[CiscoSanJose]

[HR][/HR] The Grom has less than 200 miles on the odm and this morning I decided to check the compression since the my adapters for my compression tester came in and I did not have a small 10 mm spark plug adapter.

I checked the compression with both of my testers and I got between 100-105 psi with a stone cold engine with no warm up.

setting up the test with my old tester


second tester reading 100-105psi


testing heat on the exhaust, heads and cylinder, warmed up the engine a bit

head temp around 160-171 deg F


cylinder temp 160-180 deg F WOT




exhaust temp taken from the pipe leaving the head 311-337 deg F WOT

 

[slevin]

good info, meant to check my compression before i broke mine in but never got to it.

I wonder what mine is at with 2,500 miles on the clock now.

 

[Brian S]

Guys,
Don't panic about the compression. It's about 160 PSI stock. The Grom has a ACR,(automatic compression release) on the exhaust rocker. Spinning the engine activates the weight on the cam and opens the exhaust valve just slightly. I don't know why they don't mention it in the shop manual. Using an intake rocker on the exhaust fix's the issue, and you get 160 PSI. It's there for starting.
Brian

 

[CiscoSanJose]

Guys,
Don't panic about the compression. It's about 160 PSI stock. The Grom has a ACR,(automatic compression release) on the exhaust rocker. Spinning the engine activates the weight on the cam and opens the exhaust valve just slightly. I don't know why they don't mention it in the shop manual. Using an intake rocker on the exhaust fix's the issue, and you get 160 PSI. It's there for starting.
Brian

Very good info to know, thanks BrianS

 

[Hotrod_Hell]

Guys,
Don't panic about the compression. It's about 160 PSI stock. The Grom has a ACR,(automatic compression release) on the exhaust rocker. Spinning the engine activates the weight on the cam and opens the exhaust valve just slightly. I don't know why they don't mention it in the shop manual. Using an intake rocker on the exhaust fix's the issue, and you get 160 PSI. It's there for starting.
Brian

I wonder if that's the reason why the exhaust has a different sound during cold start and once it's built up some heat, the exhaust sound changes?


Sent from my iPhone using Tapatalk

 

[mecevans]

http://www.hondagrom.net/forums/13-...-dynamic-compression-waveforms.html#post57676

 

[CiscoSanJose]

http://www.hondagrom.net/forums/13-...-dynamic-compression-waveforms.html#post57676

Very good information to know, thanks

Ride safe

 

[pwr2wh8]

I wonder if that's the reason why the exhaust has a different sound during cold start and once it's built up some heat, the exhaust sound changes?

i've noticed that as well and it makes sense it's the ACR which i didn't know about