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I went with the TST sliders as well. To me, short of stunt cages, they looked to be the best protection.

My only gripe is I didn't realize they would preclude the use of the Kitaco clutch cover...
 

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Great photos and explanations! Really love the thought, planning, and execution of your work. Fantastic thread.
 

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Discussion Starter #23
Man is this Grom a money pit. I just keep finding things that need upgrading because I find a stock component is lacking. i guess that's what happens when you are racing a cheap econobox bike. I guess it's nice that some parts are cheap but some are still not so cheap. One of the cheaper parts I just added were the TB Parts cam and Cameron Jones ECU flash.






PROTIP: when doing anything cam chain or timing related is to mark the chain and the cam sprocket with a paint pen or marker. It makes reassembly and getting the timing setup way easier.



The TB cam and CJR ECU flash is a game changer for the Grom. In mostly stock form, power starts dying off after about 7k rpm. The higher you rev it the worse it gets. With the TB cam and CJR ECU flash it pulls all the way to the new 10k rpm limiter with ease. Power delivery is smooth and linear. From below about 4k rpm it feels a little weaker than stock, from 4-6k rpm it feels about the same as stock, and above 6k it pulls way better than stock. I highly recommend anyone with a Grom to get a TB cam and the CJR ECU flash.

I also did the Brembo P2-34 caliper upgrade from Hard Racing and a set of TST brake/clutch levers. I added the new levers post crash since the brake lever was pretty mangled. I managed to get it back pretty close, but I don't trust cast aluminum after it has been bent a few times.






The front Brembo caliper with the CoreMoto line is a very nice upgrade. You get a very stiff lever feel that is consistent and repeatable time after time on the track. The stock setup would get mushy and the pads would start to fade after a while on the track. Ultimate stopping power on the Brembo upgrade is very much improved and the modulation is very nice. I'm a one finger braker and with the stock setup my middle finger would get a workout. Now I don't need to use nearly as much force at the lever and it's much easier to modulate the lever depending now much braking you want. I'm not really fan of "shorty" levers, but I would call these more like 3/4 length levers. They are adjustable and fit my hands very nicely, the quality of the fit and finish is top notch.

In the last post I mentioned I had a lowside crash due my dragging the footpegs really hard in a right hand corner. The TST Industries crash protection held up really well, and the bike was still very much rideable after bending back both brake levers. I continued the race day and had a blast doing it. I have another set of slider pucks, but I can just spin the cups and they will be good for another crash.









I picked up a set of Driven Racing TT rearsets so I don't have anymore issues with dragging footpegs anymore. I chose the Driven because they allow standard and GP shifting in the same kit vs being pigeonholed into having only standard or only GP shift like the Woodcraft.



PROTIP: Use the rear wheel axle as a punch/swingarm holder when removing the swingarm pivot bolt. It's actually the same bolt/part number.






After a day at the track using the Driven rearsets, I can confidently say they are worth every penny. My biggest issue after the last few times at the track was how easily the pegs would drag and how unsettling it was at first. I eventually starting getting used to my toes dragging, then when I got really comfortable with it and pushing harder, it bit me in the ass. The Driven foot position is definitely more aggressive and more suited to track usage than the stock position. The other bonus is how precise the shift action is with the heim joint linkage and bearings in the shifter pivot. There is ZERO slop in the system now. The other parts I would recommend also replacing at the same time when installing rearsets are a Woodcraft brake return spring and a rear brake light pressure switch.

While I had the rear wheel off I decided to swap out the rear sprocket to a 36T PBI aluminum unit and a new DID O-Ring chain. The stock chain could not stay adjusted for more than a few hours on track and would constantly stretch. An added benefit of the PBI sprocket is how much lighter is vs the stock steel unit. The gearing is more suited for the current track configuration I'm running on too.





The final performance part of this round of mods was the rear Brembo upgrade. I wasn't a fan of the underslung rear caliper bracket from Hard Racing. So I went with the Chimera brake bracket, the same Brembo P2-34 caliper, and a stock replacement CoreMoto brake line to match the front line.




The stock rear brake is almost useless on the Grom, like Bigfoot, I'm not even sure it exists. On the other hand, the Brembo P2-34 upgrade is almost borderline excessive. When you get on the rear brake, it grabs like no other rear motorcycle brake I have ever used. I almost want to try the stock caliper with an upgraded pad and line to see how it feels. I do really like the idea of pad commonality between the front and rear calipers. I need more time on the track to see how I like the Brembo rear caliper. I'm not a huge rear brake user, but I like to use it to settle the rear when I need to stop in a hurry or over rougher surfaces.

