Compression test

[Powerdevilz]

Hi all,

I need to do a compression test on my VFR nc30, but as you know a standard compression kit won't fit ! Does anyone in the UK have a kit I could borrow or get hold of cheap ?'

Iv got a missfire on cyclinder 3 back right I believe, manifold heats up a lot slower than the rest, new coil packs, new plug, carbs cleaned and the piston looks wet and the plug is wet so good fueling.

I found a very random suggestion that it could be the main beam relay, mine was corroded bad but when this first started running poorly on 3 cyclinders the first thing I noticed was the Rev counter was acting weird dropped out incorrect reading...

Any help greatly appreciated .

Sam

[royster81]

This sounds like a nightmare. Could it be electrical related rather then compression related ?
I've heard of rev counters playing up when reg/revs start to breakdown .

[Neosophist]

Yep, do some other tests first that you don't need an 8mm compression adapter for.

do a full electrical test, could also be a bad earth.

Check battery voltage at idle / 5000 rpm with lights on and lights off and see what you get.

check the earths, there are only a couple.

[Powerdevilz]

Cheers guys, Iv ordered a Haynes manual but if it doesn't arrive before bank holiday weekend where abouts are the earths so can double check ?

New battery so should be good but will make sure..

Re - The 8mm compression are they available anywhere ?'b

Thanks

[jim157]

The Honda factory service manual is in the document library section of this site.

[Powerdevilz]

Thanks.
Now 4days of fault finding begins lol

[newtothis]

Some compression testers have a tapered rubber cone which you just push into the spark plug hole, rather than needing to screw in. One of those should work OK even with our tiny plugs.

[Neosophist]

Cheers guys, Iv ordered a Haynes manual but if it doesn't arrive before bank holiday weekend where abouts are the earths so can double check ?

New battery so should be good but will make sure..

Re - The 8mm compression are they available anywhere ?'b

Thanks

there is one big earth under the lower left side panel down the bottom.. main battery earth too.

tested battery voltage yet?