Disassembling an SR500 engine

[@georgecurtis6463]

I know this is old but the issue of the crud on the valves and piston is just normal. Colors on the valves is also normal. Oil use can come from the oil ring or valve seals.

[@RogerHarris]

If the gudgeon pin is tight, heat can help release it.

[@edgeofvamp]

The black build up on the cylinder head and piston crown is carbon build up mixed with oil. When rubbed between your fingers it will feel like telcum powder made into a paste. You are correct on the valve, that is rust. Which unfortunately is water getting in, but that can happen if you live in a very humid area where it rains a lot.

[@submoto]

right on both things :-p That's exactly how it feels, and Denmark is crazy humid, but we have never seen it on other bikes. I was thinking that an airfirter rain cover (sock) might help

[@edgeofvamp]

I think you have the right idea about the humidity being a large culprit, but i explain below you are thinking the wrong direction. Hopefully this helps. The rust was most likely caused by 2 things working in conjunction. The 1st is that the rusted valve was your exhaust valve and it being clear of any carbon points to your bike running lean. Not to the extent of being damaging lean - just lean enough to run hotter than normal and that kept everything burned clean from the valve which includes the saving layer of carbon, oil or fuel that would keep the metal from rusting. The 2nd i have to explain the circumstance that will allow the second part be true. So most engines have a favored "rest" position and what i mean by that is every engine finds one point it favors to come to a stop during its revolution each time you shut the bike off. Which means that it can be fully closed, a valve wide open or a valve just cracked open. Your engine i believe favors leaving the exhaust valve cracked open and that is allowing moisture in while the engine is off. So the 2nd thing has to do with condensation build up as your engine cools down. So as your engine cools down and the cooler air flows into your exhaust and right into your cylinder. Then the condensation builds up on your exhaust valves and causes it to rust. It is the draw back to motorcycle exhaust being full flow straight through exhaust allows rapid cooling. I could be wrong(I am in no way saying this is THE cause), but the reason i point this out and why i am thinking it is the exhaust versus intake is that the intake valve has build up. If water was getting in the intake, it would be cleaner and the bike would have been running a bit rough at start up due to the water grabbing a portion of the fuel as it flows over and causes the bike to not receive the correct air/fuel mix. I really hope this makes sense, i apologize that i rambled on too long - i am really tired. When you clean up all the parts for reassembly, make sure to clear the rust and get oil on your fingers and rub a thin coat onto the valves. You may or may not have to do anything in the future to prevent this. With you doing a rebuild, the engine may find a new favored rest point and it will no longer be an issue. Keep the videos going and have fun riding.

[@edgeofvamp]

I forgot to mention in the other message, you probably should replace the exhaust valve or at the very least get a lapping tool and lap the exhaust valve. The reason why is the ridge around the perimeter of the valve is looking a bit burnt and when you increase the compression with the new cylinder rings could blow past that valve if it isn't seating properly. Hope it helps and have fun.

[@nfanunes]

You should also check the valve seals, they could be leaking oil from the top to the combustion chamber, they probably are as old as the bike and probably are very brittle...

[@submoto]

How do I check that?

[@nfanunes]

You have to remove the valve spring, there is lots of video tutorials on how to do that. Since you have the cylinder head out it's advisable to change them and avoid later problems down the road..

[@Niamhcotts]

Great vid guy's great teamwork. Love to get my hands on a sr500.

[@submoto]

Such a simple engine! :-) Absolutely wonderful to work on

[@magicdaveable]

Screwdriver on mating surfaces? Get a bigger rubber mallet. Geeze. Come on guys. Whenever you remove the head(not header) Always reseat the valves. When clicking on this video I did not realize you were rookies. It's Burned Oil.

[@pmacc3557]

Howdy. My 1983 SR500 that I bought last year is a beautiful machine. In 1st 2nd and 3rd gear its a bit clangy ir rattly sound from engine. 4th and 5th gear the sound goes. Is this just the way it us? I'm not sure if the engine was ever opened or overhauled, i guess not. I tried adjust the cam chain but that little bit that's supposed to move in and out whilst engine is running does not. Any ideas? Also, I'd like as a winter project to overhaul the engine, can you recommend a kit? PS; I also adjusted the valve clearance/ensured they are correct.

