Bandit Alley
MODEL SPECIFIC => SUZUKI BANDIT 250 & 400 => Topic started by: Squishy on August 13, 2012, 10:01:49 AM
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Hey guys.
Today I noticed a rattle coming from the engine area. It's not constant, but sometimes(!) happens when I let go of the throttle or apply throttle at low RPM.
The problem is that it doesn't happen all the time, I can't reproduce it.
My first guess would be the cam chain, however the b400 has an automatic chain tensioner?
I also ruled out the drive chain; when the rattle appeared I quickly pressed the killswitch and pulled the clutch and the sound immediately disappeared. I also haven't heard the above 3000rpm.
The rattle sounds like something irony is loose and vibrates against something else irony. The rattle only lasts for a couple of seconds then disappears.
Help! :( I'd rather not tear apart my whole engine (have never done this before). What else could it be?
Thanks
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I managed to reproduce the rattle and record it:
The microhpone is recording above the engine head, under the tank.
The rattle starts at about 0:19 seconds (and returns/disappears several times during the recording)
https://dl.dropbox.com/u/22072961/MF/ratel.wav
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Maybe it's just my computer, but I wasn't able to see a video or hear audio on your link.
There is an automatic chain tensioner for the cam chain. I have heard of them going bad occasionally in that they don't hold tension on the chain properly during rapid rpm transitions.
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Maybe it's just my computer, but I wasn't able to see a video or hear audio on your link.
There is an automatic chain tensioner for the cam chain. I have heard of them going bad occasionally in that they don't hold tension on the chain properly during rapid rpm transitions.
hm it's a regular .wav even works in windows media player for me.
anyway i opened the engine and the cam chain is super tight. I doubt it can cause a rattle. Or can it still rattle because of a defective tensioner?
Ps. Anyone have any tips on a tool to adjust the valve clearance? Thanks
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Like I said, may just be my computer.
Should just need a wrench, a flat head screwdriver, and a set of feeler gauges to adjust the valves. Sorry, I can't think of the wrench size off the top of my head.
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Like I said, may just be my computer.
Should just need a wrench, a flat head screwdriver, and a set of feeler gauges to adjust the valves. Sorry, I can't think of the wrench size off the top of my head.
my smallest wrench ifs 4mm and too big
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Hey Squishy
Yup...don't likel the sound of that. It does sound somewhat like a loose cam chain, but could also be a bunch of other things:
1. Check all the exhaust pipe bolts, especially those that attach the exhaust to the engine,
2. Check for loose engine mounts and bolts.
3. Check the starter and alternator mounts
Does it go away when you pull the clutch in with the engine running?
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Hey Squishy
Yup...don't likel the sound of that. It does sound somewhat like a loose cam chain, but could also be a bunch of other things:
1. Check all the exhaust pipe bolts, especially those that attach the exhaust to the engine,
2. Check for loose engine mounts and bolts.
3. Check the starter and alternator mounts
Does it go away when you pull the clutch in with the engine running?
1. I did a quick check before but will check again
2. Already checked engine mounts
3. Haven't checked those. Can't check for another week (holiday)
The sound does not disappear with clutch engaged..
Thanks!
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Okay, some days later.
Checked the valves. Some are slightly off but I doubt this can cause the sound. When valve clearance is wrong it should always make a rattle, right?
I checked all mounts and all 4 exhaust pipe mounts, checked starter and alternator mounts. Everything seems to be solid.
I haven't put everything together as I'm still waiting for gaskets. So in the meantime;
How do I check if the automatic tensioner still works? Does it have "teeth" so I can check whether it's at its last teeth? Can it get stuck? The manual is vague and only mentions I can reduce the tension by turning the bolt.
Finally, how tight is the chain supposed to be? Mine hardly has 0.5mm slack.
Thanks
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Bump.. Still haven't figured it out.
How do I check whether my automatic tensioner still works? Or whether it's at the end and can't tension any further?
(https://dl.dropbox.com/u/22072961/MF/NAK2.jpg)
(https://dl.dropbox.com/u/22072961/MF/NAKS.jpg)
Thanks
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Right, if you have clear access to the tensioner this shouldn't be too hard. You need to remove the rubber bung at the back of the tensioner, then insert a screwdriver to hold the screw inside in position. Don't turn the screw left or right (you may need a little helper to hold this for you).
Next undo the two allen screws. The tensioner unit will slowly push it's way out, but remember not to let the screwdriver turn or the screw turn.
Once the unit is out of the bike you can let the screwdriver turn, but make sure it stays on the screw head. This will tell you if you have any more travel in the unit, and/or if the spring inside is broken.
