mtx engine rebuild

[jimbob005]

hi all and how is every one ?

im needing to do an engine rebuild on my mtx when running it sounds very rummbly the guy i got it off is saying main bearings but untill i strip it down i will not tell .

now iv never done this before anything to know about before hand ? and when its apart is there anything to change when its open just to make it last longer ?

and my next one wheres the best place to get main bearing from?

thanks james

[Blau Zedong]

WANT SOCKET FIVE PONDS!
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18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth

[bikenut]

do some research on cmsnl............does flywheel move up and down......?and sound rough ( possibly feel rough as well ) when rotated with ign killed?

tinkling noises when running cold?
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[jimbob005]

@bike nut it feels rough sounds like a car wheel bearing like a grinding

[bikenut]

sounds as if mains have failed or ar about to.....any slack or play or movement of flywheel up and down??

or has a "bit" broken off under the flywheel ( more mbx) and is catching, grinding, buggering the flywheel insides??

you have a flywheel puller, manual and torque wrench??

be aware of left hand threads, pump impellor area........

and check out cmsnl exploded views....they will help.
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[jimbob005]

thanks bikenut just waiting till the weekend and ill get my self a puller and a manual ill take my time on taking it apart and take photos on my way just in case it dont go back i can see where iv gone wrong

thanks for the website

[bikenut]

hi jimbob,

study cmsnl exploded views and print the buggers off if you can, all very usefull info!!!!!!!!

glad you are getting a manual to compliment cmsnl.................and a flywheel extractor, which will fit loads of bikes, fine left hand thread..........

take lots of pics and get some shoe or banana boxes to stow parts, like all stuff under the clutch cover put in the clutch cover, when they are taken off.......

beware left hand thread on w/p impellor area ?? and flywheel extractor thread.

take your time and enjoy..........notice timing marks also :karma:
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[jimbob005]

THANKS bikenut iv orderd a puller iv taken the engine out and started striping it down taken the head and pistion looks all good not much pitting on it and the bore looks clean but turning the fly wheel it still very bad and grinding ..


is it worth doing the small and big bearing theres not much play in them

https://i154.photobucket.com/albums/s267/jimbob005/null_zps92c0b398.jpg

[bikenut]

so you didn't take the opportunity of carefully jet wash the engines outside and area,.............. its a runner so could have been left running to dry............ so no outside crap to join the inside crap..........more crank checks like up and down flywheel and endfloat............test for big end play.... rings........little end.........it was well held by the frame so making the flywheel nut and the lhs crank nut loose was easy, it has brakes...........but a breaker bar, really good socket and possible supported ......and a good purposefull w2hack with a mallet in the right direction.......but don't go over the top......

what did you learn from the g/box oil draining and dregs.......

now remove or open engine.......

so with stationery crank in a position to allow the conrod as much angle movement as poss......does it turn smoothly, don't catch, don't grab, don't stop?!.........or crunches for kellogs!.........can you see any metal flakes........if rod positioned you may be able to see thru a slit .......how is side to side tilt and side to side movement of the conrod/b/end assembly.........any up and down movement or play in the big end and rollers......

how is flywheel magnets.............

pics pics and more pics....also what you find out about bearing lube and prices etc......you have studied the cmsnl exploded views for the engine yes.........
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[jimbob005]

the gear oil was clean but on the conrod theres metal flakes . Theres no movement in the fly wheel but when moving it around by hand it grabs and feels rough.

When moving the conrod left to right theres less than .5mm of movement looking at the rollers and they look good .

piston looks good and the rings
https://i154.photobucket.com/albums/s267/jimbob005/null_zps8aa5769a.jpg

bore looks good
https://i154.photobucket.com/albums/s267/jimbob005/null_zps317e2c5a.jpg

[jimbob005]

https://www.ebay.co.uk/itm/Crank-bearings-and-Seals-set-Kit-Honda-MTX125-83-93-/190583144955?pt=UK_Motorcycle_Parts_13&hash=item2c5fa401fb

found this set

[bikenut]

hi jimbob,

metal flakes not good.......

you absolutly sure there nowt stuck to the flywheel magnets causing
mayhem..............

yes looks v clean in there and the oil was clean?? no coolant? and/or metalic mud or bits??
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[bikenut]

cant zoom in too well on the red bit?? nutted on or circliped on clutch basket.............

hows david silver for oe honda parts?

so, full eng strip well justified?.................crank should rotate with the rod flapping about, or hold rod little end and rotate crank......does rod grap and jam.....or main bearings jam.....or both...............any up and down movement in the big end...............any in main bearings??

what did you find out about main bearing lube.......see cmsnl........

price crank so you will know how much one of those is ( or new big end fitted etc ).....................

manual and flywheel extractor arrived yet?
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[jimbob005]

