Zed or dead?

[hiswitsend]

Hi,

Long time since I have posted, but just starting to get round to doing work on the bike, idea was to run through the summer and and do more during the winter, but thought I'd start off doing the shims:

Em, ok, did a little bit more....painted the covers:




Thought shims would be simple enough job as the engine is out the bike, so out with the manual, gap should be 0.08-0.18mm, and the feeler guages...

First piston at TDC, camshaft sprockets aligned as specified, take the thinnest guage, 0.05, let the measuring commence.... :scratch: hmm, it doesn't fit and would seem to be completely closed up

Turn the engine over to each of the specified positions in turn.... same story...

Decided then to check for any gaps at any cam position over the buckets and found the following:

1: in .06 measured before the heel ex .06 before heel

2: in .08 measured after the heel ex no gap

3: in .09 on the heel ex .05 on the heel

4: in .06 measured before the heel ex .01 before heel
Anyone any idea what could cause this? Knackered cams/valves ?

Here are some photos of the cams:



Similar story on most of the lobes, I was not the first to venture underneath the cam cover though, someone has been under there and having to fix things:
Over sized bolts here


Top left bolt was spinning and was a non-metric size, not the hairline fracture in the bracket, no doubt caused by pressures due to the loose bolt.

Anyway, decided that I would change the shims, see if I could get a bolt to fit the loose one, either by retapping or fitting a helicoil, or something - do not want to split the engine though.

Cams out, bearing shells don't look too bad, though not great and some scoring on the camshaft:



Camshaft:




head shells



Net result, what do people think? Expensive fix, as in more exploration needed at the least and then its gasket set plus other bits?




Engine was running ok-ish before this, other than occasionally dropping a cylinder, but cleaned up coil contacts and stuff and that seemed to cure that issue, the only other annoying trait was petrol leaking out the carb inlets, even on the move, even once the carbs were cleaned and float heights and needle valves checked..though subsequent investigation found that one did stick occasionally.

[kz900B1]

Hi I know it looks bad .But Iv'e seen similar posts in the help section in the past.Any problem can be fixed its justv a question on cost Looks like you need a helicoil kit and some new shells ok and maybe some cams if there knacked.

[zed1015]

Just measure the shim clearances on the cams base circle as per manual and re shim as required. Ignore your other measurments as they are irrelevant and not unique .Cams don't look too bad in pic's. (Check for flats on highest point of lobe) . As long as shells are not too badly scored or worn through the white metal then reuse. helicoil stripped threads back to M6 or tap to M8 if non metric bolt has taken hole dia over 1/4 in as M6 helicoil tap uses 1/4in tap drill. Cracked cam cap is no prob just remove the center bridge so you end up with two separate caps making sure you pop mark them first so they go back in the same positions. Zed.

[Al]

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The holes which have been tapped 8mm are unlikely to have not been drilled on centre. At least one looks like it has collapsed the cam bearing shell into the cam shaft and caused those radial lines.
The 8mm tapped holes should have also originally had dowels in them to keep the bearing caps straight on the head / cam bearings. Any un-even wear in the shells would testify to this. Thats what it looks like from the photos anyway. I would say that that basically scraps at least a quarter of them
Shells are about £90-100 a set.
Oversize shells are also available.

What do you want to achieve?

If you want it sorted out properly it will cost and having just been through this i would suggest sourcing another sound head if possible.
Dont buy one that you haven't seen beforehand unless you have reason to trust the vendor.

Debbens amongst others i guess, have an indexer to locate the exact position of the centre of the out sized holes according to a template and can machine out, tap, insert and renew to original spec if required.
Guess you'd be looking at about £250 for this service on that head as it stands.
Running those cams in the existing shells is probably going to rattle like a bag of spanners.
Replacement shafts is probably going to be about the same.

Your cams in new shells is not necessarily going to last that long either as the shells will wear very fast to the old cam bearing profile. Plus; if you dont get the same clearance on alignment from one side of the cap to the other, you may see premature failure of the shells with hot rattly running all the way untill it goes pop.

Quick check would be to mic the cam bearings against standard spec and plastigauge the bearings to determine the existing clearance.

Fully running again proper job option £500+
Fully running again quick job option £250
Fully running again replacement head option £150



AL

[kev edwards]

HI i had problems with the head on mine , i could not source a decent second hand one at the time , 16 helicoils was out of the question , so i made studs very slightly under the 8mm then turned one end down to 6mm one end threaded with 6mm the other with 8mm , i then ground the tap lightly so it would be slightly under 8mm , then using a pillar drill i drilled the existing holes in the head , i then used the tap to cut 8 mm threads in the heads , i measured and cut the studs so the would fit under the dowels slid the dowels back into position and cut the other 8 so they were just under the head face it makes getting the cams in a bit of a wiggle because the studs are 6mm taller than the caps but they do go in then its a nut on top with a very thin ribbed washer ,you may also need to take a little material out of the cam cover above where the studs are located as on some covers there is not enough clearance . this may sound like hard work but it saved me loads of money which i did not have at the time , and the engine now runs fine and has done for a few years , i know some will scoff at this because its not been done in a machine shop or cost hundreds of pounds but it hopefully will help others keep their machines on the road , although a decent secondhand head would be the easist solution . when i have cam cover off next i will take a few pics and post on here , good luck
p.s though looking at one of your pics you may like to try dowels in the holes on the head to see if they are still a propper fit , if they are not this would probably cause lateral movement of the caps when running .

[Big Fluff]

Fully agree with Zorded....
You can't run cam caps without dowels and expect them to run true.!
Personally, I'd look for a replacement head.

[ade woollams]

Shells are about £90-100 a set.
Oversize shells are also available

zorded you put this in your reply ,so who does oversize shells then ive never seen any

[hiswitsend]

Thanks for the replies guys.

£150 is out

So options will be to either break the bike, or change the shims anyway as it did appear to be running ok and was only checking the shims as I had no idea when they were last done.