View Full Version : Problem with loose cam chain.
Hi guys
So this is relating to my lovely breakdown thread yesterday. I finally got the bike home last night (5 hours for recovery, 3.5 of them spent waiting was a **** take) and have started to investigate the problem, which was a very loud slapping noise coming from the front cyl.
I have taken the cam cover off the front and rear cylinders and found the cam chain incredibly loose on the front, but well tensioned at the rear. I will upload some pics below so you can see the damage and exactly what i mean...
My question is what the hell has gone wrong? Presumably the tensioner? But then wouldnt the tension have gone on the rear cylinder as well? Also, is this damage irrepairable?
http://i45.tinypic.com/2uyqf7b.jpg
Front cam chain loose on sprocket
http://i49.tinypic.com/25jv2v7.jpg
And again...
http://i50.tinypic.com/2ezshzq.jpg
Damage on the inside of the rocker cover
Thanks
Matt
P.S. - Before anyone asks why my hands are so clean - I had just eaten some lunch before I took the rocker covers off :P
The SV has seperate cam chains for front and rear cylinders and therefore has to have a tensioner for each. If I remember correctly, the front tensioner is much easier to access and work on.
1952paul0
05-06-10, 03:38 PM
theres a guide at the front which is more than likely broken. I believe that the cam chains are indipendant of each other. you will need to remove the head to get a clearer picture of the problem. atb paul
rear cam chain tentioner is easier to get to than the front but sounds like the front one has broken
were there any bits in the oil?
to see the lleft chain fully you unfortunatly will have to pull the flywheel out, more than likley you have mashed up the valves of the related piston, you may get away with a new head only if the piston itself has not sustained any damage.
Pull the flywheel and you will get a better look at what happned, then you need to take the exhaust system off and start pulling the front head off to change it
maviczap
05-06-10, 07:07 PM
more than likley you have mashed up the valves of the related piston, you may get away with a new head only if the piston itself has not sustained any damage.
The valves will only have mashed up, if the chain has jumped on the sprockets and altered the valve timing. By checking the timing marks by rotating the crank and lining up the marks you'll know if the timing is out.
Plus if you turn the engine over by hand you might feel if the valves are touching the piston.
Having owned Honda's will camchain problems, its not always fatal, if you catch it early. Trouble is with the SV's front cyclinder angle, if the chain is slack, then its going to rub on the chain tunnel & cyclder head, making one almighty racket :smt012
Hi guys thanks for the response. TSM - am I going to need to drop the engine in order to try what you are suggesting?? Im not bad with a set of spanners, but this is way further than ive ever gone with anything before.
Thanks
The valves will only have mashed up, if the chain has jumped on the sprockets and altered the valve timing. By checking the timing marks by rotating the crank and lining up the marks you'll know if the timing is out.
Plus if you turn the engine over by hand you might feel if the valves are touching the piston.
Having owned Honda's will camchain problems, its not always fatal, if you catch it early. Trouble is with the SV's front cyclinder angle, if the chain is slack, then its going to rub on the chain tunnel & cyclder head, making one almighty racket :smt012
with a cam chain that loose its near certanty that its slipped, there realy is no "catch it early" with an interfearance engine, the second its even 1 tooth out then on one engine cycle it will hit the valves in most circumstances, iknow as i was 1 tooth out on my TT engine
Hi guys thanks for the response. TSM - am I going to need to drop the engine in order to try what you are suggesting?? Im not bad with a set of spanners, but this is way further than ive ever gone with anything before.
Thanks
dont think so but im not sure, you will need rad out the way, take carbs off etc at least,
maviczap
05-06-10, 07:18 PM
with a cam chain that loose its near certanty that its slipped, there realy is no "catch it early" with an interfearance engine, the second its even 1 tooth out then on one engine cycle it will hit the valves in most circumstances, iknow as i was 1 tooth out on my TT engine
Lets see what ShadFX finds out when he strips it down. Pointless taking the head off, if the timing is still correct. It'll save him time & hassle, if he just turns the engine over by hand whilst its in the frame.
