ive been having some ignition problems lately - the bike(3ln 90 exup 30000ks carbies clean and plugs no longer fouling) has been misfiring, sometimes hardly at all, sometimes chronically. how can i determine the cause of this? i have replaced a suspect lead (ok i only had a spare supression cable but it should still work) otherwise would i beable to hear the misfire through the carbies? how can i test the coils? if its the electronic ignition then how can i test it? am i looking at hundreds to get a new box?
through the carbs- is there any chance the valves are stuck slightly open with carbon if you already had running issues?
its possible, but would that cause the bike to misfire??? i mean sometimes it can be barely noticeable and then it can be like running on 3 or less! thinking about it it tends to get worse as the ride goes on, ie doesnt misfire to bad to start then gets worse and worse and when stopped seems to be better when started again, but thats what seemed to happen yesterday?
had a compression test lately? I just wonder because there isnt any way it can backfire through the carbs unless the intake valve is open during detonation...maybe I'm on the wrong track but seems suss.... also no water in oil/ oil in water?
ahh sorry prob a miscommunication, im not hearing the misfire through the carbs, i was saying should i beable to isolate a cylinder through the carbies that is misfiring? i tried the tube trick that was used to balance the carbies (hold a tube up to the end of it and u can hear the sound of the individual carbies, well, cylinder 3 sounded great, didnt miss a beat, sounded clean too... the other 3 were different, (when i took the plugs out last week the only right plug was the 3rd, the others were carbonised) cyl 4 sounded ok, tiiiny bit missy but not really, cyl 1 and 2 were the worst which doesnt make sense in terms of a coil going or something, but cyl 2 was alot quiter than the others (i think a carb balancing issue) but there was a weird electrical type noise coming out of the 3 suspect cyclinders like a sparky/tapping noise kinda strange very hard to describe could be valves not seating properly thus letting me hear the spark?? (haha im sure u will have a good laught with my most probably extremely bad theory <!-- s:roll: --><img src="{SMILIES_PATH}/icon_roll.gif" alt=":roll:" title="Rolling LoL" /><!-- s:roll: --> )
Does it missfire more going uphill, etc? Don't know if this helps, but maybe you can determine more from the spark plugs: <!-- m --><a class="postlink" href="http://roadstarclinic.com/content/view/70/127/">http://roadstarclinic.com/content/view/70/127/</a><!-- m -->
na no-ones laughing you're having a fair go.. I dont mind a compression test because its cheap and easy, and in 10 minutes you can figure out whether the basis for your entire bike (the motor) is in good health. I've chased misses before, and if you've already looked at plugs and leads there isnt much left
well all the plugs except the 3rd had carbon on them, which i just figured was due to the bike running slightly rich (im hoping to take it to my friend who has some fuel/air sensing guages) otherwise i figured it was due to the fact i hadnt tightened 1 and 2 up enough the previous time causing slight loss of compression?
well i took the bike for a good long ride after changing the spark leads, and no more misfire of death yet... but its still not perfect <!-- s:alcoholic: --><img src="{SMILIES_PATH}/icon_all_coholic.gif" alt=":alcoholic:" title="Alcoholic" /><!-- s:alcoholic: --> and doesnt idle smoothly, still getting that slight misfire... but at least the bike is now rideable! when you hold the throttle on have the bike reving say at 8k (neutral) does your engine tick over beautifully, or do you get a burble, misfire?
yup synch the carbs, take it for a good cleaning ride(hard and high). if your not happy after that then pull you plugs aout and have a squiz, from that you should be able to figure out whats going on. chance are that after doing these two things you will probably fix your problem.
Ciaran recommended some stuff a little while ago called Subaru Top End Engine Cleaner – available from any subaru dealer, at about $18 a can. The stuff is basically oven cleaner but you spray it down the throat of your carbs and it burns out all the carbon and stuff from the valves and headers. I did this, and then followed it up by balancing the carbs, and the bike idles beautifully now. I’ve never heard it so smooth before.
The can is well worth the money. It sounds like a crack pot idea, that’s why it’s taken this long for anyone else to try it. Rest assured though, instant improvements to be had. My fizzer is in need of some attention soon and it is on the to do list. I have a hunch that with a balance and the cleaner it will run a whole lot better but won’t solve your 'slight miss' problem. I cant back that up with any hard evidence but I am working on trying to solve a similar problem atm. If the post to America was a bit faster i might have had a more definite answer but not just yet. I will update you when things progress.
for those who may wan t to know, simply using water does a pretty good job of this as well. put about 200ml of water into each barrel over 1 minute. ( hold the revs high 6-7K, it will try do die, and u don't want it to do that.... ) If you out of town or in a place where you can make a bit of noise, pull your can off and watch all the **** fly, most enjoyable, but messy.
