For those not in the know, I was gifted an XT that had been sitting in a shed for about a year which the owner retired due to a knocking sound. When it passed into my hands it wouldn't start, due to a worn starter clutch. Thats all in this thread here: Hello from Tas :))
Getting this bike started was the initial hurdle before I could work on the 'knock', and now I've got some video samples of the sound itself I thought I'd share and see what you all think!
First thing, how did I start it? I figure this might be helpful for someone else who has a similar issue. Starter-clutch repair has been discussed before, but in this instance I was able to get the bike going without any major repairs. Simply put, even my very worn starter clutch would engage the engine at least once or twice if the weather was warm or if the bike was tilted very far to the right-hand-side (away from the kickstand). All I had to do was clean the sparkplug and charge the battery beforehand. The proceedure was simply to tilt the bike while it was sun-warmed with the choke out and hold in the starter for a while. Took a good eight seconds before it engaged enough times to fire up the engine. After that it actually started the bike pretty reliably. Some notes: When I got outside the other morning to work on it, I noticed that it was sitting in the sun and realised I might have a fair chance of getting it going. I'm not sure if it helped to loosen the dowels on the starter-clutch plate, but I had been testing the sparkplug the day prior and so was running the engine with it out. Without compression the starter clutch engaged and spun the engine, I think letting it run like this might've unstuck a spring or doodad in the mechanism somewhat as well. For reference it was about thirty degrees-celsius (86F) out when I got it going.
I will still be replacing the starter-clutch, but for those looking for a quick-fix with minimal tooling try warming the bike and tilting it (maybe even run it without the sparkplug in for a bit). Anyway, on to the topic of the thread!
Here is the bike starting from almost-cold, I did have it running for about sixty seconds prior to this (apologies for the mess, student house :p):
Importantly, this is it with the choke on at an unsteady RPM. In the video I have to occasionally pull the choke up before the bike stalls.
Here is the bike at a warm idle with the choke off:
After talking to the original owner, he said this was exactly how the bike sounded before he retired it. It had been taken to a mechanic, who had narrowed the problem to the top-end of the cylinder, but couldn't deduce much further than that.
If you can't access the video, I would describe the sound like so: Frequency: High pitched compared to the engine though not necessarily a squeal. Almost like a teaspoon hitting a tin cup very quickly. Tone: Metallic Consistency: Constant and quick tapping, seems to be in-time with the rotation of the engine. Not random, very regular. Occurs with the same timing relative to the engine every time it taps. Volume: Pronounced at idle, gets buried under the engine above that. Louder on the video than in real life (phone can't pick up bass very well). Conditions: Occurs constantly while engine is running. No trigger conditions. Other symptoms: None that I can tell. I haven't ridden the bike yet (no license till I get it working), but the owner didn't note any drop in power or altered performance characteristics as a result of the noise.
If you aren't very good at hearing engine noises, I would recommend this video here as it has some audio of an XT running normally in the background (this helped me identify the noise better, I'm not affiliated with the uploader and have no opinions on the content in the video):
Personally I think its something to do with the valvetrain. Maybe the timing chain is slapping the casing as my friend guessed? Its definitely ill, though I'm not sure how serious it is. Some people have said it might be a knock, but I don't think so. I think calling it a 'knocking' sound isn't quite right, its more of a tap.
First congratulations on getting it running! To me it sounds like a problem with the cam or rocker arms.This usually comes from running them low on oil or not opening the bleed screw after a oil and filter change. If you pull the rocker covers,you should be able to tell what is going on. It might just be a really,really loose valve. When I got mine, the valves had never been adjusted , were loose and it sounded a little like yours, tho not as loud. Good luck and keep us updated on what you find out.
Glad you were able to start the bike. From the sound of it, before you run it any further, locate the source of that noise and do whatever it takes to fix it. Something's seriously wrong. Running the bike without fixing the problem will only aggravate things - possibly to the point where a simple fix becomes a hugely expensive repair. Best of luck, and keep us posted..
"Never let your sense of morals get in the way of doing what's right." Isaac Asimov
I'll echo their suggestions... cam chain, rocker arm, huge valve clearance, low oil. I wouldn't run it anymore until you've at least checked the valve clearance and what you can access through the valve covers, and removed the oil filter to see what it looks like. The oil check bolt should produce oil almost immediately after starting. If not, the pump is bad or the passage is clogged.
Your warm idle sounds very high. These bikes are cold natured (even in 80+deg weather), so it's normal for it to need some choke to idle for the first few minutes.
This shall pass, be still and know. 2006 XT225, UNI filter, ProTaper bars, MSR handguards, SS front brake line, Shinko 241's.
