Need the bolt specs for a 98 yamaha lx1200. Had to put new pistons and jug install. What are the bolt specs for the top of the engine

The specs are .003" on the intake and .005" on the exhaust.
To prepare the engine to set the valves you need to do this. Pull the spark plug out and remove the valve cover. You will then want to turn the engine clockwise as viewed from the flywheel end until the piston is a TOP DEAD CENTER on the compression stroke. Both rockers arms will be loose. You will then need to take a pencil and stick in the cylinder until it touches the piston and put a mark on it. Pull the pencil out and then put another mark 1/4" higher. Put the pencil back in until it touches the piston and then turn Clockwise until the top XXXXX XXXXXnes up with your reference point. You are now ready to set the clearances.

Air cooled 50cc motors usually have 4 long bolts holding the head on, they go up through the 'jug' and through the head to bolts under a decorative cover or just out inthe open. remove nuts or entire bolts and then use a mallet to whack the 'jug' (cylinder) to break it free of the lower gasket, pull jug up and off piston, remove old piston by circlips or other retention and install new one. pinch rings and work jug back over piston, lower onto case gasket (if you didnt rip it removing it) and button back up. Check cylinder before replacing piston to make sure a new one will work. If the walls are scored, you will have to get it bored and use a +.25mm piston.

did he have the engine checked for alignment, usually if the pistons seized, the damage can be more to the sleeve or the hole head, the aline ment would need checking.

G'day. The torque specs for the 8mm head bolts is 18ft/lbs.the jug?(cylinder or barrell) is just tightened down even & firm, as there is no acess for a torque wrench.
OK. other things to note.
Clean the cylinder first in solvent(kero or fuel).Then in warm soapy water in a bucket. Dry-(compressed air is best for this-wear eye protection).once dry lubricate all power valves with oil.
Using a clean white rag-soak the end in your 2 stroke oil & wipe the inside of the cylinder surface untill the rag comes back clean(you will need to do it a couple of times-turn the rag over & do it again).Lube the new piston just before assembly-Also pour a little oil down the main bearing oil holes & over the big end too.
Other things to be sure of are-
Piston on the right way round-arrow to the exhaust.
Rings right way up. Some 2stroke dirtbike rings will only go one way up.Look CLOSELY at the ring ends-on the upper or lower surface there may be an etched dot or "T" or "N" or other marking. the mark goes facing up(on both rings unless single ring piston).
rings positioned with end gaps over the locating pins(the ring grooves have a pin in them to stop the ring turning)
Piston pin clips in correctly.
Powervalve moves freely.
Again-watch when you fit the cylinder-it can be tricky to keep the ring end gaps over the locating pins as you feed the cylinder over the piston.
Hope this all helps
Regards(done this a thousand times)Andrew Porrelli

You need to remove the fuel tank and then the engine. You then remove the top head by removing the four bolts holding the head and cylinder jug on. slide the jug upwards off of the piston. To remove the piston you will need to separate your case

Put the piston in with the mark on the top of the piston facing the exhaust port of the cylinder. put one circlip in the piston in the bore seated correctly in the groove. place piston over rod facing correct direction and insert wristpin into piston and through the rod needle bearing in the top of the rod. insert other circlip and seat correctly in groove. install compression rings with letter or any markings facing up. markings usually located at end gap on either side. install oil ring with straight ring on top squiggly ring in center and straight ring on bottom all in the same groove which will be the lowest groove on the piston.stagger all the ring end gaps. do not let all the gaps line up. install base gasket on engine case. clean everything and make sure everything stays clean. slide cylinder over piston and compress rings with fingers and finesse cylinder over piston. do not force. put nuts on studs and tighten to spec in service manual. install head gasket correctly and put head on and put nuts on studs. tighten to spec. reassemble rest of motorcycle and get hurt! have fun

Go to the site below and you can download a free srevice manual for your bike.

http://www.carlsalter.com/motorcycle-manuals.asp

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