Head Removal, Bolts seized

[Sparky 61]

OK, so the rolling chassis is coming along so I decide to remove the top end and change rings, seat valves etc. BUT, some bright spark designed the bolts to be recessed allen type which are seized in (I dont think the head has ever been off), after rounding one head off and snapping my allen key socket off in the head of another (which I can't now get out of the head because of the size of the access hole) I am looking to remove the sub head as I call it (the cam carrying part which is detachable), removed all of the bolts, removed the shim buckets but it still does not want to come off, I am figuring that I have to remove the valve springs as well, which will be interesting without being able to use a valve spring compressor as the head is still bolted to the engine. Anyone has the same problem and has a way out of this prediciment. Cheers

[kilika2]

I'm no master at this by any means but I have seen other people respond and talk about drowning it rust buster. And then lots of heat. And then another technique of welding a bolt to said rounded end. Iirc the hole is extremely small and I had a similar difficulty getting an Allen wrench in there. Hopefully someone smarter than I will chime in too.

Hope that is a start.

Chris.

[reelrazor]

too late now, but:

a) use VERY high quality allen sockets.

b) use an impact driver.

c) being too late, I kinda think you are screwed..very very hard to deal with this without marring the cam bearing surface..getting heat to the relevant portion of the nuts is nigh on impossible.


Removing the valve springs will do no good that I can see. Very very odd that these seized as they live submerged in oil. The external ones....yeah, the inner ones? Very odd.

[Rooster]

Yes the previous owner of my bike had it worked on then it was abandoned for 10 years. the top and bottom half may be separated on the engine and pulling all the valve springs may allow you have the movement needed to get the top half off. it will be tight and there is a possibility of damaging the bores where the shim buckets reside but it may work ok, the bone head who took mine apart pried the top half off bending all 8 exhaust valves in one shot. there is a tool for in engine spring removal which is a air fitting threaded into the spark plug hole and then connected to an air compressor it will keep pressure on the valves from being pushed down and may assist in getting the springs off, if you push on the retainer and have a buddy get the keepers for you it may work as the valves may not push down during this anyway.

Do what you can it's not impossible if you actually are willing to try, I had the springs out and back in to get mine back on the engine 4 times cause i had no idea how to get it all together and springs in already wouldn't allow me to put the top half on so no springs in will let you get the top half off.

[Sparky 61]

Thanks all, I did use an impct driver and Draper profesional socket, but I think the problem might have been in the length of the hex socket. Hhave got some new ones now which are longer so fingers crossed. I will try when my kids go home tomorrow. Removing the broken hex head might prove interesting though. If worse comes to worse I will look at drilling the head of the rounded one, very slowly and carefully. Nothing is impossible, got ships over worse so I am sure I will get over it.

[reelrazor]

the top and bottom half may be separated on the engine

NOPE.

the cylinder studs that the head nuts are screwed onto begin in the upper engine case half. The engine cases are held together with bolts-including two bolts whose heads are under the cylinder block. You CANNOT get to these studs unless you can remove the nuts in the head. Period.

and pulling all the valve springs may allow you have the movement needed to get the top half off. it will be tight and there is a possibility of damaging the bores where the shim buckets reside but it may work ok, the bone head who took mine apart pried the top half off bending all 8 exhaust valves in one shot. there is a tool for in engine spring removal which is a air fitting threaded into the spark plug hole and then connected to an air compressor it will keep pressure on the valves from being pushed down and may assist in getting the springs off, if you push on the retainer and have a buddy get the keepers for you it may work as the valves may not push down during this anyway.

Do what you can it's not impossible if you actually are willing to try, I had the springs out and back in to get mine back on the engine 4 times cause i had no idea how to get it all together and springs in already wouldn't allow me to put the top half on so no springs in will let you get the top half off.

NONE of this makes any sense. Removing the valve springs gets you no closer to removing the head. The valve springs are part of the head assembly

I don't know what you mean by "top half" ..if you mean the cylinder head itself..the studs pass from the head all the way to the engine crankcase. The cylinder block is ?? the "bottom half" ?