Lets see what ShadFX finds out when he strips it down. Pointless taking the head off, if the timing is still correct. It'll save him time & hassle, if he just turns the engine over by hand whilst its in the frame.
the valves could be bent and you wont know by turning it by hand, thats what i did, engine would have worked with problems, this can be tested but needs head out of frame to do a leak test on each valve
if its just the tentioner then it can be replaced, if it the camchain strip then im not sure if that can be changed in the frame, some bikes can
maviczap
05-06-10, 07:46 PM
According to the God of Haynes, the guides, tensioner blades and chains can be removed with the engine insitu.
To get to the tensioner, you need to remove the carbs. This make any access easier anyway.
Careful because the bolts holding it in place are made of cheese
Hey all
Going to do as suggested tomorrow and try and turn the engine by hand and see if the timing marks line up, I think ive read a couple of guides somewhere for checking valve clearances which told me how to do this... Keep your fingers crossed for me its not slipped and it all lines up!
maviczap
05-06-10, 08:54 PM
You have to do this anyway, if you're going to feck around with the camchain & cams, as the cams should be left in the correct position so that they're in position when you come to refit the camchain assembly
yorkie_chris
05-06-10, 11:28 PM
Big question, what happened when it stopped? Did you just hear slapping and pull over, or did the engine conk out/seize?
Some good valid points so far. Let me clarify easier access to front cam chain tensioner - the rear is hard up against a frame member, if I remember correctly, and cleaning the old gasket of when half of it had welded itself to the engine was really difficult and refitting was more awkward.
When you turn the engine by hand you will need to manually apply a little chain tension as the chain can jam with that much slack in it. I would remove both plugs and gently turn the engine witth a little tension applied manually by pushing the guide through the hole where the tensioner was removed from to check the timing, but stop immediately you feel any resistance and reassess the situation.
Hey guys - little update, but first some answers:
Chris - No, I stopped the minute I heard the slap, no conking out.
Ned - thanks for the advice :)
I have turned the engine by hand this eve - It seems to turn freely without too much hassle, I am seriously hoping that the chain hasnt jumped around too much and cained the valves...
I am now way out of my depth mechanically, so a friend of mine is coming over to help tomorrow, he also has a ton of tools which I dont have which will be useful. We are going to take the carbs off, drop the engine out of the frame and pop it on a bench and try to assess the situation.
Ive just been looking at prices for some of the bits I may need *gulp* if it comes to over £350, I think im going to have to abandon it. I only paid £750 for the bike anyway, and the rest of the bike is absolutely fine, and I dont mind breaking it..
Does anyone have any rough idea what sort of money this repair may come too? Im figuring its going to be at least cam tensioner, possibly the chain itself if its been stretched, new valves and maybe camshaft?
Hey guys - little update, but first some answers:
Chris - No, I stopped the minute I heard the slap, no conking out.
Ned - thanks for the advice :)
I have turned the engine by hand this eve - It seems to turn freely without too much hassle, I am seriously hoping that the chain hasnt jumped around too much and cained the valves...
I am now way out of my depth mechanically, so a friend of mine is coming over to help tomorrow, he also has a ton of tools which I dont have which will be useful. We are going to take the carbs off, drop the engine out of the frame and pop it on a bench and try to assess the situation.
Ive just been looking at prices for some of the bits I may need *gulp* if it comes to over £350, I think im going to have to abandon it. I only paid £750 for the bike anyway, and the rest of the bike is absolutely fine, and I dont mind breaking it..
Does anyone have any rough idea what sort of money this repair may come too? Im figuring its going to be at least cam tensioner, possibly the chain itself if its been stretched, new valves and maybe camshaft?
may be cheaper to replace the engine as a whole unit and then use the old one for parts to ebay etc..
yorkie_chris
06-06-10, 09:54 PM
If it did not stop with big CRUNCH then you might get lucky and it will be fine with just new tensioner.
Check the timing, if it is where it should be then try a new tensioner and see if it runs ok.*
*of course after you turn it by hand to make sure
Spanner Man
07-06-10, 06:34 AM
Good morning all.
