Compression tester / fittings

[Anorak_ian]

Last night I found my engine (Ruggerini RD211 twin) has a compression problem in one cylinder, the bike still does 80mph no problem at all.
At least that's what the speedo states, so lets say 70mph.

I thought I heard a hiss at the rally but I haven't heard it since, but now when I kick the engine over I can feel that the first compression stroke is well easy to kick around when compared to the second. Oh dear.

Anyhow, my question is this, is it worth whipping out the injector to fit a compression tester?
I haven't taken the injectors out before, as I had no need to, and I'm sure that I read somewhere that if you take them out you mess up the settings? Or is it just like a spark plug?

What compression tester or fittings will I need for this engine?

I hope it's not the rings, I don't fancy running it in all over again.


Cheers Ian

[Stuart]

Taking the injectors out shouldn't mess up any settings. It never did on any diesel I took them out of.

[sbrumby]

Yes you can take off the injectors, but i dont know it will tell you a lot. I dont know of a compression tester that would replace the injector. It would have to read at least 500psi. Far better to turn the crank with a socket on the nut that holds the flywheel on, this should give you an indication of the difference between the two cylinders. then if you remove the manifolds and do the same with a down feather in the ports it will tell you if the valves are leaking on the low compession cylinder. If they are not leaking and you havent noticed anything out of the cylinder head gasket then i am afraid it is the rings.Hope this helps.

[Anorak_ian]

Sound advice Sam, thank you.

If it's the rings, then I've got some quick running in to do before going to Hamm

Will we be seeing you at Hamm this year?

[Anorak_ian]

Well, I got a torque wrench on the engine bolt, keeping the same speed and power up and adjusting the wrench until the clicks stopped.

The first cylinder to stop clicking (Right pot) was 30 to 35 Lbft, the second was 60 to 65 Lbft
All the valves are at the correct gaps and look to be returning to the same height.
So it looks like it's the rings. I'll rip in to it tomorrow

[sbrumby]

You are on the right lines, and a good idea to use a torque wrench. Did you try the feather in the manifolds ? They could still have the correct gap but not be sealing correctly. I am only saying this as its much easier to lap the valves and not disturb the barrel. Another thing to bear in mind is if there is junk in the injector it will not close properly and will blow back. Checked with the pipe disconnected and engine turned over, diesel will spit back. I dont think this will be the case with you as you would have serious loss of power.

[Anorak_ian]

I couldn't find a feather but I'll rig something up, maybe some Christmas tinsel would do the job.

I checked the injector no probs there.

[Redkite]

Hi Ian, Amazing it still performs so well on one (and a half) pot?!
Academic now, as you've already diagnosed it. but for future ref, Last year I bought a comp. tester kit off of evilbay which came with adapters, I used it to test my Rugger MD150 with this adapter which replaces the injector. Not sure which injectors your RD uses, but here's the numbers off one of mine. C91 CKLL66P 12170. I've added a pic of the kit and the adapter next to the injector. Can't recall exactly, but I only paid about £35 for the whole kit!
Bob.

[coachgeo]

Hi Ian, Amazing it still performs so well on one (and a half) pot?!
Academic now, as you've already diagnosed it. but for future ref, Last year I bought a comp. tester kit off of evilbay which came with adapters, I used it to test my Rugger MD150 with this adapter which replaces the injector. Not sure which injectors your RD uses, but here's the numbers off one of mine. C91 CKLL66P 12170. I've added a pic of the kit and the adapter next to the injector. Can't recall exactly, but I only paid about £35 for the whole kit!
Bob.

I once got what appears to be an identical set from Harbor Freight.

[Anorak_ian]

Thanks Bob, I'll keep an eye out for the kit.

Well pretty sure that it was a head gasket that was blowing.




This one's interesting; take a look at the circle on the right side of the piston crown.
Yes that's one of the valves that has left its mark in the thin layer of crud.
I remember that there were two base gaskets (bottom of the barrel) but one ripped as it was only paper, and as the other barrel only had one gasket, I didn't bother finding and fitting another.




Due to the engine being in the frame, I had to take the studs out as the head wouldn't clear the frame.
There's always one that won't play nice. Good job I had a drimmel.