strage power delivery

[jmw76]

Hi Guys,
I have finally rebuilt the GSXR engine in the JMW.
I ran it last weekend and it has this really strange poer delivery symptom.
When you open the throttle and start to load it up with a few revs it develops this rhytmic power delivery feeling. It's hard to describe. It feels a bit like a drive chain with a tight spot in it where the power is delivered in a not so smooth fashion. There is a feeling of some sort of resonance that builds up of only a few hertz (cycles/second) that appears to be directly tied to engine speed (not road speed).
The engine doesn't appear to miss at all, it just has this rhythmic feel and is not developing it's full potential (maybe only 90%).
I have played around with the carb jetting a little and retarded the ignition timing a few degres but the problem persists.
My carbs now sit at a slightly higher angle on my custom manifolds. Maybe there is some float bowl flooding (floats too high) that is causing the symptom.
Another theory is that now that I have increased oil pump capacity I may be getting some sort of oil surge in the cooling circuit through my head oil coolers.
Has anyone ever had experience of a similar symptom?

All input welcome.

Peter.

[Hillsy]

Have you checked / changed the emulsion tubes in the carbs? They tend to wear oval over time and then supply erratic fuelling under partial throttle.

A real common problem on FZR/YZF's, but it can happen to any bike over time .

Also, have you balanced the carbs?

[jmw76]

Thanks.

The problem is not with the emulsion (needle jet) tubes. The symptoms occur from partial through to full throttle. It is a problem that wasn't present prior to the engine blow up.

Changes for this rebuild include the following:
- dot head
- higher CR, now at a genuine 13:1
- low dome height pistons (Wiseco 81mm - CK101 kit)
- new intake manifolds (carbs now angled at 24 degrees to vertical. A change of about 10 - 12 degrees from std)
- higher capacity oil pump (cooling - head circuit up by 40%)
- ignition timing set 2 degrees retarded from std (based on expectation of more efficient combustion from modified head)
- colder J10A plugs (new)
- float height set at 20mm (to lower fuel level to compensate for higher carb angle)

Has anyone ever experienced mild detonation on a GSXR 1100. I have checkled plugs and they are not showing an signs of problems in this area but was woundering if this rhythmical fault could be due to detonation. It is not random. It is very regular. So I suspect probably not detonation related.

Any other ideas?

Peter.

[Hillsy]

Try a hotter plug? What's the stocker - 7 or 8 isn't it??

[jmw76]

Stock plug is a J9A.
Why do you think a colder plug would cause this?
I have been running J10As with the old (milder) config without problems. I selected the colder plug as a bit of insurance against detonation.
I wouold expect a plug problem to give a random misfire symptom. But I may be wrong.

Lean surge?

Lower fuel level with greater angle carbs sounds like two negatives to me.

[jmw76]

Plug colour is certainly not indicative of running lean. If the float level is any higher it will just flood.
I did try higher float levels and bigger mains (up from 140 to 150) plus lifting the needles one notch (4th clip slot from the top). It made no noticable difference.

[Dynomutt]

What carbs are you running? If you are running the stock Mikuni BST CV carbs then set you float height back to stock 14.6mm+/-1mm. dropping it to 20mm is too far. Start at the stock setting and work from that. You may well find that the fuel level is too low and the surging is caused by the mainjet not being immersed in enough fuel. The DOT head does sit the carbs at a different angle, but the float height remained the same. so first off try resetting the float to stock heights and work from there. Leave the ignition a couple of degrees retarded, this will help prevent any detonation, make sure you run on as high an octane as you can get. I suffered detonation on my 650 when I built it, I cured it by using some different plugs which had a slightly protrusion on the nose, this put the spark further into the cylinder enough to let the burn complete before cylinder pressure rose enough to cause the detonation. Get the bike on a dyno and check out what it is actually producing and what the fueling is doing.

[jmw76]

Carbs are RS40's as detailed earlier. What exactly did your 650 do when you detected detonation?
From my understanding detonation is a quite random event and makes a rattling noise (if you can hear it above all the other GSXR oil burner noises).
The symptom I get is very regular and repeatable. It is almost like a tight chain or wheel bearing but is connected to engine revs not road speed. You can hear it on the exhaust as a rhythmical note. It just doesn't sound smooth and crisp.
Despite all this, I still had 3rd FTD at Winton last Sunday.
If the engine was running properly it would have been much quicker.

