DavidSS Posted May 31, 2011 Posted May 31, 2011 Hello all. I'm new to this forum. I recently bought a project bike to restore. It had been sitting in a guys garage for 3 years! He said it ran fine before he stored it. Unfortunately, he left the gas in it! I figured I would be able to fix it fairly easy since I have worked on 2-strokes in the past and know them pretty well. Here is what I have done so far drained tank, refilled with good petrolremoved the carb and completely cleaned it. checked all the holes and made sure it was clear.adjusted the float height, set the fuel mix valve. even checked the main needle.removed the spark plug and cleaned and gapped to .024changed the crank oil.charged up the battery I figured it would start, after all that it will not. Not even a little. The bike is getting spark. It is getting fuel. What else could be wrong???? Could the 2-cycle oil pump be causing a problem? Perhaps it is too rich and it keeping the fuel from igniting? Could it have something to do with the CDI (capacitor or regulator system?) Any suggestions as to where I should look next? BTW, I looked at the intake reeds. From what I can tell they are OK. I don't know much about these and what they should look like. also, I sprayed some carb cleaner down into the cylinder, just before putting the plug back in. Kicked it over, and it actually started for about 2 seconds! It has not started since.... Even tried push starting it! HELP!
Moderator Airhead Posted May 31, 2011 Moderator Posted May 31, 2011 Hello all. I'm new to this forum. I recently bought a project bike to restore. It had been sitting in a guys garage for 3 years! He said it ran fine before he stored it. Unfortunately, he left the gas in it! I figured I would be able to fix it fairly easy since I have worked on 2-strokes in the past and know them pretty well. Here is what I have done so far drained tankremoved the carb and completely cleaned it. checked all the holes and made sure it was clear.adjusted the float height, set the fuel mix valve. even checked the main needle.removed the spark plug and cleaned and gapped to .024changed the crank oil.charged up the battery I figured it would start, after all that it will not. Not even a little. The bike is getting spark. It is getting fuel. What else could be wrong???? Could the 2-cycle oil pump be causing a problem? NO Perhaps it is too rich and it keeping the fuel from igniting? Could it have something to do with the CDI (capacitor or regulator system?) NO It's sparkingAny suggestions as to where I should look next? BTW, I looked at the intake reeds. From what I can tell they are OK. I don't know much about these and what they should look like. They should look flat and resting on the reed cage also, I sprayed some carb cleaner down into the cylinder, just before putting the plug back in. Kicked it over, and it actually started for about 2 seconds! It has not started since.... Even tried push starting it! HELP! David, is the choke working, signs of wetness on the plug?
DavidSS Posted May 31, 2011 Author Posted May 31, 2011 David, is the choke working, signs of wetness on the plug? thank you for the sanity check. As far as I can tell the choke works. If you can call that a choke. It doesn't really choke like a traditional "flap" type choke. I did a test the other day, where I took the spark plug out and made sure it was dry, then put it back in, and I kicked over the engine about a dozen times, with the fuel on, and with choke on. Then took the plug out again to see if it was still dry. It was just faintly wet. This was before I cleaned the carb (for the second time).... I can try this test again today, and see what the plug looks like. I have not replaced the plug, just cleaned and gapped it. Should I try a new plug? My common sense tells me it should work as is! When I tested the spark, (laid the plug on the side of the head fin and kicked over engine) I got good yellow looking spark from it. That should be OK to ignite the fuel right? Could there be a wiring problem that is keeping the engine from firing? Perhaps the magneto? Also, as a test, I moved the slide needle up from the 4th notch to the 5th, to see if leaning the fuel would make any difference. Obviously it did not, so will put it back to the factory 4th position. How about the 2-cycle oil? It just occured to me that I did not replace that, and who knows how old it is... would that make a difference?
Moderator Airhead Posted May 31, 2011 Moderator Posted May 31, 2011 thank you for the sanity check. As far as I can tell the choke works. If you can call that a choke. It doesn't really choke like a traditional "flap" type choke. I did a test the other day, where I took the spark plug out and made sure it was dry, then put it back in, and I kicked over the engine about a dozen times, with the fuel on, and with choke on. Then took the plug out again to see if it was still dry. It was just faintly wet. This was before I cleaned the carb (for the second time).... I can try this test again today, and see what the plug looks like. I have not replaced the plug, just cleaned and gapped it. Should I try a new plug? My common sense tells me it should work as is! When I tested the spark, (laid the plug on the side of the head fin and kicked over engine) I got good yellow looking spark from it. That should be OK to ignite the fuel right? Could there be a wiring problem that is keeping the engine from firing? Perhaps the magneto? Also, as a test, I moved the slide needle up from the 4th notch to the 5th, to see if leaning the fuel would make any difference. Obviously it did not, so will put it back to the factory 4th position. How about the 2-cycle oil? It just occured to me that I did not replace that, and who knows how old it is... would that make a difference? 2 cycle oil will not make a difference to starting, the yellow spark is a concern, blue would be better so it might be this...more of that later. as far as the choke or shall we call it 'starter jet' goes despite what is printed on the knob here is a description of its operation on your bike...but to me the spark is the one. it's late now so....
