smart51
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| posted on 12/11/05 at 04:12 PM |
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R1 low compression
I've just done a compression test on my R1 engine and the results are not too good.
1 - 110 psi
2 - 98 psi
3 - 129 psi
4 - 103 psi
each of these readings goes up by 1 psi after a few drops of oil have been dripped in through the spark plug hole.
Mr. Haynes suggests that the minimum pressure should be 192 psi with 206 psi nominal and 213 max, and with no more than 14.5 between max and min.
my lowest cylinder is half of the nominal and there is 26 psi max difference.
I did the test with the engine warm rather than really hot. Would this make much difference?
What could be wrong other than valve seating and head gasket? How do I check and how do I fix it?
[Edited on 12-11-2005 by smart51]
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ChrisGamlin
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| posted on 12/11/05 at 04:38 PM |
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The first thing I would ask is do you know that your gauge works properly? Also what problems do oyu have with the enigne that made you do a
compression test?
Could you test the gauge on another engine which you know is OK?
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andrew.carwithen
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| posted on 12/11/05 at 05:19 PM |
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Did you carry out the test with all the sparkplugs removed?
This'll allow the engine to crank over at a greater speed due to the lack of resistance and hence the readings will be higher.
Andy.
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smart51
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| posted on 12/11/05 at 08:02 PM |
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I didn't have all the spark plugs removed. I'll try that tomorrow. More importantly, I didn't have the throttle open, it was just
at idle!
The reason I was testing the compression was that I failed my SVA on Thursday on emissions, specifically HC too high but CO OK. It idles quite
roughly. someone suggested that it might be misfiring or not burning all the fuel and that I should test the compression. So I did. I'll do
it properly tomorrow.
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ChrisGamlin
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| posted on 12/11/05 at 08:34 PM |
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You say you were doing it "at idle"? Just checking but I assume you mean the throttles were at their closed idle position, and you werent
actually running the engine whilst doing the test? 
If its just emissions thats the problem Id say the first place to start would be the carbs etc, low compression is a possibility but if they are the
only symptoms then not a very likely one IMHO.
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smart51
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| posted on 12/11/05 at 09:28 PM |
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No, the engine wasn't running the throttle was closed to its idle position.
It was suggested to me that poor idling and high exhaust hydrocarbons could be a symptom of something more serious and that a compression test would
help assess the general health of the enigne.
I have previously stripped the float chambers and vaccuum chambers and cleaned them out with carb cleaner. I also removed the idle mixture screws and
cleaned them out with carb cleaner. Not knowing much about carbs, what else should I have done / should I now do?
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G.Man
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| posted on 12/11/05 at 10:46 PM |
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Did you lean off all the primary jets?
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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smart51
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| posted on 13/11/05 at 10:20 AM |
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Repeated the compression test this morning with the throttle wide open and all the spark plugs removed. These are the results in psi without / with
oil dripped into the cylinder.
1) 155 - 155
2) 95 - 99
3) 151 - 156
4) 153 - 155
the manual states 192 psi min, 206 nominal and 213 max. 155 is 75% or nominal, 95 is just rubish.
What can the problem be?
[Edited on 13-11-2005 by smart51]
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ChrisGamlin
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| posted on 13/11/05 at 10:53 AM |
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Sounds a bit ominous, but again are you sure the gauge is OK, and its sealing well when screwing into the plug holes?
Does the engine look like its been taken apart at any point?
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G.Man
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| posted on 13/11/05 at 10:55 AM |
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Well you definately have one cylinder dodgy, but it may be the only one?
Source of the motor?
How old?
How many miles?
Crashed?
Likely to be needing valve seats, but could be a dodgy bore...
Remember, bike engines are far more prone to thrashing and wear than a car engine of equivalent miles...
If its done 20-25,000 miles its VERY likely to want a rebuild...
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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smart51
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| posted on 13/11/05 at 01:16 PM |
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I did the test a couple of times on each cylinder so I would expect the results to differ if wasn't sealing correctly.
