Can you see what's wrong here? SR125 project

[h00dwink]

Little back story. August 2011, Got a promotion at work which featured a 25 mile each way commute. Didnt have a car at the time and didn't want to use my GSXR as a hack.
Thought i'd buy an SR125 work horse as they're bullet proof.
A little bit of ebay watching and £350 later i had bought this beast

https://sphotos-c.ak.fbcdn.net/hphotos-ak-snc7/303083_10150782217895257_7950247_n.jpg

Got a train from Eastbourne up to Norfolk to pick it up then went straight to Reading on it for the festival (hence all the strapped on stuff).

After a reasonable amount of commuting on it, it suddenly decided to give up whilst i was overtaking a lorry on a dual carriageway last November.

Bikes been sat since then and finally got the motivation to start taking it apart to find out what was wrong.

Will get some other pics of stuff that went wrong taking it apart (cheese nuts, sheared bolts)

Split the engine apart to check the piston out as i presumed it was just the rings that had gone. Couldn't see anything wrong with it then turned to the valves and this set alarm bells ringing.

https://sphotos-g.ak.fbcdn.net/hphotos-ak-ash4/319600_10152304373715257_1337969861_n.jpg

Now waiting for a valve spring compressor, cam chain sprocket and a new valve to proceed some more.


TLDR; Bought bike, bike died, bike sat a year, bought tools, damaged valve found.
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[Ja7]

So after all that are you using the gixer as a work hack

[h00dwink]

no sir, in january my nan had a prang in her car and finally decided to give up driving. which was LONG over due.
so she gave me her car, so i'm now cruising around in a 100% official old person mobile. same as this, same colour
https://images04.olx.co.uk/ui/6/51/69/1274355164_94554269_1-Pictures-of--Skoda-fabia-estate-2004-1274355164.jpg
which is why its taken so long to get round to sorting the sr out
____________________
Sahf East Winnah 4LYF
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www.youtube.com/h00dwink updated regularly

[h00dwink]

ok so it's update time. had to wait a while to get christmas out of the way before sinking more money on the sr.
before i started this project there was no reasonably priced SR125 engines on ebay. after throwing a lot of money stocking up on tools required etc there is now one on ebay for £150 delivered. had that been there before this i would have just got it. anyway i have plowed on.

well replacement parts arrived
https://sphotos-e.ak.fbcdn.net/hphotos-ak-snc6/6344_10152410864330257_1241440152_n.jpg
that cam chain sprocket cost more for the guy to send from greece than i paid for it in total.
the bolt in the clamp is about to be cut down to fashion the inlet rocker shaft remover.

https://sphotos-c.ak.fbcdn.net/hphotos-ak-ash4/427697_10152410864415257_733603721_n.jpg
something to take care of later as drilling out snapped bolts is not fun.

https://sphotos-h.ak.fbcdn.net/hphotos-ak-ash3/538533_10152410864315257_1379817139_n.jpg
top right of this picture is the inlet rocker shaft. a cold engine renders removal impossible.

https://sphotos-a.ak.fbcdn.net/hphotos-ak-ash3/59908_10152410864545257_1123504018_n.jpg

cook for 20-30 minutes near the middle of a pre-heated oven at 200c/gas mark 6

https://sphotos-h.ak.fbcdn.net/hphotos-ak-ash3/530389_10152410864695257_1357875162_n.jpg
you'll know the engine is properly cooked when the metal expands enough to relinquish the vice like grip on the inlet rocker shaft. take note of the delightful aroma that has filled the kitchen as well.

https://sphotos-g.ak.fbcdn.net/hphotos-ak-ash4/312337_10152410864660257_1205140141_n.jpg
the end result. now allow the engine to chill before continuing.
until next time home boys.
____________________
Sahf East Winnah 4LYF
https://bikepics.com/members/h00dwink/00sv650s/
www.youtube.com/h00dwink updated regularly

[h00dwink]

ok here's the valve removed from the engine to show you the extent of the damage.
https://sphotos-f.ak.fbcdn.net/hphotos-ak-ash3/540831_10152410927720257_1603287407_n.jpg
____________________
Sahf East Winnah 4LYF
https://bikepics.com/members/h00dwink/00sv650s/
www.youtube.com/h00dwink updated regularly

[Tim..]