YPVS TONE Posted June 1, 2011 Posted June 1, 2011 Sounds to me like a fueling issue if you say you sprayed carb cleaner in plug hole and it run. Check to make sure jet in floatbowl for choke is clear . Try blowing down hole "B" in oldgitonabike's picture you should be able to feel air coming out of "A". If not the choke jet is blocked. Try soaking in carb cleaner or if it is stale fuel which has gummed up boil a kettle and pour hot water in the float bowl and let it stand for a while and see if this melts the gum, making sure you rinse out floatbowl with carb cleaner afterwards. DON'T start poking bits of wire down the jet or you will enlarge the jet.
DavidSS Posted June 1, 2011 Author Posted June 1, 2011 2 cycle oil will not make a difference to starting, the yellow spark is a concern, blue would be better so it might be this...more of that later. as far as the choke or shall we call it 'starter jet' goes despite what is printed on the knob here is a description of its operation on your bike...but to me the spark is the one. it's late now so.... I am fairly confident the "choke" is working. However, I did not take that section apart to clean. Looked like it is just a mechanical spring operated plunger and since it was doing its job I chose not to disassemble it. As for the rest of the carb, I used carb cleaner and sprayed in every hole I could find and made sure I saw a stream of fluid coming out of each end. I soaked all the disassembled parts (needle valve, pilot jet and main jet, and so on) in the cleaner. And yes.... I did use some small wire to clear the plug in the pilot jet, but was careful not to ream it out. Its clean!
DavidSS Posted June 1, 2011 Author Posted June 1, 2011 Sounds to me like a fueling issue if you say you sprayed carb cleaner in plug hole and it run. Check to make sure jet in floatbowl for choke is clear . Try blowing down hole "B" in oldgitonabike's picture you should be able to feel air coming out of "A". If not the choke jet is blocked. Try soaking in carb cleaner or if it is stale fuel which has gummed up boil a kettle and pour hot water in the float bowl and let it stand for a while and see if this melts the gum, making sure you rinse out floatbowl with carb cleaner afterwards. DON'T start poking bits of wire down the jet or you will enlarge the jet. I did clean the entire carb with carb cleaner, and sprayed in every hole I could find. so item "A" is clear. I did poke a fine wire through the jet to unplug it, but I doubt I enlarged it.
Moderator Airhead Posted June 1, 2011 Moderator Posted June 1, 2011 .........When I tested the spark, (laid the plug on the side of the head fin and kicked over engine) I got good yellow looking spark from it. That should be OK to ignite the fuel right? ...... OK then it seems the carb may be ok Like I said earlier I would not bee happy seeing a yellow spark, you need to get the multimeter out DT175MX Ignition checks There were two versions of ignition systems on DT175MX bikes. The mk1 version from the earlier bike had a 7 wire CDI the early bikes had a round section swing arm. The mk2 version had a 6 wire CDI, the red wire is absent on these. These bikes have a square section swing arm. The HT cap (AKA spark plug cap) unscrew it off the HT lead, it is supposed to be a resistor cap so should be around 5K Ohms The ignition coil primary...Orange wire to battery neg should be 1 Ohm +- 10% The ignition coil secondary...HT lead to battery neg should be 5900 Ohms +- 20% If the readings are much higher, check the ignition coil has a clean ground connection. Yes and the ignition coil mounting is a wiring harness ground point too, so check its clean and bright there. Disconnect all the wires from the CDI. Then using your multimeter on the loom side of the connectors. Black probe on a clean part of HT coil ground point Red probe on...... Orange, Meter to 200 Ohms, expect 1 Ohm (HT coil primary) Brown, Meter to 2k Ohms, expect 420 Ohms for mk1 and 300 Ohms for mk2 (Magneto charge coil) White/Red, Meter to 200 Ohms, expect 12.4 Ohms for mk1 and 10 Ohms for mk2 (Magneto pulser coil) Red, Meter to 200 Ohms, expect 13.6 Ohms for mk1 only. (Source coil 2 or high speed coil) Black female connector, Meter to 200 Ohms, expect dead short repeat for black male connector Any difference in the results for the two black wires may possibly be rectified by cleaning the front engine mounting bolt and a little of the frame behind the bolt head, then tighten to torque spec. Black/White, Meter to 20K Ohms, with ignition off expect dead short, with key on expect open circuit, with kill operated expect dead short (Engine kill operation) If all these tests are good you would be well advised to try another CDI. If they are not good...reading higher...disconnect and clean any plugs/sockets you find along the way, if the magneto coils are reading lower, new ones needed if more than 10%...or so the book says
DavidSS Posted June 1, 2011 Author Posted June 1, 2011 OK then it seems the carb may be ok Like I said earlier I would not bee happy seeing a yellow spark, you need to get the multimeter out oldgitonabike, these are great instructions!! I will check the electrical out and get back to you. I'm going to owe you a million! I sure hope its something simple like fraid wires or bad grounding, because I don't know were I will find a new CDI for cheap..... stay tuned.