[Dynomutt]

You'll know the sound and feel of an uncontrolled ignition which is all that happens with detonation. As the spark ignites the mixture the piston is still moving upwards towards TDC, the flame front on the ignited mixture moves across from the plug tip outwards towards the cylinder edge.
The rising piston and expanding gases cause the pressure to rise quickly enough and high enough to cause spontaneous ignition of the as yet unburnt mixture at the edge of the cylinder.
This then causes the second uncontrolled flame front to collide with the advancing spark derived flame front, which causes the piston to be rattled.
It is this sound and vibration which is also known as 'knock'
It will cause damage to and ultimately failure of the piston, evidence is usually a nibbling of the edge of the piston crown in the point farthest away from the spark plug tip, usually the valve pockets for the exhaust valves.
In many cases it will nibble down the side of the piston and burn through behind the rings, which is when you start getting all your oil blown out through your crankcase breathers.
In severe cases the vibration will cause a catastrophic break up of the piston, which is the messy bit.
Cures for detonation are numerous, lower the compression ratio, use a fuel of sufficient octane rating ( knock resistance) retard the ignition timing a few degrees ( this reduces the distance the piston has to travel after ignition to TDC and lowers to pressure build up in the cylinder giving the flame front enough time to move all the way across the piston crown and completely burn the mixture)
In my case I used plugs from a ZX12R CR9EKPA instead of the CR9E, the ZX12R plugs have a protruded nose electrode and placed the point of ignition further into the cylinder and closer to the edge of the piston crown, thus giving the flame front a small headstart and allowing completion of the burn before the cylinder pressure rose enough to cause detonation. I did however lose a set of pistons to detonation when I first built the motor.
Damage often occurs to the bigends and main bearings as well, as the vibration is transmitted down the rod and vibrates the crankshaft. It is a very destructive event.
It doesn't sound like that is your issue though. What were the dyno graphs like when you had the bike set up? You may just have a resonance occuring at a certain point, you could try raising the needles to richen the midrange slightly which will alter things slightly and may be enough to stop it. What figures you are dialling your cams in to?
I would also change your float height 20mm is too low, if anything you need to increase the fuel level if the carbs are tipped over slightly, I would go 1mm to 2mm below stock witht he float heights which will raise the fuel level slightly, it may be that the pulsing is due to a lower than optimal fuel level for the mainjet causing fuel cavitation below the jet.

[jmw76]

Some interesting thoughts.
The engine has not seen a dyno at this stage.
The standard float level for the RS40's is 17mm.
I might try playing around with the float levels.
I am running needle valves with viton tips as I have found these are less sensitive to vibration and hence flooding in my application.

I am currently running 98 unleaded fuel with a dose of Nulon Pro Strength octane booster to give me a little more detonation protection. I do not think I have detonation and I plan to ultimately drop back to straight 98 fuel.

I was wondering if the octane booster might be the problem. I have never used this stuff before. I have used Tolulene and it didn't give any problems previously.

This motor is only built for racing. It never sees the road. My race car is not street legal.

[jmw76]

I forgot to add.
When the car was running (prior to rebuild) I ran a float height of 18mm.
After assembly of the engine and first start, I had to change the float height to 19mm to stop uncontrollable floading (fuel was dripping out everywhere). THis is actually the height that I ran at Winton. I changed to 20mm at the end of the day in despiration but did not run the vehicle with that setting on the track, so I am unsure what the effect might be.

[Dynomutt]

Try dropping back to 18mm and see what happens, if it is no different then at least the float height can be ruled out. If something has only happened since doing something I would revert back to how it was prior to that happening.
What ignition system are you running?
I'd look at around 36BDTC to 34BTDC with 13.5 comp, and see how that feels.
Ultimately the dyno is the best place to see what is going on, although I realise that as your motor is in a car that may not be easy to find someone with a dyno capable of running it and whom also has an understanding of tuned GSXR motors and Mikuni RS flatslides. One more thing are you running the carbs open/stacks or with individual filters? I've found some filters can obstruct the airjets on RS carbs which floods them really easily, simply notch out the offending area of internal lip to clear the airjets.
I saw some cheap foams ones on a mates 1216 RS38, the dyna limiter was set to 8K whilst he was running it in, and after I put it on the roller to check the fueling, the limit was raised to 10K and it still felt like it was limiting at 8K, even tried another dyna 2000 box and the same thing, it was then I found the foam filters blocking the airjets, and making the bike go massively rich at 8K causing it to feel like the liiter was cutting in. Just an odd coincidence, that I've never seen since, but had me scratching me arse for a few moments.