If all is well the tensioner will want to push outwards and spin the screwdriver with a fair bit of force.
To refit the unit you need to screw the "pusher" all the way back into the unit (you'll see what I'm on about when you remove it). Now you need to keep the tension on the spring with your screwdriver as you line the unit back up with the engine, and bolt it back in position. Now let the screwdriver turn and the tensioner unwind :thumb:
If it doesnt' start turning the screwdriver by itself give it a little hand as you may have backed the screw out enough to get it a little tight.
Again you'll understand what I mean when you have a go at it :beers:
Hope this helps and I'm sorry if it's a bit vague.
Bullet5. :grin:
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Thanks. So there is no "teeth" like some other bikes where it skips to the next one until there's no more teeth?
Before I do this... wouldn't my chain be loose if the tensioner wasn't working properly? The chain seems really tight (max 1mm play).. this is OK right?
Also won't I need a new gasket for the tensioner?
thanks!!
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Yup this is what it looks like:
http://www.ebay.co.uk/itm/SUZUKI-BANDIT-GSF-400-GSF400-1991-1992-91-92-CAM-CHAIN-TENSIONER-CHAIN-BLADES-/150870786637?pt=UK_Motorcycle_Parts&hash=item232099824d
No teeth are used, it's just a wound up spring inside that can snap. It is possible to open it up and fix it but it requires some work :thumb:
No you don't need a new gasket for the tensioner aslong as you are careful removing it.
And it depends on where you are judging this "slack" If you think about it, the only place in your engine there will be slack is between the bottom cam chain sprocket burried deep in depths of the engine and the rear (inlet) cam. You can't judge the tension of the chain by simply pulling up/down on the chain between the inlet and outlet cam sprockets. :wink:
Bullet5.
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Yup this is what it looks like:
http://www.ebay.co.uk/itm/SUZUKI-BANDIT-GSF-400-GSF400-1991-1992-91-92-CAM-CHAIN-TENSIONER-CHAIN-BLADES-/150870786637?pt=UK_Motorcycle_Parts&hash=item232099824d
No teeth are used, it's just a wound up spring inside that can snap. It is possible to open it up and fix it but it requires some work :thumb:
No you don't need a new gasket for the tensioner aslong as you are careful removing it.
And it depends on where you are judging this "slack" If you think about it, the only place in your engine there will be slack is between the bottom cam chain sprocket burried deep in depths of the engine and the rear (inlet) cam. You can't judge the tension of the chain by simply pulling up/down on the chain between the inlet and outlet cam sprockets. :wink:
Bullet5.
Hm.. Well how else would I know whether my cam chain is worn (=too long) and I need a new one? My 400 has done 60000KM btw.
The sprocket doesn't look worn at all
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The sprockets are tough as old nails, they aren't going anywhere fast :motorsmile:
The chain stretches as it gets older, so the only real way to check if it's within limits is to accuratly measure the distance between a set number of pins (the distance and number of pins will be specified in the manual for your year bike).
Hope this helps,
Bullet5.
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The sprockets are tough as old nails, they aren't going anywhere fast :motorsmile:
The chain stretches as it gets older, so the only real way to check if it's within limits is to accuratly measure the distance between a set number of pins (the distance and number of pins will be specified in the manual for your year bike).
Hope this helps,
Bullet5.
Yes, I measured the length exactly like mentioned on the picture in my manual, which is 21-pins. I measured 139.85mm with a digital caliper and the limit is 143mm. I thought it couldn't be right or can the chain really stretch 3mm more?
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3mm takes a long time. The chain should be fine :)
The distance between each pin is 6.66mm (at present) so 3mm more stretch is quite a lot really :beers:
I'll play the sound link to my old man later and see if we can knock some ideas up as to what it is.
All the best,
Bullet5.
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3mm takes a long time. The chain should be fine :)
The distance between each pin is 6.66mm (at present) so 3mm more stretch is quite a lot really :beers:
I'll play the sound link to my old man later and see if we can knock some ideas up as to what it is.
All the best,
Bullet5.
Ye that's what I meant.. I thought 3mm was a LOT and figured it couldn't be right? (--> What is the default length between each pin?)
Thanks!
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I'm not 100% sure on that one as there is no specified measurement in any B4 manual.
I do however have a brand new DID Cam chain I'm fitting to my B4 VC of which I can check the lengths, but this will be a minimum figure not an "ideal" figure as the chain is new and will stretch quickest while it's bedding in (first few thousand miles).
I'll try and have you a figure for my new and "old" chain (no idea how many miles that chain has done) by this evening. :wink:
Bullet5.
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Right, well seen as both of my cam chains are still out of my engine (thanks a lot Wemoto :rant2: ), I've been able to measure them for you.
