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Post by nikfubar on Mar 3, 2013 22:44:42 GMT 1
First ride of the year & the muther f**ker goes bang, bollocks Took the head off & this don't look good. Bike ran great all last year so why this happened I don't know only doing about 90 & the engine dies, pull in the clutch & the tacho drops to zero, let the clutch out again & the engine turns over but won't fire. Coast to a halt, temp guage reads 95 but the rad is quite cool, last time I looked it was 55 degrees. Let it cool down, kicked it over & it starts BUT don't sound good, only good thing is I broke down next to a pub, 3 pints later waiting for the recovery truck & the bloke thinks I want recovering cos I've had too much to drink Left hand piston Right hand piston Luckely the head is ok but look at the colour of the plugs, looks very lean Right what caused this, lean mixture looks like I'm gonna need a rebore & pistons etc hope the cranks ok
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Post by cb250g5 on Mar 3, 2013 22:49:49 GMT 1
When mine ate the front of the pistons like that, it turned out to be undersize stingers in the exhausts.
You've not made any changes there have you?
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Post by nikfubar on Mar 3, 2013 22:56:39 GMT 1
The exhausts were designed & built by Slinger (aka Glyn) to work with the Mick Abbey fast road tune, he knows what he's doing, gonna be something I've done
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Post by marsbar350 on Mar 3, 2013 22:57:26 GMT 1
thats a fooker nick werent you saying in some other posts about it running lean
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Post by arrow on Mar 4, 2013 0:44:24 GMT 1
Strange, the pistons would suggest lean mixture but the plugs do not.
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Post by steve h on Mar 4, 2013 0:59:35 GMT 1
Everything the same as last year? fuel? Plug looks grey on my monitor. Hope your cranks o.k.
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Post by bryan on Mar 4, 2013 1:54:43 GMT 1
if crank was twisted it only affects the right cylinder as left controls the timming. Looks like deternation on both cylinders backed up by alloy specks on the plug. Bottom end should be ok as flow of exhaust should send anything out the pipes.
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Post by flames on Mar 4, 2013 6:30:42 GMT 1
are you running autolube or pre mix? my elsie looked like that when it nipped up.and i traced it to my pump not pumping oil thro.but my pistons were eaten in the middle,and had just started on the edges.yours look like its in the middle,but fanned out to the front of the pistons.hope you get sorted soon bud.
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iainw
Drag-strip hero
Posts: 289
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Post by iainw on Mar 4, 2013 9:55:39 GMT 1
It looks like a classic four corner seaizure, and the crown has also expanded then clipped the exhaust port. It wasn't going onto reserve was it?
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Post by midlifecrisisrd on Mar 4, 2013 10:19:08 GMT 1
that's an absolute p1sser nik.
don't like the look of the pistons breaking up.
best to re build then get on a dyno to check jetting. know mine felt rich but turns out it was rich on the mid but lean at top. plugs looked rich so i was considering leaning it so you never know without a gas analizer.
did you have fresh fuel in or was it full from storage?
steve
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Post by midlifecrisisrd on Mar 4, 2013 10:24:29 GMT 1
forgot to add, did you up the oil to compensate for the higher fuelling for the tuned motor?
steve
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Post by bryan on Mar 4, 2013 12:01:43 GMT 1
in the pic with the spark plug is it the head from the bike as plug and head dose have some colour to it. Is the top of the pistons melted or peppered like its sand blasted.
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Post by nikfubar on Mar 4, 2013 18:12:33 GMT 1
Thanks for replys, OK Fuel was only about 3 week old standard unleaded. Plenty in tank so not going onto reserve. Last year jetting set up was in warm weather & it was bloody freezing yesterday. The oil pump has standard shim setting but the wheel is set to the next notch. Think the pistons got so hot the crowns vaporised as they look like they have been sand blasted & there was a build up of ali particles on the plugs & head plus you can see chunks which broke off the crown squashed against the top of the piston.
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Post by arrow on Mar 4, 2013 18:15:13 GMT 1
If it was set up in hot weather then it will run leaner in cold conditions.
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Post by nikfubar on Mar 4, 2013 18:19:38 GMT 1
If it was set up in hot weather then it will run leaner in cold conditions. What a pisser gonna do as you suggest & increase the shim stack clearance, also raise the needles one notch & only use super unleaded fuel in the future. Hopefully its only pistons & rings will have to check the bores out
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Post by arrow on Mar 4, 2013 18:23:58 GMT 1
Nick, you would get away with the same carb set up year round on a standard bike and most times on a tuned bike. Trouble is they get more fussy with the higher the state of tune. Race bikes are often set up for 'on the day'.
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Post by lcrider on Mar 4, 2013 19:33:05 GMT 1
Looks like they ran week and ran hot . a little more oil in the mix may be after the build .
