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Discussion Starter · #1 ·
In fact they make it worse. I was thinking about the effect of the kits on oil pressure and started studying the engine lubrication diagrams from the manual. The more I studied it the more it seemed like the top end oil kits would drop the pressure at the cam shafts.
So... I decided to measure the pressures. The pressure at the rocker arm shafts (the 17mm nut on the cylinder head) was higher then the pressure at the socket head on the head cover. Obviously connecting these two with a hose will only lower the pressure at the rocker arm shafts (and thus lower the pressure at the cam shaft bearings). Also, if you study engine diagram in the manual,the intake and exhaust cams are both feed equal. The head cover socket bolt leads to low pressure, high volume oil passages that are meant to cool the cylinder head by flooding it with oil, it is not a high pressure oil passage that is meant to pressurize bearings.
There is a another reason to not use the oil kit even if it did work. The oil flowing to the head cover is not filtered by the oil filter, it comes straight from the oil pan (although it does pass through a coarse metal screen), so it could potentialy have small metal shavings which you don't want flowing through your cam shaft bearings.

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Thanks for confirming what I thought all along. There was a reason the race bikes of the time didn't use cam oiling kits. Just curious, what were the pressures exactly?
 

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Discussion Starter · #4 ·
Just curious, what were the pressures exactly?
This is going to seem strange, but the oil pressures were 3psi at the rocker arm shaft and 1-2psi at the head cover bolt. I checked the pressure at all the bolts and it was the same. The guage was a very accurate gauge. I thought this to be too low but after some checking this seems normal. The main oil gallery pressue at the time of these readings was 60psi, (spec is between 43 and 85psi). The rocker arm shafts are feed from this main oil gallery through restrictive oil jets. The purpose of the oil jets is to keep the pressure up in the main gallery and the crank shaft bearings. My crank bearings are fairly new, and the cam shaft bearing clearances were plasti-gauged and were .002" (normal spec is .0013-.0026 and max allowed is .0059). So you can see sloppy clearances don't account for the low pressure. Also, I've done about 10km of sport touring and a couple of hard track days on this engine which had new OEM rocker arms installed. They still look new.
Still, I would like to confirm by comparing other peoples measurments. You can measure the oil pressure at the rocker arm bolt with the same adapter used for measuring the main oil gallery pressure.
 

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The other OG
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from what i remember yoshi never ran a top oiler kit,the endurance test in ragnars
magazine scans ran for 1/2 hr at 10-11,000 from memory with 120 degree track temp
without failure ,20 years ago ,the oils are so much better now and with a better cooler
any failures would brobably be caused by cam manufacturer , incorrect spring pressures
or valve floating
 

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so it lowers the pressure a little, but increases the amount of oil.
 

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so it lowers the pressure a little, but increases the amount of oil.
That's my guess. I don't think this has been talked about here before. It's true that Yosh didn't use top-end-oilers, but then I have had heard they had another internal trick that essentially did the same thing. Unfortunately I never got details on it.
 

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The other OG
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hey dan got the barrels-lookin good,looks like i'll have to increase valve reliefs for the
30-26 valves i got,but i've done that before.talking to a friend that has ported one of these heads before ,found same results as rajay.up to 20% increase in flow with high porting -raising the roof. cant wait.
 

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hey dan got the barrels-lookin good,looks like i'll have to increase valve reliefs for the
30-26 valves i got,but i've done that before.talking to a friend that has ported one of these heads before ,found same results as rajay.up to 20% increase in flow with high porting -raising the roof. cant wait.
Glad it's what you wanted....those had seriously low mileage!:biggrin
 

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That's my guess. I don't think this has been talked about here before. It's true that Yosh didn't use top-end-oilers, but then I have had heard they had another internal trick that essentially did the same thing. Unfortunately I never got details on it.
I don't remember if it was UK Lee who posted something or where I read it but I think Yoshi blocked some of the internal passages to move more oil around to other locations on the head.
 

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I also remember reading a theory (posted here) that the top end oiler kits were originally designed for big-bore blocks/crankcases. When the bore and crank clearance broke into the internal oil passage way it was welded shut and an external oil supply was needed for the cam bearings.
 

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yep - when fittiting big blocks you need to machine the upper crankcase to accept the massively oversize liners. nine times out of ten when machining the case you break through into the small bore feed gallery that pumps oil upto the studs and onto the rocker shafts - when this happens the engineer will block off the galleries alltogether to prevent oil pressure loss - often called dry blocking because of the blockage you now need the top end oiling kit to re-introduce it to the bungs :)

when running cams with a lot 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 more aggresive profile on the replacement cams without bouncing at high RPM this is achived by the extra pressure that the uprated springs exerts on the follower - and hence the camshaft lobe also. all this extre pressure can quickly take its toll on normal rockers at the point where the camshaft runs - the pad. so for really hot cams the rockers are modified by having the their existing pad material ground off and then this surface is replaced by hard welding and results in a much harder surface - just like a standard rocker it wont last 5 minutes unless its effectively lubricated - top end kit provides this!
 

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yep - when fittiting big blocks you need to machine the upper crankcase to accept the massively oversize liners. nine times out of ten when machining the case you break through into the small bore feed gallery that pumps oil upto the studs and onto the rocker shafts -

If one knows how to do this correctly, they never machine into the oil passage. Ask me how I know. :punk

Jay
 

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I wish i could find the info and picture, but ive seen information from yoshimura saying to drill the oiling hole in the rocker arm to a bigger size. This was done when you installed bigger cam/springs. Im sure theres more to it than that as im guessing drilling the hole bigger would lower the pressure.
 

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I'm going to start checking the pictures in the magazine scan thread - I know that Schwantz's '87 Superbike had the connecting link between the cam buttons, but I don't think it had an oil feed (just going by memory).

It'll be interesting to see how many of the modified/race GSX-R's in that section use some kind of top-end oiler kit.

My motorcycle mechanic is heavily into the old GSX-R's (sorry - not "old", but rather "oil-cooled"). :burnout

I want to see what he has to say as well.

JD
 
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