Lastly I swapped the stock OG fender for a newer SF fender in Matte Axis Grey Metallic. I always liked the look of the SF fender and when I realized that the lower mid fairing and tail was the same Matte Axis Grey Metallic color I knew I had to get one to see how it looked.




I definitely like the change up in looks with the new fender, it doesn't look like such a toy when it was yellow.
 

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Discussion Starter #24
After that last round of mods I tried keeping up with an Ohvale GP-0, I tried my best but in the end I couldn't keep up. I was definitely way down in the power/weight ratio, and way under gunned in the tire department. Next up will be a set of more track oriented tires. I'm leaning towards the Kenda KD1 as the price is VERY appealing.

 

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Discussion Starter #25
So I'm starting my 2020 season race prep early.

I picked up some MNNTHBX solid bar mounts. They are really nicely machined and fit is superb.



I definitely noticed they introduce more vibration into the grips. If they provide a little more feedback to me on track then I'm ok with that. I didn't notice much difference putting around on the street.

Since I had the top triple off, I decided to get rid of that ugly ass chrome steering stem nut for a Yoshimura Works nut. It's honestly a small aesthetic item, but it looks way more "Race" lol. I can always just safety wire it to look like its there for a legit reason hahaha.



My eBay special lever guards finally came in. They look like they are pretty high quality, and I'm pretty sure they are a direct knock off of Gilles Tooling lever guards. For $40 I'm not gonna nit-pick them, they seem to work well. When they break, I'll just buy another set of them or maybe go with the barkbusters mounting kit and get a full wrap around solution.




I picked up one of those Honda OEM number plates. It required me to drill two holes and two half inch spacers to mount it, but it was a very simple installation. I'm gonna get a set of number plate and side decals for the Grom from SeventySeven decals made up pretty soon to tie everything together.




I found out pretty quickly that the Pirelli Diablo Rosso Scooter was a great tire, but when I was pushing my pace faster on track I could feel the front tire starting to go after about 3-4 hard laps. I decided I needed to try a more track oriented tire, as I started researching tires and it basically came down to the Mitas, Dunlop, or Kenda.



I decided to try the Kenda basically on the rave reviews and the price. I can almost buy two sets of Kendas for the price of one set of the Mitas or Dunlop. If they work at the pace I'm currently riding at for a while, great. If I get faster and find the limitations of the Kendas after a few races, great. They were cheap and worked for a while, and I'll start looking for a new track tire. I'll probably wait to mount these until my local track reopens for the season. If I end up taking the Grom out for a few street rides in the cold, the Pirelli's will be more than up to that task.

I picked up a Healtech Quickshifter for the hell of it. I have a Translogic quickshifter my R6 and love it. We'll see how it works on track next season. I also picked up a Factory Pro shift kit to go along with it.




The HealTech quickshifter is a fairly easy install and the app is pretty easy to use and make adjustments to the QS. I can tell the drive and acceleration after a shift is much improved. It feels like the bike just jumps out after the shift. Even the fastest clutchless upshift isn't as fast as the QS. I still need to install the Factory Pro shift kit, but they advertise that you can shorten kill times another 5-10ms.

Now we go over to the engine support mods for track usage. I figure since I'm going to be running the snot out of my bike on the track, I may as well fortify it to some degree by removing the "weak" links. I got a Takegawa high flow oil pump, Takegawa timing chain tensioner arm, and a Chimera hardened chain tensioner button. These are not Supporting mods, but I also got a Takegawa slipper clutch, Kitaco clutch springs, and JC Racing aluminum oil spinner. These are "while its apart" mods, I need to remove the clutch basket and oil spinner to install the shift kit and the high flow oil pump.





And for those curious as to why I went with the aluminum oil spinner vs a replacement clutch cover like the Kitaco, the TST frame sliders aren't compatible with the aftermarket clutch covers. I definitely value the protection of the frame sliders.

Now to the good stuff. I've been in contact with Vinny's Custom Shop and Cameron Jones Racing to do some engine development. I guess lets start from the intake side to the exhaust. I sent out a spare throttle body to MaxBore to have it bored out 2mm larger to 26mm. Thats the largest you can bore the stock throttle body out to. I did a velocity port on the throttle body after I got it back.

