conizme Posted April 17, 2014 Share Posted April 17, 2014 Hi guys, for my first post I've got a problem for you, to do with my XVS 125. So last night I was changing my standard plugs (they were in good condition, just for longeivity) to some nice fancy Iridium ones, which to my suprise, caused the bike to fail to start with the starter motor. I checked the plugs to see if they were sparking and they both were, so not sure why this was happening. I bump started the bike and it fired right up, then turned it off. After this it started on the starter motor fine about 10 minutes later. The problem, is that this morning I tried to start the bike again with the motor, and it wouldn't fire. I tried bump starting it for a good 10 minutes and it just would not start. I thought I could fix the problem by changing back to the old plugs, which also didn't work, and if anything made it worse. In the end I put the new ones back in, pushed the bike to a hill and bump started it down that, which fired it up, although it didn't sound as healthy as before. (Excess fuel burning off maybe?) After a couple of minutes it sounded like it used to and I thought all was well. (Apart from now it has a sound coming out of the rear cylinder's exhaust, almost like flopping a piece of stiff card, like a 'wop wop' sound) Also noticed there is barely any carbon build up on this exhaust, where as the front one has plenty, although this was like this with the old plugs, and while the bike is cold, no smoke comes from the rear cylinder's exhaust, it all comes out the front. (Misfiring before perhaps? Just not as severe?) While riding the bike now, it definitely sounds like it struggles sometimes, and only has a top speed of around 50mph if I rag the absolute tits off it.. it's like it's misfiring, and I seem to have lost a bit of power. Also on deceleration in the higher gears it can make quite a lound gurgling or popping sound. So, I'm wondering.. What could cause this problem? It sounds electrical to me, but I don't have a clue about the electrical side of bikes Thanks in advance! Link to comment Share on other sites More sharing options...
dt502001 Posted April 17, 2014 Share Posted April 17, 2014 Sounds to me like its running on one cylinder does the rear pipe get hot? Link to comment Share on other sites More sharing options...
conizme Posted April 17, 2014 Author Share Posted April 17, 2014 Sounds to me like its running on one cylinder does the rear pipe get hot? Thanks for replying, I think it's firing as I can feel pressure coming out of the pipe, and I'm fairly sure it gets hot yeah, but I haven't tried to touch it haha Edit: Just left the bike running, and both pipes do get hot. Link to comment Share on other sites More sharing options...
dt502001 Posted April 17, 2014 Share Posted April 17, 2014 When the bike is cold you can quickly touch it as it warms up without getting burnt,there will be pressure even if it's not fireing so go check it. Link to comment Share on other sites More sharing options...
conizme Posted April 17, 2014 Author Share Posted April 17, 2014 When the bike is cold you can quickly touch it as it warms up without getting burnt,there will be pressure even if it's not fireing so go check it. Yes, both the pipes get hot, although only the front one smokes when it is cold. It did this before I changed the spark plugs and this new starting problem came about though, so I don't know if a problem had started before and this is unrelated? Link to comment Share on other sites More sharing options...
dt502001 Posted April 17, 2014 Share Posted April 17, 2014 Well as even new spark plugs can be defective I would suggest you put in the right plugs and see what happens,irridum plus will not give you any more performance so just put in what is called for and save your money. Link to comment Share on other sites More sharing options...
dt502001 Posted April 17, 2014 Share Posted April 17, 2014 You could also try running a can of sea foam through it and see if it cleans up the starting problems,as it dosent sound like you up to rebuilding the carb. You have allready tried the Itilan tune up so kinda narrows it down a bit. Do you have a compression tester? If so check both cylinders Link to comment Share on other sites More sharing options...
conizme Posted April 17, 2014 Author Share Posted April 17, 2014 Well as even new spark plugs can be defective I would suggest you put in the right plugs and see what happens,irridum plus will not give you any more performance so just put in what is called for and save your money. As I said in the original post, I did try the old spark plugs, although this still didn't work, and in fact it seemed like it had less chance of starting. I more had the iridium ones for longeivity as they last a bit longer and I found a good deal. You could also try running a can of sea foam through it and see if it cleans up the starting problems,as it dosent sound like you up to rebuilding the carb. You have allready tried the Itilan tune up so kinda narrows it down a bit. Do you have a compression tester? If so check both cylinders The bike started perfectly before changing the plugs, now it doesn't like to start on either pair.. Doesn't sound like a carb issue to me. I don't have a compression tester no, do you think the compression may be low? What would average compression be? It should be wise to mention the bike is only just about to touch 7000 miles, but it was rarely run by the previous owner. Thanks for the help so far by the way, appreciate it. I hope I'm not about to open a whole can of worms haha. Link to comment Share on other sites More sharing options...
