broken camshaft

[guest668]

got to the bottom of problem ...camshaft had broken where cam sprocket connects and bolts holding sprocket have gauged into the cylinder head wall. Have filed down the casing wall to take away any roughness and flushed engine through to remove any debris ..though not much came out...Am wondering if I can get away with just fitting new camshaft and reusing cylinder head...sprocket seems ok and chain is fine to.

Does anyone on here have a spare camshaft that they would be prepared to sell me?

Take a look at the pictures!!!

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[guest668]

pic of camshaft

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[johnr]

depends where in the stroke it was when it broke. if either valve was fully open when the cam broke, then the piston may well have hit it. even if it did so gently it may have bent the valve. id be taking the head off and checking them before i put it together.

[guest668]

the cylinder head is already off and checked valves are all ok

[johnr]

if you can get hold of some, id get some plastigauge and check the cam bearings in the head. also id replace the camchain, theres no telling what damage the breakage did, it might not be visible but the chain may well be weakened by the impact of the break. if the engine has a strainer for the oil pickup id check it out and make sure you have all the bits of the broken cam. if you can and the cam hasnt worn the plain bearing in the head i reccon you might get away with a fresh cam and trying it. but id change the oil and filter after say 50 miles just to make sure you have all the fragments, and perhaps try a magnet on the oil filter to pick up any fragments in there.

[guest668]

THanks John sound advice... this is probably a stupid question though but does the srx have a cam bearing? if so whereabouts is it or is it built into the cam which i will have to replace ...

[Steve H]

Ouch! were the bolts loctited in ?. I have a number of spare cams PM me if interested 

[guest668]

im not sure if i loctited them or not which probably means i didnt !!!!!!!!!! they certainly will be next time!!!!!! Have PM"d you thanks for the help and the offer

[johnr]

no, the cam runs directly in the head and wear is prevented by the pressure of the oil forced into the plain bearing. this is a typical arrangement for modern engines, but wear can be accelerated when engines are revved hard from cold or before oil ets round to the head and cam. if its worn, then im afraid the head is pretty much scrap. but its unlikely that has happened, but worth checking just in case. the plain bearing is the smoorth surface that the cam runs in the head in.

[guest668]

thanks for all the help and advice and especially steve H for coming up with a replacement camshaft...

[guest668]

but im still baffled as to what could have caused this...bolts werent loctitied but then they werent loose when head was inspected ..though as i said in previous thread i had trouble turning engine over but that was probably caused by the nuts on cam sprocket digging into the casing wall...trying to move it round probably made it worse...has anyone ever had anything similar happen?

[themoudie]

Aye beezer764,

The bolts not being 'Loctited' caused the grief! From looking at the colour of the oil and sediment left in the cylinder head and the 'lumps' lying in the pool of oil in the bottom of the 'bearing' area adjacent to where the sprocket would be, I'd be reluctant to run the motor without a full strip and clean out of the pickup filter for the oil pump in the bottom of the sump and a new paper filter. Bits of case hardened steel don't do bearings or bearing surfaces any good and if you are cantering along and they cause a bearing to lock up, your health maybe impaired!

I have an acquaintance, who recently took out the 'busa and "opened it up"! The oil went rearwards in the sump and the oil pump sucked air, at "warp factor" the engine just "stopped"! He managed to grab the clutch and came to a halt, the engine wouldn't turn over and he was recovered. 'busa cam chain had snapped and shed hardened steel through the motor! Camshaft seized in the head!! £1,500 - £3,500 for parts and labour, depending whats found when the cases are split.

If you need a workshop manual, I can supply a *.pdf scan and the Clymer, XT600 & TT600 manual is very good as well. I hope you get it sorted.

John's & Steve's comments, absolutely agree with, the chain may look OK! But if you've cracked a plate, it may let go later on, get it changed, in my opinion.

My regards, Bill.

[johnr]

busa sumps and pickups are baffled to prevent the sort of oil surges you mention. i wonder if he has over revved it on a gear change or missed a gear to make the camchain snap, that doesnt sound like a 'short of oil' type seizure to me. id expect the cams to start to eat the head and the main shells on the crank to let go, but not in an instant following quick acceleration. some of the sprint guys with turbos are running sub seven second standing quarters and the only mods to lubrication are extra oil feeds to their humungous turbos!!!

[guest668]

camchain was intact in this instance and the bolts were still connected to camshaft splines.....oil in real light doesnt look bad have flushed it through the engine....is the oil pump hard to get at..it happened while bike was on tickover after being reluctant to start so was lucky.

[guest668]

rather than go head long into a full engine strip to get at sump could i not put some engine flush into some oil run it through then drain and then check oil regularly to see what conndition is like and caheck magnet to see what turns up??