DavidSS Posted June 3, 2011 Author Posted June 3, 2011 oldgitonabike, these are great instructions!! I will check the electrical out and get back to you. I'm going to owe you a million! I sure hope its something simple like fraid wires or bad grounding, because I don't know were I will find a new CDI for cheap..... stay tuned. @ oldgitonabike, Well I checked out all the wiring to the CDI and coil... it is all good, and within specs. This is just CRAZY! As a sanity check I scuffed up all the connection points with sand paper, and I bought a new plug, and checked the spark again. It seemed to be brighter. From what I can tell, it is sparking sometimes blue, sometimes a mix of blue/yellow. I made a small video of it. If i could figure out how to post it so you could see it, then perhaps you could tell me if it is acceptable. I can't believe that the CDI would be bad. I would think it either works completely, or it would be completely dead. Not just weak. After all, it is mainly just a capacitor in that black box, with a diode.
NE0 Posted June 3, 2011 Posted June 3, 2011 just my pennys worth..... its not something simple like the engine kill switch being on OR a faulty ignition switch is it? Its just that I purchased a new ignition switch from yambits the other week, fitted it and the bike would NOT start, no matter what I tried. everytime i turned the key to ON it was being grounded, yet everything checked out fine until I turned the key... you can see the culprit arrowed, I simply moved the leg away from the solder and it all worked. I appreciate this seems unique and you are getting a spark, but are you testing the bike one way, and when it comes to actually trying to start it doing something different. if you're confident fuel is getting through, and you've got a spark...... is there anything else which is different........... i.e you're turning the key, setting the kill to off, the fuel tank breather is clear. Is there anything your doing at the time different which is causing the problem. I'm just thinking out aloud here... Are you cranking by hand, or standing to one side of the bike, are you doing anything different which might give you another clue where to look. Are you getting a spark at test start, Perhaps sitting on the bike causes a wire to be under stress and grounding like the kill switch...stuff like that?
Moderator Airhead Posted June 3, 2011 Moderator Posted June 3, 2011 you say you checked the wiring...did you check the source coils resistances and HT coil resistances? You have done right to brighten up the connectors, I agree that the CDI is working so thats OK. You are now mentioning a blue spark but initially a yellow one. Naturally you have tried again and it still wont start? is there nothing...not even the odd pop? Try a new spark plug and if you can muster some help a push start might be good.
DavidSS Posted June 3, 2011 Author Posted June 3, 2011 just my pennys worth..... its not something simple like the engine kill switch being on OR a faulty ignition switch is it? Its just that I purchased a new ignition switch from yambits the other week, fitted it and the bike would NOT start, no matter what I tried. everytime i turned the key to ON it was being grounded, yet everything checked out fine until I turned the key... you can see the culprit arrowed, I simply moved the leg away from the solder and it all worked. I appreciate this seems unique and you are getting a spark, but are you testing the bike one way, and when it comes to actually trying to start it doing something different. if you're confident fuel is getting through, and you've got a spark...... is there anything else which is different........... i.e you're turning the key, setting the kill to off, the fuel tank breather is clear. Is there anything your doing at the time different which is causing the problem. I'm just thinking out aloud here... Are you cranking by hand, or standing to one side of the bike, are you doing anything different which might give you another clue where to look. Are you getting a spark at test start, Perhaps sitting on the bike causes a wire to be under stress and grounding like the kill switch...stuff like that? I know the kill switch is working correctly because I have tested it twice. Once electrically (meter) and also have ruled it out by having it on, and checking for spark, and then turn it off and verify that the spark is non-existent. However, it kind of has those symptoms so I can see how you could assume that.
