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DYI01's street/kart track build

31K views 97 replies 20 participants last post by  Pard 
#1 ·
So I recently picked up a used 2015 for $2000 with 511 miles on the odometer. I looked for a while till this gem popped up and drove about 165 miles each way to pick it up. It had a Vagabond fender eliminator kit, TST front flush mounts/electronic flasher relay, and some cheap Aprilia style mirrors. Besides those mods it was completely stock, hadn't even had the first service done. My plan for the Grom is to build it up to be a bike I can ride to my local Kart track, spend a few hours there, and ride back. The track is about a 10 minute ride from my house, so its super convenient. I can pack some snacks/drinks, a few tools, mini tire compressor, camping chair in a backpack, wear my track gear over there, remove the headlight/taillight/tag and be good to ride.

It passed inspection without issue and I got the reg/tags/title/insurance all sorted out. The first thing I did was swap out the stock Vee Rubber tires for a pair of Pirelli Diablo scooter tires. I hadn't found many reviews of these tires but I figured I'd give them a shot. The literature on them makes it sound like they are just a downsized version of the Diablo Rosso Corsa 3 tires.





Front tire profile


Rear tire profile


These things are miles better than the stock Vee Rubber which felt like I was riding on some Lego tires. The profile on the tires makes the Grom turn in really fast, and they hold a line pretty damn good. I feel like I can get on the brakes without fear of the Vee Rubber tire just washing out. It's a very confidence inspiring tire. I'll be able to give more feedback on the tires once I get some more miles on them, but initial impressions are very good.

I wanted some lower and wider bars to be able to get down and off to the inside of the bike, and get a bit more weight on the front end. I ordered up a set of the ProTaper Honda Mini bars as they are lower/wider/and should hold up to a crash way better with the center brace. I topped them off with a pair of the Domino MotoGP grips.



I went simple on the footpegs and went with a set of PSR's. I may go with a set of Driven or Woodcraft rearsets in the future, but these made a huge improvement in grip, which was my major gripe with the stock footpegs.



Next on my list for track prep was getting some real suspension on the bike. I'm kind of a suspension snob and need a really tuneable suspension and have it setup correctly. I also ride an R6 with a full RaceTech setup and it's amazing. After doing lots of research I went with the Racing Bros fork kit and shock simply because of all the adjustability. For most people the Ohlins will probably be suitable as an upgrade in the forks, but I think it would drive me crazy not being able to tune it. The Racing Bros shock only adds a high speed compression damping circuit over the Ohlins, and its a good deal cheaper too.









Fork tubes clamped in the vice using the Racing Bros foork tool.


Heating up those fork lowers to soften up the threadlocker.


Nasty crud between the lower and tube.


Cleaned the crud off.


Removing the spring cap off fork tube.



Done installing the fork kit.


Rear shock is a breeze to install.

The suspension REALLY made a big difference to the Grom. Tires were a big jump, the forks and shock were a leap. The suspension doesn't just bottom out with me bouncing on it. With stock suspension at pace if you hit a mid corner bump, I felt like I was getting bounced off of my line. Now the suspension just moves and bumps barely upset the chassis. Under hard braking I could pretty much get the fork to almost bottom out, now there is actually support under hard braking, and I'm not afraid of bottom out, as we all know once the fork is bottomed out, the tire is the next thing to slide. This Grom is just a pleasure to ride around town, or in anger on the kart track. Next time when I service the forks I will use 10w oil as I'm close to the end of the adjustments on the forks using the recommended 7w oil.

While I had the rear cowling off to install the rear shock, I went ahead and installed the new CustomLED BlasterX tail light and Targa fender eliminator kit. I know this is an aesthetic mod, but for me, it was more of a quick change setup for the track. Two nuts off the back of the tail light and the plug and it comes out. Two nuts and bolts for the tag and it comes off, and we all know how easily the headlight comes off.



Part 2 in the next post.
 
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#43 ·
I decided to try something different with the clutch springs and swap out 3 of the SMR +30% springs for 3 of the Kitaco +60% springs. It should effectively be a 45% stiffer setup if my math is correct. I definitely like the feel of the stiffer clutch lever and call me crazy but it feels like its easier to control. The slipper clutch still functions really well, I was concerned the extra spring pressure might impede the slipper clutch action, no issues there.







