Speedshop Posted June 24, 2012 Share Posted June 24, 2012 Maybe give me a bell at the speed shop, if we're not as busy as we have been over the past few weeks I can talk you through the CDi. 01580 880768 Link to comment Share on other sites More sharing options...
Cosmo Posted June 24, 2012 Author Share Posted June 24, 2012 Hello there folks! Thanks for all of the help and advice. This is a case of lack of familiarity and with the advice that you are all giving plus me getting to grips with the bike, i have now found the CDI unit. It whelps when you know what you are looking for! I have been cleaning earthing points on the bike and I've made a new one from the battery negative. I wasn't happy with where it mounted to, as it appeared to have snapped in the past and somebody mounted it in a poor earthing location. Anyway, after much cleaning and testing, here are the results: HT cap replaced - 5.3 ohms. Ignition coil primary - 1.8 ohms Ignition coil secondary - 5.8k Onto the CDI: >>>Orange, Meter to 200 Ohms, expect 1 Ohm (HT coil primary) The initial reading was 1.8 ohms but since cleaning, i cannot get it below 3 ohms. >>>Brown, Meter to 2k Ohms, expect 300 Ohms for mk2 (Magneto charge coil) I'm getting 301 ohms. >>>White/Red, Meter to 200 Ohms, expect 10 Ohms for mk2 (Magneto pulser coil) I'm getting 12 ohms. >>>Black female connector, Meter to 200 Ohms, expect dead short I'm getting a dead short. >>>repeat for black male connector There is little difference when i repeat the tests. I am also getting the short on the last part of the test and an open circuit with the ignition on, so all is well here. All in all, two meter readings are not as per the spec - orange wire and the white/red. I'm starting to think the pulser coil but if it has been changed, it ran fine for 20 years like this. But i'm learning about the machine, which can't be bad. Saying that, at times i think i'd rather remain ignorant and have a running bike instead! Hahaha! Regarding the mixture, when you adjust the mixture screw on the carb, which way richens it and which way weakens it? And is there a ball park figure for setting it, such as all the way in and then screw it out X amount of turns? I've adjusted it for smoothness while the engine is running and i've even tried adjusting it half a turn at a time before attempting to accelerate down the road like a scolded cat, only to have the engine die under load at around 5000 rpm each time. Apart from the tick over, it masks no difference to the running of the machine that i can notice, at least. If this was a car, i'd suspect the accelerator pump but even then it would stumble and hesitate before picking up. Sigh... Link to comment Share on other sites More sharing options...
Cosmo Posted June 27, 2012 Author Share Posted June 27, 2012 I'm trying to insert pictures but i'm at a loss as how to do it... Link to comment Share on other sites More sharing options...
Moderator Airhead Posted June 27, 2012 Moderator Share Posted June 27, 2012 I'm trying to insert pictures but i'm at a loss as how to do it... see the FAQ's subforum to new members forum cosmo Link to comment Share on other sites More sharing options...
dt502001 Posted June 28, 2012 Share Posted June 28, 2012 I would like to suggest that you take a socket with you and run the bike at 5000 or where ever it runs crapy as long as possible and imedatly shut the bike off and pull the plug out and check to see if looks lean( white). The reason for doing it imedatly is that after riding even short period at low rpm the plug will return to a normal colour. You mentioned cleaning the tank and I suspect that your fuel flow may be to little to sustain high speed running. Does the bike immedatly re turn to normal running once below 5000 or does it take a bit to catch back up? if so I would suspect a lack of fuel flow.And the plug colour is the easy way to tell if its black the it's electral, white fuel.This should help take the guess out of which you should be trying to fix. Link to comment Share on other sites More sharing options...
Cosmo Posted June 28, 2012 Author Share Posted June 28, 2012 That's an excellent suggestion! At the moment, the bike is in bits regarding the ignition side of things but once i have the weekend out of the way, i'll follow your advice. Regarding it's symptoms, the bike returns immediately once you back off the revs. It will rev higher off load and it seems better in 1st and second and tends to rev a little higher than 5000 rpm but will still die, where upon it immediately runs again without hesitation once you back off the gas. No stumbling or hesitation as you would expect with a fuel related problem but again, it's all a process of elimination, so i'll get it all put together and give it ago and post the results. Thinking about the ignition side of things, the reading to the ignition coil seems out, so i've found a second hand one as well as an aftermarket one. I'm dubious about both if i'm honest but i can't find NOS. There is a guy in America advertising NOS for MX175's but whether that is a typo on his part or it's another machine, i have no idea. The fact that it's also for other bikes, such as an IT175 doesn't help - it makes me think there may be an MX175, as he has the wording correct for the other models. Needless to say, i've held off on that score. Any suggestions as to the mixture screw? Which direction is to make the mixture lean and which direction is to richen it? And if i screw that screw all the way in, how many turns would you back it out as a starting point? In the meantime, i've ordered a carb rebuild kit and i may well take the plunge (no pun intended) with an ultrasonic cleaning bath. And Paul, some of my readings are out on the ignition side? Suggestions on a postcard, please...!!!... >>>Orange, Meter to 200 Ohms, expect 1 Ohm (HT coil primary) The initial reading was 1.8 ohms but since cleaning, i cannot get it below 3 ohms. This is why i've ordered another coil. >>>White/Red, Meter to 200 Ohms, expect 10 Ohms for mk2 (Magneto pulser coil) I'm getting 12 ohms. Thanks once again for everyone's suggestions! I am going away on Saturday and won't be back until Wednesday, so i'll tackle these things next weekend. I'm so tempted to say ohm, sweet ohm...!!!...hahaha! (it's good when you laugh at your own jokes!) Anyway, back to the plot...by the time that i return, the spares that i ordered should have arrived. And Paul, me old mate, me old mucker, do you recon i need another magneto pulser coil? Everything else out of spec has been ordered apart from the owner... Link to comment Share on other sites More sharing options...