[jmw76]

Running std GSXR 1100 J ignition system. Never given any problems in the past.
I will try a few different float levels when at the track next.
Using K&N style single pod filters. The rubber mounts do not in any way obstruct the pilot/air bleed jets.

A thought I had is that maybe vibration is an issue. The new manifolds are fabricated in Aluminium with a silicon adaptor hose to the carb spigot. I will check to ensure that the carb can not directly recieve vibration from contact with the Al manifolds. There should be a slight gap so support is only by the silicon tubes.

[Dynomutt]

From your last post I now realise that you are not running the stock GSXR intake boots. These ally/samco spigots you have made how much longer than the old mountings are they? Increasing the length of the intake tract will change the requency of things somewhat. I've just built an FZR1066 hybrid motor which is fitted into a Genesis frame using FCR39 carbs, the intake tracts had to be lengthened to let the carbs clear the frame rails, this has caused a change in the frequency at and just off idle, almost like a sort of wobb wobb wobb wobb rythmic affair ( apologies for the less than musical nature of the description). This may be what is happening with yours but higher up the range. Changing the lengths of the intake tracts can have a pronounced effect, it can lead to more fuel drop out on a cold engine when starting, and a change in the intake charge velocity.
On the FZR hybrid I had some 60mm extensions welded onto the original intake stubs which I then blended in to the same finish and made into a smooth transistion internally, the bike will be going on my dyno in a couple of weeks, there is enough margin in the extensions to be able to shorten the inlet tracts by upto 20mm if needs be.
Is it possible to refit some GSXR 40mm intake rubbers to you engine? Ideally your new intakes would put the needle twice the distance from the valve face, as it was on the stock bike, this is to ensure that the intake pulses arrive at the valve as it starts to open. There is an equation to work out the best length of intake tract, however you can shorten them or increase them by multiples of 2, or 4 etc rather than odd numbers. If you have an intake tract of 200mm and the pulse travels along it once, by shortening it to 50mm the pulse will travel along it 4 times but will still arrive when the inlet valve is just opening. Norton discoverd a similar thing back in the early 90s with the rotary, and worked on a specific distance between the needle and the rotor tip, it is a siilar formulea to making expansion chamber tuned lengths. Easiest way is to use the double method, so you want you intake to be twice as long as the stock one if it cannot be the same as stock.

[jmw76]

Hi Dyno,

Interesting thoughts on the inlet tract length.
My inlets are about 10mm longer than standard.
I had been working on keeping the overal inlet length (manifold, carbs & ram tubes/air cleaners) about the same length. I realy didn't give any thought to the location of the needle/jet. Maybe this is an issue.
I like your wobb wobb wobb wobb rythmic description. I would have desribed my problem more like RrrrRrrrRrrrRrrr with a frequency of a several hertz that kicks in under load and when the revs get to 6000+.
I can probably take 5mm or so off may intake stub length without too much drama.
I think initially I will try to play with different length ram tubes to tune out the resonance.

I did check to ensure that vibration transmission to the carbs was not an issue. I am comfortable this is not a factor.

Cheers

[Hagarr]

Aftermarket manual cam chain tensioner??

Tension too tight?

Burr on the gears?

Maybe I'm missing the point but why do you think a harmonic sound would equate to cylinder pressure or fuelling issues?

[jmw76]

Hagarr,
Thanks for your thoughts.
I am runing the std cam chain tensioner. Brand new cam chain and all the gears appear to be in good order.

I am not really hung up on looking at fueling issues, but I am struggling to find some logic to explain the strange sypmtoms.

The rhytmic sensation only happens when the engine is loaded up with a few revs on (6000 rpm+). At low revs and at light loads/light throtle the sensation is not there.
Based on this, I have ruled out obvious things like wheel bearings, tight drive chain, tight cam chain, etc.

The problem is also very even, though rhytmical, which tends to rule out random/irregular events like ignition misfiring, detonation, etc.