What was the root cause? Snapped cam chain?
____________________
Project builds: My VFR400 nc30 build thread + Honda Britain Rep VFR + What? Another VFR +Project 'cos I want one' + V8 coffee table
www.marshallracing.co.uk
OCD - Helping to bring the standard of my bikes up and make me slowly go mad since 1999

[h00dwink]

cam chain is fine. presuming the timing was off. not much of a mechanic so fault finding isn't my prime area.
so if someone is able to give me some wisdom please do.
lack of oil perhaps? really unsure. getting over the hump of taking out the valve and fitting the new one has given me hope that it will be rideable very soon.
still more jobs to do though after the engine is back together. gotta get a new battery eventually. need to strip and clean the brakes. was considering doing the suspension but not sure if i can be bothered now as it wont make it any better at all haha.
anyway here's a couple of pics and where i will finish for this evening.

how the valve looks now, with the new one in place
https://sphotos-h.ak.fbcdn.net/hphotos-ak-ash3/542180_10152411078330257_1782451397_n.jpg

https://sphotos-b.ak.fbcdn.net/hphotos-ak-ash3/59986_10152411078310257_1444203710_n.jpg
____________________
Sahf East Winnah 4LYF
https://bikepics.com/members/h00dwink/00sv650s/
www.youtube.com/h00dwink updated regularly

[UnspeedySam]

Nice project. I have been planning on learning how to take engine top ends to bits for ages but I don't have a garage or a whole lot of free time so that makes things difficult.

Why did you need a new cam chain sprocket? Just thought the old one looked a bit worn?
____________________
Riding: BMW R1150RT `02 bought mildly crashed
Fixing: Also the BMW as I get less broken bits
Gone: ZZR600 '00, TRX850 '97, RXS100 '93, JS125-6B '07, BMW R1100RS '93, Kawasaki ZX-6R-J2 '01, Honda Bros NT400 NC25 '88

[Sload]

Love the engine in the oven picture, the puzzled look on the other halfs face gave me a chuckle
____________________
Honda Varadero >> Triumph Speed Four >> Honda CBR1100xx

[h00dwink]

i dont have a garage, this is being done in my spare room-cum-makeshift workshop.
don't have loads of free time which is one reason this has been happening in bursts. have next week off work so hoping to get it near finished.

need to get a set of feelers to set the valves. rebuild the engine and fit it back in the frame.
do the brakes.
clean chain
source battery
hopefully get an mot sorted.

the cam chain sprocket was needed as i damaged the old one during removal. the bolt was stuck fast. with a socket on the lower bolt to hold it in place i couldn't get it off. had to wedge an allan key in to it to hold it still. resulted in it bending a little. so thought it best to replace it. was only £8 for the new old stock part.
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www.youtube.com/h00dwink updated regularly

[Valentino Mossy]

I had a convo with my mum over watching a program where they stuck bits in the oven to release stubborn bits.
She said "blah blah, smell would stink the place out, theres no way your doing that in my oven".


Didnt have the heart to tell her i did such thing when she went on holiday for a week ! LOL !
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[Tim..]

You need to find out, the same thing could happen again spoiling all your hard work.
Cam timing doesn't just change. Could be a faulty cam chain tensioner.

I would def be having the cylinder off to have a look at the piston and little/big ends too.

Ps I hope you lapped that new valve in.
____________________
Project builds: My VFR400 nc30 build thread + Honda Britain Rep VFR + What? Another VFR +Project 'cos I want one' + V8 coffee table
www.marshallracing.co.uk
OCD - Helping to bring the standard of my bikes up and make me slowly go mad since 1999

[h00dwink]

Knew I would have over looked something. Trip to halfords tomorrow is in order. Can get a kit and feeler gauges. Won't take a few minutes to pop the valve out again.
If its the tensioner then it's an easy enough replacement. Not looked that far into it, but do know that it needs to be found to not make all this a waste.
____________________
Sahf East Winnah 4LYF
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www.youtube.com/h00dwink updated regularly

[h00dwink]

From prior look as the engine is in 3 separate parts. The piston is in a reasonable condition as are piston rings. Cylinder is fine with no damage/scoring worth mentioning.
What would I need to be looking for lower down as a problem source? Had presumed it was all up top where the issues were.
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Sahf East Winnah 4LYF
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www.youtube.com/h00dwink updated regularly

[Tim..]

