TOPIC:

Patton wrote: If the engine hasn't been run regularly for quite some time, a few hundred miles may loosen things up enough to produce even better compression figures.

Good Fortune!

True, a gpz11 motor I had which had been stored outside for a couple of years was really poor, down to 50 psi cold. After running it up for 10 mins it had more than doubled. If I had run it on the road and loaded it up it would have improved more I guess. I had an 1170 kit to fit so it was purely just out of interest to see how bad it was.

Chris, unless you are using oil and there is excess smoke when hot I' d leave it as is, for now anyway. These bikes are very powerful and even if you are down 10 percent on power how often do you actually nail it wide open - most of the time I'm on 1/8 - 1/4 throttle unless I have an open road without traffic or law enforcement.

A block hone, grind in valves, new rings, gaskets and oil seals and maybe even new camchain will be on the cards sometime in the future, just not essential to do right now.
Worst case scenario would be over the next few thousand miles it starts smoking worse and using more oil and the idle will be rough. At this stage you're not risking the engine grenading or locking up.

Tyrell Corp wrote: .....unless you are using oil and there is excess smoke when hot I' d leave it as is, for now anyway......

Hmmm. I am using oil. I consumed 3/4 liter commuting this summer. About 500 miles total. I have a short 8 mile commute - so 16 miles each day. City mostly.

Not sure if all this is getting burned by the leaky seals. Seems like a lot for just the seals...

Once the bike is warm there is no noticable smoke from the tail.

I think you have more of an issue with your leak down tester
then your motor.
At 70 to 85% that motor should not run.
20% is consider'd a very high leak down number.

That is something I need to confirm.

I focused on getting the orifice 1 mm using a pin gauge, set in epoxy with mold release. Just pushed the pin out once set. So that part is good.

But I also used an old compression tester's hose and plug fitting to make the thing. And the tester's hose leading to the plug hole is old and shows visible cracking.

But then I discounted this as a potential problem, as the other tester I used in this posting; the compression tester, was brand new, (I needed one because I cut up my old one ) and it confirmed the lower inside numbers and higher outside numbers. So either way there is consistency. But I suspect my leakdown is not as bad as the numbers currently show.

Bike is put up for winter now. So I cant warm it up to retest. I have valve seals on the way now from KZ enterprises. Ill throw them in & measure again next year with an improved tester.

Cheers
Chris

There are new leak down test sets on ebay for less than $40.00 delivered. I wish they were that cheep when I bought mine!

You should be able to borrow a leakdown tester from Advance Auto for free. They have a free loaner tool program. Ed

chconger wrote: ...I am using oil. I consumed 3/4 liter commuting this summer. About 500 miles total. I have a short 8 mile commute - so 16 miles each day. City mostly.

Not sure if all this is getting burned by the leaky seals. Seems like a lot for just the seals...

Once the bike is warm there is no noticable smoke from the tail.

no noticable smoke from the tail -- indicates that the oil rings are okay, which oil ring condition the leak-down test doesn't address (except to perhaps infer that worn compression rings could mean that the oil rings may also be worn). Hence the excess oil consumption might be from either leakage or from blow-by into the crankcase that's pushing crankcase oil out through the crankcase vent.

Is there any indication of oil leakage while riding?

Is the crankcase vented into the airbox, or into open air, or possibly (GOD forbid) through an aftermarket filter attached to the vent or hose from the vent?

Good Fortune!

Patton wrote: Is there any indication of oil leakage while riding?

Is the crankcase vented into the airbox, or into open air, or possibly (GOD forbid) through an aftermarket filter attached to the vent or hose from the vent?

Yes there is a "seepage" from the valve cover gasket over #1 . It started after the valve cover was disturbed for some shimming. The cover was tightened down, but torque was not measured, when putting the valve cover back on after shimming, so perhaps a proper torque would clear the leak up.

To me..it explains a tablespoon of the lost oil, if that. It takes 2-3 rides to notice oil and want to wipe it off. Jeans stay clean.

The valve cover gasket is in nice condition

There is a hose from the crankcase vent up to the underside of the stock airbox,

Cheers
Chris

chconger wrote: ...there is a "seepage" from the valve cover gasket over #1 . It started after the valve cover was disturbed for some shimming. The cover was tightened down, but torque was not measured, when putting the valve cover back on after shimming, so perhaps a proper torque would clear the leak up.

