[ygolohcysp]

I wish I had half of your time and skill, I have to half redneck my stuff...lol

Thank you, though I am burning way more time on this than I had imagined, and more than I should. I'm imminently going to be shifting into getting several things done for other people. This is just my guilty pleasure that I can't seem to turn away from. Just got the shock put back together. I still need to charge it with nitrogen tomorrow, but it was good enough to get it on the bike and set the preload. Honestly, I think I may need one size up on the spring weight, but we'll see.

Also, with everything on it except for an exhaust I need to build, a gas tank, and plastics, I can still pick it up. I think it's still just a tad less than the pocket bike for weight, but much larger, and probably about double the power. If it's not raining Sunday, I'll take it in to work and weigh it on a pallet scale.

[92xjunker]

I wish I had half of your time and skill, I have to half redneck my stuff...lol

[ygolohcysp]

Update time again!

I've gotten a lot more done, while seemingly taking forever and because of that, feeling like it's dragging on forever.

I finally made the levers. The brake side is a little smaller than the shifter due to the kick start lever needing to clear the tab sticking out. I've neglected taking any close up of the brake side, but here's a couple for the shifter. Plus, it's easily swappable from normal shift to GP shift. It's in GP configuration in these pictures.



I then made the pieces for mounting the oil cooler, and needed to flip the frame over so it would be easier to weld onto the bottom of the frame, so I pulled the engine and swingarm, and disassembled everything except the front suspension. I don't really have any good pics of the oil cooler mount process, but while I had that out, I also reinforced the swingarm. Decided to try to eliminate bad flex before test riding.

Mocking it up. You can also see the UHMW chain slider I made.




All the junk on the table under/around the swingarm is just so I can get it to where I can see the area to weld easier, and have my torch hand resting on something to allow me to have a more consistent gap. Straight line welding has become rather easy. Welding on round tubing, especially as small as 3/4" diameter is not as easy.

While welding the oil cooler mounts, I also made some brackets to mount the ignition coil, the CDI, and also a few small places to be able to wire tie the wiring harness to the frame. Started reassembly. Luckily, the chain clears through the window that I made for it!




And finally, just so you can all laugh at me and call me old just quiet enough that I can't hear what you're saying, this is how I have to read the stamping on carb jets now, apparently. Take a picture and zoom in.



I've since added a rear brake hose (haven't added fluid or bled it yet, gonna delete the reservoir first). I also now have enough hose clamps to finish plumbing the oil cooler in. Picked up the two electrical connectors I needed to complete the kill switch. I currently have the rear shock disassembled as well. I needed a stiffer spring. In order to mount the aftermarket springs (Race Tech), I also needed to swap out the ramp style adjuster for a threaded body adjuster. To fit that onto the body, I had to pull the shaft because that wouldn't fit over the lower clevis. While disassembling, I found that the bottom out bumper was rotted. So despite having everything else I need, that part is being delivered tomorrow. Then I can reassemble that. I think I'm going to trade in the tiny bottle I have for my mig welder for a nitrogen bottle and be able to charge the shock myself. That way once I can start testing, I can modify the shim stacks without having to worry about getting it charged again (the place that can do it is cheap, but an hour away). Once I have the shock done, all I need is an exhaust, and a gas tank and I can test it out!

[ygolohcysp]

More updates. The other day when I woke up (still on nights), it was warm, and going to get dark soon, so I hurried up and took the bike outside, pushed it up my driveway, and rode it downhill, with no foot pegs and no working brakes. On the plus side, it's stable, and it wants to turn. On the down side, I'm now even more impatient about wanting to try this thing under power. Another up side is I finally got a picture that gives this thing a sense of scale, behind my car.


I have since added the front brake line, bled it, and have that working. I've also been picking up some new tricks for machining, and working on making some rear sets. In this next pic, the main bracket is all one piece, including the round standoffs.



The oval slot is for the peg. I'm doing one M10 bolt in the center of the peg, and the levers (brake and shifter) are going to use the peg as a mount on the reduced diameter. I decided that if the peg would somehow get mildly loose, I don't want it to be able to rotate, so I milled some tiny flats so even if it's not quite finger tight, it still can't rotate. Essentially, I have both sides done except for the levers. Here's the brake side, complete with the plate that will make them adjustable that will get welded to the frame. Oh, and yes, I made the pegs too.

[Lachie]

Looking good
I want one too

[ygolohcysp]

Your machining skills are awesome. Your carpet and wallpaper, not so much. Lol. Great work so far.

