Had my 93 lowrider engine rebuilt by engine rebuilder ad have had a bad vibration ever since

.the vbration is at its worst around 2000 revs.took it back to him and he blamed this and that and after about 5000 km had to replace pistons

and rings.have nowdone about another 5000 km and the motor has to be rebuilt again.I have an idea what he has done wrong

but would like to hear any ideas as i am about to pull motor out and start new rebuild.

checking the motor alignment is a good idea, however if it is the original motor in the orginal frame chances are it is OK, but i would still check the alignment.
Having a motor completely rebuilt and after 5, 000 km and them again after another 5,000 sends up many red flags about the people or shop you are working with. I would seriuosly look into taking it to someone with more knowledge or experiance. A lot of the vibration can be caused by a lower end that is not assembled properly and if the pistons need replacing it tells me there is a problem in the lower end. I am to far away to help but feel free to ask all the questions you want to help get this mess straightened out. dsv

Thanks both of you .Have checked both alignment and replaced engine mounts previously and problem never changed.
I was suspect with bottom end alignment from the start but the mechanic refused to check it,too convinced that he couldnt have stuffed it up.I have decided to rebuild motor myself,but will get assistance with bottom end.one concern is that I want to confirm the problem.is it possible to check the alignment with the barrels off using a dail guage or will I have to wait till it is dismantled and check in double chuck lathe or similar.also what do you suggest is a acceptable tolerance.I have been told 5 thou is ok.thanks.

hi. you can pull the cam cover off & use a dial  gauge on the end of the pinion shaft  it should not be more than 0.005" out on the end of the shaft, where it  run's in the bush in the cam cover, only other way is to pull the crank out too see  ?

daddy racer is right on, use a dial indicator on the pinion shaft, but if it has more than .002" there is something wrong. You can also take off the front motor sprocket and measure the run out on the sprocket shaft. Put the big long nut back on the shaft and tighten. Put the dial indicator on the smooth section to get a reading. Again if it is out more than .002-.003 you have an out of round lower end that will cause a vibration somewhere in the rpm cycle. When taken apart and put between truin centers it should have no more than .001" on each shaft. any questions just ask. dsv

Yeah,thanks .Motor is ready to come out but I might take some readings from both spots to get an idea .Not worried about the money side of things.I forgive but I never forget.mirkin.

hi .   you can check the run out with the motor in the frame , the spec in the factory manual is up to 0.005" @ the end of the pinion shaft  max  ,         up to 0.002 max @ the mains  prefer  0.000" to 0.001" @ the mains ,

if  the motor is coming apart it's best  the tapers check out as well , & have her balanced while your in there they alway's turn out a nicer motor

Have got the barrels off .Bit of slight vertical wear front and rear of both pots.bit of wear on piston skirt as well.

interesting ,the ringgaps on both piston's had moved around to almost the same spot.

gotta start chasing up some parts now .keep you posted .

Mirkin.

The 5 thou you talk about if thats the piston to cylinder wall clearence it needs a re bore and oversized pistons.5 thou on the crank get a new motor .Harley do an engine recondition program give them a call.

Found a good mechanic and took the crank to him to check.there were that many things wrong I cant believe the motor did over 10,000 ks.

for a start the prick had put in cheap tiawanise pistons(told me he used KB's).The crank pin was pitted,the crank alignment was out and the conrods were out of true(slighted twisted.any way at least Ive found the poblem.

And mechanics sneer at us when we want to do our own work.Keep in mind this guy was someone id known for a long time and was reccomended by a lot of people.some of them club members.just goes to show you cant trust any of them. Mirkin.

plenty of blokes out there reckon they can do evo bottom ends. i get so many fuckups in my shop its not funny. i always use blokes i know are experienced and have the right equipment. in Qld i use and recommend Mitch at Dunrite Proformance.

Thanks Angry, Im not sure where mitch is but Im up in Gods country FNQ so am a bit limited where to go.(I like to go into a blokes workshop and see how things are going so wanted someone local)any way the bloke Ive found seems pretty knowedgeable so Ill give him a go.

anyone got any preferances on pistons and compression ratio's? I'm running an EV46 cam with only 20 thou O/s bores.Im leaning towards weisco 9.5:1 Thanks ,Mirkin