there's some sort of imbalance under load, and the 1&3 coil is shorting. this would explain why 2&3 warm up when 1&4 are disconnected, BUT... they're measuring the same readings and the manual says that's ok. what the blarney's going on??? anyone??? try cleaning the plugs out going to the coil pack, if it stops firing when it is hot it could be worth checking valve clearences but i doubt this, if have a freind with the exact same problem and seem to be struggling with it, there is a fuse which is worth checking but this should be fine if there is current going through, may be worth checking that it is the correct ampage, if not the wiring could have burnt something out? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted January 30, 2010 Moderator Share Posted January 30, 2010 nah, all valves holding pressure, everything moving as it should, valve wise. i've done some more fault-finding and i'm getting confident one or both of the coil packs are faulty. i've checked, traced and proven every wire in the ignition system, and they're all fine, i've even had all the switches off, tested and cleaned to no avail. the primary resistance on both pack are spot on and balanced (across the common and trigger wires) and the secondary resistances (i.e up the ht lead to across the other) are within spec. one pack runs pots 1&3, the other 2&4, the bike's currently running on 2&4, but if you unplug the coil that provides these pots the engine still runs and pots 1&3 start to warm up. electricity is like water innit? it finds the easiest route to earth, i'm wondering if there's some sort of imbalance under load, and the 1&3 coil is shorting. this would explain why 2&3 warm up when 1&4 are disconnected, BUT... they're measuring the same readings and the manual says that's ok. what the blarney's going on??? anyone??? I take it you have physically swapped the coil pack and leads around so the pack from 1+3 is running 2+4 and vice versa to see if the problem changes over and 2and 4 become the problem. My other question. Does the bike have a separate trigger for each coil, some do and i don't know if this bike has. The coil may be working fine but the pulse coil triggering it may be playing up. Love the paint job, white frame is a nice too, works really well. Link to comment Share on other sites More sharing options...
skinvandal Posted January 31, 2010 Author Share Posted January 31, 2010 I take it you have physically swapped the coil pack and leads around so the pack from 1+3 is running 2+4 and vice versa to see if the problem changes over and 2and 4 become the problem. My other question. Does the bike have a separate trigger for each coil, some do and i don't know if this bike has. The coil may be working fine but the pulse coil triggering it may be playing up. Love the paint job, white frame is a nice too, works really well. Thanks bud! got sorted in the end, changed the carbs and everything worked fine. rather confusing i know, but i'm guessing it was some microscopic clearance thing in the slides. i started swapping carb internals around and got some puzzling results, so i bought a second hand set and tried them on. voila! it was a right pain in the ass, but i guess fault finding can be like that... i shouldn't get cross as it's a hobby but i was getting there. still... all's well that ends well. thanks for all the tips guys! Link to comment Share on other sites More sharing options...
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