|Making Power Anything to do with fabricating and modifying engines, carbs, ignition, etc. goes in here.|
|02-24-2011, 05:19 PM||#1|
The Soft Serve Enigma
UK Lee's HOW TO MAKE BANDIT/GSXR CAM LINKS
The following articles were all written some time ago by Lee Workman, aka UK Lee. He's built several bikes which have been featured in SF Mag's great pages, 5 by my count, most recently the amazing Issue#200 Cover Bike--
GPZ750 - Issue 68 (Oct 99)
The Blue 7/11 - Issue 105 (Nov 02)
His Brother Dean's GSXR750 - also Issue 105 (Nov 02)
His 2nd 7/11 - Issue 116 (Sep 03) - his first cover, and the inspiration behind my build
His "words cannot describe the awesomeness" 7/11 - Issue 200 (Sep 10) his second cover bike
Anyways, he used to have these articles on his webpage and on OSS but due to some odd issues, they're not there anymore. Come to the rescue, HEATZ, from DTP Forums. He put the articles back up on DTP, and I've put them on here as well, simply because you need a DTP login to access them and since we're taking over as the #1 'fighter site in the world, they should be here too
All writing credits to Lee Workman.
Bandit GSXR Cam link tech info
These have been around for a while now but surprisingly few people actually know what the do. The same questions pop up on internet forums all over the world time and again. And more than a few folk dish out inaccurate ‘facts’. It’s pretty clear that there seems to be a lot of confusion over these cam link thingies - here's your definitive guide to exactly what they do /don’t do.
First , let clear up some terminology !
Cam link / cam to cam kits – A misnomer ! - the camshafts themselves are mounted about 30mm above the bungs you remove to fit the kit , you are actually connecting the inlet rocker shaft bung to the exhaust rocker shaft bung on the ends of the cylinder head - usually by a couple of banjo's and banjo bolts and a short ( 6" or so ) length of hose or in some cases a lump of billet alloy with drilled oil passages.
Often advertised as ‘equalising and /or increasing the oil flow between front and rear cam shafts’
Lets make this perfectly clear - These do FUCK ALL for oil flow / cooling / power or anything else to do with the engine , except add weight and complexity and an extra place to leak oil from. That said , plenty of folk think they look cool , and if that’s all they are after – then fine !
Top End Oiling Kits - similar to the above , but not the same ! these take an oil feed from another point on the engines oil circuit ( usually the 8mm allen bolt on the side of the cam cover ) and divert it to the rocker shafts via the bungs on the side of the cylinder head.
Top end oiling kits were designed for bikes equipped with Big Block motors and / or those running high lift cams and heavy duty springs with a lot of valve seat pressure.
The GSXR /Bandit oil cooled motor uses a 'dual chamber' oil pump . The first chamber supplies oil at high pressure for lubrication. This oil is pumped into the main oil gallery running the width of the engine in the lower crank case , and then is distributed around the engine from then onwards via a myriad of galleries and jets.
You can see from the lubrication diagram - the oil that feeds the rocker shafts is sucked through the strainer in the sump by the pump. This is then pumped from the main gallery running the full width of the lower crankcase , through smaller galleries into the upper crankcase half right next to the cylinder liners for 1 & 4 , this oil is then directed up around the 4 outermost cylinder studs through to the head , along the ports ( the bungs that allow access to the rocker shafts ) and through the centre's of the hollow rocker shafts . from here the oil is pumped directly into the camshaft bearing journals cast into the cylinder head and also onto the rockers through ports drilled into the rocker shafts - lubricating the contact point between the rocker and the camshaft lobe.
Remember the ‘SACS’ anonym the used to grace the panels of the older GSXR’s ?
This is the Suzuki Advanced Cooling System -The second chamber is for oil cooling.
You can see from my diagram , the second chamber of the oil pump supplies oil at high pressure to the head - upwards via the external ‘Y’ feed hoses at the back of the block and into the ports at the rear of the cam cover cam cover. The oil then moves through internal passages cast inside the cam cover. You may have noticed that the 4 10mm hex headed bolts securing the centre of the rocker cover are hollow - this oil moves down those hollow bolts through the o ring gaskets around the spark plug tubes into the cylinder head and directly onto the roof of the combustion chamber to carry away heat (SACS). This is what makes the venerable GSXR / Bandit motor “ oil cooled “ . Where others used water to remove heat from combustion chamber and exhaust valve area, Suzuki use oil.
Why the need for a top end oiler kit then ?
When fitting a big block, you need to machine the upper crankcase half to accept the massively oversize liners. 9 times out of 10 when machining the crank case , you will 'break through' the small bore feeder galleries that pump oil up the studs and onto the rocker shafts. Where this is the case , the engine builder will block off these broken galleries all together to prevent oil pressure loss. ( often called 'dry blocking' )
You can see in the pic the oil ports right next to the rear , outermost cylinder studs . This crankcase has just been machined to accept the liners from a big block , and the arrow on the right shows where we have broken through into the oil gallery that will eventually supply oil to the cams.
You now have the problem of no oil going up the stud holes to feed the rockers , hence a top end oiling kit. It simply takes pumped oil from the cooling circuit and re introduces it directly through the bungs in the head to the core of the rocker shafts and onto the cam / follower surface. Similarly , bikes running high lift cams / heavy duty springs need extra lubrication due to the high pressures exerted onto the cam lobe by the follower. A top end oiling kit significantly improves oil flow around this area - indeed many aftermarket cam manufacturers in the states insist a top end oiling kit is used. In the case of a big block - As long as the crank case ports have been blocked off properly ( assuming the galleries were 'broken into' during the crank case machining ), all oil pressure is maintained , and the rockers / cams are lubricated much more effectively.