I had an assistant hold the chain on a work surface while I measure it with some mechanical verniers. I measured 141mm for 21 pins, from the center of each pin. This actual value may be a tiny bit either side, but only by perhaps .5 of a mm at most.
Quick note though, my engine is a VC varient '93 so the chain may be a tiny bit different (wouldn't have thought so, but there's nothing online to suggest they didn't change that too) :stickpoke:
So if yours is actually 139.85mm then that sounds alright to me. Afterall, a chain can't get shorter :bandit:
Hope this helps somewhat.
Bullet5.
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Right, well seen as both of my cam chains are still out of my engine (thanks a lot Wemoto :rant2: ), I've been able to measure them for you.
I had an assistant hold the chain on a work surface while I measure it with some mechanical verniers. I measured 141mm for 21 pins, from the center of each pin. This actual value may be a tiny bit either side, but only by perhaps .5 of a mm at most.
Quick note though, my engine is a VC varient '93 so the chain may be a tiny bit different (wouldn't have thought so, but there's nothing online to suggest they didn't change that too) :stickpoke:
So if yours is actually 139.85mm then that sounds alright to me. Afterall, a chain can't get shorter :bandit:
Hope this helps somewhat.
Bullet5.
Thanks a lot for all your effort. I guess it's possible but it does have 60.000km on it. I redid the measurement a couple of times and even on the mechanical on it was 140mm...
Perhaps the rattle isn't caused by the chain - but then I don't know what else it could be. I'll redo the measurement for the chain the next time I can just to be sure.
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It's alright bud :beers: I've got a bit of free time on my hands anyway.
Have you checked the tensioner yet, and have you drained the oil recently? If there's any metal filings in it you know you're in trouble.
We'll find the cause one way or another :grin:
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It's alright bud :beers: I've got a bit of free time on my hands anyway.
Have you checked the tensioner yet, and have you drained the oil recently? If there's any metal filings in it you know you're in trouble.
We'll find the cause one way or another :grin:
I've drained the oil 2000km ago.. but will do it again as soon as I can (i'm not at my bike right now).
Anyway bandit 600 and 1200 I think have 'teeth' in their automatic tensioner so when you open it you can check whether it's on the 'last' teeth - and therefore can't tension any further.
Does the 400 have this kind of tensioner? Where the spring pushes the tensioner and then it clicks into a teeth?
like this:
http://www.youtube.com/watch?v=iu9ahRl2NXg&t=1m28s
edit: Though from what you said and what my manual says it would be more like this one:
http://www.youtube.com/watch?v=eGr9aMAg6dU&t=1m7s&hd=1
So basically I could turn it anti-clockwise and manually make it tighter?
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Yep, it's just like the adjuster in the 2nd link :thumb:
I would not advise you to manually tighten it as you may get it stuck, then the chain will run far too tightly and you'll rapidly wear the guides and increase wear rate of the chain.
I know you've said you've checked the valves, but they can cause a right racket. Get them all dialed up exactly the same while you've got the cover off. :)
Another think to check is oil on the bearing plates for the cam shafts. If they're not getting enough oil or a feed line is blocked that can cause a issue.
The next thing I would do is make sure that all bolts on the bike are tightened up correctly. Something like a loose battery box or rectifier could cause a horrible noise. Make sure nothing can vibrate against any other part of the bike.
My only other thought is piston slap, but that really shouldn't happen yet as the engine only has 60,000km on it so unless it's been abused all it's life that shouldn't be the case.
As I said before though, if there's any metal in the oil then we know it's something in the engine causing the noise, not just some other part of the bike vibrating, which it could well be seen as it only happens at low rpms.
Bullet5.
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Okai.
Well, I wanna rule out the cam chain adjuster. (since from the sound, location, behavior @ low rpm it's my first guess)
What if I turn it clockwise, as said in the manual. Would it snap back into position if I release the screwdriver like on the 2nd youtube video? This way I know it's not stuck/malfunctioning. Right?
Perhaps I can give it 1/4 turn tighter just to make sure it's not the cam chain? (I doubt 1/4 turn can do much harm?)
Yes I've checked and adjust all valves. Some were tight (e.g. 10mm barely fit through some intake). But like I said if the valve clearances were off it should've rattled all the time?
I've got everything off (tank, carbs, ignition coil, waterpump, radiator, etc.) and checked for any loose parts.. engine mounts, radiator mount, battery, shock, couldn't find anything. Then again I'd say the sound is coming from the engine area (or waterpump).
Engine's not been hammered. Carefully ridden by previous owner and I always make sure it's warm before revving it.
