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Discussion Starter · #1 · (Edited)
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After beating on our koso 170 4 valve that we built a couple years ago, we decided to bump it up a notch to make more power but also make it as reliable as possible. In order to do that we had to go with a 63mm piston (forged of course) and a tad bit less compression to reduce the risk of detonation when running on pump gas. We also added many performance and longevity features on to the piston it self, here is just a few below


  • Frictionless Coating
    • Each piston comes with a specialized coating on the skirt edges that reduces piston slap and is made to be frictionless. This allows the piston to move even more freely in the cylinder. This coating reduces scuffing and provides back-up lubrication and works well with engines with longer rods and Nickasil cylinders.
  • Strutted Piston Skirt
    • The piston skirt utilizes a strutted design over a full round design. Having a strutted design not only reduces the weight but provides key points that can be machined to increase overall piston strength where the rods connect. This characteristic shaves off undesired weight and can be designed to help keep piston structure sturdy. This also helps with less friction due to reduced amounts of material against the sidewall of the cylinder.
  • V-Shaped Accumulator Groove
    • The V-Shaped groove that sits between the first and second ring was machined with an intentional purpose of relieving the top ring by adding volume between them. What it does is accumulates residual gasses from the combustion chamber. This will help prevent premature wear on the rings and provides an overall improved ring seal


for more info and pricing click on the link below

https://www.drowsports.com/drowsports-4-valve-180cc-honda-grom-ceramic-cylinder-kit/
 

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While in theory it potentially sounds good...

Give us specs and dyno sheets on the 170 vs the 181. That will revel all! :lemo:

Have to admit, I am interested. :dontknow:
 
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While in theory it potentially sounds good...

Give us specs and dyno sheets on the 170 vs the 181. That will revel all! :lemo:

Have to admit, I am interested. :dontknow:
Agree with all, very interested.
 

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I should have added:

11cc's IS a bigger bore, and should give more oomph. The question that needs to be answered, is the gain worth 328.50 bux?
 
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see, im on the position where i want to possibly re-ring the 170, and you cant just buy FUCKING RINGS from koso so id have to lay out about 130 for just a piston, + head gasket and such. for 200 more a nickasil cyl and new piston? worth it maybe. would like to see the numbers as well.
 

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see, im on the position where i want to possibly re-ring the 170, and you cant just buy FUCKING RINGS from koso so id have to lay out about 130 for just a piston, + head gasket and such. for 200 more a nickasil cyl and new piston? worth it maybe. would like to see the numbers as well.
do you have ring part numbers? could probably source just rings through webike. I did that with my kiatco 60mm bore headgasket for my 164cc when i needed just the HG.
 

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ordered a set for measurement testing and future use, looking at design compare to Takegawa 181-4v. Might be able to use on Takegawa engine if piston measurement of valve placement are same.

I also wanted to compare oil piston holes and wrist design of piston and also skirt design of cylinder compared to Takegawa.

you know me I like to mess with my engine and the price is right
 

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do you have ring part numbers? could probably source just rings through webike. I did that with my kiatco 60mm bore head gasket for my 164cc when i needed just the HG.
i do not. TBH, i haven't pursued it too much. I do however find it extremely annoying none of the vendors or koso itself offer rings. Its a fucking service part.
 

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Discussion Starter · #11 ·
The goal for this kit is to be a replacement/ upgrade if you already have a 170 4v and looking for more oomph or simply need to rebuild but cant due to the lack of parts. We will also be offering it with the koso 170cc 4v kit and replace the cylinder and piston with ours
 

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Discussion Starter · #12 · (Edited)
ordered a set for measurement testing and future use, looking at design compare to Takegawa 181-4v. Might be able to use on Takegawa engine if piston measurement of valve placement are same.

I also wanted to compare oil piston holes and wrist design of piston and also skirt design of cylinder compared to Takegawa.

you know me I like to mess with my engine and the price is right
We dont have a takegawa kit in the shop to compare it to but ill get some pictures of it compared to the koso 4v. Is the takegawa piston cast? also how much does it weight
 

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We dont have a takegawa kit in the shop to compare it to but ill get some pictures of it compared to the koso 4v. Is the takegawa piston cast? also how much does it weight
that is why I'm buying it to do some comparison and looking at the material and other stats and I will mix match Tak 181-4v parts with Koso 181-4v parts

Biggest things I found out about the 4v engines and reliability is the way the oil catch can is plumbed and the basic do not let any unburned fumes such as a return line from the crank case vent back into the airbox.

I know guys in the bay area who have blown their Koso 170-4v engine due to various failure to adjust their A/F mixture correctly or timing not set correctly in the mapping and the use of the proper ECM. Most out here in the Bay area that have HOT rodded their groms are using Aracer, either mini2+, mini 5, or top of the line RC1.

this info is taken from JapanWebike site on the piston
Aluminum-cast piston Compression ratio 12.5:1 Adopted a high compression specification
Piston in pursuit of high performance and durability. Piston top is finished with high accuracy by NC machining.


my used Takegawa piston with one compression ring on it with carbon build up wt 129g or 4.56oz
Technology Electronic device
 

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How much are the 181-4v piston and rings are going to be on sale for by itself and same with the cylinder to, never know when owners need replacement parts esp the piston/ring set?????
 

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Discussion Starter · #18 ·
that is why I'm buying it to do some comparison and looking at the material and other stats and I will mix match Tak 181-4v parts with Koso 181-4v parts

Biggest things I found out about the 4v engines and reliability is the way the oil catch can is plumbed and the basic do not let any unburned fumes such as a return line from the crank case vent back into the airbox.

I know guys in the bay area who have blown their Koso 170-4v engine due to various failure to adjust their A/F mixture correctly or timing not set correctly in the mapping and the use of the proper ECM. Most out here in the Bay area that have HOT rodded their groms are using Aracer, either mini2+, mini 5, or top of the line RC1.

this info is taken from JapanWebike site on the piston
Aluminum-cast piston Compression ratio 12.5:1 Adopted a high compression specification
Piston in pursuit of high performance and durability. Piston top is finished with high accuracy by NC machining.


my used Takegawa piston with one compression ring on it with carbon build up wt 129g or 4.56oz
View attachment 78446
here is a picture of our piston with all the rigs and another one of the piston with one ring Scale Gas stove Kitchen appliance Stove Kitchen scale Font Silver Fashion accessory Metal
Also our piston offers double broaches to allow more oil in the wrist pin and also has double pin oilers
 

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I like the way the piston is designed with the side coating and other upgrades that Takegawa should have done for their 181cc pistons.

Can't wait to test the Koso piston out in the Takegawa engine. I might just replace the cylinder and piston and just keep my 5 axis Takegawa DIY head that I ported and matched the intake and exhaust I/D mating surface to the Koso 30mm inlet tube and my Finbro exhaust pipe.

The days of the grom engine HP future upgrades just makes me smile esp when you can beat most Big Block Harleys light to light in Santa Clara or the Bay area.
 
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