It is so predictable and repeatable. Bring the vehicle up to 6000 rpm in 3rd gear under acceleration and it appears. Lift off the throttle and it disappears. Put some throttle on again and it comes back. Power is down a bit, but it still pulls hard when you give it heaps.

I hooked onto the idea of the problem being fuel related when I read somewhere that high float levels gives a wet, rhythmic, soggy feeling under acceleration. This is the closest description that I could get to what I was observing.

All other thoughts would be greatly appreciated.

Peter.

[Benz]

How about the air side? Maybe a vacuum pipe is blocked/bent, or the air feeder to the diaphrams is restricted somehow, making the diaphrams pulse? Or the air tubes to the float bowls are restricted.......maybe.....
You might have low vacuum/leakage on the engine side that is fucking up the carb/diaphram regulation, but only in a small range. Just my 2c.

[Dynomutt]

No diaphrams on Mikuni RS40 flatslides.

[jmw76]

Thanks guys.
RS40's are flat slide, 40mm carbs with no vacuum diaphrams (designed for high performance applications). THere are no vacuum tubes that go anywhere. THe intake system is really quite simple.
I just checked the lengths and the new manifolds are about 20 - 25mm longer than the original rubber units. Unfortunitely it is not easy to go back to the original set up. THe reason for build these new manifolds is primarily because I did not have a set to work with the DOT head and the RS40s.
Here is a link to some pics of the engine details
http://s1085.photobucket.com/albums/j427/pwstone/JMW%20race%20car%20technical%20details/

Check with mikunioz.com.au for a set of Mikuni manifolds. They are very close to the standard length.

Can you easily change your exhaust length?

[jmw76]

The problem I now have with changing intake manifolds is that the head and manifolds have been modified as an assembly.
I would have to make changes to any other manifolds I fitted.
I can shorten the current ones a little.
The exhaust system is not easy to change, since there is a lot of chassis tubing you have to work around.
The exhaust is exactly the same as it has been since the vehicle was built back in 1997.
Do you have a reason for thinking the exhaust is a concern. It is probably a bit restrictive. It might be costing me 1 bhp in 170 or so.

Along with intake length, exhaust length is another useful tuning aid.

[jmw76]

Well after a lot of research, I am still stumped to explaine this strange behaviour that I experience on my GSXR engine.
I understand that intake and exhaust tuning can make a difference to the power delivery curve but I have not had anyone who can confirm what really could be causing this strange symptom.

I am back at the track in a couple of weeks. Maybe I can track down the problem then.
I will also see what tests I can conduct away from the track to eliminate a few things.

Any other ideas out there????????

[TurboKat]

Turbocharging ? ;)
Seriously though Peter, that thing of yours is screaming for a turbo, with bugger all space restriction it would be a lot easier to fabricate the manifolding, etc than a bike.
MMMMM... 300 HP. [:p]

[jmw76]

Yep.
Turbocharging or supercharging has crossed my mind on several occassions. The problem is that it bumps me into a differnet class for some events. Currently I sit comfortably in the under 1300 Formula Libre class.

Anyway, I have performed another simple test today.
With no load, I progressively lifted the revs through to just over 6000 rpm. Guess what! The problem does not occur. It gets a bit fluffy but that is likely due to the mixture being not quite right at very light throttle openings and lots of revs.

This test tends to rule out a number of mechanical issues such as tight cam chains, oil pressure surging issues, alternator issues, etc.

I am now back to focussing on fuel. My favorite theory at present is that I am getting some mild detonation issues due to the high CR. I am currently toying with testing this at our next track day on the 13th of March by using a high octane racing fuel. If the problem disappears then I guess I have the answer. Then the only issue is do I continue to pay mega bucks on fuel every time I race or do I just lower the CR.
Maybe 13:1 is just too high for an old GIxxer with a 750 head.

Has anyone else had issues with CRs being too high for the fuel?

I know the F3 guys have to run exotic fuels to cope with their 15:1 CRs on their restricted engines.

Peter.

