WR125X Help

[Wr125Help]

[Robby]

It is highly likely to be the battery.

They get old and die. They die a lot faster if they were left discharged for any time - and you mentioned that the seller had to charge it up.

As a battery ages it looses capacity in terms of amps, but not volts. So if a new battery could provide 10 Amp hours, a knackered one may only provide 2 Amp hours. Both will still show about 12.8 volts.

Smaller batteries die faster. Seeing as its a 125, the original battery likely only had 4Ah. Luckily for you, small batteries are cheap, you should get one on ebay for 20 quid. Make sure to charge it for a few hours before fitting it to the bike.

[Wr125Help]

An update, tested with a screw driver, absolutely nothing, no sparks or anything

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[Riejufixing]

[Wr125Help]

[P.]

No, you don't want that.

You want either a Yuasa or Motobatt, in this case I prefer the motobatt

[Riejufixing]

That is a very inferior spec battery, although it is sealed lead acid. The CCA (basically the oomph the thing can put out to start your bike) is only 44A. The motorbatt one is double that. When it's cold, the better performance is worth having. Despite being really tight, I would normally go for the better one.

[Riejufixing]

[Wr125Help]

[Riejufixing]

[Nobby the Bastard]

Or you've not used it for 3 months because of lockdown....
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Wr125Help]

[Wr125Help]

[Wr125Help]

Update - start motor was completely burnt out, took it apart and all the magnets were shattered into pieces

[Riejufixing]

Ow, nasty. Still, at least you know what the problem is, and you've got a decent battery (unless you've cancelled it).

Some used starter motors on eBay, £22ish.

[Wr125Help]

[1198]

[Robby]

Interesting. That's another thing to add my list of things that used to never go wrong, but do now.
The amount of cost-cutting on recent Japanese 125s is worrying. It's like they took a leaf out of Ford's book, and deliberately fitted components with a short service life for no noticable cost saving.
Case in point - sister in law's old CBF125 had a set of worn out brushes in the starter motor at something like 20k miles. I would expect them to last the life of the bike. Must have taken some effort from Honda to track down a supplier for seriously inferior parts.

[Wr125Help]

Another issue with the bike now, when filling it up with coolant it will only take about 0.1 litre before it’s overflowing out of the radiator, so bought another thermostat, but now I also have a loud vibration/knocking in the water pump

[Robby]

I assume you had drained the old coolant out first? And you're pouring it into the rad filler slowly.

I can't remember if this is the bike that had silicone sealant everywhere - lots of moderately fucked 125s on this forum.

Anyway, best thing to do is some investigation. Knocking from the water pump is unusual, but I reckon you're somehow dropped a pebble or a nut in there. Get the pump off and have a look for something being caught in it.

Filling - does the thermostat have a small hole drilled in the metal plate? It should, this allows a small amount of coolant through so you can fill the system without having the thermostat open.

Total system capacity is probably only a litre. Make sure everything is clean and properly assembled, slowly fill the rad, then start the engine with the rad cap off and let it warm up. This takes bloody ages.
Eventually the thermostat will open and the water level will drop. Turn it off, top up the rad, put the rad cap back on. Then top up the expansion bottle to the correct level and you're done. Check the level in the bottle after the first couple of rides.

[Wr125Help]

[Wr125Help]

[Robby]

I had a similar-ish problem on an SV650 years ago. The water pump was built into the crankcase cover, and relied on the crankcase cover gasket to keep the oil and water from mixing. This gasket had failed, so I had coolant in my oil. You may have the same problem, or vice versa.

First off, don't ride it until it is fixed. Second, order a new, genuine crankcase cover gasket for whatever side has the water pump. Pattern gaskets are rarely very accurate.

Check the oil level, to see if it has gone up. If so, chances are you have water in the oil, and it needs draining. You'll have to drop the oil anyway to change the gasket. Also look under the oil filler plug for mayonnaise - although you only get this if the engine has been running long enough to churn the oil and water into an emulsion.

Bear in mind this is speculation because I don't have the bike in front of me, but I would be doing the following:

1. Drop the oil. Look for water in the oil - usually the water will drain out first, looking watery, followed by the oil, looking a bit lumpy.
2. Remove the crankcase cover that has the water pump on it. Carefully examine the gasket where it seals around the water pump to see if it is broken.
3. Remove the old gasket, then scrape off all traces of gasket and goop. It will take ages and be a messy job. Try to avoid getting any of the crap inside the engine.
4. Check over the water pump as much as you can, in case something is broken in there or the impeller blade are worn.
5. Reassemble the crankcase cover with a new gasket.
6. Remove the radiator from the bike. Flush it through with a hose pipe. If some oily crap comes out, it needs some detergent and a soak. My preference is to plug off the bottom somehow, fill it with a mix of warm water and Daz, and let it soak. Flush with a hose, repeat soaking with detergent until it seems clean.

Finally, when all of the bits appear to be clean and properly assembled, fill it with plain tap water and go through the normal filling process. Let it run until warm, then drain this stuff off. It should remove enough of the crap from the system. Refill with proper coolant and you're done.

In short, getting oil in the cooling system is a pain in the arse.

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