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finally started my project bike xs400 dohc


Tommy xs
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I started work on my second bike a few weeks ago, still not decided what to do with it yet.

Just thought I’d put it back together after stripping parts from it over the last few years, every time I had a problem with first bike I’d pull something off this one, even if it was only to diagnose a problem then not put it back, anyway refitted the carbs, coils, cdi rectifier, fueltap, also managed to get the front brake unseized. Tried to start it today and it fired up fine except only on one cylinder, I tested the coil by switching it with the other one then tried to trace the wires back 1st wire only went back along the loom a short way before it split back to the other coil so my thinking is its ok up to that point as other coil works fine so put in a bridge wire between that point and the coil, no joy so traced 2nd wire back to cdi tested this on other bike it works fine so put bridge wire between cdi and coil still no joy, on to third wire which went to multi connecter behind the headlight then on to r/h switchgear

So tried a spare switch and another bridge wire to the coil, still no spark on the first cylinder, well I do get maybe one weak spark now a again which it was doing before I started tracing back. I have cleaned every connection and the rest of the electrics are all working . I think a bit more head scratching before I get to the root of this one, any ideas anyone? :eusa_think:

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Clean the frame where it mounts tommo... av seen a moto xer need this done before,, :eusa_think:

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Yer check the earth points on the frame as Blackhat say, also i know its the simplist thing but is the spark plug at fault?

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"Tried to start it today and it fired up fine except only on one cylinder, I tested the coil by switching it with the other one then tried to trace the wires back 1st wire only went back along the loom a short way before it split back to the other coil"

Tommy

It's probably me, but I cant see any outcome to the coil switch. Did the other cylinder spark up

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don't ask me, I've had enough of trying to trace ignition feeds :madflame:

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John Cheers I'll have another go later

Noise I tied with the spark plug that is working on other cylinder and also a new one also replaced HT leads both working on other side

Jimmy I think the CDI acts as switch, other cylinder works fine, only 2 wires on the working side, the side with no spark has 3 wires

Drew I know what you mean I f#ckin hate electrical gremlins.

hope its what John said cos haven't got a clue :eusa_doh:

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if you have battery voltage on the feed wire to the coils( the single common wire from the cdi),and you have swaped coils to confirm that both are good, and you have cleand the mounting area of the coils .Then that only leaves the cdi to be faulty or if you have dual pick up coils then check them one against the other with a multy meter set in the ohms position. 1 test the resistance from the 2 wires of each pick up then test each wire for resistance to ground. also I would check the control wire to the faulty coil at the cdi that the treminal is nice and tight fitting and not spread open making a poor connection.

As the cdi is only 2d it only controls the ignition curve / timming of the spark. If you have a wireing diagram trace out the 3rd wire and find out what it does,you say it went to the rh switch so I am guessing that it is the kill switch, and if it was defective the bike would not run at all. as they are normaly closed in run position and open in the kill position

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Thanks DT50 I think it must be a bad earth like John said as I've substituted every part with parts from my other bike which is running A1, not had time to look at it since last post due to work, hopefully get on it tonight or tomorrow. If all else fails I have another loom but don't want to go down that road as its untested.

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been out in the garage tonight before the football obviously, still not found problem

must be a NW uk thing Tommy

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Yep never had a bike i couldn't find the problem in a few hours,save for 1 rz 350 17 yrs ago that the cdi was intermittent and I have never heard of or seen that again.

Good luck guys keep at it you've over looked something. Or it the salt in the air in the NW UK creating a abnormal void in the flux capasitor's haha I have no idea.

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I think I've found where the problem lies I think its in the pickups that send the signal/voltage to the cdi the P.O has threaded the wiring through the rear swing arm :crazy: so that won't help think I should have found this a lot earlier but I'm getting there

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Yep never had a bike i couldn't find the problem in a few hours,save for 1 rz 350 17 yrs ago that the cdi was intermittent and I have never heard of or seen that again.

Good luck guys keep at it you've over looked something. Or it the salt in the air in the NW UK creating a abnormal void in the flux capasitor's haha I have no idea.

Ive had that problem with the cdi only after cleaning the carbs around 4 times did I think to swap it over

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Ive had that problem with the cdi only after cleaning the carbs around 4 times did I think to swap it over

That's 2 times then they normaly just give up completely,drove me nuts I cleand carbs weekly changed pick up and coil tested the stator under every possible temp range,was only after about 4months of living with it that I bought another rz and swaped the cdi that I figured it out.

Glad you found it I did suggets to check the pick up coils,now if we could only figure out whats up with drewps fz I have stared at his wireing diagrams till my head hurt and i just cant see why it wont run its only 7 wires to hook up and by everything we have talked about he has them hooked up right?

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That's 2 times then they normaly just give up completely,drove me nuts I cleand carbs weekly changed pick up and coil tested the stator under every possible temp range,was only after about 4months of living with it that I bought another rz and swaped the cdi that I figured it out.

Glad you found it I did suggets to check the pick up coils,now if we could only figure out whats up with drewps fz I have stared at his wireing diagrams till my head hurt and i just cant see why it wont run its only 7 wires to hook up and by everything we have talked about he has them hooked up right?

Between me & you DT I'm glad he can't get it going as he left me for dust on it last year at squires :hyper:

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Between me & you DT I'm glad he can't get it going as he left me for dust on it last year at squires :hyper:

I heard that! :babyha:

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HAHAH ya but squires is still months away lots of time to get it sorted out.

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HAHAH ya but squires is still months away lots of time to get it sorted out.

I was hoping he would be on his little ped this year but that looks unlikely (poor little ped)

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Had another good look at the wiring last night the POW has butchered both the wires from the alternator and the pickups luckily I have all the parts I need on my bike 3's motor which I have never started as it was bought by my brother as a project for him, he dumped it in my garage then after about a month decided it was to much work and gave it to me. I didn't have room for it really so I stripped it down and put it in the loft of my garage except for the motor which has been sitting in the corner it might be easier to just swap the motors but have only ever turned this one over by hand I mean its only 4 bolts plus the exhausts and carbs and their both coming off anyway. I think I'll leave it till the weekend then decide :eusa_think:

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