I also cleaned the spinner which had a nice layer of sludge built up and the mesh strainer which also had some metal shavings in it. I put another 30 miles on it today and the transmission shifting seems to be getting even smoother, I don't know if it's the gears just wearing in together or the fresh oil is making it feel smoother, probably a little bit of both.
 
#44 ·
Good to know about the FP shift kit. My 5 spd likes to find a false neutral between 3 and 4.
 
#45 ·
It's hard for me to really give an exact impression of how good the FactoryPro kit works by itself. I'm mainly going off of how the stock transmission felt compared to now. The Takegawa 5 speed with the shift kit, shifts considerably smoother and faster.
 
#46 ·
I did my first track day of 2020 on Saturday. The engine and transmission ran great, no issues there. I do have a minor rear suspension squeaking issue which I think might be shock related. Early sessions weren't that confidence inspiring, it was a cold track and I had the tire pressures too high. Once the track temps started to warm up and I got the tire pressures dialed in, I started pushing it harder. It still needs a bit more tweaking, but its getting closer.

On a side note I got my number plates for this season from Seventy Seven Decals, they came out great and he gets them done quick. I would say you need a heatgun and make sure you clean the surfaces really good and the end product will look awesome.







 
#48 ·
I'm not a great photographer by any means, but I try to make them as clean as as possible. I can't stand seeing pictures online that look they they were taken with a potato. Cell phone cameras these days are amazing, and I'm using an 'older' Pixel 2.
 
#49 ·
Thanks for the video, enjoyed it.
 
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#52 ·
I took a deep plunge ya'll, I ponied up for a set of BST wheels and PMT slicks. Too bad we're all on lockdown and can't even test them out on the track. I'll get these mounted up and balanced in the next few weeks, I'm looking forward to seeing if this combo lives up to the hype!

















I also was having issues with my battery, mostly since the motor build. I think the battery was just losing cranking amps due to its age, being stock from 2015, and combined with the high compression piston and no decomp on the cam anymore. I picked up a Antigravity ATZ-7 lithium battery, mainly for the small weight savings and the higher CCA. It saves a hair over 2lbs over the stock battery and has double the CCA of the stocker as well.





The bike starts up WAY stronger than it did on the stock battery with the motor build, it's hard to feel a 2lb difference though lol.
 
#53 ·
Wow, I'm excited to hear your opinion on the rims and tires. Hope you post a video of the next track outing!
 
#54 ·
Yea I'm pumped to see how these things perform. I actually just got invited to a last minute private track day for less than 10 people. Problem is, it's tomorrow and I won't be able to have everything installed in time. I'm just happy to get out of the house and on the track for a few hours. I'll definitely be doing some recording of the day.
 
#56 ·
False neutral is any neutral besides actual neutral between 1st and 2nd.

Please let me know what you think of the BSTs. I'm considering a set as well.
 
#58 ·
Update time! It's a big one this time around.







I mounted up my BST wheels a few weeks ago and had two trackdays out on them. I can firmly say the gain on these these wheels and tires is REALLY impressive. The bike accelerates quicker and transitions corner to corner, full lean to full lean so quickly and easily. If you thought the Grom steered fast before, its even lighter and faster now, it's really silly. The corner speeds and grip level with the PMT slicks have gone up considerably, if I had to put an arbitrary numerical figure on it, at least 15-20%. The total gain with the new wheels and tires combined is amazing. These wheels are NOT cheap, but if you're into doing trackdays and racing then they are completely worth it.









I got a set of Composimo RaceBarz because I wanted to get lower and further forward to get a bit more weight on the front end. These things are top notch quality and are awesome on the track. The kit uses Woodcraft risers and clip ons which are some of the best you can buy. The machined bar adapter is is also very nicely finished, nothing but praise for the quality of the kit. I like the position the clip ons get my body into, but I ran into another problem/limitation of the Grom platform with my lower body and legs which I will be addressing in another post in the future.
 
