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Valve work

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ken anderson.03/12/2019 18:31:05
8711 forum posts
808 photos

hello wilco-its been mentioned on the forum about using torx driver(star screwdriver head?) get a grip in the bolt head hole......or what I would do is drill the head off the bolt, remove the rocker gear and then you'll be left with the stump sticking out-get a hold of with some grips and out it should come...same for Tom,i did this with mine to get the rocker cover off...


ken… 1.. grip dept..

Edited By ken anderson. on 03/12/2019 18:32:13

John Wagg03/12/2019 18:35:45
104 forum posts
19 photos

Another forum I frequent have suggested the use of a "torx" bit (appropriate size) forced into the allen bolt head. Sometimes a slight tap on the bolt head helps to loosen the thread.

Martin Harris03/12/2019 18:36:04
9402 forum posts
255 photos

Several ideas in no particular order:

Dremel a screwdriver slot with a grinding disk

Use Mini Mole grips on head

Hammer in Torx driver

Use Screwgrab compound

Hit screw head to shock free threads while applying torque

Drill head off bolt - using a left hand drill is even better and may result in it freeing during the process.

[A few duplicates posted while I was thinking/typing!]

Edited By Martin Harris on 03/12/2019 18:44:10

Paul C.03/12/2019 18:40:25
661 forum posts
159 photos

Sharp tap on the bolt head with hammer & punch can sometimes helps free things up. Don't get over exited with the hammer though , worth a try before getting the drill out .


Wilco Wingco03/12/2019 19:34:14
237 forum posts
3 photos

Screwgrab ordered delivery at the w/e. In the mean time I will try the Torx drivers and see if they will do it. Can't be any worse than it is at the moment. Will keep you updated. smiley

Wilco Wingco06/12/2019 14:26:59
237 forum posts
3 photos

Got tired of waiting. Cut a slot in the head of the bolt, soaked it in WD 40, left for a couple of days, a couple of light taps with a tack hammer, came unscrewed no problem. Not quite sure what did the trick, could be a combination of any of the above. Now soaked the head bolts in WD 40 and will leave for 24 hours before trying with a new Allan key. May just brush the heads to remove any "debris" that may prevent the key from seating properly before attempting to unscrew, a few light taps to be on the safe side with the Allan key in place. ???? wink 2

Engine Doctor06/12/2019 14:54:28
2530 forum posts
39 photos

Hello Winco . Sorry for late reply but trying to sort out the club subs renewals for 2020 with the added CAA and optional card business !!!

Cutting a slot is a good method especially if the bolt is knackered anyway and its accessible . For the head bolts use a good quality HSS Allen driver  link . They are sharp and grip far better than ordinary allen keys . Clean out the socket in the bolt head before inserting the allen driver so as to make sure the driver fits right into the socket . An old sharpened small allen key is ideal for this as they are pretty useless for undoing allen screws. Also a sharp tap on the end of the allen driver with a light hammer usually loosens them . Dont forget to undo and do up diagonally and dont over tighten them . Do replace any damaged/rounded bolt with a decent quality bolt when re-building.

Good luck and let us know how you get on


Edited By Engine Doctor on 06/12/2019 15:05:34

Tim Flyer06/12/2019 15:15:38
1295 forum posts
236 photos

What I have used with some success to remove head bolts and others from old engines is simply heat before trying any other methods . Aluminium expands far more than steel when heated . Strip & clean engine as far as possible then place on a brick and heat it as much as possible with a heat gun . Let it cool . Then apply plus gas WD40 or light penetrating oil to bolts. Leave a couple of hours or overnight and the bolts should be loose . When the crankcase gets very hot that will actually stretch the steel bolts.

Wilco Wingco09/12/2019 22:28:01
237 forum posts
3 photos

Thanks guys for all the tips and information. I will need to remove the head as the stuck valve, now moves thanks for the tip on long nosed pliers, but the valve spring is broken. Trying to collect all I need before attacking the head but I cant get the head gaskets, even Just Engines are out of stock. So any ideas as to what I should use?, it seems to be a choice between brown paper or silicone sealer, or a combination of both. frown

Engine Doctor12/12/2019 16:27:47
2530 forum posts
39 photos

Hello Wilco . When you say head gasket do you mean the Cylinder head to the cylinder joint / If yes then the gasket here is a thin Aluminium washer there may be two . If you mean the rocker cover that cover the valves then then there is no gasket need or fitted . Some FS engines like YS need a rocker cover gasket but the ASP don't have any pressure in the valve gear and the cover is just to keep the dirt out .. Os engines have a gasket fitted to the rocker cover but its not really needed .

There is no oil supply to the valves or rockers and they should be oiled after every few hours running.Also apply a few drops down the push-rod tubes to lube the tops of the cam followers . A good quality mineral based 2 stroke oil is fine provided it doesn't have any Castor oil in it

Wilco Wingco13/12/2019 09:58:29
237 forum posts
3 photos

Thanks ED. Yes according to the exploded diagram I have there should be two head gaskets, I have not removed the head yet as I am still waiting for the new springs to arrive from Just Engines. If they seem too be OK is it enough to just smear a little silicone sealant in the surface and re use ?. I may try and cut some from 0.5 mm gasket paper or would that reduce the compression too much do you think??. This really is proving a very educational experience. thinking

Engine Doctor13/12/2019 10:41:58
2530 forum posts
39 photos

Hello Wilco. The originals will be fine . I usually anneal them by heating before refitting . Be very careful if you try this as too much heat can destroy them . If in doubt just clean and refit them . Dont use any silicone or gasket paper it will do more harm than good .There may be one or two gaskets/shims the diagram shows two but just refit the same that came out . If I'm stuck for a head Gasket or shim I cut one from annealed Litho plate . Also Be careful not to over tighten the head bolts as once a head is distorted its a throw away job.

Hope it all goes well


Denis Watkins13/12/2019 10:46:40
4525 forum posts
121 photos

Just seen your post Wilco

You can get reasonably priced Laser cut gaskets by letter post from

USA, but is by letter post and very low cost

Have used for a rebuild on 3 motors, all running well

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