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Discussion Starter #1
On my Red/White grom I decided replace the DrowSport 181-4v piston that is used on a upgraded Koso 181-4v kit with my new Takegawa 181-4v piston and also clean and re-port the Takegawa head both intake and exhaust port and open up the I/D of the port to match the inlet and exhaust pipe. Took the carbon off the valves and sort of polished it as much as possible trying to remove the pits and such. Last step will be polishing and smoothing out some of the ruff cuts. Only the exhaust port, inlet tube and throttle body will be polished.

ruff opening of the 34mm Koso throttle body and cleaning up the butterfly valve
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took out the ruff inside of the Koso inlet tube, polishing is next
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the old Red Neck dermal tool does most of the work
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valve cleaned off and polished, lots of pits on the face of the valve, last step is lapping the valve to the head.
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Takegawa intake porting
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Exhaust porting
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cleaning up the bowls of the head and I will also clean up the head and valve seat area and also do a valve lapping.
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I will also remove the Takegawa 15/15D cam and re-install the 10/10D cam since this cam gives me more power on the low to mid RPM range for riding thru the twisties of the Santa Cruz or Milpitas mountain roads
 

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Discussion Starter #2
so far been riding the grom "2 weeks" with the new takegawa piston and I must have done something correctly, not sure if re-porting the head or cleaning/polishing the valves, porting/polishing the inlet tube,lapping the valves or re-installing the 10/10D cam but this grom rips really good. I'm surprise at the pickup and go this time around and the other new change is testing the Aracer mini-5 that replaced the mini-2+.

I'm starting my second Takegawa 181-4v porting today, going to do the same porting on the intake port and port/polishing on the exhaust port plus cleaning and polishing the valves and valve lapping.
 

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so far been riding the grom "2 weeks" with the new takegawa piston and I must have done something correctly, not sure if re-porting the head or cleaning/polishing the valves, porting/polishing the inlet tube,lapping the valves or re-installing the 10/10D cam but this grom rips really good. I'm surprise at the pickup and go this time around and the other new change is testing the Aracer mini-5 that replaced the mini-2+.

I'm starting my second Takegawa 181-4v porting today, going to do the same porting on the intake port and port/polishing on the exhaust port plus cleaning and polishing the valves and valve lapping.
Thoughts on the Mini5? Thinking of upgrading as well from my Mini Plus 2
 

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Discussion Starter #4
Thoughts on the Mini5? Thinking of upgrading as well from my Mini Plus 2
night and day change, I have 2 groms so I put the first mini-5 on the yellow/wht grom and it made it EZ for tuning and such esp when using the BT smart phone connection and the AF-1.

I just copied the settings from the first mini-5 and installed it in my Red/wht grom mini-5 setup and went riding for about 10-20 miles and the AF-1 dialed in the A/F mixture.

I'm using the Koso 34mm with a 10 hole F/I and Takegawa 10/10D cam.

second Takegawa 181-4v head ported, just need to re-clean/polish the valves and lapping and I'm done.
Nov 5 2019 port polish Takegawa head.jpg
 

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Have you thought about testing a different intake manifold? Takegawa makes a shorter one, I think kitaco has a similar one too. The koso seems like just a fatter version of the stock intake. I'm thinking about getting the GF rev wedge and their billet TB mod and a fatter air filter. I have the big chimera silicone intake but it necks down to use the same size air filter as the regular size chimera. I'm not sure what the CFM rating is, haven't looked into any of that.
 

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Discussion Starter #6 (Edited)
Have you thought about testing a different intake manifold? Takegawa makes a shorter one, I think kitaco has a similar one too. The koso seems like just a fatter version of the stock intake. I'm thinking about getting the GF rev wedge and their billet TB mod and a fatter air filter. I have the big chimera silicone intake but it necks down to use the same size air filter as the regular size chimera. I'm not sure what the CFM rating is, haven't looked into any of that.
I have the Takegawa shorter inlet tube but never used it, this came with my super-head 181-4v kit when I bought it from Japanwebike when they had a xmas sale Dec 2018, could not resist the sale price of $999 which came with all the hardware except the ECU junk that they sell.

Takegawa super heads are intake ported but not exhaust ported and GFZ does a great job with his ported head, Koso, takegawa, OEM head, NEO head, etc.