neversaydie Posted April 18, 2014 Share Posted April 18, 2014 Plugs screwed in finger tight, then a quarter turn with socket, or torqued up to spec as in manual Still got the right lead on the right plug? If the plug caps need the screwed top on the plugs to fit correclty, double check that the screw tops are tight on the plug Check and set the plug gap as per the manual Clean the old plugs and set the gap as per the manual Make sure you dont cross thread the plugs when fitting Link to comment Share on other sites More sharing options...
conizme Posted April 18, 2014 Author Share Posted April 18, 2014 The plugs have the right leads on yeah, and the spark plugs have the correct gap. Something I noticed this morning, when I can get the bike started, if I put my hand over the front exhaust (the black sooty one) and rev the engine, a browny black fluid gets sprayed over my hand. It doesn't smell like petrol, so I'm not sure what this is, could it be oil? Or just water and carbon? This doesn't happen with the rear exhaust.. The front spark plug didn't seem to be oil fouled.. The bike makes a popping sound on deceleration, and sounds like it misfires on acceleration in the low revs.. Could the spark plugs be too hot or too cold? Link to comment Share on other sites More sharing options...
jimmy Posted April 18, 2014 Share Posted April 18, 2014 It will be water condensation, nowt to worry about there. When you changed the plugs, did you check the leads did not get disturbed either at the cap or the coil. Either way take the plug cap off and trim about 10mm off the end of the leads Link to comment Share on other sites More sharing options...
conizme Posted April 18, 2014 Author Share Posted April 18, 2014 It will be water condensation, nowt to worry about there. When you changed the plugs, did you check the leads did not get disturbed either at the cap or the coil. Either way take the plug cap off and trim about 10mm off the end of the leads Good to know, thanks mate. Just wondering why it doesn't happen with the rear one? And what would you mean by trimming 10mm off? Trim it on both ends? Sorry haha Also worth mentioning that the Front HT Lead has always been loose, but I can still hear a click when I push it on. Link to comment Share on other sites More sharing options...
jimmy Posted April 18, 2014 Share Posted April 18, 2014 Unscrew the lead from the plug cap and using a stanley knife or similar cut off 10 mm from the end of the lead. If the other end is screwed into the coil, as opposed to being bonded in, then trim that end as well Link to comment Share on other sites More sharing options...
blackhat250 Posted April 18, 2014 Share Posted April 18, 2014 Get a compression test, i bet that rear cylinder has a burnt valve, [ popping and banging] its been running lean, [carb needs settup] this would give poor starting,, Link to comment Share on other sites More sharing options...
dt502001 Posted April 19, 2014 Share Posted April 19, 2014 Get a compression test, i bet that rear cylinder has a burnt valve, [ popping and banging] its been running lean, [carb needs settup] this would give poor starting,, +1 Link to comment Share on other sites More sharing options...
conizme Posted April 20, 2014 Author Share Posted April 20, 2014 Get a compression test, i bet that rear cylinder has a burnt valve, [ popping and banging] its been running lean, [carb needs settup] this would give poor starting,, Ok, thanks for your help, I will try and get a compression tester asap. What are the compression values supposed to be? The spark plug from the rear cylinder is a normal colour however, could it still be running lean? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted April 20, 2014 Moderator Share Posted April 20, 2014 according to the manual 1,200 kPa (12 kg/cm2) at 400 r/min Compression pressure (at sea level): Standard: 1.200 kPa (12 kg/cm2, 12 bar) Minimum: 1.100 kPa (11 kg/cm2, 11 bar) Maximum: 1.300 kPa (13 kg/cm2, 13 bar) Take out the plug from the cylinder you are not measuring, earth out the pair of sparkplugs so you dont damage any ignition components. Full throttle and hit the button. Link to comment Share on other sites More sharing options...
conizme Posted April 20, 2014 Author Share Posted April 20, 2014 according to the manual 1,200 kPa (12 kg/cm2) at 400 r/min Compression pressure (at sea level): Standard: 1.200 kPa (12 kg/cm2, 12 bar) Minimum: 1.100 kPa (11 kg/cm2, 11 bar) Maximum: 1.300 kPa (13 kg/cm2, 13 bar) Take out the plug from the cylinder you are not measuring, earth out the pair of sparkplugs so you dont damage any ignition components. Full throttle and hit the button. Cheers buddy, will have to find a compression tester and get back to you! Link to comment Share on other sites More sharing options...
Kelan walker Posted September 18, 2021 Share Posted September 18, 2021 On 4/20/2014 at 7:28 PM, conizme said: Cheers buddy, will have to find a compression tester and get back to you! having similar issue (second cylinder only fires up if i rev the bike) and saw somewhere else it might be the voltage regulator Link to comment Share on other sites More sharing options...
Moderator Snakebite68 Posted September 19, 2021 Moderator Share Posted September 19, 2021 That's a 7 year old Thread... Your best bet would be to introduce yourself in the New Members Welcome Area... Tell us about yourself and what bikes you have and after a bit of a 'chat', post your problem Thread in a suitable Forum. Don't go straight for the cl*t dude! It's just not done!!! Link to comment Share on other sites More sharing options...
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