CB125 Superdream Solenoid

[richjp]

Hi all

Bit stuck - am part way through my CB125 Superdream rebuild, which I have posted about on and off over the last little while.

Previously I have rebuilt the engine, which I got going a while back. Since then I have stripped the whole bike down and am in the process of reassembly. Now I have the engine back on, but have a problem with the starter solenoid.

I am getting the often reported clicking from it, but the battery is new and fully charged and if I bridge the solenoid the starter motor tuns no problem. For the earth I have stripped back the new frame paint to bare metal to make a good contact and the solenoid was new when I did the engine rebuild and was fine then.

Any ideas on what might be wrong / things to try next?

cheers and thanks

[Taught2BCauti...]

First, check that you have good earth continuity between battery and frame, then check the voltage going to the solenoid - when the start button is pressed, it should be very close to the voltage reading you have across the battery.

If not, there is a resistance somewhere in the circuit - so disconnect the solenoid actuator wire and check the resistance between there and the battery when the start button is pressed - or connect a temporary wires to the solenoid and test it against the battery directly.

Some solenoids are permanent earth and live to actuate, some are the other way round - but they can fail without warning.
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Honda Varadero XL125(V8)
www.TheFutureIsHere.eu

[richjp]

Cool, many thanks - will give all of that a go

I wonder if its something to do with the Earth - I painted the frame since I first had it all working, so maybe that is causing a problem, though I thought I'd stripped back the frame paint where the earth wire attaches to the engine mounting bolt. Anyway, I shall report back

[Teflon-Mike]

The solenoid on these is a FANTASTIC bit of almost Victorian Electro-Mechanical Engineering... could be a prop in a gothic horror movie. its REAL BRASS! And it is held together with SCREWS!
Take it apart and clean the wonderfully big block of brass that is the contact bridge. Might benefit from a little bt of careful filing to flat any pitting off; clea the rest f the insides out with thiners and dose with WD40.. one of the few REAL places its actually apropriate... re-assemble. Shuld work a charm.

Elsewise; starter similarly s pretty Gothic and new brushes are available from Dave Silvers for about a tenner; (reminds me I have two sets that need to find their way to actual motors I could be don the warm at the mo!). Again clean the woderful brass armature; then clean and grease the bushes and the planet gear.

Problem in the soleoid is oft 'cos the contacts on the starter need doing,making the solenoid arc and oxidise the contacts; while the starter goes highwr resistace both mechanically and electrically increasing load making wholeplot more 'hit and miss'.
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[richjp]

Great, thanks Mike - will give that a go too at the weekend and report back.

cheers

[richjp]

OK, solenoid sorted - just me being dim - using too big jump leads (am using car battery to get the engine going again initially). Having switched to smaller set starter motor engages fine.

However, not firing - lots of phut, phut, phut exhaust puffs, but not fully engaging. Sparks are blue and look strong, but am worried that maybe petrol is contaminated with water from when I cleaned the tank out earlier in the year.

So question, once the fuel tap is off the tank - how do I remove the white plastic tube that goes up into the tank - I assume I need to do this so as to allow the tank to fully empty? Last time I didn't remove this pipe and emptied the tank by turning and shaking, but probably didn't get everything out.

cheers
Richard