I bought that spare head to send out to Vinny and get some light port work done. I wanted to do a very light head build to make a bit more power and to fortify the valvetrain for extended high RPM use. No big valves, just kept the stock ones in there and added a dual valve spring setup and DHM titanium retainers. Every head Vinny does port work to, he does a valve lapping to make sure they seal really well. Since I decided to keep the stock valve size Vinny recommended to not really open up the port diameter, but do a lot of clean up work inside the port to get it flowing better. The entire intake tract of my engine starting from the airbox tapers from 70mm at the velocity stack to about 21mm at the intake port of the head. This taper will keep the intake air velocity high. He did taper the inside of the exhaust port from the baby valve to keep the exhaust gas velocity up, but the the exhaust port exit was opened up quite a bit, basically matched to the exhaust gasket inner diameter. The Yoshimura exhaust is a smallish system, so it should work great for a small bore, high velocity setup. I wasn't looking to make just high RPM peak power, I wanted a good spread of power over a wide RPM range. This should make great mid range and a bit more top end power.

The last part of this whole endeavor is having Cameron Jones developing an ECU flash for this headwork. So I sent him the whole setup: My modded airbox, air filter, silicon connector hose, throttle body, intake manifold, injector, the ported head, and a spare ECU. He's going to be able to do testing on the headwork with different intake/exhaust/throttle body setups and with my own setup to develop a whole line of new ECU flashes for a mildly ported stock valve head setup.I know He's recently been doing development on a stock bore Grom with a high compression piston, so that could be in the mix too. All I know is I'm excited to see what he comes up with and how it all works out.









So now we wait!
 

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Love this build thread! Good work.

I'm thinking a proper quickshifter would be good fun. Right now I have a momentary switch on my handlebars wired up to my ignition coil that functions as a ghetto QS. Its a shame I always seem to find a false neutral between 3 and 4 with it.
 

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Replying to subscribe. I'm in Okinawa, so no racing out here, but there's a big empty parking lot near my house I'm getting ready to use for some fun "track" days. I have a 14T sprocket installed, and on the way currently I have Ohlins cartridges, swingarm bushings, Yosh RS-2 exhaust w/ EJK system, Ebay high-mount footpegs, replacement levers and shift/brake pedals, Kenda tires, Goodridge front stainless brake line, EBC sintered Double H front pads. I still need to order an intake, and I think I'm going to just turn around and sell the EJK and get a flashed ECU from CJR -- I've been on the fence about a cam considering how cheap the TB part is, your post might be tipping the scales for me to go ahead and get it. I still need to make a decision on a rear shock too -- I was thinking about just getting a YSS off Ebay or Amazon, but I'm going back and forth on that or the Racing Bros MonoR. It's only another $100, and I can select the spring rate and at least adjust rebound. Still haven't pulled the trigger though.
 

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Discussion Starter #28
Love this build thread! Good work.

I'm thinking a proper quickshifter would be good fun. Right now I have a momentary switch on my handlebars wired up to my ignition coil that functions as a ghetto QS. Its a shame I always seem to find a false neutral between 3 and 4 with it.
Yea definitely get a real quickshifter vs a ghetto QS. From my experience with the Grom and my R6, is you need to make a very deliberate and positive shift. If you do a half ass or mindless shift you will have issues. The R6 transmission is light years smoother and more positive shifting than the Grom. Im hoping that the Factory Pro shift kit will make a big difference. I also ordered up a new stock shift star to see if I can round out the points of the star to make shift a bit easier.

Replying to subscribe. I'm in Okinawa, so no racing out here, but there's a big empty parking lot near my house I'm getting ready to use for some fun "track" days. I have a 14T sprocket installed, and on the way currently I have Ohlins cartridges, swingarm bushings, Yosh RS-2 exhaust w/ EJK system, Ebay high-mount footpegs, replacement levers and shift/brake pedals, Kenda tires, Goodridge front stainless brake line, EBC sintered Double H front pads. I still need to order an intake, and I think I'm going to just turn around and sell the EJK and get a flashed ECU from CJR -- I've been on the fence about a cam considering how cheap the TB part is, your post might be tipping the scales for me to go ahead and get it. I still need to make a decision on a rear shock too -- I was thinking about just getting a YSS off Ebay or Amazon, but I'm going back and forth on that or the Racing Bros MonoR. It's only another $100, and I can select the spring rate and at least adjust rebound. Still haven't pulled the trigger though.
I would HIGHLY recommend the CJR ECU flash for the TB parts camshaft. For the price it's probably the best mod you can do to increase the power. Cameron Jones currently has hands on my ported parts, and depending on how well his tuning goes with those parts, you guys on the forum may have another way of making some cheap and easy power with a ported head/throttle body/camshaft/ecu flash package. Definitely get an adjustable unit you can spring for your weight, it will make the biggest difference on the bike.