I found that when I did my own ported Takegawa 4v head and also ported and polish the Koso 34mm throttle body and inlet tube port/polishing and using the Aracer mini-5, the engine response was greatly improved esp when I went back to the 10/10D cam from the HOT 15/15D cam. On the Takegawa input port I try to do sort of a dimple style porting or ruff porting and on the exhaust port I do a polishing and on the valves I clean off all the black material to a polish finish and to me that greatly improved the flow of exhaust and intake fuel/air with the help of lapping the valves.

I'm still using my DIY OEM stock airbox with the BMC washable air filter, replace rear rubber hose "Koso 30 dia" and open mouth front cover. My engine is loud going down the road but people in car notice I'm coming up on them, I'm also still using the Finbro 183 full exhaust system since it has a larger I/D pipe than most of the other pipes out there plus it is a high mount for my 2014 grom and only change on that pipe was a added bung and re-packing the muffler with a tighter material reducing noise.

Like I said before in all my posting and build the biggest changes that helped my grom build is the CCV "Crank Case Venting" or so called oil catch can which is Takegawa since I like their full flow design using the intake valve cover and GromFatherZ's adjustable cam tensioner using the Koso cam arm kit.
 

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My rev limit was still 9750 when I first got the catch can so I never really got to see how bad it was. I think I need to reroute one of the lines when I get the bike back together. I have a straight up pump but I still get some ticking after long wheelies. I think the line I have going around the back of the motor is filling up with oil too easy because it slopes downwards when the bike is up in a wheelie. If it was sloping upwards it might not be as bad.
 

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Discussion Starter #8
My rev limit was still 9750 when I first got the catch can so I never really got to see how bad it was. I think I need to reroute one of the lines when I get the bike back together. I have a straight up pump but I still get some ticking after long wheelies. I think the line I have going around the back of the motor is filling up with oil too easy because it slopes downwards when the bike is up in a wheelie. If it was sloping upwards it might not be as bad.
I don't do wheelies and I have just a HD oil pump but talking to my friends that ride the mountain roads around San Jose and Santa Cruz area they notice their engine stays cooler when going up long ass mountain roads since the extra copper pipe in the modified oil pump picks up the oil EZ and helps cool down the engine better on steep up grades.

The reason for the GFZ adjustable cam tensioner unit is that it stops the cam chain from hitting the upper roof part of the cylinder wall, if you look at most Grom modified engine running BBK kits the upper channel wall is being blasted with the cam chain being bowed outward due to the higher RPM scrapping metal flakes off the upper roof causing engine failure when the metal parts goes between the piston pin, rod bearings/crank bearings and transmission bearings. All my engines that I built from the BrianS 170-2v to the Finbro 183-2v and the latest Takegawa 181-4v shows upper roof wear in the cylinder wall channel due to the cam chain scrapping the roof under heavy RPM load in the 7-10K range.

By the way the better 4v engine is the Koso 170-4v esp if you upgrade the piston size from 170 to 181cc which Drowsport sells. The reason for my pick of the Koso is better piston which is forged and Takegawa is cast and the way the head intake port is designed which is a lot larger than the Takegawa intake port. Let Kenny "GFZ" do a port and polish on that Koso 170 head and it will out run the Takegawa pass 10K rpm, in the low RPM to me the Takegawa will take the lead if all the other parts on the engine are matched correctly with the right map and exhaust pipe.

If running 2V engine the JE piston for the 183 finbro is a good deal if and only if GFZ builds a one off 183 cylinder, Finbro 183 cylinder suck and the other 2v BBK kit that is great if you are going 2V is the NEO kit best bang for the money if they go on sale like xmas time.

I always check Japanwebike or HardRacing or any of those other vendors around Xmas time for sales and dive right in and buy spare parts.
 

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My rev limit was still 9750 when I first got the catch can so I never really got to see how bad it was. I think I need to reroute one of the lines when I get the bike back together. I have a straight up pump but I still get some ticking after long wheelies. I think the line I have going around the back of the motor is filling up with oil too easy because it slopes downwards when the bike is up in a wheelie. If it was sloping upwards it might not be as bad.
Just noticed my straight up pump was installed wrong. The tube is supposed to go through a tiny hole and end up between the cases. I had the whole tube to the outside of the right side case.
 
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