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+--- Thread: Cylinder Compression... (/showthread.php?tid=77557)
Re: Cylinder Compression... - red98 - 06-03-17
Another one for valve clearences :thumbup ....re-grinding the valves would help your compression figures aswell....
had my X7 rebored a couple of yeasr ago...£50 per cylinder + new oversized pistons and rings , dont think thats your problem though .....
tommy , showing your age there buddy :lol ..those old bikes would have been "overhead valve" engines , valves operated by a push rod from the cam located close to the crank , these new fangled motor cycles have the cam on the top and driven by a chain...called "overhead cam" engines.....still important to check valve clearences on the fazers after head removal....
Re: Cylinder Compression... - anutz - 06-03-17
(06-03-17, 05:15 AM)sirgalahad3 link Wrote: All the problems described could be caused by incorrect valve timing. As the cylinder head has been off check and check again.
That's timing, not valve clearances.
I know this is 100% spot on, it took me several attempts when i did it but got the mark dots lined up 100% and wound it on manually several times, no change in position, so timing is spot on...
looking more and more like clearances, so will be measuring and report back shortly...
Re: Cylinder Compression... - tommyardin - 06-03-17
(06-03-17, 07:55 AM)red98 link Wrote: Another one for valve clearences :thumbup ....re-grinding the valves would help your compression figures aswell....
had my X7 rebored a couple of yeasr ago...£50 per cylinder + new oversized pistons and rings , dont think thats your problem though .....
tommy , showing your age there buddy :lol ..those old bikes would have been "overhead valve" engines , valves operated by a push rod from the cam located close to the crank , these new fangled motor cycles have the cam on the top and driven by a chain...called "overhead cam" engines.....still important to check valve clearences on the fazers after head removal....
I think I might have known that Red LOL
I still have a set of four 1959 BSA Super Rocket push rods in my shed, don't ask why but it just seemed wrong to bin them. he eh
Re: Cylinder Compression... - tommyardin - 06-03-17
But with saying that Red I had an old BSA M20 (1958) that was side valve I bought it after I passed my test in 1966 and it had a Monza sidecar on it, I rode it about 20 miles to my home I have never been so scared in my life, I just could not get it to go around corners.
Billy W one of my mate has a big Kwacker (900) with a single adult chair on it, I go in the chair on some coast runs in the better weather and he knows what he is doing, the guys that are on solos don't get to the coast many minutes before we do, 102 was fastest we have had out of the Kwacker combo two up Billy on bike me in the chair. :eek
[/size]What Billy lacks in top speed he make up for with skill and balls.[size=78%]
[/size]The picture was not my M20 but exactly the same, colour and year, mine was a bit tattier that this one, but, it wasn't a rough old dog I bought it off an old boy (Who was probably 10 years younger than I am now LOL) and he had it from new and had it serviced regularly and generally it was loved by him I think.If I had it now in that condition looking at about 5 grand or more[size=78%]
Re: Cylinder Compression... - tommyardin - 06-03-17
[size=1em]Makes me laugh looking at that old Beezer now, the old Amal carb with the remote float bowl hanging out the side. always dripped fuel no mater how many red fibre washers you put on it even leaked with a smudge of Red Hermatite between each washer.[/size]
[size=1em]Ah they were the days of Vibration through your body and oil up the legs of your jeans :lol and did not even have to wear a skid lid. lol! how f-----g dangerous[/size]
[size=1em]And all with a compression ratio of 5 to 1. [/size]
[size=1em] :rolleyes FFS[/size]
[size=1em]The other thing I recall that used cause a uproar was sit on the combo start it up pull the coke lever round just a tad to raise the revs just above a thump or two, tread it into gear and get it to move off at about 2 or 3 miles per hour and get off it.[/size] :eek
Re: Cylinder Compression... - anutz - 07-03-17
So...
Had the top off the head...
Measured Exhaust 1 - fine, bang in the middle of 0.21-25
Measured Intake 1 - 0.09, fecking tight, and valves 2 and 3 look just as tight, well out of the 0.11 - 0.20 recommended
Hoping that this will cause good readings when resolved....
