Loud top end knock. Anyone know what it is?

[Rider115]

One night, while I was riding, I unexpectedly hit a fairly large rock lying in the middle of the road. Shortly afterward, I noticed that my low oil pressure warning light had come on. Without hesitation, I disengaged the clutch, veered off the road, turned off the bike, and arranged to have it transported back home in the bed of a pickup truck. To prevent any further damage, I left it in fourth gear with the clutch secured using a bungee cord. It became clear that the rock had knocked a hole in the oil pan, approximately the size of a half-dollar coin. After replacing the oil pan, the motorcycle ran smoothly and shifted gears without any issues.

Fast forward about 200 miles, and I started hearing a subtle knocking sound, accompanied by a noticeable increase in engine temperature and slight loss of power while cruising on the highway. Worried about the situation, I took the next exit, as I exited the off-ramp, the motorcycle abruptly shut off and emitted a harsh, metallic grinding noise. Once again, it had to be transported in the back of a pickup truck. My assumption is that the bike had shut itself off due to overheating, and thankfully, the terrible noise was not the result of complete engine seizure, as the bike could still be started. However, I'm still not entirely certain if the initial incident with the oil pan was the cause of the knocking sound.

Now, I find myself with a motorcycle that has a rather bothersome knocking issue, and I'm faced with the decision of whether to repair it or consider scrapping it. If anyone has insights into what might be wrong with it, it would greatly assist me in making an informed decision. Thank you for your assistance.

Linked is a video of my bike in its current state: 

 

 

 

[Triple Jim]

My guess is that a connecting rod bearing was damaged when the engine lost oil, and it has continued to get worse.  From the speed of the banging, it seems like it's happening at crankshaft speed, not cam speed.

[cornerslider]

I would NOT run that any longer. I'm not sure I would "scrap" it, but I would get the motor looked at by a mechanic. How many miles are on the bike? Good luck, let us know how it turns out-

[Rider115]

@cornerslider

Its creeping up on 17k. I dont really know any mechanics that I can trust. My biggest fear is I'll end up paying some guy $700 to tell me my motor is toast or I'll pay someone $2000 to rebuild it and it starts knocking again after 50 miles. Based off of what I've seen online, if my rod bearings are spun I'm better off getting a new engine all together as rebuilding it can be just as expensive if not more and its liable just to have another failure. I feel like I'm stuck between selling it with the knock for $1500-$2000 or getting it fixed and just hoping I'm not upside down in it afterwards.

I appreciate the feedback,

Edited October 2, 2023 by Rider115

[Triple Jim]

You don't have a location in your profile... where are you?

[Rider115]

I'm in South-Eastern Pennsylvania.

[M, Hausknecht]

Well, you can't buy a new engine unless it comes with a new bike. You can buy a used engine, from part out of a crashed bike, and it may or may not be just fine. I've bought used engines for $1500-2000 and they were in good, healthy condition. Your motor can be rebuilt for no more than that, but I wouldn't go to a dealer but, instead, a small shop with a good reputation. Try the WERA bulletin Board for recommendations inn your area.  https://forums.13x.com/index.php Disassembly and rebuild with new rod and crank bearings isn't difficult to do, and a good mechanic can easily determine if other stuff needs replacing (hopefully the camshaft journals in the head are ok so you won't need another head).

Basically, you have 4 options: (1) sell/part out the bike to get as much money out of it as you can; (2) rebuild the motor; (3)buy a used motor; and (4) park it and quit riding. All will involve time and money except the 4th option which, personally, I would find to be the least desirable option. That must've been a pretty big rock. Good for you not falling down.

[cornerslider]

17K isn't much on the CP2 motor. If you are happy with the bike, I would have it rebuilt. I'm having my top end rebuilt over the winter. Mine has about 10K track miles on it (17K total). Even after MANY hard miles, it still runs great. My compression is slightly low, but I likely will never sell it. I can justify the rebuild for that reason alone. You just have to ask yourself what's right for YOU. Good luck -

[twf]

Drain oil and see if you have metal shavings in it. You can also take oil pan off and strainer. If you find gold bearings are gone.

[Rider115]

I think I'll try to find a smaller highly reviewed shop around me, have them break it down and give me a quote so I can make an informed decision from there. 

It was a pretty large rock. I think the only reason I was able to keep it up is because the hole was in the left side of the pan, so the oil only coated the left side of my tire.

Moments before disaster struck:

Moments after disaster struck:

Thanks for the help, I'll keep yall posted.