Suzuki DR125S engine problem?

[krisply]

hello folks.

my bike died en-route: I seem to remember misfirings and irregular power before finally dying.
turning the ignition key on/off (it's a kickstart) I noticed the electrics were gone.
as I was at the top of a hill with some way to go I did a rolling start
which succeeded in getting the engine going again but it developed an ever louder knocking noise, absolutely no power, then died again at the first trivial incline.

my guess is something is shot in the timing department.
there must have been some sparking going on despite lack of electrics for lights/binnacle, else no running whatsoever, no?
I took the noise to be the valves clashing with the piston but how's that possible with a timing chain?
I have dismantled the engine and can see no damage so changing the piston rings.

does anyone have any idea what might have happened?

[Robby]

Sounds like to different problems.

No electrics - meaning no charge in the battery or a loose/broken wire to the battery usually.

Knocking noise from the engine - usually a sign of bottom end engine trouble.

These should be two mutually exclusive problems; one does not cause the other.

No idea why you decided to change the piston rings.

[Hahadumball]

if top ends fine itll be the bottom end...

electrics are easy just trace wires back with a volt meter.
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Fin: no matter how much I look at It I can't understand what was going through my head, all I remember is going about 80 and redlining it to stop it seizing.
360 Deg... Five 1/4 turns. :- Teflon-Mike 18 Jan 2015

[krisply]

Paul, there is some side-to-side play at the conrod big-end although none vertically or front-to-back. can I take that as a fault or just an engineered wiggle factor?

[Suntan Sid]

[krisply]

Suntan,
at the moment I'm baulked at getting the sprocket nut off and dwelling on not wanting to dismantle any further anyway.
it sounds like the feeler gauges have to be applied with access to the crank shaft! that right?

is there any chance the noise is from the top end: the timing chain jumping a tooth and bashing the pistons/valves, the valves suffering too much wear?
with the piston off, the small end can be leaned from side to side a good 1mm.

taking apart the crank case is to me a big job and I _really_ want to avoid it if I can.....

[Suntan Sid]

[Suntan Sid]

[krisply]

[Suntan Sid]

Here's a thread about adjusting the cam chain tensioner on a DRZ125, can't imagine it's much, if any, different on your model!

https://www.thumpertalk.com/topic/527880-just-got-a-04-drz125-have-s/
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[krisply]

I broke the gasket sitting under the cylinder block - a tear caused by the movement of a wooden block under the piston when refitting it.
can I apply some instant gasket and get an adequate fix?

[Suntan Sid]

[krisply]

status: my wits end!

after having replaced piston rings (pointless, as a previous poster noted) and adjusted the chain tensioner, I did not get the spontaneous recovery I'd hoped for!

I checked the CDI against a haynes manual table of resistances and there were a few values out of whack so I picked up a used replacement. no joy.

with a good spark observed and timing verified, I thought the only thing left was the carb so I applied a carb kit, replacing seals, all jets and the needle.
still nada!

it will not turn over. a marginal ignition but it doesn't even cycle the engine.
to recap, the orignal problem was the loss of power, followed by engine clatter, then 5 mins of gradual power decay to nothing.

this is a really low mileage bike and I am loathe to abandon it after an inversely proportional amount of maintenance!

can anyone give me a pointer or two?

[Suntan Sid]

What is the exact model and year of the bike?

From what you've written, I assume its an electric start only?
Have you checked the starter motor, etc, with your multimeter?
Have you tried bump starting the bike?

The wiring loom must be relatively simple on your bike, have you checked it thoroughly for any damage to the insulation, are all the earths solid, ie bolted up tight with no dodgy connectors?
Have you checked the output from the generator?
Is the battery good?

You say you have rebuilt the carb, I don't know the exact model, but from what I can see via google, the carb has a diaphragm, did you check the diaphragm for any splits or holes?

If you know that the timing is correct, the cam chain tensioner is working correctly and the bottom and top end, (including the valves and cam), are within spec, then your problem must be either fuel or electrical.
Given that you're saying the bike doesn't turn over, properly, that would suggest your problem is electrical.
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"Everybody needs money, that's why they call it money!"

[krisply]

thanks Sid.

the bike is a Suzuki DR125S of 1985, kickstart!
yes I have tried jump starting down hills, and if it turns over at all it is forced immediately ceases if the bike hasn't a certain speed.

the battery is good.
I haven't checked the loom/earths but there's a strong spark!
so I should get a substantial ignition, no?

the carb is a Tokei. what diaphragm?!

the fly wheel marking shows correctly through the case bolt hole when the cam sprocket scribed line is level.
I have not checked top/bottom end, valves for spec.