[jimbob005]

when spining it by hand it still jams up

nothing on the magnets

https://i154.photobucket.com/albums/s267/jimbob005/P9150011_zpsbcdb7079.jpg

https://i154.photobucket.com/albums/s267/jimbob005/P9150006_zps265bc093.jpg

https://i154.photobucket.com/albums/s267/jimbob005/P9150010_zps7e64c7a7.jpg

thanks james

[bikenut]

hi james,

so big end ok ( hopefully )?? and mains jam..........

see cmsnl for how mains are lubed........crank seals will be a clue......

manual has arrived ?? amd you are cool with the balance shaft timing marks, w/pump impellor etc........

no damage to cyl or piston and you have sussed rings, type and the "EXPANDER"..........you know of the "pegs" and very thin section of unported cyl where the ends of the rings "end up", for easy non breakage of piston rings when reassembling engine.

find out if and where the crank case "dowels " are, see cmsnl ( really good resouce and its free ! )......

you have a peg spanner for the nutted on clutch basket? if it is that type...............from memory is a circliped on basket?????????

did the bike jump out of gear? no, good.

so, strip engine, following manual and grouping parts together, like all parts under the clutch cover can be stored in the clutch cover.............etc.

any oil leak by final drive chain oil seal?

when eng apart, just remove ctrank and leave gears etc in place.........suspect flywheel main has gone due to lub failure but clutch side one is ok?? cos its lubed differently...........suss out how....

more pics..........

deeper look at eng parts when stripped......

when ready make new parts required list and cost..........

how was little end, rollers all ok and cage intact...........rings in spec.........big end free to rotate, no bad signs on big end rollers and cage, and all in spec.......

its defo an engine fault rather than g/box.......as crank will not turn 360 degrees with out locking up.??............clucth side crank nut is off now and g/box turns ok???? but crank still doesnt??

take your time and enjoy.
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[jimbob005]

hi there not had much time to carry on with this till today and i can say its one of the main bearings have failed

when opened up found this

https://i154.photobucket.com/albums/s267/jimbob005/P9260119_zpse527682b.jpg

https://i154.photobucket.com/albums/s267/jimbob005/P9260124_zpsc2aa0f2b.jpg

and then i taped out the over side to see that bearing

https://i154.photobucket.com/albums/s267/jimbob005/P9260126_zps0e433f48.jpg

https://i154.photobucket.com/albums/s267/jimbob005/P9260125_zpsa7450630.jpg

[/list]

[bikenut]

8o) wwwwwww lovely...........just as well you didnt run the engine again.........any damage to casings, gears etc and did you find out about the non f/wheel side main bearing lube method........ 8o)
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[jimbob005]

no damage to the casing but its riped the oil seal so will replace this and the lh bearing

all the bits have been kept up at the crank end of the engine all the gears look good

iv not looked how the bearings are oiled ill having a good look at the haynes

[stinkwheel]

[bikenut]

see cmsnl and look at the crank seals.......have a good look........stinkwheel suggests you look at the piston also.........will look 2morrow, hope i can zoom in to see............check rings, barrel......ports
if bits have ended put in the piston crown, they wiil have gone via ports etcc........
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[bikenut]

8o) having looked at an mtx piston crown this morning, the crown has a mottled appearance ( sand cast? ) as normal,

but your piston does have more than this, all the bits of bearing cage etc. having made there way to the combustion chamber......

you can see at more or less 6 o clock, marks ( flats ) made by debris........2 smallish "flats"..........right on the edge of the piston crown.........

any chunks missing on the rings and where they fit into the piston....or imbeded debris.....use a magnifying glass.....

how is the cyl head..........

and how is cylinder bore........any chunks missing by the ports or gawjes, tram lines, deep grooves etc.....anything that will break the rings.....etc.....

how is the inner crankcase chamber ( where the crankshaft lives ) for embeded debris and any cracks...........

how is the big end bearing, can you see the roller surfaces through the conrod "slit".........

and how is the little end caged roller bearing and the gudgeon pin, not to mention the little end eye in the conrod........

all the debris has gone somewhere ( some down the exhaust pipe ) .........
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[jimbob005]

Ok i have taken all the parts around to my local bike shop and had a guy look over it the big end is good and the casings are useable the boar is ok the rings are ok there's some in dents on the head but still useable .

All cleaned out no bits in the gearbox side just all in the cranck, head and cranck bearings

So should be all ok should I try cleaning out the exhaust or will it just get blown out?


Thanks for all you help guys hope to have it back on the road soon

[bikenut]

:D so its viable to repair the engine....good news........

to be safe, check that no bits have gone down the exhaust pipe.........big bits would rattle ( and cause mayhem on there [passage from the crank case chamber to the exhaust ) ...........majke your self happy that there is nothing lurking in the exhaust which the motor may "draw" back in and cause distruction..........kadency..........did you suss the clutch side main bearing lube???????
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[stevo as b4]

I'd hone the bore and fit a new piston and rings as a matter of course though now your into the engine. The small end bearing and all oil seals are musts as well.

You might get away with just one new main bearing, but what's the point when 2 cost a few £ extra at the most.

I would be happy to buy pattern gaskets for most engines, except for the head gasket which I'd always use OEM parts or better.