Posts
178
Joined
9/27/2021
Location
Fresno, CA
US
Edited Date/Time
11/6/2022 7:04am
Hey everyone!
I had this build posted on a pit bike forum but that has slowly died since the beginning of this build (2012) so I figured why not post it on the MX forum of the internet. Probably get some criticism for this ridiculous bike but here we go.
It began life purchased as a 2001 TTR 125L with a BBR frame cradle, BBR exhaust, and BBR springs. Overall bike was pretty solid and was a good deal we got with a stock xr100 for $2000 as a package. (Back in 2009)
Next I purchased a basket case 2008 KX100 and traded it for a set of 2001 YZ80 forks/triple clamps. Got the forks installed and ended up remounting the shock to try and level out the bike. We also rebuilt the engine with a hot cam/rev box/ and a hi comp piston.
I ran this setup until 2014, riding the local motocross tracks jumping a lot of things that shouldn’t be jumped and just having fun.
I ended up destroying the rear hub breaking the flange along with the linkage bearings. So then I installed a hub from a newer model TTR which has thicker flanges and a set of Prowheel rims/spokes. So far these have held up well luckily! Also added a LE aluminum swingarm and linkage to replace the old steel one.
Next up was a LE remote resi shock that I then revalved with gold valves and a fast 50’s spring. So far she’s worked well other than I’ve gotten fatter lol. So I need to re work all of the suspension at some point.
And then it started to burn oil and make some sad noises so it was time for a rebuild. That’s when things went EXTREME!
Ended up seeing a raptor 125 builder in GNCC doing 4 valve head conversions along with some other really cool mods and as it shares the motor with the TTR I knew what I wanted to do next. So I bought a 65mm piston and a big valve head for a zuma 125 and started to do some homework. Unfortunately we couldn’t fit a sleeve into the stock cylinder with good confidence due to loss of material. Ended up buying a 74mm full aluminum cylinder and piston kit (my machinist is a mad man and suggested it) (Stormin Norman) It ended up being a lot of machine work and custom parts to make it happen. I won’t go into the entire story but I think the photos will speak for themselves.
So specs are this point:
Engine:
232cc 4valve engine
74mm bore x 54mm stroke
Nikasil cylinder
TTR125 LE cases
Big valve zuma 125 head
Aftermarket camshaft
Lightened flywheel
Lightened crank
Counterbalancer, bearings, and gear removed (gear replaced with an aluminum spacer)
Heavy duty valve springs with Titanium retainers
2011 TTR 125 transmission (stronger countershaft design)
Raptor 125 clutch setup
Kickstart delete (aka countershaft breaker)
Keihin PE 28 carb
BBR big filter kit
Engine oil cooler
Electrical:
Modified 2003 TTR125LE harness
-key delete
Stock CDI box
Innovative Motorsports Wideband O2 sensor
Hour/RPM meter
Antigravity 4 cell race battery
Electric start conversion
Suspension and chassis:
2001 YZ80 forks
-race tech gold valves (need to update valving)
-.38 springs (need to increase spring rate)
TTR 125LE shock
-Gold valves (need to revalve)
-Fast 50’s Spring
-Race Tech Bladder Cap
Original frame
LE aluminum swingarm
Prowheel rims and spokes
Tall seat foam
Lowboy pegs
Mika mini hi bars
Bar risers
ASV levers (not my favorite)
Misc:
14t front sprocket
49t rear sprocket (might change)
Old tires (plan to replace once engine/chassis is dialed)
OlmyCreations Graphics
I know I’m forgetting some stuff.
As far as it’s current status it’s burning oil. Performed a compression and leak down test which all checked out perfectly fine. Which is sure hope with less than an hour on the clock. Which should mean bad valve stem seals so got those in order. Then my camshaft sprocket (one of the custom parts) is deforming and wearing super fast so I have a new set on order being made from 4140 also added some slight revisions to my design.
With the nature of the top end being from Taiwan makes obtaining replacement parts not as simple as going down to the Yamaha shop and get it. So the new top end gasket is on order from overseas. I also ordered an extra set of gaskets and a extra piston kit just in case supply craps the bed later on.
It’s only been ridden 2 times in its current state due to a clutch slip issue (finally solved) and my previous OKO carb having a float failure. Power seems really good but no power numbers at this point haven’t gotten a good baseline test to work on improvements
Anyways now for pictures!!!!
I had this build posted on a pit bike forum but that has slowly died since the beginning of this build (2012) so I figured why not post it on the MX forum of the internet. Probably get some criticism for this ridiculous bike but here we go.