LOL Thank you for the compliment. You're entirely correct about the carpet and wallpaper! Interior decor is the reason I could afford this house that has two garages and a nice setting. I should try to clean the place up a bit and see if anyone is interested in a KR BBQ this summer in the Allentown area.

Anyway, I got back to work, and things have been hectic since then. I'm either working (nights, which sucks), or working on this bike. I tried to update once, but it was right as the site was updated, so that post got deleted.

Let's see ... I finally made the lower triple.




I have the swingarm kind of made. I'm almost done with mounting the engine currently, and then I'll be able to better plan the exact path of the chain, and then add more material to the swingarm to help make it more rigid with a spot for the chain to pass through. Here is how it sat for the first time as a rolling chassis.



The needle roller bearing/thrust bearing setup for the swingarm with the preload from that threaded collar works amazingly well. Such smooth motion with no play. That's the R6 shock mounted. The most recent pic I have has the engine sitting on scrap I-beam pieces just for visual. I currently have the lower mount done, and have the upper mount ready to just weld together. I also have the top two tabs welded for bolting a rear subframe to. In just a short time, I'll have the upper mount and other tabs welded on tonight. Maybe finish the subframe as well.



I've made plates to weld to the rear of the vertical portions for providing adjustable bolt points for rearsets. Need to make the rearsets. I have all the controls on the way. I have the oil cooler that I still need to make mounts for. I just received the stainless steel tubing for attempting to make an exhaust, as well as sheet aluminum for the outer portion of the muffler, and potentially making a fuel tank/cell out of. At this point, for full funtionality, I think I only have just a couple things to purchase. Rear brake hose, hoses and banjo fittings for the oil cooler. For now, and for testing, I may just use the new K&N air filter that I had gotten for the CRF because it fits, but I'm still thinking about making an actual air box so I'm not screwed if I end up having to do a race in the rain (yes, I can get rain race tires as well).

I've already rebuilt the forks with the Racing Bros cartridge kits. Essentially the same things as the Ohlins kit, but slightly more expensive, only one set of springs. BUT, I have external clickers for compression and rebound now, which the Ohlins doesn't offer, plus a tiny amount of spring preload available externally as well. After getting the kit, I realized that it wouldn't allow me to gain the extra inch of travel as I had planned on, which the Ohlins kit would have let me do. So I did what any normal person would do. I ordered 12mm ground finish rod, bored it out the same size, added the threads and valving holes, and made my own dampening rods to hold the new cartridge valves that were an inch longer!

It's taking longer than I had envisioned, partly because I'm back at work. Partly because I hadn't really thought about having to make every single piece like threaded tabs to weld on for subframe mounting or shock mounting, etc. And yes, I did made the entire swingarm, including all the parts for the axle adjusters.

Also, just to point out, I'm in the building phase. Once everything is made/mounted, including tabs for mounting fairings, then I'm going to actually do the finish work. I'll make some of the welds less ugly and stuff like that.

[92xjunker]

Didn’t even notice......too busy staring at the work. lol

[y2ktj]

lmao

[Lunatic]

Your machining skills are awesome. Your carpet and wallpaper, not so much. Lol. Great work so far.

[ygolohcysp]

I'm almost 6' 1", weigh about 185. And yeah, it's my legs that suffer the most when racing. I don't feel too bad on the Kat, but I'm getting older, and my knees can't take a long time on the Kat, just general riding. After 2 hours or so, I need a break. On the crf150f, my legs feel pretty good until the end of an endurance race. On the pocket bike, my knees have had it after about 15-20 minutes. It's just so small that I'm forced to spend almost 0 time actually sitting on the seat. I'm hoping with the bike I'm building that it'll be capable enough to let me not have to hang off so far and be able to lean over further without scraping hard parts.

[buffalobill]

The limits of physics

Ok, and so we can get a clear idea of the physical challenges of racing a mini bike; what's your height and weight?
I'm having a hard time on my Kat, because my legs are so long. My knees are a bit over bent, so I have to use more force to push up and change sides in chicanes. Fatigues my legs quickly.
I'm gonna raise my seat a couple inches just to reduce my knee angle.

[ygolohcysp]

Did you post a concept drawing of this project? I'm sure you're building a mini slab side gsxr!!!

I thought I might have, but I guess not. I never did a very detailed drawing. I essentially took a lot of measurements off my pocket bike that works so well. I did a drawing to scale just with functionally important points like heights and angles and locations. Axles, forks, tank, seat, rear sets, swingarm pivot, etc. I then compared those to a Grom, which I don't think works well without a LOT of mods, and also compared it to a professionally built R6 race bike. It's actually quite funny how closely the pocket bike emulates the correct placement of rearsets, seat, etc (granted, all of that modified with how it sits now). Then I set about making a sort of skeleton sketch using axle heights, planned fork angle, and then drew a frame to connect those points.