I don't know the milage of the engine or how it came to be for sale.
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OX
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| posted on 13/11/05 at 01:53 PM |
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its worth checking the things that arnt gonna cost any money first and 20,000 miles is nothing for a road going r1,most the times they dont even need
the shims doing on the big service,but if its been track dayed lots of times and had plenty of animal abuse then the valves do stretch a little which
closes the gap up on the shim which then leaves the valves open.it might be worth taking off the cam cover and giving them a quick check. r1 engines
are designed to burn oil to save on wear ,but if there run low then the poo hits the fan...but if youv checked everything then like g man says a
strip down could be on the cards
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andrew.carwithen
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| posted on 13/11/05 at 02:19 PM |
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Yep,
Agree with Ox.
Gotta be worth checking the valve clearances first.
Usually, a compression test is carried out to compare readings between cylinders - not necessarily to compare to a reading given in a manual etc.
So it does look like you've got one definite dodgy cylinder as the rest are comparable with each other.
Did you retry the test after drizzling a little oil down the bores?
If there was no significant increase in the readings then it would suggest a problem with the valves not seating properly.
However, if you suspect a head gasket problem, then dependent on where it has blown, there are several symptons you can look for.
Check for emulsifying of the oil (looks like white goo) - caused when water gets mixed with the oil.
Is there any significant white smoke (water vapour) or blue smoke coming out the exhaust when engine is hot?
You could also carry out a 'sniffer test' on the coolant system to check that exhaust gasses are not getting in the waterways.
HTH,
Andy.
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zzrpowerd-locost
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| posted on 13/11/05 at 02:37 PM |
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cooling system will presurise up alot more than normal if gasket is leaking to a water way or heavy breathing if leaking to oil way or oil in water or
water in oil. Or it could be blowing between to cylinders so presure is leaking to no 1 or three.
Check valve clearances first thou!
[Edited on 13-11-05 by zzrpowerd-locost]
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jack trolley
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| posted on 13/11/05 at 03:00 PM |
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Where did the engine come from? Some countries only get de-tuned versions - Switzerland and (maybe) Germany.
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smart51
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| posted on 13/11/05 at 03:50 PM |
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I took the cam cover off to look at the inside. I haven't got any feeler gauges I'll get some tomorrow lunchtime. I can get a piece of
paper between the cams and the exhaust valves but not between the cams and the inlet valves. Doy you have to get the shims from a yamaha dealer?
That'll be another week's delay then.
The oil round the cams is still the red colour it was when it was put in. The oil round the clutch is the same. That's not to say that there
isn't "mayonaise" in the sump or elsewhere.
I don't know where the engine originated. it came from Edinburgh. Is there anywhere on it where it says 4XV1 or 4XV7 so that you can tell?
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andrew.carwithen
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| posted on 13/11/05 at 05:03 PM |
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If you have to reshim the valves, then I'd have thought any Yamaha dealer should have them in stock and you do it on an exchange basis (at
least, that's how it used to work twenty-odd years ago at my local Kwacker dealership when I had to reshim the valves on my ol' Z650!)
You'll probably find, however, that you'll be able to swap a few of them between cylinders before having to go to the dealers.
Andy.
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smart51
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| posted on 13/11/05 at 07:18 PM |
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I would hope that they'd have a stock of shims but I wouldn't count on it. From experience, they stock NOTHING other than aftermarket
indicators and exhaust cans.
It looks like I'll have to reshim. Has anyone done this before? Any tips? I've read through the haynes manual and it looks tricky.