[@christopherangelimmanuelwa8303]

well, if it's a ticking sound, it could be your rocker arm, They just get worn. But in that case you would be hearing it in all gears. Have you had a look at the gear discs? sometimes they also need replacing.

[@pmacc3557]

@@christopherangelimmanuelwa8303 hi and thanks. Gear discs, you mean the gear cigs inside? Iv not opened engine yet

[@christopherangelimmanuelwa8303]

@@pmacc3557 watch this from about 11:00 :-) kzbin.info/www/bejne/l4O4aHmlqrJjkJI

[@christopherangelimmanuelwa8303]

forgot to add the link haha. but it's there now

[@submoto]

@@pmacc3557 kzbin.info/www/bejne/l4O4aHmlqrJjkJI at 11 minutes

[@Mirannaceste]

It looks like water or water vapor in intake / exhaust track or maybe just a little bit in the gas. Third circle is burned on the piston, so that´s the main reason of the oil leakage and burned in the head or also check the valve seals. I see, that the cylinder it looks like the mirror, it should be finnished more like honing cross pattern. Nice video manual.

[@PsychoticAnarchist69]

all along the watchtower by Hendrix? damn you guys have got good taste in music!

[@57corvettehead]

brown on the exhaust valve due to the heat absorbed by it when in the open exhaust stroke. The residual oil and gas depositing on the valve and then being super heated on the valve and burning to that brown color.

[@Detailmonster]

Is there a next part of the video you will put online?(reassamble and set up)

[@submoto]

unfortunately I had to put it back together in a rush (luckily everything works). I had no camera. I kind of explain that in my next vid. but I simply didn't get the time to film anything. It was extremely hectic during my last days in Denmark

[@RoosterPb]

Question when you put the rocket box back on did it have a gasket or did you have to make one or I didn’t have one at all ?

[@submoto]

hmmm. yeah, there is no gasket for that. I used liquid gasket I think. ...I'm pretty sure

[@submoto]

I used the Haynes manual, youtube, and a friend. It's quite doable :-) let me know how it turns out!

[@MrDudeface69]

Looks like some good carbon buildup.

[@submoto]

turned out to be oil. It was due to a lean mix. My spark plugs looked nice and brown, but the engine was getting too hot, which expanded the cylinder and let oil in. I ended up having to bore out the cylinder and getting a bigger piston. This time I measured the mixture on a Dyno. Dyno tuning is a must, as soon as you get a new pipe or air filter

[@CSSSharks]

Hi, live in Denmark as well. I have almost the same problem, what company do you send your cylinder to? (bore and honing) :-) Love the videos!

[@submoto]

they are called Ingana :-) should be the first hit on google

[@stevenlinford4312]

Just subbed, thanks for the SR Videos. Keep em coming!

[@submoto]

Awesome :-) Do you ride an SR too?

[@stevenlinford4312]

I built one about 8 years ago and loved it. Regrettably I sold it, and had been in search of one in my area for years because I missed it. Just found another and I'm making it right. Rebuilt the carb, replaced the steering bearing, wheel bearings breaks, exhaust, etc. Got it running well, but it burns oil. So it looks like I'll be rebuilding the engine this winter!

[@submoto]

Pretty much in the same boat then :-) Luckily these engines are extremely easy to work on, and quite cheap to rebuild, really

[@stevenlinford4312]

+SUBMOTO Definitely, glad to see people are keeping them alive!

[@pmacc3557]

I have one , very nice bike. I love the difference between riding the sr and then my new R7, sr500 like an armchair 😊

[@braidongreer2172]

The black is signs of excessive oil burning especially in large amounts like in your engine the brown on the exaust valve is a good sign it shows that you have perfect or close to perfect fuel to air ratio in a closed oil engine plus that valve would be back if your valves were leaking oil.

