BAWC Forums

Coop getting handy.

ChargerX3 wrote: ↑Thu Oct 02, 2025 6:38 pm Coop getting handy.

Just doing what I do and over complicating things. Should have pulled the dang governor and called it a day.


Coop

Needed a place to mount that rpm max device.




Made this little bracket. It’s held on with a velcro thing it came with. I could drill and screw it in, but the Velcro should be nice.

Hope my 360 can see it so I can get an idea when reviewing videos. Prob not but I can hope. I think this was the last piece I needed to get done.


Coop

Went out and finally got to test the stuff we did.

To recap we went from 57 to a 67 rear sprocket.
We went from a 12 to an 11 crank clutch.
Fixed the rpm to get full 3600 out of the pedal.

I added an engine rpm logger so I could figure out her top speed.

https://youtube.com/shorts/ZKGTEKWlV68? ... q_bDPcgTpB
https://youtube.com/shorts/Rxio5HfgwcM? ... wbZZ7WK_n7

So with the logger and the long strait away she got to 2950. So I’m calling it 3000. Which with the math is 14mph. I figure she got around 11mph at the autocross. So we got some more mph but still taking too long to get to max rpm.

Going to start modding and starting with exhaust. But also really thinking I need to get a higher stall clutch. Get it out of the hole a little better.

Just thoughts.


Coop

The more I talk and read. I do need a diff clutch. Mine is made for just easy engagement and cruising in a mini bike. I need a meaner clutch. Main problem is my crank is 5/8 and most clutches are 3/4. So I guess a sleeve is needed. But I want it to engage much higher especially seeing as I will eventually want this thing to rev to around 6k.


Coop

https://www.bmikarts.com/Inferno-Fire-3 ... _4981.html

I think this is the clutch I’m gonna get. With a sleeve to make it work on my kart and some weights to fine tune the engagement.


Make this thing take off around 2300rpms and that will deff help its take off speed.

Also found a whole group who races with these engines and my kart. Kind of cool. They keep them stock and have way higher gear ratio. Mine is like 6 something. They keep around 3. So I do think it’s my clutch.




Coop

Went with a different clutch for two reasons.

One the clutch I posted had a spot to go into the keyway. That’s perfect. One whole piece, so it’s not gonna twist. Except if you are gonna sleeve it and you need a larger keyway to hold the sleeve, but then the clutches keyway wasn’t gonna be big enough. Anyways, it was just easier to go with a different clutch.

Also the clutch I wanted summit had on sale half or even more than what these kart websites had it. And it needed a keyway, so ifs much easier for me to make a bigger keyway than try to get two to work. I actually think it’s gonna be enough from the sleeve I bought.

Anyways. Clutch and sleeve bought, with some springs so I can adjust the rpm some. I’m taking start out around 2,200…maybe get up to 2,500, just depends on how well this works.


Coop

Okay. Today was exhaust and a clutch mod.

We did this mod where you cut the spring and make it tighter so it doesn’t start for much higher rpm.
https://youtu.be/gpo7GGSS8ZY


Needless to say. It was a pain. Hard. And didn’t work.

Worth a shot for free.

Next we did exhaust. Had to cut the chain guard some but it’s all good.





Wish I would have recorded it running as it sounded so much better and wasn’t too loud. If I had designed it I would have angled it up some so more the chain guard would be left. But oh well it’s okay.

Happy with the exhaust. Not with the clutch but I have a real clutch coming so not to stressed about it. Was just hoping a free mod would work better.

Also made the kart driver do most the work. She got to run a skill saw but not the saw saz or the grinder. She did all but one bolt. Also, first time she’s used an open end wrench and we about came to blows over it. She kept loosening it. Then turning it back like a it ratcheted or something. So it wasnt getting looser…I had a whole hold the light moment.

Coop

I’m frustrated. I just spent 7 hours of work and got nothing accomplished.

Well got a lot done, nothing fixed.

Got a 3,100rpm spring for my current clutch. Swapped it over and it’s wanting to engage at around 1,800

Fine. Let’s move to a real clutch.