I'll drain the oil next time.
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Yes you can turn the adjuster clockwise to see if it springs back, but remember it won't give much of a kick as it's being pushed by the guide and chain. :)
Yup, the valves would've made a continous rattle, and if they were tight they'd actually have been quieter upto a point. If you couldn't hear the valves then something would be wrong :thumb:
Ah! Water pump. Now that could be the answer. With 60,000km of miles under it's belt those bearings may be on their way out, but again it's just one of many possibilities. :sad:
The engine doesn't sound very healthy at all in the video you posted. Even if you've got the standard exhaust on (which I hope you have) it shouldn't make that much of a racket.
I really hope that oil is clear.
Bullet5.
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The engine doesn't sound that rough at all in real life.. It's because I used my mobile-phone very close to the engine. Yes I have an aftermarket exhaust but the engine sound is way louder than the exhaust sound in the recording.
One more thing.. does the waterpump pump continuesly or does it get triggered at a certain temperature? (since the 400 is officially water/air/oil cooled)
Will report back in some days (might be a while) but I'll have some days off soon.
Thanks for the help up to now :)
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Glad to hear it! That did sound like one very noisy motor :bigok:
If the water pump didn't run constantly then you'd have steam forcing it's way though gaskets. :thumb:
I believe it speeds up when the revs increase, and once the engine gets warmed up the fan cuts in aswell to help cool it down.
Look forward to hearing your findings.
Bullet5.
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I just thought about what you said about the cam chain having only slack at the bottom of the chain.
Well, I think it's possible to measure the slack at the top because if you'd push the chain at the top (between the two cams) the cams could just rotate and allow for slack. The cams aren't fixed?
Ps would you say I need a new enginecover gasket? It's only half a year old
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Indeed the cams aren't fixed however they are held stiff by the valve springs pushing on the lobes. :thumb:
You'll have one hell of a job trying to turn a single cam by hand.
As long as the gasket isn't damaged/ripped then it's fine to reuse it, so long as you make sure it and the mating surfaces are perfectly clean.
Bullet5.
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Well, today I checked the tensioner. Turned the screw a little clockwise and noticed the slack increasing on the chain. When I stop turning I can feel the tensioner wanting to turn back left. When I let go the tensioner snaps into place, just like on the movie (http://www.youtube.com/watch?v=eGr9aMAg6dU&t=1m7s&hd=1). So, the tensioner seems to work. Here's a movie on the chain slack https://dl.dropbox.com/u/22072961/MF/NAKS.avi.
Anyway, I re-checked the valves and put everything together. The bike fired up and luckily nothing exploded. However the rattle is still there :(.
I haven't drained the oil yet.. I said before the rattle isn't constant, but I can now pretty much reproduce it at ~2000rpm. It does really sound like the chain but it's super tight and the tensioner seems to work :stickpoke:
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Hi Squishy sorry for not posting up sooner but with bullit5 being so helpful i kind of left you guys to it,
anyway i can not listen to the rattle because my laptop is crap but looking at the picture of the chain and cams i think the cam chain shows signs of damage.
If you look at the middle links there looks to be silver marks on the otherwise brown/gold chain.
if this is correct and not just light/reflection i would take a closer look.
Also check the guide that is fitted to the cam cover.
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Hi Squishy sorry for not posting up sooner but with bullit5 being so helpful i kind of left you guys to it,
anyway i can not listen to the rattle because my laptop is crap but looking at the picture of the chain and cams i think the cam chain shows signs of damage.
If you look at the middle links there looks to be silver marks on the otherwise brown/gold chain.
if this is correct and not just light/reflection i would take a closer look.
Also check the guide that is fitted to the cam cover.
Hi Chris,
No need to apologize, thanks for the help :grin:
You're right, there are signs on the cam chain.. However I just thought it looked like some of the coating or whatever came off from age. Or would you say the white spots can only be the result of metal vs metal ?
I've looked turned the crank several times while looking at the chain and because it's so tight I really wouldn't know where the chain could rattle against.
(https://dl.dropbox.com/u/22072961/MF/NAK.jpg)
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The cam chain simply stretches with age and should not show marks.
I would take the tensioner off and have a good look around with a light.
Look in the hole that the tesioner fits in and around the guides.
i had a similar thing happen to me when a cam sprocket bolt came out and luckily wedged against the top guide, made a hell of a rattle as it keep rubbing on the cam chain.
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The cam chain simply stretches with age and should not show marks.
I would take the tensioner off and have a good look around with a light.
Look in the hole that the tesioner fits in and around the guides.
i had a similar thing happen to me when a cam sprocket bolt came out and luckily wedged against the top guide, made a hell of a rattle as it keep rubbing on the cam chain.