It began life purchased as a 2001 TTR 125L with a BBR frame cradle, BBR exhaust, and BBR springs. Overall bike was pretty solid and was a good deal we got with a stock xr100 for $2000 as a package. (Back in 2009)
Next I purchased a basket case 2008 KX100 and traded it for a set of 2001 YZ80 forks/triple clamps. Got the forks installed and ended up remounting the shock to try and level out the bike. We also rebuilt the engine with a hot cam/rev box/ and a hi comp piston.
I ran this setup until 2014, riding the local motocross tracks jumping a lot of things that shouldn’t be jumped and just having fun.
I ended up destroying the rear hub breaking the flange along with the linkage bearings. So then I installed a hub from a newer model TTR which has thicker flanges and a set of Prowheel rims/spokes. So far these have held up well luckily! Also added a LE aluminum swingarm and linkage to replace the old steel one.
Next up was a LE remote resi shock that I then revalved with gold valves and a fast 50’s spring. So far she’s worked well other than I’ve gotten fatter lol. So I need to re work all of the suspension at some point.
And then it started to burn oil and make some sad noises so it was time for a rebuild. That’s when things went EXTREME!
Ended up seeing a raptor 125 builder in GNCC doing 4 valve head conversions along with some other really cool mods and as it shares the motor with the TTR I knew what I wanted to do next. So I bought a 65mm piston and a big valve head for a zuma 125 and started to do some homework. Unfortunately we couldn’t fit a sleeve into the stock cylinder with good confidence due to loss of material. Ended up buying a 74mm full aluminum cylinder and piston kit (my machinist is a mad man and suggested it) (Stormin Norman) It ended up being a lot of machine work and custom parts to make it happen. I won’t go into the entire story but I think the photos will speak for themselves.
So specs are this point:
Engine:
232cc 4valve engine
74mm bore x 54mm stroke
Nikasil cylinder
TTR125 LE cases
Big valve zuma 125 head
Aftermarket camshaft
Lightened flywheel
Lightened crank
Counterbalancer, bearings, and gear removed (gear replaced with an aluminum spacer)
Heavy duty valve springs with Titanium retainers
2011 TTR 125 transmission (stronger countershaft design)
Raptor 125 clutch setup
Kickstart delete (aka countershaft breaker)
Keihin PE 28 carb
BBR big filter kit
Engine oil cooler
Electrical:
Modified 2003 TTR125LE harness
-key delete
Stock CDI box
Innovative Motorsports Wideband O2 sensor
Hour/RPM meter
Antigravity 4 cell race battery
Electric start conversion
Suspension and chassis:
2001 YZ80 forks
-race tech gold valves (need to update valving)
-.38 springs (need to increase spring rate)
TTR 125LE shock
-Gold valves (need to revalve)
-Fast 50’s Spring
-Race Tech Bladder Cap
Original frame
LE aluminum swingarm
Prowheel rims and spokes
Tall seat foam
Lowboy pegs
Mika mini hi bars
Bar risers
ASV levers (not my favorite)
Misc:
14t front sprocket
49t rear sprocket (might change)
Old tires (plan to replace once engine/chassis is dialed)
OlmyCreations Graphics
I know I’m forgetting some stuff.
As far as it’s current status it’s burning oil. Performed a compression and leak down test which all checked out perfectly fine. Which is sure hope with less than an hour on the clock. Which should mean bad valve stem seals so got those in order. Then my camshaft sprocket (one of the custom parts) is deforming and wearing super fast so I have a new set on order being made from 4140 also added some slight revisions to my design.
With the nature of the top end being from Taiwan makes obtaining replacement parts not as simple as going down to the Yamaha shop and get it. So the new top end gasket is on order from overseas. I also ordered an extra set of gaskets and a extra piston kit just in case supply craps the bed later on.
It’s only been ridden 2 times in its current state due to a clutch slip issue (finally solved) and my previous OKO carb having a float failure. Power seems really good but no power numbers at this point haven’t gotten a good baseline test to work on improvements
Anyways now for pictures!!!!
Because he could that’s why!
Love it. It’s fun working on bikes just like it’s fun riding bikes.
I remember talking to you about a year ago at DT-1 in Tulare, the 4V head is super trick.
I'll have to hit you up as I dive into my TTR125 project bike, trying to figure out it's issues.
The Shop
First start ever
https://youtu.be/WBTdTBCl2Cg
Another running vid
https://youtu.be/C57apHS6m3U
First time riding it (running way too rich and clutch slipping) (had tried once prior to ride it but clutch slipped way too much to even do a lap)
https://youtu.be/8XVecxqI-2w
Hope your build goes smooth and just enjoy it!
Got my extra piston and gasket kits in this week for the top end. Installed the new valve stem seals so should be ready to rip once I have the sprockets.
There’s a few current issues that would need to be addressed to build another.
- Cam sprocket hub (current model discontinued)
- Redesigned cam sprocket (to match new hub)
- Random OEM parts add up
- Some things are still a little janky
It’s not cheap lol.