[@submoto]

Yeah, it REALLY looks like the oil was getting through the cylinder wall tbh. Oh cool about the intake valve. I was worried it could be rust. I feel like I was getting a rich mixture during idle (although I was on the smallest available jet), but I couldn't really get her up on a Dyno, as long as she was burning oil. I know the jet needle is pretty good. I get a beautiful brown plug at mid-range. Once I'm not burning oil, I'll get her on a Dyno, and if she keeps drowning during idle, I may have to dig into the timing or something. The carb is almost brand new, so unless it's defective, I really don't think that the rich idle is coming from there.

[@braidongreer2172]

+SUBMOTO You just confirmed my suspicion the fluffy carbon deposits are signs of a rich mixture but because the exaust valve is still brown not black than that means it is not always rich or perfect because your mixture changes between idle and open throttle leaving the exaust valve still pretty brown.

[@submoto]

Oh cool! :-D Yeah, I'll get to the bottom of it eventually! It's a bit strange that the idle mixture is so rich. but the burn marks (carbon) is still burned oil, right?

[@braidongreer2172]

+SUBMOTO Yes you will always be burning oil it's a fact but you have been burning more than normal but not too much because the entire piston is not burned. So from what I can see your engine is in good shape.

[@submoto]

The oil lever has been dropping by about 0.5L for every 100 miles approx. :-/ It's a real mystery

[@RoosterPb]

So did you have to do anything to the cylinder ?

[@submoto]

Absolutely. It turned out that the guy before me had just switched out the pipe and air filter (with a pod), without jetting it correctly. Most likely just by looking at the spark plugs, rather than getting it on a Dyno. And so the engine got too hot over time at expanded the cylinder, thereby allowing oil to get past the piston, which is what was burning. So I had the cylinder bored out (honing alone wouldn't have done it, got a bigger piston, and then rejetted with the help of a Dyno run :-)

[@RoosterPb]

I see. I may have to do to mine as well.

[@jamesmcgrath1952]

I have one, it's the bike I have the most fun riding. Just got a recall notice for the engine oil line flare nut (may leak oil on to the back tire). I think I can handle that fix lol.

[@submoto]

yeah, mine is leaking again, I may have change my gaskets,even though I used new ones last time. so weird

[@jamesmcgrath1952]

@@submotoIt's not a biggie for me. My old BSA used to leak all the time, never could get it to stop.

[@stanislavdeviatkin6985]

hi. that bolt, on the camshaft... wich side did you rotate it to put it off? I try to rotate as the other bolts, but it doesn't move.. like it is welded..

[@submoto]

Стас Девяткин I rotated like a standard bolt I think

[@stanislavdeviatkin6985]

+SUBMOTO maybe there is something like locktite.. Japanese already rotated it.. before me. )) thanks for the answer.

[@thepyrodude]

Stanislav Deviatkin when I come across one that is super tight or if I suspect lock tite was used I will put a bit of heat to it with a propane torch.....then they come out easier....and they are standard thread rotation left lose right tight

[@benjaminholman704]

Was there a gasket or anything for the rocker box

[@submoto]

Benjamin Holman nope. according to the manuql, liquid gasket is to be used for the rockerbox

[@benjaminholman704]

SUBMOTO awesome thanks I've been having trouble finding the answer sadly it's one of the last steps until my dad and I have mine running. So thanks for your help.

[@stanislavdeviatkin6985]

Hello. Did you have such sr problem, as engine knocking ? I want to buy a second- hand sr400. 52000 km. but it knocks, and I'm afraid. )

[@submoto]

It wasn't knocking, although my GS550 had that problem. It was fixed by adjusting the valves. quite easy. but there is a difference between knocking and plinging. if I remember correctly, one is early detonation, and the other is late detonation. so in most cases, either a valve adjustment needed, or a carb adjustment. I don't know how much damage it could have, and I suppose it depends how long it has been doing it. worst-case, you might have to look inside the engine, and check the damage. best case, adjust the valves. you could ask the seller to adjust the valves to correct tolerance (an easy job), and if it goes away, buy it. It might also be running lean, so run the bike for 15 minutes at 60kph ish (without going to idle), then push the kill switch. wait til it cools a bit, and look at the spark plug. if it is white, then the carburetor is too lean, and this could potentially have damaged the engine. most likely due to a new exhaust or air filter being installed, without the propper jetting.

