Pointy low compression. - SV650.org

21-04-12, 11:51 AM

Hi,
I put something up a while back about my bike basically not starting, found the problem to be bent valves.
Anyway, I've now put new valves in (that I've grinded in), used new head gaskets, new stretch bolts, and made sure the timing is what it should be (not making the same mistake twice). So, I get it all back together, go to start it... Nothing.
Compression test is literally reading next to nothing in both cylinders - I can crank it over by hand with the spark plugs in!
I have this horrid feeling the piston rings are dead, but I can't work out how, as they were working fine before I started the work, and the pistons haven't been out of the barrel.
Any ideas?
Cheers,
George.

embee · 22-04-12, 11:12 AM

Valve clearances??

22-04-12, 12:52 PM

All within spec

TSM · 22-04-12, 03:11 PM

check you have timed up correctly, it seems that your valves are not fully shutting, you could try turning the engine over 'by hand' without the cams in as that would make sure all the valves are closed.

24-04-12, 01:54 PM

I can confirm that the timing is definitely perfect, having just checked for the millionth time.

flymo · 24-04-12, 02:43 PM

remove plugs, give it a squirt of oil into the cylinders and try again. If it makes no difference then it wont be rings. Also, with the law of troubleshooting, always look at what was changed first.

Do you have a compression tester?

24-04-12, 03:31 PM

You've beaten me to it, I was just about to post that I've done that this afternoon and nothing changed :S
Yeah I do have a compression tester

Shims are correct sizes, clearances are within spec, timings are spot on, valves were replaced and grinded in (I had my ex's father come round and help sort these out so I highly doubt there's anything wrong with them due to his experience), new head gasket, new cylinder head (stretch) bolts, new oil seals, new springs, new retainers, new cotters, new spark plugs, new fuel, new coolant, new oil.

I just... Don't have a clue anymore

George.

flymo · 24-04-12, 03:58 PM

whip the cams out and check for compression. Just a thought, when the valves were ground in, did you leak test them with some fuel?

24-04-12, 04:05 PM

I'm probably not going to be able to get back at it until thursday now, but I'll definitely give that a go then and let you know.

Yeah, no leaks at all, unlike before

21-04-12, 11:51 AM	#1
Georgekp123 Guest Posts: n/a	Pointy low compression. Hi, I put something up a while back about my bike basically not starting, found the problem to be bent valves. Anyway, I've now put new valves in (that I've grinded in), used new head gaskets, new stretch bolts, and made sure the timing is what it should be (not making the same mistake twice). So, I get it all back together, go to start it... Nothing. Compression test is literally reading next to nothing in both cylinders - I can crank it over by hand with the spark plugs in! I have this horrid feeling the piston rings are dead, but I can't work out how, as they were working fine before I started the work, and the pistons haven't been out of the barrel. Any ideas? Cheers, George.

22-04-12, 11:12 AM	#2
embee Member Mega Poster Join Date: Jul 2003 Location: Warwickshire Posts: 2,804	Re: Pointy low compression. Valve clearances?? __________________ "Artificial Intelligence is no match for natural stupidity"

22-04-12, 12:52 PM	#3
Georgekp123 Guest Posts: n/a	Re: Pointy low compression. All within spec

22-04-12, 03:11 PM	#4
TSM The Sick Man Mega Poster Join Date: Nov 2004 Location: Peckham.SE.LDN Posts: 4,768	Re: Pointy low compression. check you have timed up correctly, it seems that your valves are not fully shutting, you could try turning the engine over 'by hand' without the cams in as that would make sure all the valves are closed. __________________ OTR: KTM 690 Duke R 2015 Full Akro SIDELINE: Kwak ZX636 A1P 2002, Red, R&G's, Yoshi, Double Bubble Screen GONE: Kwak ZX-7R P1, Full Akro, Undertray, Screen GONE: SV650S K2 Very Bruised & Without Fairing, Motovation Frame Sliders, R&G Ally Sprocket Toe Protector, HEL 2 Line Setup, GSXR K1 600 RWU Forks, Barnett Clutch & Springs, Penske 8981 Shock, Gilles Ti Rearsets, Steel Barends, Scottoiler, AFAM Chain & Sprockets, Twin FIAMM Horns, Skidmarx Bellypan, Full Micron Zeta Steel System, Cut down undertay. Forum Problems & Information / Site Suggestions

24-04-12, 01:54 PM	#5
Georgekp123 Guest Posts: n/a	Re: Pointy low compression. I can confirm that the timing is definitely perfect, having just checked for the millionth time.

24-04-12, 02:43 PM	#6
flymo Member Mega Poster Join Date: Jan 2008 Location: North West Posts: 3,124	Re: Pointy low compression. remove plugs, give it a squirt of oil into the cylinders and try again. If it makes no difference then it wont be rings. Also, with the law of troubleshooting, always look at what was changed first. Do you have a compression tester? Last edited by flymo; 24-04-12 at 03:01 PM.

24-04-12, 03:31 PM	#7
Georgekp123 Guest Posts: n/a	Re: Pointy low compression. You've beaten me to it, I was just about to post that I've done that this afternoon and nothing changed :S Yeah I do have a compression tester Shims are correct sizes, clearances are within spec, timings are spot on, valves were replaced and grinded in (I had my ex's father come round and help sort these out so I highly doubt there's anything wrong with them due to his experience), new head gasket, new cylinder head (stretch) bolts, new oil seals, new springs, new retainers, new cotters, new spark plugs, new fuel, new coolant, new oil. I just... Don't have a clue anymore George. Last edited by Georgekp123; 24-04-12 at 03:32 PM. Reason: Added info.

24-04-12, 03:58 PM	#8
flymo Member Mega Poster Join Date: Jan 2008 Location: North West Posts: 3,124	Re: Pointy low compression. whip the cams out and check for compression. Just a thought, when the valves were ground in, did you leak test them with some fuel? Last edited by flymo; 24-04-12 at 03:59 PM.

24-04-12, 04:05 PM	#9
Georgekp123 Guest Posts: n/a	Re: Pointy low compression. I'm probably not going to be able to get back at it until thursday now, but I'll definitely give that a go then and let you know. Yeah, no leaks at all, unlike before

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