[Dynomutt]

It's unliely to be detonation, the symptoms you describe are not those of an egine suffering uncontrolled ignition events. Detonation is random rather than rythmic. Retard the ignition timing by 4 degrees and run the bike, that should rule out any detonation or pinking. You can simply slot the mounting holes on the backplate and rotate it to retard it. 13 to 1 should be fine on decent fuel, 98RON unleaded will be ok. I've just done an FZR1066 genesis/EXUP hybrid running 13.5 to 1 at 36deg BTDC, with no detonation issues at all running on 98RON unleaded fuel. I don't know if you can get it over there but there is a product called 'power pour' which is an anti detonant additive developed for drag race engines. It is very good at reducing detonation without messing around with the octane rating. I have some here for when I'm dynoing incase of issues with fuel quality, but so far have not needed to use it on the FZR.
What figures have you got your cams dialled in at? I still think it is more likely to be a resonance due to the fueling, bringing it up with no load won't really rule much out. Can you record the sound and email it or post it here.

[jmw76]

Thanks Guys,

I kind of agree about the detonation thoughts. I would also expect it to be random. The only reason for not ruling that one out just yet is as a result of a conversation with an engine building friend who said he knew of an engine built to run on LPG that had very strange symptoms similar to mine. They reduced the CR and the problems disappeared.
I have already knocked 2 degrees out of the ignition timing with no noticable effect. I can take out a bit more just to check (although a messy operation at the track). I am also planning on trying to get hold of some AvGas which should prove the same thing.

Here are the complete rebuild specs for reference:

· GSXR 1100 J base engine
· GSXR 750 J high port cylinder head
· GSXF 1200 cylinder block over bored to 81mm
· 81mm bore, 58mm stoke = 1196cc
· Std 28.5mm inlet valve x 2
· Std 25mm exhaust valve x 2
· Block decked 0.035” = total squish height of 1.1mm (0.043”)
· Cylinder skirts cut back to allow better gas flow between adjacent cylinders
· Combustion chambers modified to de-shroud valves, increase swirl and reduce CR
· Wiseco CK101 pistons modified to provide effective valve clearance
· Inlet valve piston relief = 0.160”, Exhaust piston relief = 0.100”
· Std GSXR 750 J camshafts (duration In/Ex = 292/286, 248/242 @ 1mm)
· Valve centre lobe timing In/Ex = 106/104.5
· Valve lift, In = 9.0mm, Ex = 8.5mm
· High flow oil pump mod for improved cooling (40% capacity increase to cooling circuit)
· Enlarged oil galleries for improved flow
· 0.002” piston to bore clearance
· Modified intake and exhaust ports
· Custom made large bore, semi downdraft inlet manifolds mated to Mikuni RS40 carburettors
· CR = 13:1

Cheers

[jmw76]

Forgot to add.

I normally run the vehicle on 98RON unleaded fuel which is readily available in Aus. For this rebuild I also added Nulon Pro Strength Octane booster to give a bit of detonation protection. Supposedly this bumps the RON up to about 101 - 102. Never used the stuff before so I am still sceptical. Maybe it has something to do with the problem. Hence the plan to change fuels.

Peter.

[jmw76]

OK.
So here is some further good oil gleaned from another of my engine building friends and part time motorcycle racer.
He has experienced problems on older motorcycle engines built with high CRs running pump gas.
His words - "When the CR is too high you feel a vibration set in as the revs rise and you load up the engine". This sounds familiar.

It appears that detonation can manifest itself as a rhythmic vibration. Power delivery drops off also.

I have purchased 40L of AvGas to run at our next event.
I will post my findings later, but remain confident for the time being that I am on the right path.

Cheers

Peter.

[Redmohawk]

If it turns out to be a det issue a cheap and effective way to reduce det and bump up your fuel ron a few points is Toluene (paint thinners).

It is a little hit and miss with some higher ron fuels in its effect, as some already have a little in the mix to start with but I belive most of the 98 ron fuels dont now.

Be aware it is a Det suppressant more than a octain booster but same same for this really , up to 30% is ok after that motor needs specifice work to use it (burnt valves is an issue over 30% on a stock high comp motor) Also wear gloves and don't drink it etc is carcinagen.

Alot of the old octain boosters sold were Alcohol and toluene.

[jmw76]

I have used Tolulene in a 10% mix before. Even at 30% it really only lifts the RON a couple of points or so.

AvGas has a RON of about 108 - 111 and MON of about 100.
In small quantities is readily available to racers (the outlets are required to check race credentials) at about $2.50/litre.
If you buy it in bulk it is $1.80/litre.

This is pretty economical compared to a home brew Tolulene mix which is not as effective and messy to handle.