[@bilbobaggins4905]

black stuff is built up carbon deposits from combustion and is very normal but a chunk braking off could score the cylinder

[@submoto]

yup. I tool it to the machine engineers. Turns out its oil the cylinder was worn to 1/10 too big, so we're having to bore out the cylinder and get a larger piston :-) that should do the trick

[@hansgustafsson708]

As a twostroke rider I can tell you that the black stuff is burnt oil.

[@submoto]

Awesome thanks :-) Yeah I saw a few 2-stroke pics on the internet, and it looked quite similar. Good to know where my oil was going :-p

[@logicinthebox]

Well now you've gone and done it, time to invest in some more tools, so you can be the machinist, hackaweek will show you the complete process.Buy the way,how much do tools cost in Den,do you have snap-on and mac,craftsman?I saw the Ford tools I didn't know they made tools.Doing a great job!!! the black material is carbon as you already know,Sea Foam cleaner works well for clean-up. If you need to find TDC compression stroke in the future, hit the kick start lever or rotate the crank and put your finger over the spark plug hole till it farts. good luck & peace, I will be watching the whole tear down & rebuild.Thanks

[@submoto]

I absolutely love the hackaweek vids! such an inspiration! I'm not quite sure what snap-on and mac is, but tools aren't too expensive here ...I mean no more than in other places probbly. Oh cool trick for TDC, thanks :-) I only knew the trick with the screwdriver.

[@thepyrodude]

SUBMOTO you should never use a screw driver on these Yamaha 500 engines just use the timing marks on the magneto or finger over the plug hole

[@rsullivant]

Pretty sure I now the answer, but when you refer to an engineer, you are referring to what we call in Texas (and Oklahoma) a machinist? Keep up the good video work.

[@submoto]

yup :-) they insist on being called 'machine engineers'a :-p

[@RCTUN748]

Hi, can I ask something,? I own sr400 Fi, I plan change crank(SR500) and piston close to origin SR engine style, but I'm not sure the cam and valve is same to sr400/sr500 :(

[@submoto]

From what I understand, both engines are pretty much the same, only the size of the cylinder is different, but I have never worked on an SR 400. if yiu like, I can ask around. what year is your engine?

[@hodaka1000]

Apparently the heads are the same except for the cam I've been told they won't run right if you mix the cam from a 400 to a 500 or from a 500 to a 400 You've gotta use the correct cam So if you change the crank or whatever you do to convert it to a 500 you most likely would have to find a cam from a 500 for it to run right

[@revivemotorcycles]

Stroke is different so piston head dome is different but rings are interchangeable valves also for top end work even 500 gaskets work on 400 just need to get a 400 piston if your piston is broken. Hard to find.

[@MidwestMotoRider]

Nice work man!

[@submoto]

Thanks :-) I feel like I'm getting more and more confident with the bike, but I still have a lot to learn

[@jeremyatkinson4976]

You pour petrol down the inlet and exhaust ports one at a time then you can check much easier if there's any seepage and where it's leaking. The exhaust valve is tan due it running hotter. You have to lightly hone the bore or the new rings won't seat and the oil may well be not coming past the rings but down the guides which you haven't disassembled to change the oil seals and check if the guides are worn. Do the job properly

[@foxtrot_casademos5456]

the brown stuff on your valve is liquid damage is cause by coolant or water getting in fron your piston by entering from the gasket on your valve cover

[@submoto]

has to be water then, being an air cooled engine. ...rain

[@hodaka1000]

@@submoto Well let's face it it's not coolant That brown just looks like a good colour it's not black and it's not white If water could somehow get past the ("valve covers"?) rocker covers it's not likely to get into the combustion chamber

[@hodaka1000]

