Author Topic: L12B Valve Clearance Adjustment (Read 2272 times)

ssashton · « **on:** August 07, 2021, 12:04:44 PM »

Hi,

I am a new owner of a 2012 Jazz with 1.2 i-VTEC engine, the L12B.

I have read people saying the slightly older 1.2 i-DSI L12A needs valve clearance adjustment at regular intervals. Is this also nessicary for my L12B engine?

If so, can anyone point me to a guide or at least the clearance spec? All I seem to find is for L12A or L13A.

Thank you!

ssashton · « **Reply #1 on:** August 07, 2021, 12:36:37 PM »

Found it myself!

http://www.hondafitjazz.com/manual3/en/html_en/000000000001755.html

Jocko · « **Reply #2 on:** August 07, 2021, 04:56:27 PM »

My DSi has done 145,000 miles and never had the valve clearance looked at. I don't know of many that have.

ssashton · « **Reply #3 on:** August 07, 2021, 05:51:16 PM »

Mine is on 81K miles. I just finished the check. Everything was within spec, but some closer to the max. than others.

Spec for intake is 0.15mm - 0.19mm. Exhaust is 0.26mm - 0.3mm.

I used two feeler gauges as a 'go' or 'no go' system. Intake 0.152mm and 0.178mm. Exhaust 0.254mm and 0.279mm.

I adjusted the clearance so that the smaller gauge would slide but the larger would not. Prior to adjustment I noticed the larger gauge would often fit easier in the left-most valve of each cylinder. I wondered if this is due to the i-vtec system which I understand switches between using 8 valves or 16 valves to help economy. Perhaps the the left-most valves get more use!

culzean · « **Reply #4 on:** August 07, 2021, 07:08:22 PM »

Tight valves are a problem ( if very tight gap, valve can be prevented from closing properly when engine gets hot and valve stem expands - this can cause valve to burn out - the valve head normally gets cooled when closed by the seat conducting heat from the head ), slightly loose valves are happy.

Never even checked let alone adjusted valves on any Honda I have owned, and never had a problem.. I can live with slightly noisy valve gear, but have seen too many occasions where things that have been messed with that didn't need to be have caused problems. If it ain't broke, don't fix it.

On my motorbike the tappet clearance actually gets larger as the engine warms up, caused by the aluminium of head expanding more than the steel of the valve stem ... may be the same with all alloy engines for all I know.

ssashton · « **Reply #5 on:** August 07, 2021, 09:58:31 PM »

Hopefully I have not set anything too tight, I went by the workshop manual linked in my second post.

I've read some people who had poor torque at low RPM and easily stalled engine had significant gains by setting it right at higher mileage. Apparently recommended by Honda at 90K though I don't recall where I read it. It is "SERVICE REMINDER ITEM 9" in the cars system.