We had timing chain slap on both bikes. It is most obvious at idle and can be a light knocking or clicking sound. Difficult to identify where it's coming from other than somewhere in the engine. A yellow check engine light not a red one. Fix when you can.
There are two guides on either side of the timing chain which have plastic wear surfaces. These run up against the chain. The plastic wears away and/or chips. Sometimes you can see fragments of plastic in the oil when you drain it. Pass the drained oil through a strainer to collect them.
All other comments above regarding the top end, cams, valve guides, valves, sleeve bearings, timing chain, adjustments and rocker arms should be taken seriously. If the ticking sound is valve related, you can inspect the clearance via the cover access on each side. Wouldn't hurt to make sure the top end is receiving oil as mentioned. With the cams bottomed out, I think clearance is around 0.004". Take pressure off the rocker arms and check for slop. Shouldn't feel any. Good luck.
Update! Thanks for all of your replies, and for your patience! I've been out of the house all week and managed to squeeze in some time this morning to look at the valves. The plan was to also look at the timing chain condition if I had time before I planned to leave to visit the family (about four hours away).
TL;DR: Valves were adjusted wrong, intake was set to exhaust spec and exhaust was loose. Fixed, noise improved but still persists. Rockers are fine. Oil is going around ok but the bike was ran very low at one point going off the service history. Looking more and more likely that it's also the timing chain guides. Maybe melted and ruined from the low-oil incident.
So to start I had another look over the service history of the bike during breakfast. There were a few things I spotted that I thought were interesting...
Service history findings:
One of the technicians noted that the bike oil-level had gotten very low - down to less than 200mL! As a result they recommended the owner check the oil more often.
The valves were adjusted in that same service. So they've been done at least once.
So I've firstly gotta say you guys nailed it, absolutely I reckon this situation was caused by low oil, I think I've got a case together for what happened, but before that I'll go over the suggestions from you all I was able to try out:
Answers to suggestions:
Oil seems to be getting to the top end. I forgot to test while running but looking at the bleed screw showed oil, everything else under the covers was well lubricated.
The rockers showed no side-to-side play- the bearings seem completely fine actually.
Tried the screwdriver test to see the location of the noise, its on the left side of the bike in the location of the timing chain.
On to the valve service:
Pulling apart the bike and getting to the intake covers was a doddle thanks to klm4755's thread DIY XT-225 valve adjust, with some supplementary advice from blancolirio's video on YouTube YAMAHA XT225 Valve Adjustment. Not wanting to be underprepared I also had my Cyclepedia Service Manual on hand. Really for those following this thread trying to find a solution to their problem, the klm4755's post is really more than enough on its own. The video is also just fine, note though that both might be showing off older XT models - mine didn't have the three indents but instead a marked 'T' next to a line for top-dead-centre. I thought it was scratches on my stator but the service manual set me straight
Inspecting the rockers showed they were sturdy, and the bearings were still in good nick; no lateral play at all. The *ahem* adjusted valves were a different story- check out the gap on the intake!
It was set to exhaust spec - 0.15mm... The exhaust was not only a little tight for clearance (dragging a bit much on 0.15mm) but a little loose on the locknut; I could undo it with my hand. I fixed both of those up pretty quickly.
Now the bike sounds a little better, or its running better anyway. It didn't need help not-stalling like before and came up to temp heaps quicker (sorry, sideways video and YT studio no longer lets you rotate clips):
I think the sound is a little better too, but its not totally gone. I had a look at the timing chain and span it using the starter before I put the bike back together. Looking down at the chain I think I noticed some slight wobble as it was spinning, my friend took this rather artistic slow-motion video:
While the bike was running, I did the screwdriver trick and thought the clicking was most prominent on the join between the stator cover and the radiator fins of the cylinder. I think I may have the same issue Muniac had with the timing chain guides.
My hunch is that the engine was run without oil like you all say, and the lack of lubricant/coolant carrying fluid burned out the plastic guides on the timing chain. They must've melted and gone brittle, letting the chain break free and slap the housing. I didn't filter the oil sorry, again limited time on this little expedition.
Anyway, that's my guess - but I think you all might have a better idea than I do.
Is the cam chain tensioner functioning correctly? Best I recall... you remove the outer bolt which is essentially just a plug. Insert a screwdriver and you can turn the plunger to remove tension from the chain. The plunger should be spring loaded in that, if you release it after a few turns of the screwdriver, it should spring back.
Also from memory (old CBR known for cam chain tensioner issues) is that they make the most noise under deceleration. When rev'd up in neutral, there'd be quite the clatter as it wound back down.
They also make some inexpensive bore scopes that work manually or even with your phone. One of those might be handy to look down in there and see the condition of the cam chain guides without taking a bunch of stuff apart.