To me..it explains a tablespoon of the lost oil, if that. It takes 2-3 rides to notice oil and want to wipe it off. Jeans stay clean.

The valve cover gasket is in nice condition

There is a hose from the crankcase vent up to the underside of the stock airbox,...

Oil loss from the valve cover leakage does appear minimal, and would not seem to explain oil usage of 3/4 liter in 500 miles.

Excessive crankcase blow-by venting into the air-box would be combusted and presumably appear as smoke from the exhaust; but there's reportedly no smoke from the exhaust.
Perhaps there actually is some minimal exhaust smoke that has gone unnoticed.

Is there any oily residue inside the muffler at the exhaust tip? Or is it a normal bone-dry light coating of soot?

Given the frequent short commuter trips, there would be numerous cold engine starts with the temporarily leaking valve seals allowing oil to escape through the exhaust with each and every cold start.
Perhaps that might explain oil usage of 3/4 liter in 500 miles.

Worn valve guides is a conceivable issue, but seems highly unlikely given the low mileage.

Good Fortune!

Valve guide oil seals make blue smoke, particularly bad if stored for weeks between starting and if left parked for any length of time on the side stand.

My GSX1100ET when in daily use just used to puff a little smoke on start and clear it's throat nicely when warmed, if Ieft parked a few weeks on the sidestand it would make a smoke screen. Dodgy rings will smoke all the time from cold starts even when in daily use, valve guide oil seals much worst when left standing.

My lightly tuned gpz11 was insanely quick but used to guzzle oil, it wasn't excessive on cold starts but when hammering it there would be a puff of blue smoke on every downshift, confirmed by my modern sportsbike riding mates following behind.

I never got to see the exhaust when riding it hard but this was confirmed to me and explains the high oil consumption. I (think) most oil oil will get burned when throttle is shut, not open. Revving it up in neutral isn't loading the rings enough to see this if the rings are tired.
( When the throttle is shut when engine braking , the rings are working in reverse to seal a partial vacuum = a motor spinning at 6k with throttles shut wants a lot more air then the idle circuit designed for 1k can provide, hence the engine braking effect).

I'd source some NOS rings and a decent gasket set plus oil sealsand do a top end rebuild as planned maintenance for sometime in the future, if you only do a low yearly mileage on it then no urgent hurry, it will likely go on like this for a few thousand more miles.

Finally, apart from critical big end bolts, head nuts or primary and clutch nuts I don't bother with a tourque wrench. The head alloy M6 threads are very prone to stripping and most big torque wrenches are far too inaccurate at low tourque settings. Do it by feel, trust your hands instead.

Well the head is off.

I marked the timing chain, removed the cams and shims / buckets with the intent of the "rope trick" to remove the springs. But soon realized that my valve spring compressor can not access down the side of the springs, as they are down in a "hole".

So that was the tipping point: I removed the head. Then removed the valves with a c-clamp socket homemade tool. Went slick & quick.

Things are fairly carbon'd up in there, So I plan to clean it all up and lap the valves.

Now...while checking the valve guides for play with the valve stem, I noticed very small play in 2 of the exhaust valves. Ill try to put a number on this and report back on the state of all of them more carefully; but I expect I should not feel any play at all?

I looked at the cylinder walls. I could not see any cross hatching. I am not sure what a "glazed" cylinder looks like but i would say they are glassy. No sign of any damage.

Also noticed a lot of carbon in the intake ports. More on the center 2 ports then the outside. How does that get there? Normal?

No more wrenching required to remove the head block...so you know where this is going

I have not noticed any wet oil in the exhaust pipe. Ill check more carefully. As well I can have a look at the vent hose to the airbox to see for any tell tale.

So you stripped it already? that's keen - carry on!

What you are seeing is probably normal, the valve guide play can only really be numbered if you have internal and external mics , a wobble test is less accurate.... I'd try substituting different valves and seeing is it the guide or the valve stem worn? I guess the former, but when I'm in doubt I take it to my local bike shop who has a shit hot top mechanic with 30 years on bikes and who has a 'feel' for these things.

Sometimes it is a close call on judgement on what you can 'get away with' ... even factory tolerances seem quite conservative in places. The easy bit is spending 5k rebuilding everything from crank up, the clever bit is getting another 10-20k miles out of it with new rings and valve grind if the components are servicable.

These are motors are amazingly well engineered , have faith !