compression testing on engines out of the frame/on the bench

[28hodge]

I’ve got two engines I want to do a compression test on, neither are in bikes but both have starter motors on them still.

Can I simply attach a battery/battery charger to the starter motor and spin the motor up like this? or will it not work?

is there a better way? Windy gun on the bolt that you use to turn the engine over when checking valve clearances?

[Kurlon]

You can light the starter with a battery, don't think a charger will have the surge capacity to do it.

[28hodge]

Ahhh yeah should have said its a boost pack charger thing, but if it'll go off a battery that'll do.

Thanks

[Neosophist]

If the starters still attached then thats the best way to go.

Engine wont move too much but make sure your not trying to turn it over balanced on the edge of a bench etc, 60kg lump on the toes isnt good :)

I clamed mine in an old black and decker workmate type thing when I was working on it.

Assume you know about compression testing but while its on the bench check the valve clerances first. Seen bad results from over-tight valves before :)

[Morespeedvicar]

Like Neo said it should move about much, but deffo make sure its secure! Take the other plugs out aswell, and be prepaired for a few good sparks when you eerrr touch the lead to the battery!!

[vfrman]

And I would pull all the plugs so it turns over easier.

[28hodge]

Cheers, I'll get the plugs out of it first and have a big bench at my dads so i'll sit it in the middle of that and make up a timber frame for it too so its not just sat on the crank.

Have to make a compression tester out of an old plug first. Hopefully i'll get good compression out of them.

[krisztian_andre]

Like Neo said it should move about much, but deffo make sure its secure! Take the other plugs out aswell, and be prepaired for a few good sparks when you eerrr touch the lead to the battery!!

If you want to avoid the sparks use the starting relay.

[28hodge]

started to make up the compression tester, sort length of pipe with 9mm ID so will take a M10 tap so i can screw the compression tester in.

Had to file down the OD of the pipe to allow it to fit snugly into the disassembled plug. Problem i have that no matter what i do, no solder will stick to the plug, it just runs off, no amount of flux or cleaning is making any difference.

Anybody got any other suggestions how to attach the two parts together?

Im thinking brazing, or am i going to have the same problems? Is liquid metal going to be strong enough? all the torque when i tighten the plug down will go through the plug still. but i am going to have to screw the compression tester into the pipe once the plug is in the engine.

Would epoxy glue/resin work?

Any advice

[Morespeedvicar]

You may need some stronger flux, mine soldered fine. You using plumbing flux or electrical? I would think resin would work, its not like its going to get really hot.