I have disassembled and reasssembled at least 100 Yamaha inline fours, and at least that many from other brands. trust me, the head nuts dont come off, the head don't come off.

[Sparky 61]

Reelrazor, sorry to mess about, but on the 90 FZr Exup engine the head definitely splits into 2 parts and upper part which has the cams in and a lower part which houses the valves, I have never seen it before either but its made like that for sure. I have no idea what purpose this serves and I can't think of any. I have stripped down numerous engines (including some the size of a small house) and I have never come across this configuration in either car, motorcycle or ship. I can't see how it can be any easier as you have to remove the valve springs in order to remove the top section because of the angle the valves sit in the head. Maybe it was some ides that if you got a cracked head you could replace the combustion chamber part only, which never caught on.

[buzzawak]

I dont think we are all talking about the same bike ?

[Rooster]

NONE of this makes any sense. Removing the valve springs gets you no closer to removing the head. The valve springs are part of the head assembly

I don't know what you mean by "top half" ..if you mean the cylinder head itself..the studs pass from the head all the way to the engine crankcase. The cylinder block is ?? the "bottom half" ?


I have disassembled and reasssembled at least 100 Yamaha inline fours, and at least that many from other brands. trust me, the head nuts dont come off, the head don't come off.

So the part that I'm in agreement with is the head is held down by the hexagonal nuts and you have to loosen them off to remove the head in one piece, the part that doesn't make sense is how you can disagree when two people on other parts of the planet have the same type of cylinder head. If you go to any Yamaha dealers web site and go under the OEM parts finder you will discover that all the heads from 1988-95 have the same head design on the micro fiche. It likely does not need to be separated if you don't have a problem with either half and you can leave them together. So your right you may never have seen them in two halves, but they are a 2 peice and they even have a gasket that goes in between and it came it the rebuilt kit I ordered from England.

[Sparky 61]

No problem Rooster, I am an ex ships engineer so I am used to people thinking I am talking rubbish, goes right over my head . Sometimes when I used to go to sea we have to do the impossible with next to no tools so some of my ideas were a bit Heath Robinson, I have cleared the broken Allen key from the bolt now with a week of slow precision drilling (an hour here and ther) so I shall continue on my quest to remove said cylinder head (both parts) in one move. I have just ordered a spare engine as well, just in case you can never have too many spares for old bikes like this I will get it all back together, hopefully before the Summer

[DonTZ125]

Guys, RR is not only a mod, he is also an experienced Yamaha mech. This is one of the VERY few times he is even partially incorrect; he obviously did not realise you were talking about splitting the actual head. The other models of FZR do not have this little trait, and his comments are entirely correct based on that.

Now. Speaking as a mod who was not part of the argument. Overt insults are not needed on this board, and were not needed in this topic. There will be no flames allowed. Keep it in your pants, or take it in your hand and walk.

Topic locked for 24 hours to allow tempers to cool.

[reelrazor]

I'm sorry, I missed the FZR 1000 detail...

and was basing my advice on the 600..

[Lastmile]

I've found my self about in the same position as you Sparky. I started to remove the bolts and they won't budge. Anything you would have done different? I have the fzr 600 so taking off the subhead will not work for me.

[Sparky 61]

Hi Lastmile,

No, I used decent sockets and a Impact Driver, people say to soak in WD40 etc but to be honest if the oil hasn't broken through the seal of the bolt head I can't see it making a difference. The stupid thing with the design is that the size of the holes they have left only just allows for the allen bit and it has to be a long reach one to get a purchase on the bolt, so it is more likely to twist and snap, which one of mine did and that has screwed me right up as I had to end up opening the hole to be able to drill it out, but it is harder than the bolt head with obvious results. I would say buy new, impact specific, long reach (but not too long) allen socket before you start, as the only thing I can think of is mine may have been weakened with previous use. I have ordered some more online but I wont touch the other bolts until this arrives. In the meantime its hours of slow and ponderouse drilling out of the head which is knackered. Best of luck.

[Stig]

could you not have got a local engineer to spark erode the bolt out?. Their machines are large enough to fit the whole engine in situ to enable access????
My local charged £25 to take 2 fittings out a top yolk that the previous owner had snapped deep in the alloy