DirtyDT

Just to add. I know it is electronic ignition but I wanted to reference it against a points system as it was easier to visualise. Does the coil terminal earth go back to the CDI? I wonder if it does if that is earthed properly or there is something wrong with the earth side. You would still get the power but not break the earth continuity.

I have been thinking about this whilst eating popcorn with Tommy. In old systems the points stop the earth when they open and that fires the coil. The coil body is earthed but that may be a bit of a red herring because normally there are also 2 terminals (feed and earth) ignoring the coil body earth, power is fed to the coil and only when the second terminal earth is broken by points being opened does the coil fire. So assuming the coil is getting enough feed to power it up - and not too much - the break in the earth side should make it discharge. The earth from the terminal and the earth from the body may be the switch so when the terminal earth is connected it charges and when the body earth only is connected it discharges. Hence the kill switch, or ignition, being connected to that wire too on older bikes. Therefore if the coil is connected to the battery feed direct, and assuming that the power to the coil is enough and correct and the coil body is earthed to the battery, by connecting and disconnecting the terminal earth should fire the coil. If that works then there must be a short in the earth terminal wire either grounding it out or a break not allowing it to charge. Er... I think but i might have got that wrong. It did make sense when I wrote it though.

:popcorn:

I found this LINKY, not sure if it is accurate nor if they actually have them but there cant be much more to check!

Not much of a hello, more a want. Topic locked.

Thinking about the feed or neg. most coils are directly earthed to the frame so it must be feed. Er, I think!

I have no idea to be honest. I know some bikes have a ballast resistor to the coils and if different coils are fitted then this is either bypassed or a new resistor is supplied. The original resistor is built into the harness where it is needed. Could the current be too high. I am just clutching at straws here but unless you need an exorcist, as assuming you have swapped out everything else then it is mighty strange. I would guess that some bike coils need one voltage and some another. A bit out of my depth in knowledge.

This is weird. The coils will need to charge until they are ready to jump to HT mode and fire. Is the power they are getting enough to get to that stage? If you can manually fire them then something in the system is drawing the power?? Is there some sort of balance resistor in the wiring that has broken?

Is the fluid coming out the bleed nipple? If not then you need to get suction on it or reverse pump the fluid from the nipple up to the master cylinder. If the fluid has pumped through to the nipple and all the air has come out of the system then you need new seals.

So far the discussion is going against the idea. I would estimate over 100 years of riding experience in the replies so far and, in the limited replies, not anyone thinking it is good. That may change. I wouldn't advocate putting a drop of diesel in or a drop of 4 stroke oil either.

A great dream. A great looking finished article. Just don't do it. Save your cash and do it to something with more power. We all know that customs are slow, cumbersome things for people who can't handle real bikes (I am sure others may disagree ;-) ) and that even 650 cc customs can be ridden by people like my old aunt Sally - and she is dead. So keep the dream but do it to something with a bigger engine than a 125. The shame of being undertaken by a moped or tractor awaits. It would look great on a 1100cc or above.

Never ever. Not sure what it would do to your cat converter or lambada sensor for bikes that have them. Why would anyone want to?

Do these bikes have built in immobilisers with the TDI matched to a passive transponder in the key? If you are getting a pulse to the coil, it would suggest not but that is all I can think of apart from setting light to it.

I think you need part number 5VLF21100033 This fits the following models 2005, 2006, 2007, 2009

It's a GTMX Probably 72cc but could be an 80cc. Made in 1979 - or that is the VIN. It is a 2 stroke. LINKY

Cheers, I will have a look later when I get home. They do sell repair kits but the seals are the wrong size in them! I brought a yam XS360 kit but the seals are 14mm so if anyone needs one - I haven't fitted it. I also ordered a XS650 kit but it came from the states and customs want £11 extra to deliver it so I can't be ar5ed to pay that for something that I only want the seals from and they may not fit either. They can fly it all the way back to the USA.

I have decided that RD2 is going to be Marine Blue. It is a stock '76 UK colour for an RD so it won't upset anyone - I think! I don't have a tank etc for it yet so I am thinking of using the stuff off RD3 as a start. Not sure yet.

Interesting. Does this apply to master cylinder seals as well?

Yeh............!

Sounds like a good plan. If you already have a direct earth to the CDI and put in a direct earth from the coils (both direct to the battery), why not put a third in to the earth on the pulse coil area and engine in case something is not allowing the engine to earth back to the battery correctly?

I am glad you got it sorted. Always do cheap and easy fixes first. Don't forget that we are a club too so, if you fancy it, stick around there is plenty of bike and non bike banter here.

Most people who want a little more noise slip a can only on. I don't know if a system exists but you could get one made. They weld/braze a lambada sensor threaded plug on a system if you want to retain it. I am not sure if anything de-cat'ed would pass an MOT these days.

Sticking valves stick open and this would show as a possible low compression. A couple of things to check. 1) you say no resistance on the kick starter - does the kick starter turn the engine over? 2) take out the plugs turn the bike over putting your thumb or a cloth over each plug hole. Do you feel different compression in any? Make sure the HT leads are out of the way or you might get zapped by one of them. If it is the valve sticking open it could be as simple as a little Plusgas on the valve. The valve could be bent or it might not be the valve. Hard to tell at this stage.

LINKY

Have you tried a different carb on it? It could be the choke playing up so the symptoms would only appear when coming up to temp.