Compression test reults

Been a while since I posted on this, so here is where I am at with this.

Through August into Labor day I've had the heads and valves done, shop said there was some rust and corrosion on three of the valves, with one being minor. However he did say that all of them cleaned up nice and will be fine. Cleaned the bit of corrosion on cylinder two that had formed at the top. The pistons are nice and shiny and the rings were all within spec, so I believe that they should be fine. Discovered a guy at work that works on Honda CBs and had a bead blaster, so I was able to clean the exterior of the jugs very nicely. A nice coat of fresh black paint has been applied to the jugs and the head with the edges sanded silver. Looks pretty good I must say.

Carbs have been disassembled and cleaned very thoroughly using "In the Church of Clean", glad I broke the carbs apart, two of the throttle shaft seals were bad and one was questionable in my opinion, so it would have happened sooner or later. Reassembly wasn't horrible just had to be careful and methodical, the pictures and drawings really helped, using Chacal's reassembly plate really helped getting those little buggers lined up correctly. Have just finished bench synching and setting the floats (that took a while, on and off, on and off.....), but it's done and I have documented everything for later down the road.

So I believe that tomorrow I am ready to start reassembly and do a compression test, if that looks good then on with the carbs, plugs, tci, ect and see if this bad boy will fire up, hoping for a joyous Labor day tomorrow.

Have a happy and safe Labor Day careful out there!

 

I saw someone dead at the side of the road just today. That's all the incentive I need.

 

Okay, so the results weren't as promising as I'd hoped, but oh well it is what it is, I'll get it yet.

Keep in mind that these results are on a cold engine at appx 5300 ft., also to try to save money I tried to reuse the original rings to see if they would work, (cleaned pistons and rings very thoroughly) I'm guessing now they did work to a point, that being said here is what i came up with last night...

...Dry................Wet
1 110.................210
2 100.................205
3 110.................215
4 115.................220

I also lost 12-15 lbs compression in 1 & 4. From the first time I tested.

The Valves were done at a shop , but #2 was slightly tight

...EX......IN
1.007..... .005"
2 .005.... .004"
3 .008.... .005"
4 .007.... .006"

I haven't pulled the shims yet, but I think I can swap the exhaust into the intake and get a new exhaust shim. I see what everyone is saying about get a metric feeler, thought i had one, now I think it is standard with metric conversion.....oh well

I had new gaskets, fresh oil, I checked the tolerances on the rings and grooves, all seemed good, the only thing I didn't check was piston skirt clearance.

So I'll throw it out to the guru's, any thoughts?

 

I LOVE IT!!!

One way to know if you have trouble on a compression check is if they have too great a spread on PSI but these look about the same all the way!

And the pressures are acceptable in my opinion!

I however am not sure what the book is asing for... but it is comperable to mine, and it runs out GREAT!!!

 

Thanks for the input, I'm gonna finish putting her back together and see what happens. Hopefully it all works and it will live again, it's definitely been fun and interesting doing this, now I'll get to see if I did it right.

 

Massimo have you ran the engine since the re build?

 

Not yet, I got the pistons and jugs back on, the head put back on, cam shafts reinstalled and timing marks lined up, checked valve clearances again to find that #2 ex and in were slightly tight, decided that was ok for the moment (I said moment guys), put the camshaft cover back on and did the compression test, at that point I had to stop, it was getting late and for a first time rebuild, I took my time to make sure o rings, seals, and gasket were done right. I had the piston rings lined up right before we put them in the jugs, we ended up doing it by hand, as the ring compressors were tearing up the gasket material, so I think the rings are in relatively the correct positioning.

But to make a short answer long I didn't get around to starting it, need to put carbs and spark plugs back in still.

 

Don't worry about the Rings being in any "Correct Position"

Scientific Studies proved Ring Gap positioning irrelevant; but it remains an ages-old convention still in use.

 

The exception to this, I found recently, is in 2-stroke engines. There you only have two rings, but you also have little pins in the piston that align with the ring gaps and keep them offset from each other.

For 4-strokes, though, I definitely agree with Rick... the rings will move around all by themselves once their back in the engine, so it doesn't matter where they're initially aligned.

 

It LIVES!, Not only is she running, but at the moment, without a total synch or carb tune it is running pretty well. Still have some idle issues to work out and does seem to have issues with idle taking off by itself up to around 4k and not wanting to come back down. I think that it may be the vacuum seals, they seem pretty stiff.

But MOST OF ALL IT RUNS!!!! I am so happy/relieved to hear it run, can't wait to finish the front brakes and fix idle issues and try it out.

 

Congratulations! Glad to hear it.

BTW, 100 PSI at 5600 feet, dry, and cold, is not too surprising, and (IMO), not anything to be too worried about. Remember that we lose about 20% ambient pressure up here compared with sea level.

Any plans for a shakedown ride to the 'springs? Next couple of days don't look that great, but Friday and Saturday aren't looking too bad.

 

Congrats and job well done!
The idle will probably work out when the sync and other adjustments are done.