I'm currently on the fence on if I should pickup a high compression stock bore piston like a Kitaco 12.2:1 forged or a DHM 13:1 cast unit. I'm 100% sticking with stock bore as I want to stay in a certain class for racing. I've been doing a lot of forum searches and reading what little info there is on high compression stock bore setups. If anyone reading this post has one give me your thoughts about it.
 

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It's been a few months, got any updates?

Interested in the FP shift kit feedback.
 

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Discussion Starter #30
It's been a few months, got any updates?

Interested in the FP shift kit feedback.
As the Grom sits in my garage right now. I just pulled the motor the other day.


I actually just got my ported head/ECU/throttle body/airbox back from Cameron Jones about a week or two ago. I decided to go with a DHM piston and it just so happens he had a DHM piston to install on his OG shop bike. He installed my parts on his bike and built the ecu flash around those parts. I also decided to go ahead and also install a Takegawa 5 speed while it was all apart. At the point where the head, jug, piston, case covers, clutch, flywheel, etc... are all off, its not much more work to just go ahead and split the case and swap the transmission gears. I was waiting on a few new OEM parts for the transmission swap because I there are a few OEM parts that are reused in the Takegawa 5 speed and I don't want to put in any used parts. I also picked up a SMR 6 disk clutch and their 30% stiffer springs.

My "Super Sport 125" made good power on Cameron's Dyno, and I'm pretty confident it will break 15hp once fully broken in and running some good synthetic oil. Heres a few screen shots of a short video he sent while tuning on the dyno. It sounded mean in the video! My friend said it reminded him of a WW2 fighter plane lol.





So give me a few more weeks to tear everything apart then build it. I will make periodic updates and I'm planning on recording the progress too. I have a video I need to edit of pulling the motor.
 

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Cool - good luck. I love my 5 spd, but still sometimes get annoying false neutrals if I get lazy shifting.
 

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Discussion Starter #32
So I was able to put in a few hours of work on the Grom today.

Pulled the head and Jug.




Clutch cover removed.


Oil spinner, oil pump, and clutch removed.


Stator cover removed.


Flywheel removed.


Timing chain, tensioner, tensioner arm, and lower pulley removed.


Next steps are to split the case and install the 5 Speed and then reassemble with all the upgraded parts.
 

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Im so glad that we have a stock class called "monkey bike" class down here. It really keeps me from spending a lot of money on my bike. We cant alter the motor or intake at all, we're only allowed to put an exhaust on it and suspension/chassis modifications. I have a feeling I'd have a small fortune wrapped up in my bike if wanted to run the modified classes.
 

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Discussion Starter #34
Im so glad that we have a stock class called "monkey bike" class down here. It really keeps me from spending a lot of money on my bike. We cant alter the motor or intake at all, we're only allowed to put an exhaust on it and suspension/chassis modifications. I have a feeling I'd have a small fortune wrapped up in my bike if wanted to run the modified classes.
My local track just transitioned over to "DMV MiniGP" and is now affiliated with the SFL/NJ/SC MiniGP organizations. We don't have a monkey bike class under the current rules. My Grom is an F1 machine at this point. Most of the guys in F1 run TTRs and CRFs, I run about mid pack with the guys here. The Grom needs a bit more power and gearing to make up that ~60lb weight difference on just the bike. I could also spare an extra 10 lbs off my gut lol.
 

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My local track just transitioned over to "DMV MiniGP" and is now affiliated with the SFL/NJ/SC MiniGP organizations. We don't have a monkey bike class under the current rules. My Grom is an F1 machine at this point. Most of the guys in F1 run TTRs and CRFs, I run about mid pack with the guys here. The Grom needs a bit more power and gearing to make up that ~60lb weight difference on just the bike. I could also spare an extra 10 lbs off my gut lol.

Oh nice, I run SFLminiGP in the monkey bike and F1 classes. I'm debating on putting the stock muffler back on and running stock 100/125 class. I run F1 class just to get more seat time, a lot of the groms down here in F1 all have DHM kits since DHM is a local company and sponsors SFLminigp. I did the 3 day mini camp that MiniGP puts on and was able to meet a lot of the NJmini people who were all extremely nice and helpful. Im sure you'll love racing with the miniGP family. Good luck with the up coming season, our first race is this weekend.
 