Speedshop Posted July 12, 2012 Share Posted July 12, 2012 The way we test things like this is to warm them with a hot air gun and watch to see if the resistance climbs steadily. If it faulters or fluctuates the winding is duff. That said I have a suzuki generator in that tested fine until we sun it up and ran the ignition for 10 minutes on the test bed, after this time the pulser coil broke down. If you left it and went back to it it was fine again for a few minutes. These bikes are not sensitive to minor specifaction differences in ignition coils, you really don't need NOS item, after market ones are just as good (so longs as you don't buy the cheapest made in China rubbish from ebay). An old coil could break down, but so long as you have the right type of coil it won't cause the problems you have. We design and build CDi systems and run our units on a variety of coils as we know the OEM coils are likely to have been replaced by now. In many cases the OEM coil spec isn't available and a modern equivilent coil runs equally as well. The old 1R/12K coil is good example, popular in the 70's not available now. If you know what machines that coil was fiited to and still is still fitted to you can still buy a one new from the OEM factory, guess what, it comes as 0.6R/8K and runs exactly the same as the old spec. We stock a range of coils for points and CDi machines - none of which are made in China Link to comment Share on other sites More sharing options...
Cosmo Posted August 10, 2012 Author Share Posted August 10, 2012 Many thanks for the update, especially when none of you have heard from me for a while. I apologise profusely - but my father got rushed into hospital with a blood clot that moved to his lung. Needless to say, everything else just got put to one side while i rallied around to support my mother and help her cope at home. My father is OK now and will pull through but he looks as if he has done six rounds with Mike Tyson with the treatment. I won't go into details, as it will put you off your lunch but sometimes the remedies seem far worse than the symptoms... The information about the coil makes interesting reading. I used to do similar things with TV's to fault find, except we would freeze them instead. But these are niggly faults and can take an age to track down. I'm not saying that i haven't any ignition faults but it seems to be pointing towards carbonation. The bike runs a little rough (see below) but at least seems more willing to rev now. But i won't know until the carb is reassembled correctly. (again, please see below) I have done a little with the bike. After exhausting the ignition side of things, i turned my attention to the carb. In hindsight, the fact that the bike was perfect before storage and then had a gummed up carb should have spoke volumes. A thorough clean didn't help much and in the end, i bought a commercial ultrasonic cleaner. I was lucky enough to find somebody who deals in second hand units, as they cost the earth when they are of a large capacity with a heater, too. And you just can'y clean a carb thoroughly enough by hand. At least i can't... This seems to have helped no end. I say seems to - i have just rebuilt the carb using a carb repair kit and i just need to bleed the 2-stroke and then take the bike out on a spin. The only thing that concerns me is the float bowl retaining pin. Apart from it sliding in, there seems no way or retaining this rod and it could easily vibrate out. While there is no way that it could come out completely, with the inherent vibrations of a 2-stroke, it could slide along enough to take the float bowl out of perfect alignment and thus cause flooding. Maybe it wasn't an issue before because it was gummed up. Has anyone else experienced this or had paranoia about it? On Monday, the seat will come off and will be sent away for recovering. At this rate, i may well join it! Recovering, that is! Thanks again and best regards, Phil. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 12, 2012 Moderator Share Posted August 12, 2012 ................ The only thing that concerns me is the float bowl retaining pin. Apart from it sliding in, there seems no way or retaining this rod and it could easily vibrate out. While there is no way that it could come out completely, with the inherent vibrations of a 2-stroke, it could slide along enough to take the float bowl out of perfect alignment and thus cause flooding. Maybe it wasn't an issue before because it was gummed up. Has anyone else experienced this or had paranoia about it? ......... do you mean the float retaining pin Phil? if so this cannot slide out because the shape of the actual bowl holds it in when the bowl is re-fitted Link to comment Share on other sites More sharing options...
