XV125 SYMPTOMS - PLEASE ADVISE

[Kelum]

The engine has run around 48000km by now. At this point coils can be malfunctioning, sure I will check coils tomorrow. Will let you know, in the mean time please guys make sure you drop in stuff that come into your mind here on my particular issue...thanks a lot..

[Kelum]

Hi guys, I set up a 6mm gap between two electrodes on a circuit board to check the spark quality, and cranked the engine, the spark wasnt orange it was blue and was well defined..however, the spark goes well and after say 30secs of run the spark stops...the running cylinder too slowers, that means same thing happening in the other plug also...thats why I experienced a stop in both cylinders when riding. After this stop spark occurs again and the engine runs...so I know now the ignition coils could be the next suspect, is it possible for both coils to behave the same way like this, or is it the TCI unit or the connectors in between two keep killing me? Been going through Hyenes V twins manual and I picked up the idea. Will check coils next n keep u guys posted...please advise on the issues I have raised here...

So now I know there's a problem with ignition system but not with the fuel system....the bike had some sighing like thing anyways since the times I bought it...so it must have had the problem developing or like this even then I guess..

[Airhead]

for now just check all connectors are clean and bright on the CDI, the coil, coil ground etc etc

[Kelum]

Hi...checked the coils and connectors and all are ok with continuity and standard ohm values...now I have removed TCI unit, TCI unit repair was posted here before, but he didnt mention how he checked trnsistors for him to determine that transistors were faulty...no BCEs known so how can I check things?

[Airhead]

hmm dismantling the CDI is risky...what if it isnt that?, could it be the pickup sensor...I dunno really

[Kelum]

hmm dismantling the CDI is risky...what if it isnt that?, could it be the pickup sensor...I dunno really

Yeah buddy I didnt make any harm to the unit, being very careful here, how can I check the pickup? manual says pickup should have around 192 ohms...is that it?

[Airhead]

yeah if that what the manual says just check it and check it again at the exact time the ignition cuts out

[Kelum]

Am pretty sure the problem lies in the TCI unit or the pickup...am confused with checking it, I mean I have the socket found with three cables, two from pickup and one from neutral switch...am going to use another multimeter cos may be mine seem to have a bad calibration, its a cheap Chinese shit,,,will borrow a frnd's. I placed probes on two white-green and white-red wires and set it to continuity check and multimeter was ok for continuity...its a single coil, a same wire coiled so there should be a continuity right, but the ohms am not sure if the multimeter working correctly it doesnt show zero initially but 1..and keeps showing 1..at kohms settings I think its showing a higher value given in the manual...XVS125 manual...must double check with a good multimeter...so the bike having pickup coil to give idea to the tci unit on present speed right..TCI unit getting power from battery and pulses from pickup..if TCI unit making sparks with power transistors..how come pickup coil is to be blamed...can u guys clarify this...rectifier getting AC voltage from Stator coil or magneto right?

If pickup doing all this how can I repair it...? nervous!

[Airhead]

1, pickup must be within the spec tolerances

2. Sometimes a faulty pickup will open circuit as temperature rises so when engine hot, spark is lost

[Kelum]

pick up coil, stator, magneto..are these three different units? what if the pick up coil is faulty mate? are they available to buy?

[Kelum]

Can someone help me understand this? Please clarify what is meant by IGN B+12...has he meant to check the line coming from ignition coil to spark plug..should it have 12 volts when ign and run switches on? Is it safe to deal with ignition coils when cranking, I mean I had the pulses running in me the other day when doing that it scared the shit outa me..

There should be pulsating very low voltage from the pickup coils. These pulses triggers the CDI (ignitor) to fire off the ignition coil and produce the spark for the plugs. The low pulsating voltage could be checked using an analog/meter type VOM setting to low. On cranking, the needle would appear to be flickering.

• there should be spark at the plugs when cranking;
  
• if none, check that one terminal of the ignition coil has an IGN B+12 (12volts when IGN & RUN switched on);
  
• the other terminal of the ignition coil should be pulsating from 12 to 0 when cranking;
  
• if none, check the CDI and its connections;
  
• the CDI should have its own IGN B+12;
  
• the CDI has other interlocks from the neutral light, clutch switch and side stand switch;
  
• the CDI main triggers are from the pickup coils;
  
• the pickup coils produces very low pulsating voltage when a magnet is moved / interrupted across its face;
  
• the distance of the pickup coil to the magnet is critical;
  
• the time the pickup coil pulses is critical;
  
• the interruption of the magnet across the face of the pickup coil is caused by a small rectangular plate or tab attached to the 'rotor'.
  

[Paulwhite]

hi kelum

ok .... the stator is the big round coil that the manetic flywheel spins round, in the crank case there will be a little black plastic "coil?" ....thats the pulse coil, im not sure which wire it is but it will only be 2 or 3 wires max! where as the stator plug will have 4 thick wires.

im not sure what the above tex is on about......sounds like IGN B+12 stands for ignition (black) = the positive 12v ??? but dont quote me on that.

just a question....have you cleaned the carb? i know you say its an electric problem but its sounding to me that your pilot jet is blocked....

i got something similar the other week, bike felt like it was miss fireing and would "judder" (only just felt it) when slowing down, also allot of carbon buildup, turned out to be a blocked pilot jet. so just check it out

as to your electrical problem ur best bet would be to spend a weekend taking the left side crank case off and having a look inside. that way you will know whats what, then go from there.