Moderator Airhead Posted June 3, 2011 Moderator Posted June 3, 2011 Can you get hold of a compression test gauge, you need to see around 100 psi
DavidSS Posted June 3, 2011 Author Posted June 3, 2011 you say you checked the wiring...did you check the source coils resistances and HT coil resistances? You have done right to brighten up the connectors, I agree that the CDI is working so thats OK. You are now mentioning a blue spark but initially a yellow one. Naturally you have tried again and it still wont start? is there nothing...not even the odd pop? Try a new spark plug and if you can muster some help a push start might be good. Yes, I checked the wiring per your instructions and all the values were within tolerance. The spark appears to be a blue/yellow spark now. But if my memory serves me, last week it was more dull yellow. But that might have looked that way due to being outside in the sun. Where as last night I was in the garage and it was darker. And yes, I put in a new spark plug last night. And yes we tried push starting it until my sons were exhausted! But to no avail, it just is dead, not even a pop. It acts like the switch is off, but I know it is not. ... a side note... I took the new plug out last night after the exhaustive attempt to start it, and looked at it. It was damp with fuel, so I know for sure there is fuel getting into the cylendar. could it be a timing issue??? like for example the plug fires when the piston is in the down position. Like 180 deg out? Is that possible on 2-strokes? Just grasping at straws now. Should I measure how much voltage is getting put into the coil (orange wire). I can do this with a storage scope and high voltage probe. I'm an engineer and have resources However, are there any printed spec that will give me an idea as to what the voltage should be? I'm about ready to turn this bike into a boat anker!!
Moderator Airhead Posted June 3, 2011 Moderator Posted June 3, 2011 Yes, I checked the wiring per your instructions and all the values were within tolerance. The spark appears to be a blue/yellow spark now. But if my memory serves me, last week it was more dull yellow. But that might have looked that way due to being outside in the sun. Where as last night I was in the garage and it was darker. And yes, I put in a new spark plug last night. And yes we tried push starting it until my sons were exhausted! But to no avail, it just is dead, not even a pop. It acts like the switch is off, but I know it is not. ... a side note... I took the new plug out last night after the exhaustive attempt to start it, and looked at it. It was damp with fuel, so I know for sure there is fuel getting into the cylendar. could it be a timing issue??? like for example the plug fires when the piston is in the down position. Like 180 deg out? Is that possible on 2-strokes? Just grasping at straws now. Should I measure how much voltage is getting put into the coil (orange wire). I can do this with a storage scope and high voltage probe. I'm an engineer and have resources However, are there any printed spec that will give me an idea as to what the voltage should be? I'm about ready to turn this bike into a boat anker!! Dont despair David, you'll get there in the end, you need to check the compression, maybe the piston rings are 'frozen' or the crank seals passing
DavidSS Posted June 3, 2011 Author Posted June 3, 2011 just my pennys worth..... its not something simple like the engine kill switch being on OR a faulty ignition switch is it? Its just that I purchased a new ignition switch from yambits the other week, fitted it and the bike would NOT start, no matter what I tried. everytime i turned the key to ON it was being grounded, yet everything checked out fine until I turned the key... you can see the culprit arrowed, I simply moved the leg away from the solder and it all worked. I appreciate this seems unique and you are getting a spark, but are you testing the bike one way, and when it comes to actually trying to start it doing something different. if you're confident fuel is getting through, and you've got a spark...... is there anything else which is different........... i.e you're turning the key, setting the kill to off, the fuel tank breather is clear. Is there anything your doing at the time different which is causing the problem. I'm just thinking out aloud here... Are you cranking by hand, or standing to one side of the bike, are you doing anything different which might give you another clue where to look. Are you getting a spark at test start, Perhaps sitting on the bike causes a wire to be under stress and grounding like the kill switch...stuff like that? Additional questions.... when you had this similar issue, did you get spark? Did your gauge lights come on (green neutral and red oil)? because mine do. This bike is acting like part of it is grounded out, but that must be impossible. I have literally, ohmed out every wiring going and coming from the CDI to the coil and the switch, and kill switch. I'm just wondering if someone screwed with the wiring and changed something, as the wiring harness has evidence of been tampered with before I got it.
Moderator Airhead Posted June 3, 2011 Moderator Posted June 3, 2011 you have told us the fuelling is good, the spark is good so now its a compression issue, thats it...end of the line unless of course fuelling and or spark isnt good Oh and check the filter..is it disintegrating? could some of it be jamming the reed valve?
blackhat250 Posted June 3, 2011 Posted June 3, 2011 Sounds like fuel " , if it ran with solvent cleaner, is feul running [ petcock filtre,] is float valve sticking or faulty, leave float bowl off, and let petrol run through. ,, then replace bowl,
DavidSS Posted June 3, 2011 Author Posted June 3, 2011 Can you get hold of a compression test gauge, you need to see around 100 psi I will ask my neighbor. He owns a couple of bikes. He might have a gauge I can borrow..... Ah... the saga goes on! Would it help if I posted photos of some of these parts so you can evaluate? You mentioned the reed valve again. When I took that off, I did not clean it. just looked at it. Maybe I should take the carb off (again!) and look at the reeds to make sure they move. Or would that be a waste of my time?
Recommended Posts