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Post by flames on Mar 4, 2013 20:00:33 GMT 1
. The oil pump has standard shim setting but the wheel is set to the next notch. Think the pistons got so hot the crowns vaporised as they look like they have been sand blasted & there was a build up of ali particles on the plugs & head plus you can see chunks which broke off the crown squashed against the top of the piston.[/quote]
i would check pump is pumping correctly at all revs too.thats exactly what happened to mine.theres pics on here somewhere.ile see if i can find em.
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Post by midlifecrisisrd on Mar 4, 2013 20:48:26 GMT 1
Thanks for replys, OK Fuel was only about 3 week old standard unleaded. Plenty in tank so not going onto reserve. Last year jetting set up was in warm weather & it was bloody freezing yesterday. The oil pump has standard shim setting but the wheel is set to the next notch. Think the pistons got so hot the crowns vaporised as they look like they have been sand blasted & there was a build up of ali particles on the plugs & head plus you can see chunks which broke off the crown squashed against the top of the piston. Does look like they got too hot. You'll hopefully be ok with a hone as it looks like most of the bore marking is alloy from the pistons. A little more clearance may not be a bad thing. I left the pump standard but add some oil to the tank as it helps more at full throttle rather than small openings and has the benefit of stopping the tank rusting. Only ever use super unleaded since mine was tuned just in case as standard fuel is really crap. Would seriously consider going up on the main as 1 notch out should not be so disastrous at the top end. Best dyno it to be sure. As said mine is lean and you would never know by riding alone. Could be worse, could ave happened in the middle of summer ( assuming we will have one ) Steve
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Post by copper99 on Mar 4, 2013 20:52:52 GMT 1
Gutted for you mate...
Hope all is good for the rest of the year after the rebuild...
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Post by bryan on Mar 4, 2013 22:04:43 GMT 1
what plugs were you using, I keep a pair of 10EIX for rearly hot days in the standard YPVS engine in the LC, you would do well to run them all the time as they will dissapate more heat than the 9s.
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Post by nikfubar on Mar 5, 2013 0:40:23 GMT 1
Looks like I may have got away with this lightly, the rings remained intact & the marks on the bore are ali deposits which should come off with a light hone, see the third picture, if it had gone on for much longer the piston would have been holed. One good thing, from the metal that has been squashed between the top of the piston & the head I can accurately measure my squish clearance at 9K revs which is 0.88mm ;D
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Post by LC_BOTT on Mar 5, 2013 10:06:05 GMT 1
One good thing, from the metal that has been squashed between the top of the piston & the head I can accurately measure my squish clearance at 9K revs which is 0.88mm ;D I wondered that too glad to see your looking on the bright side. Are you going to hone the bores yourself? if so, what tool do you have? was thinking of buying one of these expanding blade types myself. just seen my crank sitting in a bath of water for some time, was only going to be a quick makeover and ride oh well, got to be expected with this type of bike sometime.
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Post by Roofmonster on Mar 5, 2013 13:10:31 GMT 1
Blimey that was close to putting a hole in the piston -you must have been quick on the clutch! Hope the rebuild goes ok.
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Post by mellow on Mar 5, 2013 18:42:30 GMT 1
looks fine to me nik ;D
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Post by rdstars on Mar 5, 2013 18:59:10 GMT 1
Something know one has mentioned.
Rad was cool yet the motor was running hot. Thermostat stuck ?
Still looks lean and with how cold it has been lately that will lean it out.
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Post by nikfubar on Mar 5, 2013 21:01:45 GMT 1
Just checked the thermostat & that's working fine, gonna check the pump but as people have said this happens quick when it leans out (quick dual carrage way thrash) I think the head got real hot real quick
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db8888
Thrash Merchant
Posts: 329
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Post by db8888 on Mar 5, 2013 21:20:57 GMT 1
Hi check the tank is venting correctly no air in slows down the fuel flow causing a weak mixture
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Post by flames on Mar 5, 2013 21:44:06 GMT 1
One good thing, from the metal that has been squashed between the top of the piston & the head I can accurately measure my squish clearance at 9K revs which is 0.88mm ;D I wondered that too glad to see your looking on the bright side. Are you going to hone the bores yourself? if so, what tool do you have? was thinking of buying one of these expanding blade types myself. just seen my crank sitting in a bath of water for some time, was only going to be a quick makeover and ride oh well, got to be expected with this type of bike sometime. i was thinking of getting one of those too.was advised not to,because the blade isnt fixed,it can easily catch in the ports and end with you needing a rebore or worse,damage bores to point where they need resleeving.
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Post by wallcraft on Mar 5, 2013 22:26:34 GMT 1
Lots of things to factor in here when running a tuned motor in cold conditions ie tight squish band, high comp,ramairs jetting needs to be on the rich side to be safe.
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