Naughty Nigel Posted August 13, 2012 Share Posted August 13, 2012 Sorry if I have missed anything on this thread, (there is a lot of it) but single wire regulators are usually just a simple Zener diode wired across (in parallel with) the battery. When the battery voltage exceeds about 13.5 volts the Zener diode starts to conduct, thereby preventing the battery from boiling dry, and brake lights from popping! These are crude but effective, and can get quite hot, so they have large metal fins, as often seen on older British bikes. There is no reason why a 12 Volt Zener regulator from (say) an old British bike should not work on any other 12 Volt machine as long as the generator output is no higher than the bike the regulator was designed for. They really are that simple. And if you cannot find one they are easy enough to make. Secondly, the misfiring problem sounds as if the ignition system doesn't have enough energy to generate a strong spark at higher speeds. (Higher engine speeds and cylinder pressures require a higher spark plug voltage.) On old contact breaker systems this was often caused by setting the gap too wide, (which meant that the 'dwell time' (or contact breaker closed time) was insufficient for a strong magnetic field to form in the ignition coil). This should not be a problem with modern CDI systems as the spark is created by a massive pulse of current (200 Amps or more) delivered from a capacitor charged to 250 volts or so. However, setting the spark gap too wide can cause similar problems. It should also be obvious that with such high currents flowing in the ignition circuit, (admittedly for a very short period of time - a few microseconds at most), all cables and connectors must be clean and in good condition if they are to work properly. HTH. NN Link to comment Share on other sites More sharing options...
Cosmo Posted August 25, 2012 Author Share Posted August 25, 2012 Sorry about the delays, you folks are so patient! Needless to say, reformatting the hard drive lost me the automatic login and i've been searching for a week to find my login details... You are right about the float retaining pin, Paul - it can't fall out because of the shape of the fuel bowl. However, i'm pretty sure that it can move either way by about half and inch and while it won't fall out, it can put the float tang out of alignment. Saying that, i've ridden the machine for 20 miles and it seems OK now. I will re-bleed the 2-stroke, as i'm not happy about it but it runs far better, even at high RPM's. The only fault i can find is that it sometimes takes some time to return to idle and likes to sit at 4,000 rpm and gradually make it's way down to tick over. This has become less with riding a short distance, altering the mixture and idle speed to obtain a smoother tick over, riding off again and repeating the process every few hundred yards or so. On tick over, the revs die quickly when you release the throttle but if you are riding, they gradually climb down, even if you pull the clutch in. And because of the inherent nature of the 2 stroke engine going b'dang-dang-dang-dang, this propels it forward when you should be decelerating, resulting in kangaroo jumps! (with the clutch out, of course) Again, this has lessened through twiddling of the mixture and idle screws but they aren't as easy to sort as a 4 stroke. And i'm not a knowledgeable 2 stroke person. Nigels comments regarding the zener are good. As an electronics technician, i thought of this approach myself if Neo's advice failed. Not that i thought it would. But i speed read what he written with the inevitable results and once he gave me a prod to wake me up, what he said was clear and worked well. But going back to the problems, as a few suspected, it was fuel based, not ignition. In hindsight, i should have stuck with 6 volt electrics and sorted the carburation out first and then converted afterwards. As it was, i was unsure whether it was fuel or electric related but Neo and the other folks assured me that their conversions worked and once i checked the ignition side through, this confirmed what they said all along. And the bike ran perfectly prior to being stored. Needless to say, i have a new fuel filter installed and i let it run dry now so there is no fuel in the carb to gum anything up once i park up. Saying that, i have a Z1100R1 Eddie Lawson replica with the same fault and that machine has four carbs to strip...groan! And my Ultrasonic cleaner is too small to put the four carbs in as a whole, although this would be a foolhardy approach - each carb needs to be stripped prior to immersion for best results. The seat for the bike is being recovered as i write and i have installed American reflectors on to the machine after locating the hardware stateside. I have also modified the sidelights to run American lighting as well as UK lighting at the flick of a switch, and that took some fabrication of the bulb holders within the indicator stalks for the factory look. But you folks have been a great help and i can't thank you all enough! Link to comment Share on other sites More sharing options...
NE0 Posted August 25, 2012 Share Posted August 25, 2012 Glad to have been of service. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted August 25, 2012 Moderator Share Posted August 25, 2012 Good news Phil, turn your mixture screw in about 1/2 turn clockwise to see if that helps with the slow return to idle Link to comment Share on other sites More sharing options...
dt502001 Posted August 31, 2012 Share Posted August 31, 2012 In Canada and the USA the bikes were called IT not mx but the same bike. So if you want a new coil for stock buy it now while you can. I had a 1981 it 175 sold it though as the bike had never been regesterd for the road by the dealer and back then the only way you could regester was when the bike was brand new the dealer could do it,but the original owner choes not to. I realy liked that bike.. As Paul pointed out the pin will never fall out so no worries there Link to comment Share on other sites More sharing options...
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