I have seen many engines where the valve timing has slipped due to the tensioner failing.
However, as it's usually the inlet camshaft that the chain jumps on, leading to the inlet camshaft timing being somewhat behind where it should be, often there is no valve damage.
I suggest that you re-time the camshafts, & check the valve clearances. If any valves are bent you're likely to be able to measure the clearances with a ruler.
If the clearances seem ok, it would be worth fitting a new tensioner & checking for compression. If you have compression then it's likely that the valves are ok. Then re assemble everything & see if it runs.
What one can't tell is how much damage there is to the camchain tensioner blade etc
Cheers.
maviczap
07-06-10, 07:27 AM
Saw a used K3 tensioner blade & camchain on evilbay, buy bit now for £20
But I for one wouldn't buy a used camchain,
tensioner blade & camchain tensioner maybe
Think the general advice is to upgrade your curvy tensioner mechanism with one from a pointy k3 model, but don't quote me on that, do a search of the Org
Thanks Mavi, I will take a look at that. Ive been reading up and the common procedure sems to be replace the CCT with one from a K3 as these are more reliable. Ive found somewhere that sells spare sv650 engines for £350 - Just in case!
Can anyone point me to a link on how to check the timing? I know how to find TDC, but I dont know where all the marks on the sprocket carrying the cam chain should be pointing too.. Or is that not quite how you do it? The manual ive got on my PC is actually useless.
yorkie_chris
07-06-10, 09:28 AM
Get a haynes manual IMO.
Pretty much the conclusion I came too Chris. I am not very flush at the moment and was just trying to save every penny I could.. I will pop into frauds on my lunch break and get one.
yorkie_chris
07-06-10, 09:31 AM
If you are that skint then first take tensioner out and see if it works.
With regard to changing the timing chain, I wouldn't bother....if the valves/piston turn out to be ok, I'd just replace the chain guides and the tensioner, time it up and refit.
Like Spannerman said, if the valve clearances are huge, this would suggest valve damage, (ie bent), because the valve springs won't be able to return the valves to their seats and so will be stuck "down/open".
You could be creating extra issues by engine removal and unnecessary strip-down...which if on a budget, can end up costing more money.
yorkie_chris
07-06-10, 11:51 AM
You will need gaskets for a start which are not cheap
Curvy right?
If HF don't have a Hayens, give me a shout.
Got the Haynes, £16 quid from frauds (my mate was on and put it through as trade :D) - Went to my local Suzuki dealer to try and get the special tool you need to compress the tensioner, but they said they know not of such a tool.. Either the manual ive got really is totally useless, or the bloke at the garage was totally useles.. Guess ill find out tonight when I take the tensioner out!
Will update later this evening with my findings.
yorkie_chris
07-06-10, 06:03 PM
Guy at garage is useless.
Get a dremel and a bit of sheet metal, make your own.
You do not need that until you are putting it back in, even then you can do without it (just)
Will go back to guy at garage with the part number so he cant possibly mess it up.. Its being I now need some stuff from them...
Took the plunge and took the head off in the end, the timing was well out, we had a look at the valves and piston and it looks like I got lucky (I say that, lucky would have been for it not to go in the 1st place!) and the valves and piston are undamaged! As we were taking the thing apart, it seems like someone has been in there before and bodged it right up. The thread bolts have almost certainly been out once before and re-used, so god knows what else the poor girl has been subjected too. Got a sh!t load of parts ordered up to replace everything that needs doing and also to give her a bloody big service, hopefully shouldnt need touching until her next oil change and wont need anything major doing for another 20k or so once im finished... Heres to hoping anyway. I had to dip into some savings which I really didnt want to have to do, but invest now to save problems later i spose.
Thanks for all of your help in the diagnosis of the problem, I will let you know how it goes and how well she rides once im done :) By the way.. Is there anything in particular I should be doing whilst the heads off and im giving her a major service that i may not have thought of ordinarily?
thanks
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