'85 500 engine vibration cure?

Now the races are finished in my country and i will do the service in the Husky CR500/83. I will try to install a system with no welding, means a sort of brackets on the frame. That will take a month minimum but i will share the experience
I prefer the stays in steel, instead of aluminium, you can use less section that is an advantage in the Husky situation because the pipe exhaust is just over the head cylinder.

it seems that from what ive seen of an 84 husky 250 crank, they werent so precicely made. i mean the centre to crank shaft hole to big end pin hole was accurate, and the rest varies. the outer diameter and shaft slight out of round. imagine when they where made, they only made one disc then slapped two togeother on a pin and shaft. problem is when they where made, ( mine at least) the discscentre hole off .002" one way, the big end pin hole .002" in the other direction, and 2 small drilled holes and one big drilled hole (for weight reduction balance) even more offcentre by .080" in same way as big end pin. these last three holes seem to have variance of ecact location. so when you put them togeother face to face assembled on shafts the discs must be twisted for true shafts, or right paralell discs will have the shafts off true. i spent hours chasing it back and fourth, then stopped and measured things, realised it'll never work, trued by straigt shaft, discs are off one back .003" and the other forward .003" maybe one cancells the other? im thinking to get suface ground to have it more perfect. this cause after rebuild it still shakes and its got to be hard on bearings and frame

The Fasst Flexx bars are well worth the money,both of my bikes have them and I use the pillow top grips on both also.It is a night and day feeling with the flexx bars,regular bars feel like tuning forks after riding the Flexx Bars.

That sounds like they were drilled in the same jig.
The cast flywheel has a bit of runout as well. [ a lot is more like it ]

ive read a plenty on the matter of engine balance. the common single cylinder is almost unbalancable without the two counter weight shafts to do it. the v-90 engine however is almost self balancing. you see if the crank shaft were to completely balance the pistons motion, it would cause a off balance perpendicular to the pistons motion. and so being , the crankshaft only balances about 60% of the pistons weight, leaving 40% of the piston weight unbalanced, this way only causing the 60% perpendicular off balance. im starting to suspect the magneto flywheel to be a major part of engine balance. the magneto is balanced when made, and i would assume on a perfect shaft. now years later, and the crank shaft end may be a couple of thou off centre, throwing the magneto off balance. so a normally ballanced engine may have a linear sort of vibration, i suspect a magneto vibration would be rotary, feelin on the handlebars. im thinking to remove my magneto to measure the runout on the taper between keyway and end threads. perhaps a one inch I.D. three foot long aluminum pipe slid over the end might gently persuade it back to center?

unfortunately engine vibrations are a serious matter, more than just sore hands. it will lead to bearing failure, possibly taking out the sem stator or flywheel or both. vibrations also weaken the metal making it stress crack. then the wings fall off and plumets and crashes. so whatever fancy handlebars or added frame mounts, the problem is still there, just absorbed by something else which will in turn break. the crank needs to be true and the magneto shaft absolutely perfect for ceter, as the magneto flywheel has nothing to balance against and will create a wobble rotary vibration that will far more noticeable than the crank-piston balance. if the magneto is off centre .002" it measures .004" and when rotating at high speed it may deflect to be out more perhaps.004" , measureing .008" . this is my theory anywayse that the stationary tolerance is not the same at high rpm . centrifugal forces pulling the weight on the end of the crank shaft will move it. so as rpm increases the vibrations increase. so before i tear down my motor to get the crank trued and loebs ground back to true, i will be trying to re-center the taper end for the magmeto run perfectly centered and not off by .002" . the crank was true and somehow went off .002" during assembly. so im thinking of a way to center the taper end , ill see how that affects it ....
so i went and measured the crank run out at the taper for flywheel, total runout is .003" so its really only out by .0015". i believe as per spec this is tolerable. but im so not confident in the balance. i rebuilt it with the wiseco piston and now pray its the right weight, as the old piston not weighable in pieces. i cant understand why it was balanced and now isnt.

Like ty w states at least for primary balance on a single cylinder without counterbalancer shafts the weights or un balance in weight of the crank wheels just split up the up/down which would be 100% if the wheels where solid into some up down and some front back generally discussed as a balance factor. The balance factor is a design choice which the frame and whether rubber mounted or not have a bearing on.

Exactly how fussy this is in a two stroke dirt bike is questionable as the current husky 250 and 300 share the same crankshaft and I think ktm is the same. The water cooled 500 piston was lighter. I suspect new replacement pistons are all close to the water cooled version, they are for the 430 I haven't bought any 500 ones that weren't Mahle. There are three versions of the 500 cranks in my collection. The one like the air cooled cranks can be found with a slot for the water pump, then they thinned down over the big holes, then radically changed but eliminated the lube hole. I don't know if George from uptite will come back and suggest that cutting to approximate the 87 which I called 88 crank is advisable for the dual shock models. I am kind of curious about the balance factor (and if three was any evolution of the balance factor) for the last 610 four stroke in essentially the same frame design as the water cooled bikes of this section. At least by 1999 they hadn't seen a need to add another mount but did make substantial pockets to hold the ends of the swingarm pivot bolt.

http://www.frannyk.addr.com/cafehusky/1988.500.crank.JPG
http://www.frannyk.addr.com/cafehusky/500.cranks.and.corresponding.pistons.JPG

Have just pulled my WR240 down as the vibration was getting ugly.
This was the first Husky I had reassembled out of parts and I really didn't have a clue.
The bushes in the engine rear main mount were a little loose so I loctited them in.
The holes in the frame were a little oval so I figured that if I kept the swing arm bolt done up tight I could get around that one.
The loctite fell to bits letting the bushes get worse and it doesn't matter how tight the swing arm bolt is if the holes are oval because the footpeg supports move around .
So
[ ignore the date on the photos as I was too lazy to set it right]







End bushes are just aluminium and the hole saw is a diamond one because the holes are either hardened from the factory or they work harden , either way the only thing that will touch them is diamond. Did a nice job and I will be fitting tight tophat bushes to both holes.