#59 ·






























I ordered a G'Craft swingarm from Webike and got it fully optioned out exactly how I wanted. Triple Square tube, standard length, with spool bosses, bolt on chain slider, OW type chain adjuster, OEM fender brackets, and most importantly the bearing pivots. Also picked up the superbike style lifters for the hell of it. This thing is beautiful, it's goddamn work of art, functional bling to the max. The swingarm saves weight, it should be much stiffer than the stock swingarm, and the bearing pivots are ridiculously nice. The swingarm literally has no drag on it whatsoever when the pivot bolt is torqued down to spec. I had to adjust my shock damping quite a bit to get it right again. I have not had it on track yet, but I will soon

.



These are videos from the last two trackdays I did with the new wheels and slicks. I think I did a decent job of fending these guys off for a while considering I'm down on power and/or up on weight compared to these guys. I'm just having a hell of a time enjoying my Grom.
 
#62 · (Edited)


































I finally got in a Kitaco Clutch cover, oil cooler, and Endurance lightened flywheel. The install was straight forward and I cant recommend the Kitaco gear holder tool more. It is so much better than the coin trick to lockup the gears. I can definitely tell the engine revs up much quicker with the spinner delete and the lightened flywheel. It is just marginally easier to stall the engine when taking off slowly, and you need to give it some more revs. The gains from the lightened parts more than make up for that though. I know the local roads and how the Grom's speed is affected by the uphill and flat areas very well. The biggest gain from the lightened parts is accelerating from slower speeds. 1st-3rd gears rip even faster, 4th-5th are a better, but not as apparent. Areas where the Grom would just hold speed going uphill it is now very slowly accelerating. I was able to decrease my quickshifter kill times another 5ms because the engine revs drop so much quicker now. I think the biggest indicator of the performance gain was when I went to the track. I was able to beat my personal best time on this particular circuit by .5 second and also increase my best top speed on the straight by 2mph. I was really surprised, and I didn't feel my riding had gotten better. I actually set those personal bests right out of the gate in the first practice session. The oil cooler decreased oil temps about 15 degrees F from hot to cold side, and keeps the engine running way more consistent. I could feel when the engine would get heat soaked and would lose a bit of power during extended lapping sessions, but on a 98 degree, sunny day I never got the engine heat soaked to that point. I think if you're racing a high compression or big bore Grom, these mods are a must. If you have a stock piston you don't need the oil cooler, just go with the clutch cover for the oil filter and spinner delete. If you're feeling spicy get the lightened flywheel.

And for your viewing pleasure here is video from my first actual race event of the year.
 
#64 ·
Lol, "OH $#!&"
Even my wife laughed from across the room. We have ALL been there!
 
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#66 ·
I see the picture of the lightened flywheel on the scale, did you happen to weigh the stock one? Just curious about the weight difference.
 
#67 ·


I may send my OEM one out to JC Racing to be lightened a bit further than the Endurance flywheel, but probably not as far as they usually do it. I like having the TDC markings on the flywheel, so I don't know if what little extra they might take off would be worth it or not.
 
#68 ·
Do you think you could transfer the mark yourself after they machine it?
 
#69 · (Edited)
That swingarm is beautiful.

Did G-Craft not provide any kind of tab/L-bracket to secure the rear brake line to the swingarm?

It looks like they didn’t provide any kind of tab to secure the right front corner of the wheel hugger fender either. I had to make one for my Kepspeed to secure the fender. Kepspeed did provide the L-bracket to secure the brake line though.

Takegawa has every detail, including the tab at the left front of the shock to secure the wheel hugger fender and the tab at the right front of the wheel hugger fender. They also utilize the factory chain slider. Oddly though, I don’t think they use bearings in the pivots. Makes no sense.

You just can’t seem to have it all.

What are OW type chain adjusters? I wish I could get it with the type of chain adjusters that Takegawa uses.

Do you think it will be difficult to get replacement chain sliders?
 
#70 ·
What are OW type chain adjusters? I wish I could get it with the type of chain adjusters that Takegawa uses.
OW Type is #3 in the pic (#3 also shows racing stand hook specification). You can see it is beveled where the axle block interacts with the swingarm.

87623
 
#71 ·
Any idea what you call the #1 type in those photos? They seem the easiest to use. At least I believe they wood be.
 
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