So, this is to scale, including the R6 shock and Daytona Anima 190cc motor.



The specs so far is 24-25hp (as advertised as stock performance for the 190cc motor), 200 pounds or less. The bike I'm hoping to beat is listed as being 150 pounds, but it's literally the size of my pocket bike. It has a steel frame, I'm using aluminum, but I'm also over building it to survive the typical crashing involved in racing and practice. Mine is also going to be comfortable enough for an endurance race. I think my wheelbase is going to be about 1 inch longer than a Grom. 30" seat height. Enough ground clearance to be able to drag elbow if the race slicks hold well enough. That was a problem I was running into with my crf150f. I'd lean to the right, hit my knee, then my toes, then the peg mount. Then I'd throw sparks while sliding and have to push the bike back up. I did that twice while beating someone to an apex by just not hitting the brakes to get by them. I can only guess that thinking I was crashing in front of them helped them slow down a bit. LOL

But yeah, I essentially want real sport bike performance out of a miniGP bike. So appropriate forward to rear placement of the front of the seat and rear sets, appropriate length of swingarm and angle for anti-squat, 24 degree rake. Unfortunately, I figured out to get the braking I want, I'll need to spend about $700 on the front brakes. Brembo RCS14 master cylinder, Brembo P4 30/34 caliper, Vesrah JL compound pads, and as large of a rotor as I can use and still fit that caliper. And the only reason for that caliper is specifically because that compound of the Vesrah pads is worth it, and also not available for the stock caliper, or I think even the single piston Brembo calipers.

[buffalobill]

Did you post a concept drawing of this project? I'm sure you're building a mini slab side gsxr!!!

[ygolohcysp]

One more update. I'm trying to put a real push into this project before leaving to go visit family for Christmas, and then going back to work just after new years. I've lined everything up and clamped it in place for welding the frame, made very detailed measurements from the welding table surface, and used a wire (no stretch line string) to measure from the all-thread through the headstock. Drilled holes out for the swingarm pivots I made, cut the verticals to length, clamped it all back up and started welding.



In the middle of welding, after doing everything I could before needing to flip it over, I wrapped a sock around the steering stem, jammed it into the headstock, and very half-assedly tried setting it up at approximate measurements. I'm really liking the size of this thing. I'm also finding out that it is way more rigid than I expected. I was certain I'd need to do more to get this to work, like maybe 1x1 rails under the motor and up to the headstock, but I'm really thinking I won't need to bother at this point. Still have more gussets to do, but I'm impressed so far.



I also decided to bolt the headstock down again, and then do the swingarm pivots. Did detailed measurements, used the tube I'm going to make the axle out of and a level, and used the wire. I did not clamp the frame down though, because I didn't want that introducing flex that isn't there, so only the headstock was bolted. This was a good exercise in doing tack welds 180 degrees apart, then checking alignment again. Repeat for 4 tacks 90 degrees apart, and both sides of both inserts, making sure the axle was lined up and moved easily.





The stock honda grom has 3.9 inches of travel in the front, and 4.1 in the rear stock. When I do the Ohlins cartridges and springs, I'm also doing another mod which extends the forks 1" and adds that as extra suspension travel. Because of doing that, I'm planning on also adding approximately 1" of travel to the rear. At the swingarm length I have planned, just a touch over 17", that puts me at putting the R6 shock right at 6" out from the front pivot of the swingarm to have just the right amount of travel before the shock bottoms out against the rubber bumper. This is going to be direct hookup instead of linkages and dogbones. I don't feel bad, the grom uses a direct shock. So does the pocket bike I overbuilt. I did that with a Honda 954rr rear shock. It's 4.5" out, and I needed to create an extra 1/4" spring preload collar. I think with the mechanical advantage of the extra 1.5", this shock should be perfect, give or take finding a different spring if needed.

[ygolohcysp]

Spent some more time in the shop today. Fixed the bearing/shaft for the gearbox on the lathe. Then I made all these pieces for making the swingarm mounts for the frame. The larger cups will get mounted in the frame. The one with the 3/4" hole on the chain side, the threaded one on the brake side. They are 6061 to weld to the frame rails. The threaded sleeve goes into the threaded cup from the inside of the frame rail. When the swingarm is made and ready to install, the threaded sleeve snugs up against the thrust bearings, and the jam nut keeps it there. Then a hollow shaft will tie it all together.