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Rebuilding engine big bore

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Hi tt some might have seen my other thread "burning oil" well I figured out why and that's how I got to this point to rebuild the engine , a lil history I bought the bike with 6,900 miles around 7,500 it started to tick/knock at 9,000 it started to burn oil.. So I took it apart to discover this, as I dig in more I find a lot of tilt play from the big end, with 9'000 miles I figured it's best to do the crank as well .. So the plan is stock hight/size conrod/crank , 440 big bore , put one piece valves and upgrade springs, a pair of hotcams and fcr39 ... Now this is my first build so I would love any and all opinions and thoughts on the parts, brand, and build... With all parts above should it get me in the 50hp range , is there anything else to look at while I'm there .. I wanna do this right the first time .. I'm going to take the rest of the motor out the bike split the case ill document all just for references thanx to everyone before hand

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Hi tt some might have seen my other thread "burning oil" well I figured out why and that's how I got to this point to rebuild the engine , a lil history I bought the bike with 6,900 miles around 7,500 it started to tick/knock at 9,000 it started to burn oil.. So I took it apart to discover this, as I dig in more I find a lot of tilt play from the big end, with 9'000 miles I figured it's best to do the crank as well .. So the plan is stock hight/size conrod/crank , 440 big bore , put one piece valves and upgrade springs, a pair of hotcams and fcr39 ... Now this is my first build so I would love any and all opinions and thoughts on the parts, brand, and build... With all parts above should it get me in the 50hp range , is there anything else to look at while I'm there .. I wanna do this right the first time .. I'm going to take the rest of the motor out the bike split the case ill document all just for references thanx to everyone before hand

ouch mine looked like ImageUploadedByThumper Talk1379790813.553709.jpgImageUploadedByThumper Talk1379790833.669598.jpg trouble is when you start getting hp like that its starts making the bike abit like a ktm. More oil changes etc etc good look buddy i rebuilt mine with new crank took me about a week with 3 hour days i would say its simple just you need another pair of hands for re fitting the piston into the bore and getting the cam chain up

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Also you need to find out the issue why it did this. At that milage it shouldnt a failure like that. Its ussally around the 20.000 mark. Mine went at 22.000

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Well I haven't taking the crank out yet to have a look ... My guess is the bottom end went out (cause there is alot of tilt ) sheering the needle bearing and throwing up on the piston which got stuck in between the cyl and piston and scored it all up ... I honestly can't think of anything else would you like to see more pics maybe you guys can help figure out what caused this ... This all happened after I heard a tick/knock still rode it for 2,000 more miles and then started to burn I think my knock was coming from the bottom end which explaines why that bearing went

Edited by TonyTouch

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Well I haven't taking the crank out yet to have a look ... My guess is the bottom end went out (cause there is alot of tilt ) sheering the needle bearing and throwing up on the piston which got stuck in between the cyl and piston and scored it all up ... I honestly can't think of anything else would you like to see more pics maybe you guys can help figure out what caused this ... This all happened after I heard a tick/knock still rode it for 2,000 more miles and then started to burn I think my knock was coming from the bottom end which explaines why that bearing went

im 99% sure that your theory is correct thunbsup!:D

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For reference..... When you're done could you post a complete list of your parts..... When the time comes for me to rebuild I as thinking along the same lines as you.

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For reference..... When you're done could you post a complete list of your parts..... When the time comes for me to rebuild I as thinking along the same lines as you.

440bore cylinder works. Full gasket set. Rebuild valves etc. hot rod crank or the hotrod +4mm crank . 2 litre oil. Oil filter. Flywheel puller. Crank splitter (or rubber hammer) . I think there is a complete set of ebay for around 800£

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^ yup sounds about right .. But yes I will post a list of parts and how much along with pics on taking it apart .. I still have the bottom end/tranny still in the bike I'm going to take it out and split the case .. More pics to come

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And this is where I stop for tonight .. Got it off in a bench ordered a flywheel puller and case splitter tool ... Now once I get the case split how Do I get the crank out the left side case is there a special tool for that , also how would I remove the bearings? Would you recommend replacing the balancer bearings also ?

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