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OX
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| posted on 13/11/05 at 08:00 PM |
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its hard to think of tips becouse when i used to do it everythings just second nature but one that comes to mind is mark the chain and cam gear(and
crank gear if there's room to get to it) with something thats not gonna rub off easily becouse the original lines on the cam gears wont meet up
with the cylinder head untill there bolted back in place ,,but if you do this make sure that when you put it back together that the chain hasnt spun
on the crank,,it just helps when you come to putting the cams back in to get them lined up ,,,some engines you can just do one cam at a time and then
we just zipper clipped the chain to the cam gear and rolled it out.
but apart from that ,check ,check and check again and everything will be cool
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G.Man
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| posted on 14/11/05 at 03:49 PM |
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Excessive valve clearence shouldn't cause low compression...
Worth checking but I HIGHLY doubt thats the problem...
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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smart51
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| posted on 14/11/05 at 03:59 PM |
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Excess valve clearance wouldn't cause low compression but not enough valve clearance might. I tried it with a sheet of paper yesterday and the
gaps are small to non-existant. I have bought a set of feeler gauges today and will measure the clearance this evening.
If the valve clearance is too small then when the engine is hot and the clearance shrinks, the valves may not be closing fully, causing a slight
leak.
I hope that's what it is cause I don't want to remove the cylinder head if I can help it.
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OX
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| posted on 14/11/05 at 05:24 PM |
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excessive valve clearence wont cause low compression but if the gap is to big where the shim is on top of the bucket they can flick out,you havent got
that problem becouse your shim is under the bucket,,i think..if you do need to change the shims smart ,go for the bigger gap with in tolerance ,it may
have a slight rattle but it will run sweeter
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smart51
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| posted on 14/11/05 at 07:27 PM |
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I've checked my clearances with my shiny new set of feeler gauges. Some of them are a bit low but which ones should I replace?
My gauges are in these sizes
0.076mm
0.102mm
0.127mm
0.152mm
0.178mm
0.203mm
0.229mm
0.254mm
the limits are 0.110 to 0.200 for the inlet valves
and 0.210 to 0.300 for the exhaust.
most of my inlet valve clearances are bigger than 0.102 but smaller than 0.127 so may or may not be in tollerance. A few are between 0.076 and 0.102
and so are definatly too small and one is between 0.152 and 0.178 and so is just right. I noted down which valves easily took the 0.102 shim and
which were a bit tighter.
most of my exhaust valves would easily take the 0.203 gauge but not the 0.229 and so may be in spec and a couple are between 0.229 and 0.254 and so
are just right.
Repacement shims come in 0.050mm intervals and so may shift the slightly too small towards slightly too large.
For those who have followed this thread, the no.2 cylinder has the worst clearances with 2 of the 3 inlet valve clearances being out of spec.
So the dilemma, which should I replace and which should I leave?
Also, could this, or the low compression, affect the high hydrocarbons in the emissions test?
[Edited on 14-11-2005 by smart51]
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OX
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| posted on 14/11/05 at 08:12 PM |
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when you push the guages in they should have a little drag to them.
seeing as your going to have to take the cams out anyway i would go down a shim size on all the ones that are between .102 and .127 .
the exhaust shims depends on how slack the .203 felt,other wise go down on all the exhaust shims that wont take the .229 .your better nearer the max
limit than the smaller limit,,you will probably be able to use some of the old shims that you take out anyway so just play it by ear but realy you
could do with the inbetween feeler gauge's just to see how tight all the gaps realy are..if the ones that wont take a .127 or the .229 but will
take a .120 or a .220 then its up to you but remember the gaps will only get smaller as the valves stretch in time but after saying all that if
the cams didnt have to come out to change the tight ones then i wouldnt replace any of the ones that are with in tolerance not matter how close to the
smaller limit they were
[Edited on 14/11/05 by OX]
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smart51
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| posted on 16/11/05 at 08:55 AM |
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I replaced the shims yesterday and it wasn't such a bad job, until I dropped on into the oil in the cylinder head. I tried to get it out with
long nosed pliers but it just slipped further and further out of reach.
It is now sat somewhere where it can't be seen down near the exhaust valve springs of cylinders 1 and 2. I've tried to hook it out with
wire but can't even feel it.
Will it do any damage if left? If so, How do I get it out?
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