finally found out why 810 knocked

well i finally decided to do some work on the 810 while i took a break from the 1000. I pulled the motor out so i could make room for the new bottom end that i will be building from. I decided that since i never did find out where the metal shavings were coming from, or why it was knocking i would split the cases and be certain. It ended up being a rod bearing, actually what is even more odd is somehow one rod bearing made its way under the other. When i got teh crank out, both bearing havles were on the same side of the crank overlapping eachother. How does this happen? The rod was still torqued very tight (i never touched the bottom end when i did the rebuild). You would think the clearances are soo tight that it would be very hard for one bearing to get under the other. The oiling system was fine, atleast the topend was getting oil fine so i think that wouldnt be the issue. The problem did start right after the second trip to the dragstrip, but i never moved the rev limiter on my dyna 2000 past 10,500 rpm ( the motor had gpz head/cams btw) The first pic is the oil pan, the others are the carnage

Jeez...you don't screw around, do you?!?!??!

haha, well i was home for the weekend and my girlfriend had to work so i had lots of time on my hands. Maybe she should work more often :laugh:

Wholly Crapola! :pinch: :ohmy:

Well, glad you found the problem... Unfortunately as we all have found in our own situations, the only way to truly know is Open Her Up and find the unknown WTF factor....

Sorry to hear it young man but at least you now know...

Bright side is though, now you'll be able to fix her up, mend her wounds and get some sleep for you won;t be constantly thinking about it any longer... :woohoo:

OMR

jordan wrote:

haha, well i was home for the weekend and my girlfriend had to work so i had lots of time on my hands. Maybe she should work more often :laugh:

haha i concur! how man miles were on that bottom end before you did the 810 kit? it looks like the little indent that holds the bearing halves in place let go and the bearing just spun over underneath the other? did you ever wind it up to 10k that weekend?

dont throw that away either, i wanna see that when i get back!

What does the rod look like? That sucks to spin that bearing after a rebuild. I guess there is some truth to....build the bottom and the top goes or vice versa. Drag racing season is just starting so you have a little time

Right now, behind my work bench I have a 650 crank that is just in my way, rods and rod bearings still on it. The main bearings I am using... it is the old style bicycle chain cam chain. If you want it it is yours for the cost of shipping.

hardr0ck68 wrote:

Right now, behind my work bench I have a 650 crank that is just in my way, rods and rod bearings still on it. The main bearings I am using... it is the old style bicycle chain cam chain. If you want it it is yours for the cost of shipping.

This is why this site is so awesome.

Kawickrice wrote:

hardr0ck68 wrote:

Right now, behind my work bench I have a 650 crank that is just in my way, rods and rod bearings still on it. The main bearings I am using... it is the old style bicycle chain cam chain. If you want it it is yours for the cost of shipping.

This is why this site is so awesome.

AMEM TO THAT! Thank you very much for the generous offer but i also have a whole new 750 bottom end in the garage that i may just build instead of fixing this one. Also, i have all the pieces for the bottom end in a tote so if anybody needs anything just holler and its yours.

As for the bottom end, it had just under 11k miles on it, i always used 10-40 or 20-50, the rod surface looks pretty clean and not marred up and im sure it could be reused. The other bearings all look fine with no irregular wear, and the rest of the bottom end looked perfectly fine.

hardrock beat me to it.
i was going to offer on up as well since i have both style cranks but it looks like your all set.

and as for why it spun?
the only time i ever seen a car or bike spin a bearing like that is from over reving the motor.
a lot of people think it's hp and torque that kills connecting rods and bearings when it usually engine speed.
either that or lack of oil which you said was fine.

quit flogging that poor girl so much!




who am i kidding?
most of us flog them once in awhile
that's why we build bigger instead of stock.

kawsakiman wrote:

hardrock beat me to it.
i was going to offer on up as well since i have both style cranks but it looks like your all set.

and as for why it spun?
the only time i ever seen a car or bike spin a bearing like that is from over reving the motor.
a lot of people think it's hp and torque that kills connecting rods and bearings when it usually engine speed.
either that or lack of oil which you said was fine.

quit flogging that poor girl so much!




who am i kidding?
most of us flog them once in awhile
that's why we build bigger instead of stock.

haha, yes! Everything has to break sometime, thats racing. i guess ever since the new topend was on it really had a hard life. 90% of the time it was running it was getting ran HARD. Practicing launches for the dragstrip, running it up to redline, and just really squeezing every ounce out of her.

Jordan, repectfully dis-agree. In a perfect world, Plain bearings never see physical contact.. thus no wear... look at a set of new bearing shells, a wild assed guess is that they're 60-80 thousandths deep, and could never overlap within the tolerances of an undamaged rod or main cap regardless of rpm. spun plain bearings (in my experiance) are the result of either insuficient clearance, or lack of oil. either allowing contact/wear, then partial seizing/galling causing bearing shell to travel. My 2 cents.G