The Purrfect Project (Hellcat)

[scoot newb]

I really like that oil cooler.

[scoot newb]

You may have seen this in the groups already but... going back to your question about the rear hub.

[deadwood83]

Maybe! But I've stared at that and I think I can see what went on.

First of all:
Two of the bolt securing locations look chowdered at the edge of the threads.
One of the four bolt hole locations looks chowdered inside the threads, then broke away in the same direction the chain is trying to rotate the wheel.
Looking at the one hole where we can see inside, it looks to be straight metal, nothing more.



So my conclusion is this:

• Bolts hollding sprocket were never chemically bonded (loctite)
• Bolts holding sprocket were allowed to come loose with time.
• Once bolts were loose, they allowed some radial movement and a small amount of axial play, which began to destroy the threads inside the holes.
• At some point later, the bolt holes had almost no threads, and only 1-2 bolts were partially secured. The user hit the bike with some power, and due to the imbalance of fastening faces, the chain torqued the sprocket which tore the remaining bolts out.

Proposed solution: loctite your bolts. I believe people blame whatever seems obvious or convenient at the time. Not because they have an agenda or anything, but bcause most people on the groups are quite new to failure analysis and other mechanical studies. In all likelihood, a grom hub treated the same way (loose bolts and unattended) would suffer the same fate.

What you CAN say is that tapping tolerances on a grom would be better leading to fewer loose bolt issues.

Oh, and you can see evidence of the sprocket wobble on the uneven tooth wear pattern. The outer edge of each groove is hammered really hard.

[deadwood83]

Alright, 150 miles on the ZS190.

Still breaking in the trans. Shifts well so long as the bike is moving. Probably need to readjust the clutch cable from stretch.


These tires however... They are entirely terrifying and wholly unsafe. I was feeling them out in a concrete parking lot and tried an emergency stop. From about 30mph I locked both brakes without issue and the bike still slid almost a full residential intersection before stopping. No bueno. These tires are going to kill somebody.

[RedCrowRides]

Try lowering your air pressure , you shouldnt need to run more than about 18 psi , unless you are huge .That will help the grip a lot, thats what we do in the Stunting community to address that and many run it down to as low as 12 psi. You dont want it up around 30 psi or higher .That said yes the stock tires are hard , you dont pay $1200 for a new motorcycle and get cutting edge technology tires.

[deadwood83]

Originally Posted by RedCrowRides

Try lowering your air pressure , you shouldnt need to run more than about 18 psi , unless you are huge .That will help the grip a lot, thats what we do in the Stunting community to address that and many run it down to as low as 12 psi. You dont want it up around 30 psi or higher .That said yes the stock tires are hard , you dont pay $1200 for a new motorcycle and get cutting edge technology tires.

This is the first I have heard of lowering the pressure. Will that actually work going 70+?

Originally Posted by RedCrowRides

That said yes the stock tires are hard , you dont pay $1200 for a new motorcycle and get cutting edge technology tires.

Hahaha it's true. I guess I was just expecting something okayish for stock speeds (30-40mph). There are a bunch of quite good cheap moto tires out there. I guess at this point I'm choosing between Pirelli DR or Michelin CG. Lots of people like the Pirellis, and they have no center groove so I'll probably go with those.

[deadwood83]

RIP this project. The bike was stolen from my gated community on September 4th and 'recovered' on October 9th.






With my peculiarities, i would have to take the engine and everything apart to individual pieces, inspect with a loupe, order replacement parts, reassemble, and then I still wouldn't fully trust it.


I gave the carcass, title, and keys away to a local veteran who plans to restore it come springtime for his kids. IMO, it's kind of a dangerous bike for kids.


I needed to heal my heart. So... since I really enjoyed my brother's KP mini with 223cc big bore and worked head...



2021 KP Mini. It's getting a water cooled 6-speed, 4 valve, SOHC, 300CC swap.

[China Rider 27]

Sorry to hear that! That is a tough one! All the best on healing that loss!

[cbrfxr67]

Dangit just read through all this and didn't see that coming. Thanks for sharing all your experience!

[warrenpeas]

Originally Posted by deadwood83

RIP this project. The bike was stolen from my gated community on September 4th and 'recovered' on October 9th.


Attachment 23216
Attachment 23217
Attachment 23218

With my peculiarities, i would have to take the engine and everything apart to individual pieces, inspect with a loupe, order replacement parts, reassemble, and then I still wouldn't fully trust it.


I gave the carcass, title, and keys away to a local veteran who plans to restore it come springtime for his kids. IMO, it's kind of a dangerous bike for kids.


I needed to heal my heart. So... since I really enjoyed my brother's KP mini with 223cc big bore and worked head...

Attachment 23219

2021 KP Mini. It's getting a water cooled 6-speed, 4 valve, SOHC, 300CC swap.

rip 190, you were a trailblazer with the clones.