When running cams with lots of lift and / or duration - heavy duty valve springs together with ‘hardwelded’ rockers are often specified too. The uprated valve springs allow the rocker to follow the replacement cams more aggressive profile without bouncing at high rpm ( otherwise know as valve float ) , this is achieved by the extra pressure the uprated spring exerts on the follower – and hence the camshaft lobe also. All this extra pressure can quickly take it’s toll on normal rockers, at the point where the camshaft runs – the ‘pad’ . So for really hot cams ,the rockers are modified by having their existing pad material ground off , this surface is then replaced by ‘hard welding’ and results is a much harder surface . Of course , just like a standard rocker it wont last five minutes unless it’s effectively lubricated. The valve spring is doing its best to squeeze the oil out of that contact area between cam and rocker – a proper top end oiling kit increases the oil flow to that specific area and they really do work – this is the reason that most aftermarket camshaft manufacturers who make more aggressive profiles for the oil cooled GSXR / Bandit motor specify the use of a top end oiling kit.
For the guys running heavy cam to lobe pressures , it's not necessary to strip the motor and 'dry block' it . Fitting a top end oiling kit on an otherwise standard motor WILL still significantly increase the amount of oil fed through the rockers and onto the cams . The negative effect of diverting some of the 'cooling' oil is generally considered as negligible . In any case , all the oil splashed around under the cam cover pools around the combustion chambers before draining back down into the sump via the two large drain tubes and the front two cylinder stud holes either side of the cam chain tunnel – so it’s still plating a part in cooling the head anyway !
As explained previously , the kits you see which simply 'link' one rocker bung to the other - do absolutely nothing for the cams - they're just for show.
Some kits, show a couple of feeds taken from the main oil gallery via the plug under the ignition cover and connect to the bungs on the RH side of the motor ,the other side then has a simple cam to cam link.
This WILL be effective - but only on the rockers for cylinders 3 & 4 ! , the pressurised oil has no way of getting to the rockers on cylinders 1 & 2 ! – there’s a big gap for the cam chain tunnel in between them remember !. This could be rectified by routing some hoses round to the other side as well though and although this would be just as effective as the more traditional top end oiling kits that take their feed from the cam cover – it’s more complicated and generally a lot less tidy.
MAKE YOUR OWN !
Why shell out a couple of hundred quid , when you can make your own ? It you’re not bothered about having a lump of billet alloy hanging off the side of your engine , and want a kit that is just as effective and can still look good too – then it’s relatively cheap simple to make it yourself .
We’ll start with a simple ‘cam link’ kit. The first thing you’ll need is the head bungs – 2 choices , buy some ready made ones from stainless ( they are available separately from the likes of BSR Aerotek who advertise in this very mag or just make some ! . For a start you’ll need the 14mm Hex shaped head plugs from any of the GSXR oil coolers – the bandit ones are no good as they are round with an Allen socket. Best done on a lathe - just drill through the centre of the plug and tap it M10x1.25 to accept a normal banjo bolt , face it off to ensure the sealing surface is flat and if your fussy chrome plate it afterwards !
Next is the link pipe – You’ll need some ‘re usable’ ( i.e not the crimped type ) dash 3 banjo’s . I often use old stainless brake hoses that I’ve picked up over the years , but again you can buy all the bits separately from a number of places . Make the one end up as normal by cutting the stainless braided hose & slipping the socket over . I use a good sharp pair of cutting pliers for a nice clean cut. Then use a small flat screwdriver to the flare the braid away from the nylon inner. Push the brass olive onto the nylon inner firmly , ensuring the stainless braid is on the outside of the olive all the way around. Push the banjo into the nylon pipe through the olive and lube the thread , then pull the socket up and screw it onto the banjo. Once it’s tight , fit the one end onto the head plug and measure the length that you need to trim the other end to. Cut it to length , fit the other banjo and – job done !
To create a ‘proper’ top end oiling it , there are a couple of extra steps.
First you need to get the special banjo bolt that will replace the 8mm cap head currently blanking off the oil gallery in the cam cover. This is a bit more tricky to make by yourself , but it can be done ( see pic ) I started with a 10mm x 40mm cap head bolt (only partially threaded) then drilled & turned it on the lathe to get the same features as a normal banjo bolt , but with a plain 8mm x 1.25mm thread on the end instead of the usual fine thread 10mm x 1.25mm . You can however buy this special bolt ready made ! – go to BSR Aerotek and ask them for the special 10mm banjo bolts with an M8 thread from their GSX 1400 cam link kit !
All you have to do then is tap into the cam link , either by using a Tee piece fitting ( as in the pic ) or by using a double banjo on one of the head plugs.
Simple, effective and a lot more satisfying than handing you money over to a shop – not to mention a damn sight cheaper !
So there you go – everything you wanted to know about ‘cam link kits’ but were too afraid to ask . Along the way , we’ve busted the myths , dispelled the rumours , and consigned to the bullshit firmly to the bin. You’ve learnt the facts about the intricacies of the GSXR oil system and I’ve been Lee Workman.
It’s been emotional.
Project Redefyned 7/11
If I have to explain, you won't understand.
RIP Michele "MadMadame" Monroe, 30Apr80-24Mar12
RIP Gavin "Greencheezeeta" Butts, 5Oct83-8Sep09
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