[Suntan Sid]

Now we know the year of manufacture, your carb does not have a diaphragm!

Are you absolutely sure that the clip on the carb needle is in the correct position?
Are you absolutey sure that the pilot air screw is the correct number of turns out?
Are you absolutely sure that there are no air leaks between the carb and the cylinder head?

I have a very similar bike, a Honda XL125RC, (1982).

My XL can be an absolute sod to start if it's not been used for a while, it has no electric start.

This is how I start it when it's not been in use.
Check the kill switch!!!!!!
Check fuel tap is in the "ON" position.
Put the choke on full.
Twist the the throttle 4 or 5 times.
Turn on ignition.
Kickstart the bike!

It will usually fire up if I follow this procedure.
If I don't twist the throttle 4 or 5 times it will not start.

If the bike fires using this procedure, do not be tempted to rev it up straight away, (you will just stall it and have to begin the procedure again). Let the bike idle on full choke untill the revs become erratic, then switch the choke off and leave it idling for a few minutes before revving it up.

I know the XL is notoriously slow to warm up, however, given the similarity to your engine, I can't see the DR engine being much different.

Give it a go, following this procedure, and tell us what happened.
____________________
"Everybody needs money, that's why they call it money!"

[krisply]

thanks again Sid.
just seen this - no notification by email.

I have just been installing my third CDI - I took the bike to the suzuki main dealer in Jerez, Spain in exasperation, and they said "CDI" but without testing the existing one or testing with a replacement, or offering the prospect of even obtaining a replacement for me!

I have a haynes manual for the bike with a table of resistances.
the first CDI (original) missed a few of the values, the 2nd (used, off a dealer on ebay) also missed some more, and the 3rd (again off ebay!) misses all but two!

the values given for the leads from the bike (generator etc) check out OK.

I'll try your procedure next, with the 3rd CDI regardless.
cheers....

[Suntan Sid]

Have you tied bump starting it?

I, sometimes, have to bump mine after a couple of months not starting it.

If you try this, find a bit of a hill, choke on, pump the trhottle a few times, put the bike in second gear, get it rolling, bounce on the seat and let the clutch out a the same time.
Open the throttle as your rolling, this should drag some fuel through the carb, then knock the throttle off, the bike should fire, with the throttle closed. Once it fires, don't be tempted to give it any throttle, let the choke do its work and let the bike warm up.
If the carb is set up correctly and the electrics check out, it will start using this method, you may have to do ths a couple of times before it starts!
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"Everybody needs money, that's why they call it money!"

[krisply]

So with the 3rd CDI (whose resistance values didn't correspond to the haynes table) plugged in, I also replaced the spark plug as I'd got it into my head that perhaps the bike was seriously degrading even new plugs.

I took it out for some hill starts - in 40oC here in Spain!

The engine sounded like there was a little combustion but as soon as I clutched at the bottom of the run, that stopped - no run-on of the engine at all. so it ticked over only while the pistons were being forced to move by momentum....

which just reminds me of the original death of the engine by sudden power reduction followed by a clattering then 5 minutes of fading to nothing - something surely died back there!
I've replaced the CDI, cleaned the carb and applied a kit, installed new piston and rings, checked the chain timing is correct, renewed the spark plug.

the spark looks OK, the resistances of the primary and source coils check out. is there anything going on in the generator that can effect timing of the spark even given the apparent correct status of the coils?

one definite conclusion reached: no more entrusting to fleabay offerings! I am going to send all three CDI's to Robinson's Foundry for testing and if all are as bad as they seem I'll cough up the almost £300 for a new one.

[krisply]

hi Sid

I have had the first CDI checked out by a company in the Netherlands and they tell me it is fine!
they have suggested the problem is the source coil on the stator and the likely symptoms certainly seem to tally with my experience.

cost of a new one: >>>> £350 !!!

do you know whether the GN125 shares the same engine parts with the DR125 S ? I could get a stator for one of them more cheaply!

[Suntan Sid]

Sorry, I don't know about the compatibilty of the parts!

However if you're sure it's the stator you could have it rewound.
I did this with the stator on my XL125, I'm pretty certain it cost less than £100. You send your stator off and, if you're lucky, you'll receive another, refurbished, unit back, in a few days. If they don't have your stator already refurbed you will have to wait a bit longer.
I'll try and find the companty I used and post the link.
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"Everybody needs money, that's why they call it money!"

[Suntan Sid]

It was 18 months ago but I think I used these people:-

https://www.westcountrywindings.co.uk/applications.htm

It's an unusual postal address, so I'm 99% sure it was them.
Email them first for a price.
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"Everybody needs money, that's why they call it money!"