No time right now to do any more but based on this wacky result who knows how tight things will be on the valves as i go...
Certainly this piston, with the highest readings has an issue already that could explain the low pressure
Re: Cylinder Compression... - anutz - 07-03-17
A quick look at Cylinder 2 and 3 on intake with the 0.10mm gauge i have, won't fit so these are at most 0.09mm if not worse, need to find some thinner and narrower gauges before i can get proper readings but looking like all 3 cylinder so far have significant tightness on the clearances.
Re: Cylinder Compression... - ram - 08-03-17
hope they haven't burnt the valve seats
Re: Cylinder Compression... - unfazed - 08-03-17
Inlets would be less prone to to burning as they are cooled be the intake of fuel.
Re: Cylinder Compression... - limax2 - 08-03-17
(05-03-17, 09:24 PM)anutz link Wrote: still to check the clearances but for info, how much does a re-bore cost, and would you need oversized piston rings once its re-bored, or do the normal rings just push out a fraction more to seal etc
Not too familiar with the 1000's but they are probably a plated bore so not just as simple as a re-bore. If it is a simple re-bore you would also need a set of oversize pistons and rings. I am old school and don't know much about re-plating of cylinders, but if that brings it back to standard size you might be able to use the existing pistons but you wouldn't go to the trouble and expense of re-plating without fitting a set of new rings.
Probably just the valve clearances anyway. Good luck.
Re: Cylinder Compression... - anutz - 16-04-17
Update...
Clearances are sorted, but still getting low compression, and double checked a squirt of oil in the bores does nothing...
could this mean valve seats are the culprit...
I am going to re-check my work but i was hoping that it was clearances, as they were well out of spec in all cylinders for at least one valve per cylinder.
Re: Cylinder Compression... - The Male Whale - 16-04-17
Try a leak down test next.
Whale
Re: Cylinder Compression... - anutz - 29-04-17
Hi All,
Not had chance to do a leak down test but i did re-check my work and re-checked the clearances, modified 1 or 2, and i now have 118-124 across the board i.e. all in between that range, so an improvement, if just a little one.
I spoke to a local mechanic, an MOT Tester, and he said it would run on those pressures, and its not too bad considering age, i don't know. It does fire up, and today once it warmed up i took it up and down a private road, and it rode fine, seemed to have power etc
I can get it to start, but it needs, when cold full choke and a whack of throttle, then its touch and go until it warms up, he did say to check fuel lines and carbs as well as it could be fuel starvation.
I am not sure which way to turn, do i do a leak down test, are my pressures significantly bad, i know compared to the manual they are about 50 PSI off minimum, but those with experience in seeing compression in FZS1000's are the values i have massively low.....
If so then i will just park the bike for now, have my 600 going through MOT once i have calipers sorted, so i can live without, but am keen to diagnose and fix, its a busy month however, fuel pump on my MG ZT has just died so other priorities.
Thanks
Anutz
Re: Cylinder Compression... - ram - 29-04-17
is the compression gauge a decent one? can you check it against another to make sure its reading correctly?
Re: Cylinder Compression... - anutz - 29-04-17
Its an un-branded one that cost 40$, but i do have a Gunson one, just not the right adapter, so may look for the right diameter one
Maybe if i am lucky it will be off by 60PSI and all they cylinders are fine :lol
Re: Cylinder Compression... - anutz - 29-04-17
(29-04-17, 07:22 PM)anutz link Wrote: Its an un-branded one that cost 40$, but i do have a Gunson one, just not the right adapter, so may look for the right diameter one
Maybe if i am lucky it will be off by 60PSI and all they cylinders are fine :lol
Just ordered an 12mm to 10mm adapter for the Gunson so next week should be able to test with a 2nd gauge....