We will have to wait and see what results it delivers.

[Dynomutt]

Your exhaust cam timing needs to be looked at ideally dial them in to IN106 EX110. You want a split of around 4 with the larger being the exhaust rather than the inlet.
With the cam timing you have it will feel strong, and hit as it comes on cam, but will be weak on torque just before it comes on cam. Depending on the piston valve clearance at TDC on the overlap you could go to IN108 EX112.

[jmw76]

I will look at cam timing after I sort out the main fuel???? issue. On the older build I found valve timing close to stock worked best. When I tried big numbers I tended to loose a bit to much poke when coming out of corners.

[Dynomutt]

Generally if you move the lobe centres towards TDC you'll gain torque, away from TDC gains power. But again try and keep a split of 4 between them with the larger being the exhaust. Check the piston valve clearances at TDC on the overlap, to make sure you don't have any issues. If you can't get the clearances you need then it is possible to have the valve pockets machined deeper on the pistons. If you have changed the shape of the combustion chambers and unshrouded the valve area it should have lowered the compression a little, so I don't think that detonation is an issue here.

Is that a measured 13:1 or just what was written on the box of pistons?

[jmw76]

CR is a genuine measured 13:1.

There have been a number of modifications made to the engine. Many listed earlier in this thread.
The pockets in the pistons have been cut deeper and give good clearance at cam timings of 104/104 (probably worst case situation that I am likely to run with standard cams).
Nominal intake valve clearance=1.6mm, exhaust clearance=2.0mm which gives some scope for higher lift cam later.

Block has been skimmed by 0.035". Squish height (piston to head clearance) is now at 1.1mm, which is less than the head gasket thickness).

After head modifications, chamber volumes are at a measured 21.6cc (this is a 750 dot head remember, not the big chamber 1100 head).

[jmw76]

Dyno,
What's the logic for keeping the cam numbers 4 apart (eg 106/110)??
Peter.

[Dynomutt]

Opening the exhaust cam early allows a bit more blow down which is more important than trying to get that last bit of expansion with the poor crank/rod angle.
If the exhaust is the smaller number then there's a delay as it comes on cam with a dead area immediately before it hits, and although it will feel as though it hits strongly, this is only because of the dead area being low on torque before it comes on cam. Ideally you want power coming in progressively lower down as it comes on cam. I'd look at 104IN/108EX with your set up and see how that goes.
A mate of mine is running a similar set up to yours 1216cc DOT head and cams RS38 Mikunis. He's running Busa pistons with shortened block giving 11-1 compression on 0.95mm squish.
When I built the motor, and dialled the cams in I went fairly conservative at 104/104 to start with, I shortened the exhaust and bringing the exhaust in earlier brought the power in more smoothly, and the best results came at 108 for the exhaust, I've tried 102/106 with this motor which gave less smooth results.
I'll be trying a 106/110 next to see how that fairs, once he gets back off holiday, and he brings it back over for me to run on the dyno again.

[jmw76]

Thanks,
I will experiment with cam phasing after I try the Avgas next Sunday (13/3).
Cheers

[jmw76]

Ok Fellas,

I have now attempted to run the car again at Winton on AvGas to try and check the Detonation theory.

Even on AvGas the same problem persisted.
We tried playing with carb angle (mounting them more horizontally) in an attempt to see if the float bowls might be an issue. We adjusted the mixture to suit the AvGas. All to no real improvement.

The day was pretty wet so testing was very limited.

We did manage to get a little video and from this I have concluded the issue seems more mechanical.

The sound appears to be directly related to engine speed (not road speed) and is more obvious under light acceleration and deceleration.

I am thinking maybe it is a gearbox issue. Possibly a chipped ball in the race on the input shaft. I think that would explain the association with engine speed and load.
I figure that the ball might only jam up every few revs when the balls and cage line up with an associated defect in the race.

It might even be a little too much crush on one of the gearbox input shaft bearings.

Here are some videos that highlight how the engine should sound:
http://www.youtube.com/watch?v=3_sHOF71O-E

http://www.youtube.com/watch?v=I2aqI2ia6Eg

Here is the video we made the other day at Winton (sorry about the quality. It was wet and uncomfortable, so very little testing).
It does highlight the problem though:
http://www.youtube.com/watch?v=3_-yj6yoD2s

Cheers

Peter.