Wiseco big bore compression numbers?

[Guest]

Need to re-ring the #4 cylinder you think?

Are you fouling? Running issues? What was the ring gap on the upper and lower rings? Are you sure it isn't fuel?
I'd run it.

[80GS1000]

Are you fouling? Running issues? What was the ring gap on the upper and lower rings? Are you sure it isn't fuel?
I'd run it.

Haven't fouled a plug yet, pulls really hard on the throttle. Plug looks sort of like #1 here, but with just a few shiny oil spots - it's not covered in oil. The motor used to use a LOT of oil earlier in the break-in (used to get blue smoke coming out the crankcase breather!) but that consumption has pretty much stopped. Think that it'll seal up given enough mileage?

[Nessism]

Pretty interesting break in procedure there, bud. Seems to me that by going WOT all the time you are trying your hardest to force air by the rings. I will be keeping my rebuilt engine well below redline and mostly no more than 1/2 throttle.

Read this link for information you may not be aware of. Even though the heavy throttle break-in technique goes against what most OE's recommend, there is lots of technical merit to it.

http://www.mototuneusa.com/break_in_secrets.htm

[Agemax]

high revving (but not red lining) and not subjecting the engine to high loads, as in trying to accelerate in too higher a gear. thats the key to running in new piston and rings.
when i worked for Honda uk we would get many high revving bikes in for their 1st, 600mile service, CBR's, VFR's etc. 2 identical bikes with the same mileage would have totally different power characteristics depending on how the owner ran the bike in.
the bike that was run in properly was free revving and plenty of power, then the bike that was run in badly, ie. not revving over 3 or 4 1000 revs and changing up as quick as possible was a complete snail.
a good thrashing for a few miles would loosen it up and the owners would immediately comment on how much difference a "1st service" would make to the bike.
we did try to educate owners who bought said bikes about how to run their bikes in properly but i suppose everyone has their own ideas as to which is the correct way

[trippivot]

MY racing engines get broken in by racing them WOT! after just a couple minutes of revving and idling and that is all the rings need.

Break in period beyond the first 15 minutes is a CROCK!!! from the first instant an engine is assembled and started it is beginning to wear out.

a engine broken in rough IS A FASTER ENGINE!!! PROVEN TRUE!!!

ok 80 GS1000 I think you should give me wet and dry pressure numbers

1. get the engine fully warmed up
2. remove ALL 4 plugs
3. assure the measuring tool does not leak
4. WOT during tests
5. dry AND wet comp. numbers needed to get a better idea of what is going on. ( valves or rings )

I like leak down tests but that is another expensive tool and another specific diagnosis procedure.

PM me if you like. it is winter and I have very little to do.

[Guest]

sorry to say but i think the compression numbers should be higher after a re-bore and new pistons/rings and new valves, and after that break-in mileage

well, i guess i forgot to ask about the camshafts and any other relevant changes and was jumping to conclusions

[80GS1000]

OK, got to do some more testing tonight.

Plugs out, engine stone cold because the bike is now inside the house for the winter months.

First test, 1 through 4, 120-120-120-120 across the board.

Second test with a teaspoon of motor oil in each cylinder. 145-145-145-150, holes 1-4.

So it sounds like the rings are not sealing quite right yet...?

Rings still need time to seat you think? Or is re-ringing in the future? The guy who did the top end is a 25+ year GS dragbike mechanic and machinist so hopefully he did a good hone job, bore job, and installed the rings correctly.

[Guest]

Ride it and show that guy the black plug.

[Guest]

If it leaks less than 6%, then the low numbers would be the cam timing.

Jay

[Guest]

Six percent from the wet readings? Those are eight percent.

[Nessism]

A compression increase with oil in the cylinders is normal, although I'm not sure to what extent. Sounds like a Leak Down test is in order to remove some doubt about the cam timing and such.

[trippivot]

i say those are GREAT numbers for a bone cold engine.

What are you worried about?

ring end gap is unknown
deck height is a large value
piston to cylinder clearance is unknown
cam overlap is more than stock.
test numbers from a cold engine

looks good from here. I hope you are not a hypochondriac .

get a leak down tester for more precise information,
and be sure to test it at the proper temperature.

[Guest]

He's right. 120 is great cold numbers. Could rise up to 30# when hot.
If you have determined that the black plug is oil I'd sweat that. Those oil rings need to go in a certain way. If it was the oil ring you would be smoking like crazy though. I'm pretty sure it's got to be fuel unless it's the same plug you broke the motor in with .

[lifguardct]

How are the cylinders numbered, left (shifter side) to right (throttle side) 1-2-3-4? or vise versa?

[doctorgonzo]

How are the cylinders numbered, left (shifter side) to right (throttle side) 1-2-3-4? or vise versa?

Sitting on the bike 1,2,3,4 left to right.