Re: Cylinder Compression... - tommyardin - 29-04-17
(05-03-17, 10:30 PM)Graham53 link Wrote: Tommy posted the compression figures from the 600 , these are the ones from the 1000
Dont know why it came out sideways , bloody camera phones
Sharp thinking Graham, as I thought anutz was talking about his FZS600
Re: Cylinder Compression... - tommyardin - 29-04-17
(06-03-17, 07:55 AM)red98 link Wrote: Another one for valve clearences :thumbup ....re-grinding the valves would help your compression figures aswell....
had my X7 rebored a couple of yeasr ago...£50 per cylinder + new oversized pistons and rings , dont think thats your problem though .....
tommy , showing your age there buddy :lol ..those old bikes would have been "overhead valve" engines , valves operated by a push rod from the cam located close to the crank , these new fangled motor cycles have the cam on the top and driven by a chain...called "overhead cam" engines.....still important to check valve clearences on the fazers after head removal....
Are not all modern motor cycle engines overhead valve? the really old motorcycles like my original BSA M21 was Side Valve, the BSA Super Rocket (1961) was Overhead Valve with under slung cam shaft running push rods .
If the valve settings are tight it will cause the seats on the valves to burn and also the seating in the head, they will require lapping/grinding in or replacing if they are badly burnt.
I will side with the others in here that said valves causing the lack of compression as the bike has done low mileage, if the bores still had any sign of honing in them they are not worn, plus the piston rings are under a lot of compression in the bores and will take up a certain amount of wear ,as long as the wear is uniform and the bore are not slightly oval, the usual sign of bores being worn is piston slap and a small amount light blue smoke when running, if the bike gives out a big puff of blue smoke when it first start but stops smoking after a few seconds it can point to unseated valves and/or worn valve stem/guides.
But as Red said my knowledge is of older machines, but the principles of the combustion engine remains the same, just much more refined.
As someone else pointed out a teaspoon or two full of clean engine oil down each plug hole will determine if its bores, all the plugs out to start with, oil down each bore one at a time as you test it with the throttle against the wide open stop, if there is no marked improvement in compression then it points to the valves or a head gasket blowing between cylinders.
Re: Cylinder Compression... - red98 - 30-04-17
(29-04-17, 11:35 PM)tommyardin link Wrote: [quote author=red98 link=topic=22006.msg254574#msg254574 date=1488783340]
Another one for valve clearences :thumbup ....re-grinding the valves would help your compression figures aswell....
had my X7 rebored a couple of yeasr ago...£50 per cylinder + new oversized pistons and rings , dont think thats your problem though .....
tommy , showing your age there buddy :lol ..those old bikes would have been "overhead valve" engines , valves operated by a push rod from the cam located close to the crank , these new fangled motor cycles have the cam on the top and driven by a chain...called "overhead cam" engines.....still important to check valve clearences on the fazers after head removal....
Are not all modern motor cycle engines overhead valve? the really old motorcycles like my original BSA M21 was Side Valve, the BSA Super Rocket (1961) was Overhead Valve with under slung cam shaft running push rods .
tommy , interesting thought that , yes , all modern bikes are OHV.......two basic types of internal combustion engines refered to as...overhead valve and overhead cam...OHV , OHC.... but as you have just spotted they are both OHV engines with exception of the side valve engine , these engines have the valve upsidedown within the block alongside the cylinder bore , so no moving parts in the head just the spark plugs and for any harley fans
:eek known as " flat head " think all engines are now OHC but could be wrong........OHV , OHC are a bit misleading when you think of it like that , all to do with the positioning of the cam , OHV engines have the cam at the bottom of the engine driven usually by a chain and using pushrods , as you mention , to link to the valves , instead of the cam chain on OHC engines......old terms to describe the two different engines which are years old but a bit misleading.......well spotted tommy
[/quote]
Re: Cylinder Compression... - ram - 30-04-17
(29-04-17, 07:22 PM)anutz link Wrote: Its an un-branded one that cost 40$, but i do have a Gunson one, just not the right adapter, so may look for the right diameter one
Maybe if i am lucky it will be off by 60PSI and all they cylinders are fine :lol
im sure it wouldnt be that far out but wishfull thinking. still sounds like valves though.
if it turns it to be valves burnt then it might be cheaper to find a good used head than to have them recut and replaced