jawa transmission

George Smith /

alright here's a fun one for you guys.....

I got a jawa 40 engine and tranny that is having an odd problem...

every night it locks up completely....and no it's not the piston or rings or crankshaft/bearings it's in the tranny.....it has no visable wear in the tranny and looks exactly the same as another tranny yet after a few hours of sitting it locks up eventhough there is oil in it any ideas?

Re: jawa transmission

gotta be some kinda mechanical thing.. what do you mean "every night it locks up completely" ? You're riding along and suddenly the wheel locks up and you skid to a stop?

is it a 2-speed with a kick-start? If so i'd suspect the kickstart gear gets jammed .. can't imagine what else would jam the gears if the bike otherwise runs ok.

Re: jawa transmission

George Smith /

actually it's not running at all when it locks i mean just sitting over night....thus my confusion....and everything works fine....and cylinder is in good shape....I'm truly not concerned at all with how good the cylinder looks lol and the crankshaft and bearings are fine clutch is fine but yet every night after sitting doing nothing it locks up

Re: jawa transmission

im still confused .. the sun comes up and it's locked up. Does it unlock around noon time? How do you get the thing running?

Re: jawa transmission

George Smith /

lol it locks up sitting....if you move it back and fourth for awhile it unlocks......and runs smooth after minnute but after it sits for a few hours the tranny locks up again....

Re: jawa transmission

Have you repaired or changed anything lately? When did the problem start? This sure is a weird one. I'm kinda thinking that it's somehow heat related.. as though some bearing is too tight when cold.

Re: jawa transmission

George Smith /

lol trouble is it's not getting hot even i thought same thing so i tried not running it after getting it loose and it did the same thing...it was fine for the short time i have had this motor just over the last week....and i honestly dont see any problems and nothing is tight rear wheel is loose so it isnt anything on that end of the tranny it's between the motor end of the tranny so im like confused as hell because motor bearings look find though i did break a damn ring taking it apart again :/ cylinder is beautiful so it doesnt bug me to change rings while everything is good before it messes up but still cant figure out tranny...i have a spare lower end im going to take apart see if i can get any ideas

Re: jawa transmission

one time we were out cuttiing wood in the middle of nowhere and ran out of chain oil .. all there was in the truck was some ATF and figured what the hell.. But after about a minute the chain and bar was burned .. chain sprocket stuck pretty good, too.

So what's in that tranny? Unless you put something in, you really can't say .. and maybe the last guy put in the wrong stuff.

"THIS":http://www.mopedriders.org/article_view.php?faq=2&fldAuto=17 jawa manual says use 30wt motor oil in the tranny.. If i had doubts, I'd flush whatever's there with kerosene or similar and refill, run and drain it a couple times.. maybe alls it needs is fresh, clean lube.

Re: jawa transmission

i remember now.. it wasn't ATF .. it was air-tool oil. What we shoulda done was drain some oil from the truck's engine or something.. Anyway, it burned and gummed everything up pretty good.

Re: jawa transmission

George Smith /

i flushed it twice so far this morning it wasnt as stuck as previously but ive only had 30wt and it came to me empty....now it is not loose to start off but not half as tight as before but nothing has came out odd when i drained it so i dunno....upside it is loose compared to what it was lol the world may never know the prob on this one lmao cause it is clean as new in that sob

Re: jawa transmission

well .. that's encouraging .. now im thinking the bearings could have some dried or burned residue of some sort that's binding them .. taking up clearance.

It would be nice to try different solvents in an attempt to dissolve whatever it migh be. Kerosene is pretty tame BUT you gotta be concerned about clutch pads. I have NO idea what the pads are made of. Sometimes they are cork and i think i've heard of rubber compounds, too :/

So, one caution would be to use a solvent that you're sure will not attack the clutch pads. I can't think of anything else in the gearbox that has a delicate nature..

Re: jawa transmission

George Smith /

clutch actually is fine....thus still why i was confused it appears to be worked out for time being when i get time i will get it nice and hot then drain oil and refill a few times

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