I doubt the little or big ends of the rod are the root cause but the valve has obviously hit the piston to get bent.
Would want to check the bearings for any damage/excessive play.

Edit: Looking again at the valve it looks like the top (where the collets grip the stem) has broken allowing the valve to drop, this could be be the root. Where all these parts recovered from the head?
____________________
Project builds: My VFR400 nc30 build thread + Honda Britain Rep VFR + What? Another VFR +Project 'cos I want one' + V8 coffee table
www.marshallracing.co.uk
OCD - Helping to bring the standard of my bikes up and make me slowly go mad since 1999

[lilredmachine]

[h00dwink]

Well spotted you two. Didn't mention that in original post.
It was all still held in place by the collets until I got the compressor on it. Everything was removed from the head. There's no rogue parts.
Will try having more of a mooch around it later for fault finding.
At work currently.
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[cb1rocket]

It's worth mentioning that although the valve is so bent, that isn't the con rod bent too? Should be straight
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Honda H100S2 Rebuild - https://www.bikechatforums.com/viewtopic.php?t=253852

[marc_cowley]

generally con rod shouldnt be bent as they are made stronger than the valves for instances like this, the valve should bend and sometimes damage the piston but very rarely the con rod.
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Chaly Cf70
Gpz900R

[h00dwink]

con rod's fine. as said, the valve or piston takes the damage.
progress semi-stalled for a day or two.
going to grab a low range torque wrench from a mate tomorrow and start getting the engine back together but need to wait for the base cylinder gasket.
ordered a new chain as the old one is beyond redemption.

until those bits arrive i'll probably just do some cleaning up of the wheels and sort the brakes.
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Sahf East Winnah 4LYF
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www.youtube.com/h00dwink updated regularly

[cb1rocket]

Ok sounds good, but a con rod can bend so was just checking
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Honda H100S2 Rebuild - https://www.bikechatforums.com/viewtopic.php?t=253852

[Tim..]

Just had a thought, is the valve guide and stem seal ok?
____________________
Project builds: My VFR400 nc30 build thread + Honda Britain Rep VFR + What? Another VFR +Project 'cos I want one' + V8 coffee table
www.marshallracing.co.uk
OCD - Helping to bring the standard of my bikes up and make me slowly go mad since 1999

[orac]

seen something like this before (on a gn250 and gs125), only the guy broke the valve - you maybe lucky you didnt whole the piston. it was caused be ovre revving - i seem to remeber you were over taking truck when it happen, where extra revs may have been required.

from what i understand the valve spring isnt able to close the valve fast enough for the high revs + valve bounce means the valve stikes the piston. any sign of valve stike on the top of the piston
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"with nothing left to lose, there is everything to gain. It's not the size of the dog in the fight, it's the size of the fight in the dog"

[Boobs]

Just hit it with a hammer a few times still it starts working?
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~Sahf East Winnah~

~Suzuki GSX-R750~Kawasaki ER-6n~

[h00dwink]

Small update-
engine is all pretty much back together. don't have pictures of the progress through that but there wasn't much too see.
people will understand the frustration of getting the cylinder and head on only for the cam chain to slip off the bottom sprocket. resulting in taking it all apart again and doing it properly.
just awaiting some m7 bolts as the drilled out m6 is now too wide.

so thought i'd do a small tarting up job yesterday.
before-
https://sphotos-h.ak.fbcdn.net/hphotos-ak-snc6/6345_10152430407630257_1826419884_n.jpg

after some wire wheel and polishing with autosol-
https://sphotos-b.ak.fbcdn.net/hphotos-ak-ash3/580489_10152430407620257_2025705560_n.jpg
____________________
Sahf East Winnah 4LYF
https://bikepics.com/members/h00dwink/00sv650s/
www.youtube.com/h00dwink updated regularly