YBR125 sump threads stripped

[Newbie Rider]

I did my first oil change on my (new to me) yamaha ybr 125.

 

When I pulled the plug out I noticed a metal coil around the sump plug.

 

It was intriguing but later learned that it was the threads from the case of the engine

 

Clearly they've been striped by the bolt being overtightened.

 

It seems my best option is a Helicoil kit to re-do the threads.

 

However, this YBR125 seems to have a separate metal lining in the sump, which doesn't look thick enough to be drilled out and re-threaded with the Helicoil kit for M12 1.5mm plug.

 

https://imgur.com/a/kX7ZWXS

 

If I drill through this lining and tap into the casing, is that a problem?

 

I can't work out what this metal lining is from any drawings and can't tell if it's on all YBR125s, as I can't see it on pictures of other bikes!!

 

Any guidance would be very appreciated. Thank you!!

[onesea]

Does the boot still screw in?  

Was the metal liner just the crush washer?

 

Maybe not j looking at the photo

 

A more correct answer will follow, however if it will thread in gently…. You might get away with a new crush washer and some gasket sealant.

 

 

[Newbie Rider]

Thanks for your reply Onesea. No, unfortunately the metal was definitely stripped threads…

 

I’ve not heard of gasket sealant before. Definitely worth a try.

 

I bought a new sump plug and was able to hand tighten and give a further quarter turn with a wrench without the bolt slipping, so definitely some grip left but clearly some gaps.

 

Thought doing the Helicoil job would be the most thorough approach but am very unsure about the metal lining!

[onesea]

3 minutes ago, Newbie Rider said:

Thanks for your reply Onesea. No, unfortunately the metal was definitely stripped threads…

 

I’ve not heard of gasket sealant before. Definitely worth a try.

 

I bought a new sump plug and was able to hand tighten and give a further quarter turn with a wrench without the bolt slipping, so definitely some grip left but clearly some gaps.

 

Thought doing the Helicoil job would be the most thorough approach but am very unsure about the metal lining!

I am a bad engineer my solution would be:

New crush washer a dab of this or similar,

Tighten as you discribed,

 

If it don't leak job done, this is not a high pressure point.  It's a bung to hold a liter or so of oil, with a little pressure applied when the breather cannot keep up.

 

Admittedly I would warm up gently first time and ride locally for my first ride or 2.

 

However someone before long will come along and tell me I am wrong...

 

 

 

[RideWithStyles]

did u just pull it out? or did you turn the wrong way? Poor choice of words?

anyway it is not important....

yes it looks like you ripped out the thread liner. So the metals are cast iron/alloy (sump block), then a steel collor left exposed, what would have been a aluminium/alloy threaded collar.

This is why a torque value should always be followed- now im know implying you did it but ive been the victim of dealerships f@@@in noobing the basics too it really question things.

 

Anyway The hexicoil really is ment as a layer of good contact for a weakish or worn thread repair, not to solo job. So it will bring the thread back to what it was as in the same inner and outer diameter as before. But now uve taken the liner out just coiling (with the same as the sump plug it wont particularly fit.

so depends on a few things it its a bodge or just to get going would be just to retap what is there and find a matching bolt for the width,length and pitch of the new bigger sized sump plug. torque should of been mid teens at most with soft metal liner in noddy value but now your in the stronger metal so try mids first but if still leaking go 20-25nods.

 

For gapers metal weld be better than sealant but really its a get you home or just to a garage job than long term.

 

there is more pressure built up and variations in the engine than you think otherwise theyd just bonnet fit the thing or put minimal thread on.when an engine is on tick over take the oil filler cap off, bike will run and sound different, try putting uour hand over the top of it (with rubber gloves) to seal it wont be easy, then try to seal it when you blip the revs, that is weak air pressure alone, what do you think nominal vacuum and 3ltrs of oil plus pressure baring down on the plug will be like?

 

 

Edited December 18, 2023 by RideWithStyles

[onesea]

The Crankcase breather goes into your air box, look at the size of the hose.  The connections the Crankcase is hardly a pressure vessel.  It has a vent to stop it being such.

 

I did some googling:

"2.5 to 6 psi" is the highest figure I can find for Crankcase pressure.

6PSI. Being approx 4.2 kgs cm

Force exerted by 6 psi on 1/2" or 12mm nut?  About 5kgs

 

Given my bad maths that is which really is not that much. Your 1/2 turn on the spanner would be more than that.