[Kelum]

Hey Paul buddy...I checked sparks outside with two electroded 6mm apart, the spark taking place but there are periodic stops. So I concluded electrical prob is behind. Sparking wouldnt be affected by a fuel prob right? am afraid of carb dismanteling...but wanna do it.is it possible for you to make a writeup for me on the steps from petrol line removal on?..yeah I know stator wires they deal with rectifier....pulses from pickup drive TCI to make speed-based voltage signals to ignition coils right? in this missfiring case of yours did u happen to check sparks? I'm afraid of carb because I've seen people say if you change the right mixture it will be hard to reestablish it...

p.s. where have you been, hope ur doing well, anyway am going to check hook up two wires to pick up coil connectors and connect them to a multimeter while cranking the engine..and must check if there are voltage drops when misfiring...after that will do the same for igniter cylinder outputs...

I checked what the above red lines say..spark wires were ok, one had 12.4v while the other had 11.8v

[Kelum]

I guess I would need NEW GASKETS if am gonna open the left cover ha? I have a gasket tube and new gasket set anyway..but I wanna keep gasket set for later time

I checked the two wires coming from pickup to the ignitor unit with multimeter set to AC while cranking the engine...the voltage remained around 5.21 and it wasnt really pulsing, may be it was happening so fast the multimeter couldnt resolve the change..

[Paulwhite]

hmmm hard to tell... i know its just a very slight pulse that goes to the cdi (or ecu .....the black box) but im no good with electrics......ur best bet would be to get an LED bulb and hook that to it.......you should be able to see it pulse as the volts go up and down.

and yes you would posably need new gasket if you took the left engine case off. but if you know what wires are where then u should be fine. .......

i still think its the pilot jet in the carb ......and dont worry you cant mess it up unless you start turning the wrong screws but its quite simple

tools: small (+) screwdriver, small (-) screwdriver, rag, fuel container/ (cup)

take the carb off the rubber splitter, turn the petrol off.

there will be a pipe comming from the bottom of the carb, thats the drain, there will be a screw near it which lets you drain the fuel.

undo it and drain the fuel into the cup then undo the 4 screws at the bottom of the carb,

take the cover off (use the rag) and you will see some brass pipes and 2 bits of plastic held together with a thin bit of metal.

there will be 1 big brass pipe in the middle and a smaller one next to it, undo the smaller one and blow through it (thats the pilot jet) then pop it back in and undo the top of the big one and blow through it (thats the main jet) pop it back in then put the cover on and put the screws back in, make sure the drain is closed, put carb back on the rubber splitter, and turn the tank on to prime, wait 5 seconds then try and start the bike.

thats all there is to it!.

[Kelum]

Thanks Paul..ur a great relief to have around, I wanna clean the fuel system anyways...plus must oil the engine..will have the manual handy...will update what the problem would turn out to be.

[Kelum]

Hi guys, well after a while of trials and events...It seems the problem lies with the fuel flow to the engine..

Last Friday as I was riding in the rain suddenly a huge smoke sprang up from front cylinder area and bike stopped. I got scared to death thought it was an engine seize due to an oil runout which was impossible. There was heavy wire burning smell too. So I thought since oil level was ok it was some short circuit in ignition coils. Since I was blaming to my ignition coils I thought probably they burnt out or something. The other thing was I was around 30 kms from home. So I took her to a garage to find out a short circuit. A pin of one of the coils was touching the frame. I got it fixed and came home. The bike was felt to be powerful and the misfire was not frequent like before

The missfire however exists but it seems ok...anyways I came into conclusion that the misfire is due to some block in fuel pipelines or carb, like good old Paul just suggested. Today as I was taking a 90 degree turn and a bit steepy place, bike lost its power both cylinders stopped firing, pressed start button, motor was turing but engine wouldnt start.I tried to push the bike to start it didnt work either. Checked plugs too still no starting.

Then I set the fuel cock to PRI position and pressed start button and wow the engine started. Then I put fuel cock to RES and rode home.

This suggests that there is a problem with fuel flow. Lot of pipelines under gas tank so I should label them I guess. I would clean the tank, filters, and simply everything. Anyone want to guide me? Of course will follow what Paul told.

Is there a drainage screw/line? I heard u might alter the correct mixture ratio removing carbs...is that true? how can I stay out of fuel mixture ratio issues?

What particular places do I have to look for water/fuel sediment/rust buildups? can someone guide me to all the adjustable screws? may be with images?

[Kelum]

What solvents do I need to have around before disassembling? for clean here mechs use petrol and then a blower, I dont have an access to blower...its not good to use other solvents than petrol I guess..

[Paulwhite]

just use some clean fuel from ur tank in a bowl. then u can pop it back in when ur done. if you think its your fuel line then best to open the bottom of the carb like i said before and check for bits of dirt......but if your worried about the drain screw then dont use it! just undo the bottom of the carb over a bowl to catch the fuel.(its a little more messy) there is about a cups worth in there, but you can always put it back in the tank.

i dont have a picture m8, but if you post one up of your carb and number the parts your not sure about then i can tell you what they are.

it might be worth checking your fuel pump, there will be a pipe comming from the rubber splitter that the carb sits in (in between the cylenders) that pipe will go into the fuel pump, it pumps air in and out of the pump which makes it work. check that its not got a hole in it.

the prime on the tap runs fuel straight through the pump and into the carb , the "on" dont let fuel through unless the pump is pumping and reserve is like the prime and lets fuel flow straight to the carb. so im thinking its a problem with the pump or the air valve in the tank.

[Kelum]

Here you go Paul, please locate drain screws and all for me, am a bit scared to go before knowing stuff.

Uploaded with ImageShack.us

Uploaded with ImageShack.us

I'm sorry for heckling you..u know the importance of knowing which is which before dealing with the unit..