I am planning on fitting a front mount from the top of the head to the front downpipe so
I decided to make the nuts longer instead of trying to find longer bolts.

What's wrong with a little vibration?

I'm in love !!

As to post #48 (unless some get added or deleted) by duckman above.

The frame is chrome moly and hard even when cut into the middle of tubes.
500 head nuts look virtually like the ones you made.
With my t510, 1988 I was able to make a swing arm pivot bolt (actually I paid to have a real place make me a few) just a bit bigger that still fit through everything it had to and ream out the holes in the frame. The ends where the threads go had to be true 14 mm and the special order die wasn't cheap.
They had a bunch of different designs of how the tubes went in the mono shock bikes of this section. I put a couple of pictures of an 1988 and then what cagiva/older single cam section stuff evolved to. I really like the freedom of the ankles this design provides.

Yer Fran..k my 400 has the same nuts.

Finished stay with funny nuts.

As you can see by the above photos I have done a bit to my 86/WR240 trying to stop the vibration.
This bike would shake all the nuts and bolts loose and send your right leg to sleep.
I also decided to learn how to balance a single cylinder and to try it out on this yummy little 240. [ This is the first husky I rebuilt and is a favorite ]
I decided on a 58% balance factor and started to remove metal from the bottom of my crankshaft.
I took metal off instead of adding because I like a bike to rev .
I ended up stopping because I could not believe that it could be that far out [ I had removed over 50g a side and was starting to get scared ]
Started the bike this morning , expecting the worse , and it runs just like it's supposed to , brilliant.
One tiny vibration at about 1/4 throttle [ should have taken off a little more perhaps ]
The rest of the rev range is turbine like.
Yippeeeee.

Now the 400.

nice job on that 240. ive a wr 240 aswell , an 84 air cooled. it too ran as a turbine until i lean stuck the piston. at which time it twisted the crank some. i bored the cylinder to fit a 250 piston,assuming they would be the same weight. so upon getting it running it shook bad. so i tore it down, to check and balance crank . it was out by 10 though, showing 20 out of round so i started to true it , to discover the weight wheels arent perfectly centered on the shafts. so i got it closer and its a bit better, but not perfect. now i am thinking to get it trued and reground the weight wheels to be real centered. although weight and balance is what i want to acheive. i put a wiseco piston and it was the wossner that was in it. are they the same weight. strange how it WAS so fast and smooth, and now it shakes scary to go fast. i also blew the cdi. so im trying other solutions. vespa ducatti cdi wont rev up unless trigger signal reduced. the cheap scooter ac cdi, i bought the racing one with timing advance, as per timing light the spark is at tdc not before, but my foot tells me the spark is happening like half way up the stroke. and its retarded as far as it would go, seems like im getting a double spark on this one. its a good thing ive 2 other bikes that arent so much trouble

Believe it or not TY W a couple of grams extra on the piston really does not affect the balance that much.
Here do your own calculation.
Piston + ring + gudgeon +little end bearing + little end of conrod divided by 100 and multiplied by 58 [58% balance factor]+ the total weight of the conrod big end and bearing .
Mine went
Piston all up = 343g +
Little end of c/rod = 85g
=428g
58% of 428g is 248g
+ Big end + bearing at 137g = 385g
You can see that if your piston weighed 10g more it really would not make a difference.
I would go back and true up your crank to within .0008 thou as per manual.
Ignore the flywheels as they are all over the place.
Have fun
Cheers Mike

interesting. cause the info ive read is .oo2 or 2 thousanths of an inch and i even came across yamaha ino saying 6 thou is ok. i dont have the manual for this engine but i do for the 70's to79's or so and i thought it said 2 thou ok? i must have mistaken as your saying .8 thou. is that .4thou off showing .8 when rotated , or is it.8 thou off showing 1.6 thou when rotated.
thanks a bunch

I'me quoting from the 86 manual TY.
Shafts should have less than 1 thou run out with the dial indicator on the shaft close to the flywheel.
Starts to get a little tricky when you get under 2 thou but it can be done
Checking between centres is the way to go and the manual has a picture of this.

hey thanks, i kinda figured that but stopped at 2 as i was told it would suffice. thing is that as i said way back its as if they simply made the weight wheels then put two togeother on a shaft, so imperfections in construction of weight wheels would oppose eachother when assembled. the reason i say this is when i center to the shafts( measuring bearing surface, held between centres) centre to shafts, the wheels be off. or when centre the wheels, the shafts are off. with the centre pin up one wheel is foreward and the other back,as centred by shafts . or the shafts rock if centre the wheels. the more centred the shafts are then the more off the weight discs get. so thats what threw me off was how off centre the discs are, even though they where a machined piece.in either case it wont help my import cdi read the trigger pulse coil and so darn warp coil wont engage right anyway.
cheers

Just made another stay like the 240 one and put it on my 400.
Looks to have calmed the vibrations down a bit.