 

I would be amazed if it ever got anything like that high on any bike. On my trophy 6 Psi over the area of the base of the sump would be about 1 Ton of force.

 

Then there is this:

https://bikesandtravels.com/biker.aspx?ride=854

 

I agree if for some reason the pressure is allowed to build up something is going to give.  Given the description of thread strength above it might be the plug.

 

Then on my trophy it would be seal on timing pick up.

 

The reason for a big nut in a weak casting? Maybe It's a drain hole it would take a long time to drain oil from a small hole.

 

Maybe plugs are designed like this:To reduce the chance of people putting large spanner on and striping threads.

 

I can only hope the same people did not fit the spark plugs.  Another area where a torq wrench should be used till you the feel of it.  It really isn't that much torque.

 

The other solution could be to look on internet for new sump case, base, bottom plate or whatever they call it.  

Just check how easy it would be to change. Might be engine out, might be 6-10 small bolts.

[skyrider]

15 hours ago, Newbie Rider said:

I did my first oil change on my (new to me) yamaha ybr 125.

 

When I pulled the plug out I noticed a metal coil around the sump plug.

 

It was intriguing but later learned that it was the threads from the case of the engine

 

Clearly they've been striped by the bolt being overtightened.

 

It seems my best option is a Helicoil kit to re-do the threads.

 

However, this YBR125 seems to have a separate metal lining in the sump, which doesn't look thick enough to be drilled out and re-threaded with the Helicoil kit for M12 1.5mm plug.

 

https://imgur.com/a/kX7ZWXS

 

If I drill through this lining and tap into the casing, is that a problem?

 

I can't work out what this metal lining is from any drawings and can't tell if it's on all YBR125s, as I can't see it on pictures of other bikes!!

 

Any guidance would be very appreciated. Thank you!!

obviously some gorilla had put the bolt in 

[Nick the wanderer]

Hi,

the drain bolt goes directly into the crank case so you would have to split the cases, engine out, bits everywhere job.

For me I'd be looking at ways to re-tap it using another helicoil or similar,larger bolt maybe, it's on the side so you can get at it at least.

[V650]

possibly also replace the drain plug with something like this 

Idea being that if there is a chance that any thread left might strip on the next oil change 

 

https://www.louis.ie/en/stahlbus-oil-drain-valve-10002846?partner=googlesea-ir&gad_source=1&gclid=EAIaIQobChMI--bR3ZGZgwMVGZRQBh1HowRsEAQYByABEgJNKvD_BwE&filter_bike_id=1259&filter_article_number=10002845

[Bianco2564]

If the thread has pulled you need to helicoil it, just sticking it back in with sealant isn't a fix, if it falls out you will wreck the engine and most likely come off as the oil hits the back tyre.

Helicoiling in situ is probably possible but its not for the inexperienced , if you don't drill and tap it square, the new sump plug will be on the wonk and won't seal or tighten up correctly.. Drilling and tapping into a crankcase will naturally risk sending some swarf inside, this can be limited by putting grease on the drill and tap. .

The tag to wind the coil in, can be snapped off to the outside rather than snapping off inwards.

A couple of oil changes afterwards should flush out any swarf that made it inside.

Otherwise it's an engine out and dismantle to helicoil it.

Like I say, its not a job to take on if you havent done it before, see if any local bike shops can help, old skool type shops are generally a bit more adept at this sort of repair than main dealers

[Newbie Rider]

Thanks everyone for your thoughts.

 

I'm on the same page, that Helicoil repair would likely be best.

 

I'm still not clear what the two separate materials are in the picture:

https://imgur.com/a/kX7ZWXS

 

If I helicoil this, I calculate that I'll drill out all the material that makes up the inner ring, and then be tapping new threads into the casing.

 

I'm not sure what this inner ring actually is, whether it's part of the sump, and whether it matters if I drill it out..

 

Once the screws have loosened up, I can try and take the engine out and apart to find out, unless someone can advise.

 

There's a youtube video of a bloke in India Helicoiling the YBR125, but I can't see the same inner ring on his sump. It's most clear at 2:07:

 

Thanks!

[Nick the wanderer]

It's hard to see what the inner ring is from that one pic. Have you tried to move it, is it part of some earlier repair that has pushed in? In the tube video there doesn't look to be anything like that visible.

If you are going to take the engine out and split the crank cases you will see for sure what's going on. Lot of work though and factor in a load of extra cost, gaskets n stuff, there is always extra stuff. Good experience though you will learn tons if you don't mind getting your hands dirty.