Cam sprocket alone would cost $300 in its current form. The demand isn’t high enough to produce enough to drop the price.
Cylinder and head with all the misc parts is another $1500-$1800depending on bore size
Then add in machine work and all the other random bits and pieces I wouldn’t remember until I was in it.
It’s not super practical lol your looking at a $3,500 TTR125 motor. And that probably would be before fueling and exhaust setup. You at least are close to the guy who did machine work (Pennsylvania)
I bought most of my parts years ago prices had been much lower and I probably spent 2k on the engine package. Granted I spent much more with mistakes made and what not. The entire saga is on planet minis (TTR125 playbike build) and I still have not finished it 😂.
I hope one day I can get all the equipment to do the work myself and stop outsourcing things like the cam sprocket and machine work but at this time that stuff makes this more of a very limited project. Plus as an everyday guy with wrenching skills it’s hard to cut costs when I’m paying retail for everything.
Precision motor works used to do 150cc versions for raptor ATV’s with stock zuma heads and sleeved/machined stock cylinders for around $1200 with custom pistons from weisco. Firepower minis also used to offer it as well for close to the same price. I believe both have since stopped doing motor work.
So it’s finally happening slowly but surely.
Made out of 4140 by CenCal CNC in Kingsburg from the file I provided. Glad to work with a local company instead of out of state. I need to finish up my 2 stroke then I’ll move back onto this little guy. Hopefully I can get it running before the OTHG nationals kick off.
Got the new cam sprocket installed. I hate installing these things. It’s a tight fit to get everything lined up due to the sprocket being almost the diameter of the opening and just not a lot of wiggle room to get the chain on. Also the adjustable hub is a super tight fit into the cam itself, it being a little thicker takes away some room as well. All in all it probably took me a solid 45 minutes to have the top and bottom end lined up properly with the chain in the correct tooth and then get it onto the shaft the first time.
Welded in the new silencer there’s a few pinhole leaks in the old welds on the step up in the header I need to fill. Also welded the shock mount which I had redrilled lower has ovaled out. So I made up some spacer/washers to weld up on the mount and reinforce it.
Bike was burning a lot of oil, compression and leak down tests were good so changed out the valve stem seals. Started the bike up and it was still burning oil like crazy. Pulled the engine other than looking like it was burning oil nothing appeared wrong majorly. I’m 100% sure I assembled the original oil ring set incorrectly so it wasn’t sealing. I was younger and dumber at this point it was YEARS ago. So new top end and gaskets installed with rings setup correct.
Got the top end and cooler primed with oil, and fired it up, Initially smoked a bunch but just until all the old oil was burnt off in the head and in the exhaust. Also clutch is working fine (FINALLY). One downside is some smoke from the crankcase but not too bad oil isn’t frothy at all so I’ll give it a little more time. I need to dial in the jetting. Running a keihin PE28 from a CR80. Had a 150 main in but the AFR was about 9:1 (had some blue smoke for sure) so dropped down to a 145 and now at idle we’re at 12:1. At half to full throttle it’s leaning out a lot like 18-20:1 and bogging. Currently running a 155 main but it’s not enough. I’ll try a 170 and see where it lands. I believe I do have larger jets in the box if need be. Possibly raise the needle one clip and go from there. Either way getting progress and confidence this thing will finally work sooner or later.
Test ride next weekend, suspension needs some work from last time I rode it was just too soft up front. Going to get stiffer springs and the hydraulic lock bottoming system from kroozetune. I need to get some aluminum to throw into the lathe and make a proper spacer for the silencer (currently and o2 bung and a bearing race. Need to trim the rear fender near the airbox where it’s touching the header. New silencer sounds great despite being an eBay special.
I’ll keep it updated
For some reason the forum is only letting me upload 1 photo per post.
Pit Row
https://youtube.com/shorts/bAOfM0Aarjc?feature=share
I’ve never personally broken a gear but I’ve broken 2 pre 2011 countershafts on stock motors or hot cam and hi comp piston in a stock bore just kickstarting them.
If you end up snappping anything I recommend either a 2011 and up transmission or a raptor 125 trans (though I think gearing is a little different on the raptor) they removed some snap rings and strengthened the trans as a whole.
Tall bars/risers, tall seat, PMB pegs with lowboy (if available)
BBR springs
If you want motor stuff just a simple hi comp piston, cam, and ignition wake it up quite a bit.
After that it gets expensive 😂 I rode mine with BBR springs, a hi comp piston, cam and ignition for years and had a blast. Kind of looking for another one for cheap to do that style again.
https://docs.google.com/document/d/1SI2wbJggb3_thAGuJtItTDHvQ3Kus0Cyvfs…
This is the only photo I have of the side cover oddly.
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