Will do... will open it up again anyway.
Anyway as said, I measured the chain and it's 139.8mm while 143mm is the service limit.. this should mean the chain isn't worn yet?
I will re-measure and make a picture this week.
I'd rather not remove the tensioner as I would have to re-do the timing..or is it very easy?
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Haha thanks squishy :beers:
The timing is very easy to check. :thumb:
To alter/check the cam chain timing you'll need to remove the tensioner, the inlet cam and maybe even the outlet depending on how much out of sync (if any) it is.
However to check the timing on the B4, you remove the front left engine casing, then remove the right side engine crank cover (the little round cap in the middle of the side casing tha screws off), put a socket drive on this and turn the engine over(clockwise) until the timing mark under the left cover lines up with the arrow on inside of the engine (once you see it you'll know what I'm on about).
Next you'd remove the rocker cover, and check the cam positions against your manual specs, and the number of pins between two points on each cam.
Nice simple job. :grin:
Bullet5.
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Guess I'll have to drain the oil first before removing the left engine cover? And you have to remove the cams because you can't turn them while in place because of the valves?
Btw, if you look at the picture of the camchain I posted before, you can see the left bolt also has the "white damage" like the chain, and no way the inside of that bolt could hit something and be damaged.
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Yes you'll have to drain the oil, as you need to be working on both sides of the engine.
Sorry, I made that rather hard to understand. No you don't need to remove the cams while you're checking the timing, but if the timing is out you will need to remove the top clamps to be able to move the cams.
I believe you're right about the bolt. If filings were hitting the cam sprocket then there would be damage on other parts of it too.
Still best to check out the chain and surrounding area though, while you've got it in bits. :thumb:
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Sorry for the silence! I've had some problems on the way .. a mate of mine snapped one of my sparkplugs when turning right rather than left :duh:. Also one of my valve clearance adjuster nuts was dead and I needed to buy new ones.
Well anyway.. I had a mechanic listen to my rattle and he immediately said it was the automatic cam chain tensioner.
I decided to buy a manual tensioner, also when reading about here were some said the automatic tensioner would reach its end before the cam chain was actually worn.
Well I measured the cam chain and it seems fine according to the manual. However maybe I should've also checked the timing marks. But I guess the timing won't go off critically as long as the chain is within this limit? :
(https://dl.dropbox.com/u/22072961/MF/2013-02-02%2019.56.34.jpg)
So fast forward to solving the stupid sparkplug problem and getting new valve clearance adjuster nuts:
(https://dl.dropbox.com/u/22072961/MF/2013-02-17%2017.05.02.jpg)
I just did a 30min ride and she runs really good and pulls like it should. I haven't heard the rattle since changing the tensioner so so far so good!! I really hope this solved the problem.
I just hope I tensioned the tensioner right.. What I did now was tension it in such a way that it doesn't rattle idling and revving it. I have no idea how thin the margins are on a good tensioned cam chain. It's now maybe 1/4 turn tighter from the point it stops rattling. Does the chain get tighter or looser as the engine warms up?
Thanks
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Squishy,
I just picked up my second 400, and it has the same mysterious noise you mention. Where did you get the manual tensioner, and was it a bolt in did it require any modifications.
two months down the road, have you experienced any issues?
Thanks,
Eric
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Squishy,
I just picked up my second 400, and it has the same mysterious noise you mention. Where did you get the manual tensioner, and was it a bolt in did it require any modifications.
two months down the road, have you experienced any issues?
Thanks,
Eric
Hello Eric,
I bought the tensioner on Ebay:
http://www.ebay.com/itm/MANUAL-CAM-CHAIN-TENSIONER-SUZUKI-FRONT-91-93-GSF-400-BANDIT-GSF400-92-1993-1992-/140904106511?pt=Motors_ATV_Parts_Accessories&hash=item20ce8a0a0f&vxp=mtr
It was a direct bolt-on - very easy. I had the rocker cover off but I don't think it was necessary.
I turned the tensioner with my fingers until it I felt tension and started her up.
According to a guy who is well known in my country for being very experienced, a manual tensioner should rattle a little bit with a cold engine. I waited for the engine to warm up a bit and set it so that the rattle just disappeared. Apparently over-tight is at least as bad as too lose. Now it rattles a little when I start her up but it disappears when the engine is warm (<5min).
A bit scary to turn it while the engine is running but I think (hope) it's OK now.
I've only ridden my bike for about 75 miles since (winter lasted more than 5 months) but the rattle has disappeared when it normally would be noticable within 1 mile. So, I hope it won't explode soon :bandit:
Hope that helps.