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Discussion Starter · #1 ·
Hi Chaps
Decided to check my valves clearances and they've gone tight on a couple of them. I have the manuals, proper tools so I decided to pop the cams out .

Well I would have done but if a previous gorilla hadn't tighten up the cam cap bolts up so tight.(or they've seized over time)

Being allen bolts I've managed to break two allen keys (the socket type) trying to get one bolt out. I've hit it (naughty) etc but now its totally rounded and off course its one that sunked into the cam cap

So any ideas before I drill the bolts head off ?

Also I assume I can replace knackered bolt with another H/T bolt of the same lenght and jap shims will be OK to use.:)
 

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Hi, yes standard Jap shims work available from Honda Yamaha Kawasaki etc, 7.48mm dia, use Donsy's manuals for setting advice.

If the bolt has been tightened that amount it may have damaged the head and threads, drilling the head off is fraught with difficulty. You may be better pulling the head off and getting it to an engineering shop.

Good luck.

jimboF4
 

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I'm afraid if it were mine it would be time to take the head off and get it to an engineering shop as Jim says.

If I'm tempted to reach for the hammer instead I reach for the phone.

Whatever you do , don't mix those caps up..They are machined in a line ; )

best of luck with it..It should all turnout ok.

joe
 

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Discussion Starter · #4 ·
Drilling off the Allen bolt head seems an awfull lot easier than removing the head.
At least I can drill on it and it should centralise OK being an allen bolt.
I will cover the engine over with tape etc and using a the magnet from a hard drive to collect the swarf. (Techique I've used before) .Bolt seems soft away.

Been using a decent Facom /Draper allen keys and even tried forcing a larger (imp) one into the socket but no use.

I've got day of work tomorrow so I'll be getting my best drills out.

I'll let you know now it goes.
 

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tight?

Northy;
they are grade 12.9 bolts......I had to replace all of mine, some were torqued to ~80 lbft/108Nm

yes, twisted off a SnapOn 5mm Allen wrench

asshole mechanics.....cams were 1 tooth off too:jerkoff:
 

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Discussion Starter · #8 ·
Well success ...didn't take long, stuck 5mm drill on it first just to centralise it then a 4 mm down about 8 mm then 6.5 mm drill to remove the head. The stud once the pressure was off undid with my fingers:)

Slight damage to the cap but nothing to worry about ...off center by 0.5 mm, so one side a silght grove 0.5 mm x 0.5mm

I suspect the shims have not be changed for while as most of numbers where hard to read , annoyingly it only two that were a bit tight.:wtf: but check all of them for future reference.

BTW ...couldn't get the size shims I needed from three local bike shops (spend 30 min trawling through a box of mixed up shims at one bike shop ..gave up ...so its the internet again )

Why is everything on the MV done up so tight .:ahhh:..or on my has been at least now undone most the nuts and bolts (apart from a complete engine strip)

Thank for info on the bolts, going to replace all mine as well.
 

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Good work Northy, I thought that could so easily have ended in tears. New bolts like Noel said is the way to go. The 750 engine is pretty durable so setting the clearances up right she should be good to go. You said you have the right tools so an accurate torgue wrench is a must.
Well done.
jimboF4
 

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F me. Doing the same on my 2010 Brutale...these things seem to be made from swiss cheese. Not sure if they are overtight or just tight from heat cycles, but of course one stripped.

Gonna try hex head extraction tool Powerbuilt 240094 made just for such an occasion.

I have really good Allen sockets with proper size and sharp corners and still this crap happens.

The bolt heads are marked 12.9 - but I am not sure they are actually 12.9 strength bolts.
Thinking of getting NON MV sourced M6x.10x35mm 12.9 bolts. I wonder if ARP makes something that is applicable.

First time I've ever had trouble with cam cap bolts on ANY of the myriad of bikes I have done valves on over the years.
 
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