Post Valve Check/Shim, Running Lean

[Overlord Neil]

I've just had the valve clearances checked on my bike, currently showing just shy of 44k miles and history to suggest it was done at 21k miles. I put it into a garage as i don't have the time to do the work myself, much as i would have preferred to do it myself. The mechanic found one of the camshaft bearing seats had scored slightly and burred the valve bore so he couldn't get the shims out (of the bore either side of the bearing seat) which was slightly worrying. He's taken the burr off and replaced the shims.

I think the exhaust valves were ok bar 1 but 4 of the inlet shims required changing, all were running tight. Now I notice that the bike seems to be running very lean, which would make sense as there is now a bigger valve opening (?)

My plan was to strip the carbs, clean and balance them anyway so should this resolve the problem or is there a bigger gremlin waiting to bite me?

The mechanic also suggested changing the timing chain and showed me how slack it was, which was done.

[Tarwetijger]

Tight inlets are not uncommon. Cleaning and balancing carbs is always a good idea. Although the needletubes tend to wear and therefore run rich instead of lean.
Slackening timing chain is also very common! Not very difficult to replace.

[Overlord Neil]

I managed to spend half an hour on the bike this evening, remapped the Ignitech box back to a standard TDM850 setting, made sure all the additionals were correct, TPS settings, rev limiter, etc etc. Checked the carb balance, which was nearly spot on. Also checked over the carb assembly, top of the head to see if anything obvious had been left loose/unconnected; found the airbox to carb boots weren't tight so tightened those up and took it for a trash up the road.

It bogs horribly between 2-3,000 then does get into its stride but its definitely not happy and feels like it wants to pull but can't. When I got back (after about 10 minutes) I felt the exhaust tips and the left pipe was definitely hotter than the right, only by touch so not a precise figure but the right was hot and the left was fecking hot.

I've still got to take the carbs out and clean/refurb them, I'm starting to think they might have been partially blocked whilst the work on the head was being done, he had the bike with the head off for a couple of days.

Any thoughts?

[Overlord Neil]

After the run into work this morning, the bike sits fine(ish) at anything over 4,000 but has nothing at all between 2-3.5,000 making traffic light starts a mixture of high revs and multiple grabs at the clutch to get the bike rolling. Its also pinging on the left cylinder which would coincide with the higher running temperature.

[Rubes]

Mine has the right hotter. What do the plugs look like? You can get to both easier if you remove the radiator bolts and angle it forward. The plug spanner in the standard tool kit works well. I'd guess you get her up to temp then let her idle for a bit to check the plugs on the fuel/air mixture? Mine bogs a bit. Better after much tinkering with the mixture screw.

[cobbadiggabuddyblooo]

Try going for a short ride with the fuel tap in the prime position. This will eliminate a fuel starvation to the carbies.
Running lean so start by looking for an air leak. Vacuum lines would be my first port of call and perished or cracked inlet rubbers.
As a temporary measure you can place roof n gutter sealant over the top of the air cut off valve cover on the carbies. If no luck you can easily peel the clear silicone back off again.
Float level may be the next port of call.
If no luck, I'd be taking the cam cover off and just checking the valve clearances. If all good then you can't blame the mechanic on that 1. If they are out, then ring him and get him to fix the problem he created.
I helped a few of the lads locally showing them how to check and adjust the clearances and it's just a matter of once cylinder 1 is at TDC (compression stroke) and cams are located in the right position, check/ clearances with a feeler gauge.. Then move on to cylinder No.2 and repeat as above. You can check he has the cam timing in the right position too.
Once over the initial fear of the task they all took it on with no issues and felt confident enough to do the job.
You'll only be confirming that the mechanic got it right so will give you peace of mind that it's more so maybe carby related.

[Overlord Neil]

Pretty sure its carb related now, I've put about 5-600 miles on it since the shims were done. It runs like a 60's GP bike, absolutely nothing at all from a standing start but 'ok' when it gets over 4,000. First thing in the morning it runs perfectly then starts to play around by the time I get into work so I'm guessing any crap settles overnight then gets stirred up whilst riding.

Plan of action is to strip the tank off it tomorrow as soon as I get home, get the carbs off and apart so I have the weekend to fettle and reassemble with the new FactoryPro goodies than have now arrived, flush the tank etc etc.

I took the right (visible) air-cut off valve plate off the bike and checked as it looked like it had a stress crack on the surface, but it doesn't appear to be fully through the thickness of the plastic. Why is it that those plates are the only part not ballooned off in the exploded drawing? You can buy them individually but only from specialists suppliers (in Europe).

[cobbadiggabuddyblooo]

Sounds a bit like valve clearance issue.
AS the bike heats up the tolerance closes . If the tolerance is under spec then it's closing the gap then opening the valve just enough to leak by the time your at 15 minutes down the road at work.
This problem only started since the clearances where done...Correct????

[Overlord Neil]

Yeah, the problem has only been since the valves were checked/shimmed. The mechanic said the valves were tight and needed opening up to be within spec. Rather than take the tank off, they had removed the front mounts and slackened the rear and supspended the tank vertically, I'd deliberately run the tank low and handed it to them on Reserve so they would have an easier time lifting the tank. Hence any crap in the tank would be A; well and truely disturbed and B; highly concentrated (relatively) in the minimal amount of gas. I don't think there is an in-line filter so any crap would just get dumped in the float bowls and sucked through.

The bike runs fine first thing in the morning, but not in the afternoon. Its a 13 hour cool down over night, compared to an 8 hour cool down during the day. The bike is certainly a different animal first thing in the morning to any other time.