Got a noram clutch. Was a huge pain as it’s for a 3/4 shaft and mine is a 5/8. So I a shim to make it work. It was a little big so I had to sand it down and file to down and lots of work to make it right. Same with the key. Lots of filing and sanding to make it right. It has a 3,200 spring. It wanted to engage even earlier than the other clutch.

It’s two clutches and so it must be me. I am frustrated.

Anyways have is a video of the exhaust if you are curious.

https://youtube.com/shorts/_n1RHjWWw4g? ... ZW6MGCyBtd


Coop

So I got tired of the bolts to hold the engine down. Worked fine for making a race but when I’m changing parts and gears and clutches the engine has to come off a bunch. So I went to put studs in it. Well no one makes a machine screw m7….no one. They make every other size but m7. So today I drilled out the m7, made it for m8, tapped it for m8x1.25. Drilled the counter sink holes and put in basically studs. I will lock tight those in. Also gonna cut a nut in half as I had two washers for spacing and screw those down. This will make taking on and off the motor much easier.

Still working on the clutch.


Coop

Okay. Got to keep working on the kart motor mount. Got the machine screws as studs done the other day but I also had to use washers as spacers. It has to go between the motor mount and the predator motor mount. Added to the problem of the bolts when the motor moved a little so did those washers and just made things annoying. While studs would hold washers and I didn’t need to do the next part….why not.

Thin nuts.




And after it’s all said and done. Red locktite on the machine screw and half nuts.



Coop

Nice

Chris GTO TT wrote: ↑Fri Nov 28, 2025 4:42 pmNice

Thank you. I am kind of proud of something no one will ever see. But makes it easier for me to work on it. So it’s worth it.


Coop

Good news bad news.

Good news: the new motor mount studs are so nice. The lock washer fits it perfect. I have had the motor on and off like 5 times. Super simple. I’m happy.

Bad news: I took the one cheap clutch. Put it in the lathe, took tons of material off the face of the clutch. 1400 rpm engagement. I think that’s less than before.

Screw it. Put in thicker springs in the other clutch. Suppose to make it 2500rpm. 1300rpm….i went and bought the 3500 springs. Let’s put those in. lol.

But this is beyond annoying.


Coop

I am an utter failure with this clutch. I just put in 3200rpm springs. So stiff it took me an hour to put them in.

1800rpm.


Coop

Welcome to another day of coop banging his head against a wall not understand what he is missing to mess up this bad. Today we go back to clutch 1. The max torque clutch. A simple centrifuge clutch. I’ve tried two different springs in this one. I’ve taken material off the face of the clutch shoes in the lathe. So today…..I cut 3 in half to take out weight, and make the overall diameter smaller.

Here you can see a shoe before I cut it.


65 grams.
Here are the 3 I cut




62/61/62. Two out of 3 ain’t bad. I don’t know if 10g’s is a lot but that’s what was taken out material wise.


This is how much shorter one is.


This is back together. Before I put it in the lathe the clutch shoes were even with the far right thin metal.

After the lathe they were even with the thicker metal on the left.

Now after the cutting they sit much farther down.

So to recap, we have a 3,100rpm spring in, we have taken off over 10 grams of material, and it’s around 3mm less of a circle than before.

1300-1400rpm everyone. FUCKING 1300-1400 RPM and the brake can not hold back the engine.

Hi…..I’m the problem. Now can anyone tell me how to fix it?!!!!

Please?!!!!


Coop

After looking at this, I’m gonna build my own chain tensioner.

I can get tension on the chain right now but just how it’s done it moves a little when tightening and annoyed me a lot. And can’t move the motor mount when just a little loose. So I have to get it way loose then move it. Then when tightening they move just a little and that’s a lot when you talk about chain.

Going to do a metal coupling. Put a bolt in it. Then a bolt in the motor mount. Then use some machine bolt hangers and a coupling nut. That should let me move it back and forth pretty effortless.


Also think I have some ideas about my clutch. My motor is soooo wimpy that any sort of hang up stalls out forward progress. So I’m gonna put some notches in the clutch disks (nothing I can’t throw in the lathe and fix easily) to let less surface area touch till it get higher rpm’s and that spring puts more force against the clutch.


Coop

The car group just posted two days worth of pictures. These were the best.





Coop

Nice!

Nice coop. She looks like she is loving it out there.