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Hi mate,

I did read all the topic, straight from beginning, I give you huge congratulations for the spirit, I love the chassis > power nature of your setup, and once everything's made, you just try to give some power with some minor stuff on it.

Really love the setup you get, should feel really nice to track it.

I'm following closely from now on ;)
 

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Discussion Starter #37
I put some more work in and got the case split and installed the transmission. It was way more intimidating to think about doing, than it is actually hard to do.




Takegawa transmission installed. For those who have done this before, the OEM Honda bushing was given a nice coating of Moly grease, I doused the gearset with oil, everywhere I could get it in there. I ran the gearset through gears to make sure it would shift correctly, which it did, as far as I could tell.


Case sealed up with RTV and case bolts torqued. Shift star, linkage, and Factory Pro shift kit installed.




I'm pumped with the progress so far, I past the halfway point and now its just assembling everything.


Oh nice, I run SFLminiGP in the monkey bike and F1 classes. I'm debating on putting the stock muffler back on and running stock 100/125 class. I run F1 class just to get more seat time, a lot of the groms down here in F1 all have DHM kits since DHM is a local company and sponsors SFLminigp. I did the 3 day mini camp that MiniGP puts on and was able to meet a lot of the NJmini people who were all extremely nice and helpful. Im sure you'll love racing with the miniGP family. Good luck with the up coming season, our first race is this weekend.
Man I really wanted to go to the SFL MiniGP camp, but things didn't quite line up on my end. I am going to try and make at least a few of the national races this year along with trying to run every race locally.
 

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I put some more work in and got the case split and installed the transmission. It was way more intimidating to think about doing, than it is actually hard to do.




Takegawa transmission installed. For those who have done this before, the OEM Honda bushing was given a nice coating of Moly grease, I doused the gearset with oil, everywhere I could get it in there. I ran the gearset through gears to make sure it would shift correctly, which it did, as far as I could tell.


Case sealed up with RTV and case bolts torqued. Shift star, linkage, and Factory Pro shift kit installed.




I'm pumped with the progress so far, I past the halfway point and now its just assembling everything.




Man I really wanted to go to the SFL MiniGP camp, but things didn't quite line up on my end. I am going to try and make at least a few of the national races this year along with trying to run every race locally.
Im going to try to do the entire sflminigp series this year, some of the farther away races are just kinda hard on my schedule. I'll be nice to meet you if you make it down this way for a race. As far as the camp, I'd definitely try to put it on the calendar for next year. I can tell you I'm a completely different rider than i was before the camp.

DHM's blog post on the camp if your interested.
 

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Took your advice and put in the TB Cam and CJR ECU. It’s a totally different bike over 5K RPMs now. Just gotta get around to all the suspension and chassis parts I still have sitting in boxes. Ohlins cartridges, YSS shock, front brake upgrades, new bars, high-mount China EBay pegs, and a few other odds and ends. I’m hoping to start ripping around a parking lot track in the next two months.
 

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Discussion Starter #40
I got to spend some more time assembling the motor. I forgot to take pictures of the Takegawa timing chain tensioner, 4th bearing support, and the Chimera hardened button. Here's the flywheel side of the motor buttoned up. I have a lightened flywheel, but I decided to keep the stock flywheel on because I was unsure of any compatibility issues with lightened flywheel being an OEM Denso unit from a 2017+ and using the Takegawa 4th bearing support for the OG Grom. I didn't want to potentially have a failure from the parts being incompatible.



Clutch side with the Takegawa Slipper Clutch, SMR 6 disk clutch and the SMR 30% stiffer spring set. Takegawa high flow oil pump.







With the aluminum oil spinner.



Clutch side all buttoned up and ready for top end assembly.





After gapping the rings, putting them into the DHM high compression piston.



Piston into the jug.



Piston onto the rod.



Look at the crazy crown on this piston.



Motor timed up.



Topping it off with a GromFatherz vented cam cover.





Took your advice and put in the TB Cam and CJR ECU. It’s a totally different bike over 5K RPMs now. Just gotta get around to all the suspension and chassis parts I still have sitting in boxes. Ohlins cartridges, YSS shock, front brake upgrades, new bars, high-mount China EBay pegs, and a few other odds and ends. I’m hoping to start ripping around a parking lot track in the next two months.
Awesome man! I'm glad the advise worked out for you. I know the setup isn't for everyone but I have a feeling most people enjoy it. You should start a build thread to document the process.
 
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