'85 500 engine vibration cure?

Dukkman, that head stay is genius!! Nice work.

I recently rebuilt my 91 KTM 540 and had the crank trued while it was apart. Made a huge improvement. Will definitely have my current project trued up, too.

Would love one for my 86 400..

Are you by chance making a few more to sell to the club?


Steve

Would love one for my 86 400..

Are you by chance making a few more to sell to the club?


Steve

Sorry Steve
These take all day to make with the gear I've got and would be to expensive.
Cheers Mike

No problems with frame breaking ?

Have not taken it for a good ride yet Michael.
Give it time

Finally have had a chance to take the 240 for a ride.

No vibration at all.
It,s like a big 125 on lots of steroids.
Back before I did the balance and fitted the head stay it wasn't fun to ride , the vibration made it ugly.
Now it just rips.
I will try it without the head stay to see which has had fixed it , the stay or the balance job.
Trouble is that it's so nice I don't want to touch it.
When I was younger and racing I was a 125 rider and I do like a bike that spins up quick.

yes , fast is nice like 92kph in the hundred yard dash
one friend keeps diss'n the two stroke, compares his 74 250 trials 2 stroke bike to a newer 400 one lunger dual purpose. thats like apples and potatoes. the 250 was unreliable supposedly. although the antique air filter was dissintegrating and getting sucked into the carb allong with eons of dirt. carb slide was gritty and sticking even the metering needle was sticking in needle jet and then the carb slide would still drop to closed throttle with that needle in full throttle position giving super rich fuel mix and bogging the engine. so i cleaned the carb air box and breather tube. then built a filter and reassemble. did a 10km ride without a hiccup. so there its not so bad. this 250 has yet to take more than 2 kicks to start. for a 74 it runs better than some new stuff, but as its a trials bike, it wont rip like a motocross. this 250 has 26mm carb and my 250 motocross has the 38mm carb, with that in mind its not logical to think they would be comparable. and his 400 single cyl four stroke has the bouble carb, header and performance exhaust. oh and in doing repairs found 1 out of 3 motormounts where loose. a good going over once in a while is really all thats neccessary. MAINTENANCE. actually my buddy had said "im not going to spend a penny on it . and he said that right in front of the bike hed referred to . hows that for encouraging the bike to be happy. if i was that bike i wouldnt start until i got new handle grips or synthetic oil or a washing . im surprised the bike hasnt protested more. although im sure it likes its mechanic.
anywayse all that said, dont condemn things that dont get maintenance, condemn those that dont maintain their things, otherwise you get to discover on the trailside how neglected their ride is and that it now becomes your problem to get them out of the woods.
PITA. discovered a new way to do a tow. ride staggered less than one legs lenth apart and the rear rider puts one foot on the other bikes exhaust, pushing. great for level ground , not uphill though. ride up beside and put leg out to meet exhaust end push gentle with just a bit of throttle and works ok.ive towed and been towed and find this way not as scary , one time we towed an 80 with that 400 and the 400 just coasting was too scary for me on the 80(not mine) . i was hard on the brake and fish tailed the hole way back of like14 km, the tow bike driver never even looked back to see that im right sideways fishtailing. my left foot wore a whole lot off my shoe that day. actually the problem was that the 80 owner got so drunk he couldnt even ride out of the woods, we had to double him out then double back to his bike and toe it out. he hed crashed 4 times in a hundred meteres (not kidding) and resulted with dirt getting ground into the points( flywheel cover missing) and too dark to start to diagnose on trail side. so it got towed. so i told my drunken buddy that im going to put an ignition interlock on his bike. " before it starts youll have to blow here" as i reached for my jeans zipper.

Congratulations for the nice work
Please let us know how much vibration without the bracket.
I was thinking to do the same but with a bracket attached to the under gas tank tube for my CR500/83
Great job

one old school trick iv heard of but never used is bigger tighter fitting motor mount bolts maybe those SS motor mounts from husqvarna parts and make sure there no paint on the mating surface

ive discovered that my timing was too advanced, and after retarding a bit the thing shakes less. it seems that the timing has a bit to do with shake aswell. this shake feels like a balance issue but caused by timing, and also it was missing some performance. after much reading i learned that a single cylinder engine isnt really balanced at all, rather the crank only balanced about 40% of the piston weight. if it was totally balanced out it would cause foreward and backward vibration worse than the up and down vibrations that exist currently

Removed the brace off the 240 and still no vibration so put it up on the shelf.
The engine balance was what did the trick.

Aha!!! i was just about to work on some frame bracing so i will can that. i need to balance the 400 its killing me!!
goingfor ride with a few mates around kenilworth \ imbill on the 23rx or 24th.

can i try that stay???

yep Surprize you sure can.
But do up your swing arm bolt real tight first.
PM me either on here or Ozvmx.

Pretty much swinging on it allready but i will give the bolts another round of tweaking.

im thinking it will have to come apart and get some remediation.

will send a PM shortly

Havent done much due to onset of unemployment so will need to backburner the vibes fix until some work shows up