[dandywarhol]

Resetting the clearance shouldn't affect fuelling to the extent you mention, assuming they were correctly set. If mechanic chummy replaced the timing chain your symptoms sound like valve timing out.
My original head had 4 inlet valves at minus clearance at under 10k miles - the seats had undercut.
There should also be a tiny fuel gauze filter in the tee piece that supplies the carbs

[Overlord Neil]

Started stripping the bike down tonight and found the following:

Inlet rubbers are absolutely shot to shit, so I'm guessing since they've been disturbed they are fooked, long shot but theres no-one in the Hampshire/Sussex area with a pair of Inlet Rubbers just lying around?... Or know which other Yamaha's used the same part?

Also found a tone of crap under the diaphragm on the left carb (which is the one that was pinking) not just dust and sludge bit actual bits, not good.

The Air Filter is caked solid, its a K&N jobbie so I'll flush it with clean gasoline and see if that helps things.

The jets don't appear to be blocked, which is alarming me that there might be a timing issue (sorry for ever doubting you chaps) unless of course it is just the perished rubbers, I'll get the head off tomorrow and double check the clearances and the cam timing.

Its new oil time as well so I drained the old oil out, last time around I put a magnetic sump plug in, just because... holy mother of moses the crap that was hanging off of the magnetic tip was mildly alarming. I was going to just replace the oil, having read in the service manual that the filters can do double the oil, but after the sludge that got dragged out I think I'll stick with a fresh oil filter as well.

Oh yes and the other thing I found out is the fuel tap doesn't have a vacuum shut-off anymore, or that the filler cap doesn't seal... I got the tank off but only after drowning in gasoline. My own stupid bloody fault for filling the thing up this morning, in my defence it was very early.

[cobbadiggabuddyblooo]

The large breather tube that feeds the area above the top rubber diaphram on the carbies picks up all the shit flung off the rear wheel. Rod looked at this a few years ago and did a test after cleaning the carbies. He placed a filter over 1 breather and left the breather from the 2nd carbie open as Std .
After a 1000km the filtered carby was clean and the unfiltered had picked up a pile of rubber and gunk flung off from the back wheel.
If buying inlet rubbers, best to stick with genuine Yamaha ones. I purchased some from Germany via eBay and I found once the clamps where tightened I could still manage to pop the carbies off.
So I went and bought another set of OEM genuine Yamaha rubber manifolds and they lock down nice and tight now.
Just a note on the K&N filters, after washing don't blow them dry with air as it tears the cotton particle apart. Let them dry naturally , tapping the heavy drops out and then let it rest till dry.
Magnetic plugs are tops in my opinion and well worth it.
Good idea to replace the oil filter as it seems pointless putting clean oil through a dirty filter..

Look forward to hear how things go with the cam cover off and to see if the cam timing marks line up or clearances are correct.
Get some diesel or wd40 and pour it around where the waterpipe attaches to the top of the head. The cap head bolt the holds the 90* bend pipe in place can lock itself down nice n tight. Hopefully the mechanic replaced the o ring seal on the service...

[Overlord Neil]

Form an orderly que....



So, a week after having the bike into a mechanic to have the valve clearance checked and £350 bill... the bike is in pieces in my garage. Glaring error #1:



Top tip for anyone doing Valve Timing Chain timing... don't do it a; when you are tired/irritable b' under a self imposed timeline. Make notes, think about what you are going to do and take it easy, its actually quite simple, unless you are tired/irritable and working to a tight, self-imposed timeline! A couple of additional pointers I found useful, with the exhaust timing correct, I cable tied the chain to the sprocket so the chain couldn't slip. Second point was to think it through then mark a dot on the sprocket with a destination on the chain, so when everything was loose and apart I knew where to put the sprocket. Sounds simple enough [and it is] but I spent hours chasing my tale last night.

I can only assume that the mechanic got the timing chain on 'correctly' but didn't hand crank the engine [service manual states two full engine rotations then check timing marks again]. then by the time the chain tensioner kicked in it was all over the place... that or the guy is a total fuckwit.

With the timing chain in the correct place on BOTH cams, time for glaring error #2. I went through and checked the clearances again, the timing chain must have been 'one of those things' surely an independent professional mechanic can't have made two giant feck-ups.... #1 cylinder, middle inlet valve will 'just' get a 0.08mm feeler gauge through it... the other two will just about take a 0.10mm, not good on a 0.15mm - 0.20mm range.

I was going to put the whole thing back together and take it back to the guy to fix, but then if he managed to get it so far out the first time, whos to say it won't be worse when it comes back on round 2. I've put the Fireblade back on the insurance so I can have the TRX off the road for a while to fix it properly. I'd left the bike at the mechanics for a week and expected a proper job, what I got was a rush job the day before I came in to pick it up, so seals were 'made good' with paste sealant rather than replacing the gasket and no Cobba, he didn't replace the O-ring on the 90 degree pipe on the cylinder head, just a bit more goo. Overall, really unimpressed.

Whilst its this far apart, I might crack the cylinder head to check the valve seats, maybe even get the head gas flowed whilst its off; make it a bit of a winter project.

In short, thanks for those that gave advice and sorry for not believing it.

[Snod Blatter]

£350 for that!? Are you getting any money back? Like, say, £350 back..

[Rod.s]

Faaarrrk, this sort of shit really grates my ginger at least you didn't hit a valve and destroy the engine. As you're already in there do a once over and get her ready for Summer