@@submoto I had a fella telling me that the bike in my profile photo had oil leaking out of the rear wheel hub Even though I'd owned it for about twenty years at the time and this bloke obviously didn't have a clue I couldn't convince him there was no oil in the rear hub and the oil around my rear wheel that he was insisting was oil leaking from the hub was actually coming from my well oiled chain

[@niccollingro3833]

The stuff sitting on the piston is carbon.. its just from burning gas in there

[@submoto]

Unfortunately it turned to be due to a lean mix. I had been jetting according to the spark plug color. I had really nice brown plugs, and thought I was spot on ...well I learned the hard way that only a dyno will give you an accurate enough reading. So because of the lean mix and too high heat, over time, the cylinder expanded and was letting in oil between the cylinder wall and piston rings. So that residue was actually burned oil. So I ended up having to get the cylinder re-bored and had to get a slightly bigger piston. First thing I did was get the bike on a dyno, and rejetted correctly this time. Has been running great since :-)

[@ForestCounter]

Wait a minute.. I taler jo dansk 😯

[@submoto]

Det gør vi 😉

[@tychi5916]

love you subbie! (no homo)

[@submoto]

Haha :-p Thanks!

[@tychi5916]

oh and by the way i just wanted to let you know that you inspired me to make my first cafe racer and i want to thank you. Without you and this channel it probably wouldn't have happened The bike is a 1984 Honda CB125rs, all respect to you and keep up with the videos. peace

[@submoto]

Oh awesome!!! I'd love to see the bike when you're done with it :-D you should send me project pics on my facebook page, that'd be cool! And feel free to send me any questions you may have. I can't promise to have all the answers, but I can promise to do my best to try and help if I can :-)

[@tychi5916]

Thank you man I appreciate that loads. And yeah i'd love to send you some pics of the bike!

[@docm0237]

hola

[@submoto]

Diego Casas hola :-)

[@ilhamyogihidayat]

Very big single piston engine..

[@submoto]

it's a thing of beauty :-)

[@ilhamyogihidayat]

@@submoto what is the diameter of the piston?

[@submoto]

@@ilhamyogihidayat oh... hmmm I think they are born with a 86.9mm piston and a 87mm cylinder, but I had to bore mine out a bit because oil was getting through. so my new piston is probably a bit bigger, but not much

[@ilhamyogihidayat]

@@submoto thanks for sharing..

[@MrDerbee]

Useful video, sadly, spoiled by horrible rock music drowning out the commentary!

[@submoto]

MrDerbee haha, thanks :-p

[@mfs5493]

Endless unnecessary talking. Think. plan, write, edit and abbreviate.

[@submoto]

Thank you for your feedback. Much appreciated. I can recommend you go to Ichiban Moto. He will have better videos for sure 😉

[@ZulhilmiGhazi]

carbon...

[@submoto]

Yeah, my thought as well. Thanks :-)

[@ZulhilmiGhazi]

:) you're welcome man. i don't think that cylinder need to be rebore though. the line marking in there are normal. As long it smooth to the finger, no deep scratch that visible to the touch then it's fine.. For the head, clean the carbon first before checking the leak :) don't forget to check the con-rod as well.. And good luck man :) can't wait for the next vlog... #bikelover

[@submoto]

I took it in to the engineering company today. The guy there said that the cylinder looked smooth, but that he thinks it is probably worn, so that it is bigger now. That is how he thinks the oil is getting in. but he will measure it with a laser measuring ...thing. And then he will know if it will be necessary to bore. I hope not. I don't think I have the money for that right now. He will also check the valve seats, to be sure the oil isn't coming from there either. I'm really anxious to find out of the result.

[@ZulhilmiGhazi]

i do think it's normal to have a carbon stuck on the piston and head unless u do a weekly/monthly cleaning on it.. i still think that cylinder is fine :) and i hope so man :) what size are the bore currently? is it still 00?

[@submoto]

Yeah, it looks like the engine has never been opened. The mating surface between the rocker box and the head had no liquid gasket, So I don't think it has ever been opened. I haven't measured it, but it absolutely looks like it's factory size.