So a couple of things came in and I plan on adding them in steps and record the differences in top speed, acceleration and torque.
The first of many upgrades was the low mount header and pipe for Honda Grom
https://www.ebay.com/itm/333657516537 .
First let me say that if you are expecting a bolt on don’t. The angle of the Clone exhaust port where the header meets the head and is supposed to seal with proper brass crush gaskets is way different. There will be some custom heating and bending of the header to make it fit. Took me about 30 minutes with a butane torch, with a proper acetylene torch maybe 5 minutes. Bending it to more of a 90 degree angle from the horizontal tube is all that is needed. It comes with about an 85 degree angle towards the back from the manufacturer. It will not fit, and 99% of them are made by the same company.
Once this is done then it is time to pre-assemble the entire pipe and exhaust and test fit. You will have to measure and guesstimate where you are going to “drill” a hole by the rear foot peg to attach the Muffler. It comes with all the mounting hardware you need but I added some rubber grommets which I will explain later.
After carefully planning out where exactly the mount would fit the best and not torque the other end of the pipe in the head I drilled a hole large enough to reuse the top mounting bolt from the furthest rear stock muffler mount. And test fit one more time before installing the brass crush gaskets and tightening the front of the pipe snug, I then slowly tightened the mounting brackets working my way to the front mounts insuring I had a proper tight fit on the head and the mounting bracket. You can adjust slightly as you go but if you don’t put on the springs like I didn’t make sure the hooks stay lined up. Don’t get a false sense of good fit because once the springs are installed they will self correct. At this point with a pair of vice grips I clamped down the hooks provided and easily slipped the springs on.
After double checking everything was tight, nothing loose or left undone I started the bike. While I will say I was not a fan of the sound at first but it grew on me. I grabbed a helmet and took it for a test ride.
1. I noticed increased torque right away
2. Top speed did increase but not by much 1-2MPH in 4th.
3. The baffle came loose right away. (Stopped and tightened)
4. There was now a pronounced vibration in the bike over 5,000 RPM
Installing rubber grommets (see pictures) cured this for the most part.
So there you go step 3 of my Hellcat upgrade. At least 3 more things to come and whether or not it is worth your time.