ConRod/Crank Question

[RickWilliams]

Blew my 500 at Pismo last week (on last day) It performed very well at the drags, untouchable! - doing post mortum now.

After looking at the ConRod, small end got very very hot (Blue/Brown), piston is cracked and hole in piston top, found water in case. Not sure if I blew head gaset first or after, but I noticed steam comming from the water resevoir blow off line prior to siezure. (Running 91 octain @ 32:1 with .06 oversize wisco) - still doing tear down.

My question is: The big end of the ConRod slides over the thrust washers, which gives a lateral movement of 3/16" (Web tolerance (Eyeballed in case) is 2 15/16" or 2.9375" - .0275 over spec) from left crank to right crank, is this normal for the ConRod to move that much and too slide over the thrust washer ?

I did notice on the small end of the ConRod the thrust washers are larger than the piston pin bearing allowing no lateral movement.

Another note: I did notice a clinking noise coming from the case, not loud but noticable during the week at Pismo.

[Kane]

Piston pin washers are likely worn and making a noise.

Are you saying the rod actually slides OVER the thrust washers on the big end? If so, you definitely need a crankpin and bearing kit.

[FPMXer]

I agree with Kane. If the thrust washers are slipping under the cranks big end that is bad. The thrust washers cusion the crank throws from the big end of the con rod. All cranks will have side to side play and shouldn't have any up and down play on the big end.

[RickWilliams]

I have attached a photo of the inner case/crank/rod (87H-6 bolt head), the charred jug, and piston.

You can see that the thrust washers are smaller than the big end, and the big end literally slides over the washers (Left to right) very little vertical wobble/rattle, the small end however was tight with washers as expected.

Funny thing is I noticed the knocking after about 8 hours on a new top end rebuild (Riders Choice, Lancaster), looks like I might have gotten some of my old parts put back in - can't imagine the thrust washers wearing down after 8 hours.

I definitely have some work to do, thanks for you input.

In your opinions, would you recommend changing the jug/head assembly to the 7 bolt pattern, I plan on keeping this beast for awhile, I know it requires more maintenance than my 4 stroke (Which I hate in comparison) but I don't want to rebuild the top end every 20 hours?

[Kane]

Looks like you got that engine apart just in time. That piston was about to come completely unglued and would have seriously screwed your engine.

Those thrust washers are toast. You need a rod kit, or at the VERY least, a pin and bearing kit. I'd get it apart and mic the rod.

I've never had any problem whatsoever with my 87 top-ends. But even so, more than enough people HAVE, so you may want to move on to the 88-90 top-end or have the 87 jug stud upgrade done.

Best advice.............find a new shop or, even better, do it yourself

[RickWilliams]

Thanks Kane for the advise and info.

I am going to have Duncan do the machine work for me since they are local.
Cylinder Bore/Hone and porting, head re-chamber (might go with a new power head), Crank rebuild, stud upgrade, of course new wiseco piston kit and conrod kit, and flywheel mod.

Once I have it completely tore down, I will know more of what needs to be done.

Yes, Kane you are absolutely right about a new mechanic, I have been to two shops here and I know I can't do any worse, one of the shops (A Suzuki dealership) actually asked for my service manuals.

For know I am out of commission on the 500, this may actually give me time to really tear her down and build her back up again.

Thanks for the comments!

[92rslt1]

The first problem was the gas. Second heat. If you rebuild this motor DO NOT USE stock thrust washers they will cost you a set of cases. The thrust washers are located on the wrist pin, use billet only with a rm 250 bearing. Do not use crappy gas unless you like replacing bottom ends. av100 min req.

[dhalezx12]

When I ran the 500 engine in my quadracer, it was extremely built and ran on alcohol. It was an 87 7 stud cyl. I ran no thrust washers in the crank. I ran a complete season with no damage. I dont remember what shop recomended that set up, but it run without a problem.

[hotbutta]

Originally Posted by dhalezx12

When I ran the 500 engine in my quadracer, it was extremely built and ran on alcohol. It was an 87 7 stud cyl. I ran no thrust washers in the crank. I ran a complete season with no damage. I dont remember what shop recomended that set up, but it run without a problem.

The 87 is a SIX stud

[rjatv]

Originally Posted by dhalezx12

When I ran the 500 engine in my quadracer, it was extremely built and ran on alcohol. It was an 87 7 stud cyl. I ran no thrust washers in the crank. I ran a complete season with no damage. I dont remember what shop recomended that set up, but it run without a problem.

No thrust washers ??? that sounds kinda crazy to me, those thrust washers are there for a reason, and it's to keep the rod from moving side to side, and the 87 zillas had a 6 stud head, 88-90 had the 7 stud.