Hi.

I have a 1985 GPZ600R that doesn’t want to start. I put it away just
before Xmas and it wouldn’t start again in January. I have charged the
battery, put a backup one in parallel, cleaned out the carbs, put new
fuel in the tank, tested the spark (big blue spark when against
engine), replaced the spark plugs, checked the engine isn’t seized
(can be turned over from rear wheel in top gear). I have also tried
using brake cleaner, carb clearner and easy-start in the engine with
the air filter removed. It currently turns over but does catch/start.
I am convinced the ignition is OK as the spark looks healthy.
Similarly, I believe it is getting fuel as I can smell fuel from the
exhaust pipes and it goes bang/backfires if I try to start it for too
long.

I have not checked the exhaust for any obstructions but can’t see how
this could happen it has been stored in a garage). I haven’t checked
the timing, alternator, starter motor, CDI or reg-rec but don’t see
how they could be an issue. I have I also haven’t tried bump starting
it as it is flat where I live and I don’t think I’d get enough speed
up. I ran a compression test this evening:

Compression Test

Method: Ran the engine cold and with a Wide Open Throttle (WOT). I
used another battery in parallel with the bike battery to ensure there
was enough power. Tested each cylinder 3 times and then moved onto the
next from 1 to 4 (left to right). To ensure the numbers were reliable
I then retested the cylinders (again from 1 to 4). As the readings
were very low for cylinders 3 and 4 I put a bit of oil in these
cylinders and took 2 new readings. When taking the readings I did so
after about 8-10 cycles as it was usually still rising after about 5
or 6. My results (all in psi) are as follows:

Cylinder 1 – 138, 138, 142 – Average 139
Cylinder 1 Retest – 140

Cylinder 2* – 130, 122, 135 – Average 129
Cylinder 2 Retest – 142, 140, 145 – Average 142

Cylinder 3 – 80, 82, 89 – Average 84
Cylinder 3 Retest – 91
Cylinder 3 with Oil – 108, 110 – Average 109

Cylinder 4 – 30, 29, 30 – Average 30
Cylinder 4 Retest – 35
Cylinder 4 – 48, 48 – Average 48

* On cylinder 2 I originally recorded 90, 100 and 105 but then changed
to another backup battery as it was running out of juice. The fresh
battery gave the numbers given above. Why does the strength of the
battery affect the compression reading? Is it due to the greater
inertia of a faster moving piston?

In summary:

Cylinder 1 – 139psi
Cylinder 2 – 129psi
Cylinder 3 – 84psi
Cylinder 4 – 30psi

As I understand it this could mean three things:

1) The head gasket has failed on the right-hand side of the engine as
the values slope that way. Could this be due to the bike being parked
on its side-stand for an extended period (oil starvation of some
kind)?
2) The piston rings in cylinders 3 and 4 are worn and require
replacing.
3) Adding oil to cylinders 3 and 4 did not bring back sufficient
compression, so a valve service (lapping valves to give a better seal)
is required. Would adjusting the valve clearances give any benefit?

Can anyone confirm my diagnosis and recommend where to go from here? I
imagine a leak-down test would be beneficial to pin point the exact
source of the lack of compression.

Any advice would be much appreciated. Thanks.

On Thu, 7 Apr 2011 15:55:22 -0700 (PDT), Rabbit <(E-Mail Removed)>
wrote:

>Hi.
>
>I have a 1985 GPZ600R that doesn’t want to start. I put it away just
>before Xmas and it wouldn’t start again in January. I have charged the
>battery, put a backup one in parallel, cleaned out the carbs, put new
>fuel in the tank, tested the spark (big blue spark when against
>engine), replaced the spark plugs, checked the engine isn’t seized
>(can be turned over from rear wheel in top gear). I have also tried
>using brake cleaner, carb clearner and easy-start in the engine with
>the air filter removed. It currently turns over but does catch/start.
>I am convinced the ignition is OK as the spark looks healthy.
>Similarly, I believe it is getting fuel as I can smell fuel from the
>exhaust pipes and it goes bang/backfires if I try to start it for too
>long.
>
>I have not checked the exhaust for any obstructions but can’t see how
>this could happen it has been stored in a garage). I haven’t checked
>the timing, alternator, starter motor, CDI or reg-rec but don’t see
>how they could be an issue. I have I also haven’t tried bump starting
>it as it is flat where I live and I don’t think I’d get enough speed
>up. I ran a compression test this evening:
>
>Compression Test
>
>Method: Ran the engine cold and with a Wide Open Throttle (WOT). I
>used another battery in parallel with the bike battery to ensure there
>was enough power. Tested each cylinder 3 times and then moved onto the
>next from 1 to 4 (left to right). To ensure the numbers were reliable
>I then retested the cylinders (again from 1 to 4). As the readings
>were very low for cylinders 3 and 4 I put a bit of oil in these
>cylinders and took 2 new readings. When taking the readings I did so
>after about 8-10 cycles as it was usually still rising after about 5
>or 6. My results (all in psi) are as follows:
>
>Cylinder 1 – 138, 138, 142 – Average 139
>Cylinder 1 Retest – 140
>
>Cylinder 2* – 130, 122, 135 – Average 129
>Cylinder 2 Retest – 142, 140, 145 – Average 142
>
>Cylinder 3 – 80, 82, 89 – Average 84
>Cylinder 3 Retest – 91
>Cylinder 3 with Oil – 108, 110 – Average 109
>
>Cylinder 4 – 30, 29, 30 – Average 30
>Cylinder 4 Retest – 35
>Cylinder 4 – 48, 48 – Average 48
>
>* On cylinder 2 I originally recorded 90, 100 and 105 but then changed
>to another backup battery as it was running out of juice. The fresh
>battery gave the numbers given above. Why does the strength of the
>battery affect the compression reading? Is it due to the greater
>inertia of a faster moving piston?
>
>In summary:
>
>Cylinder 1 – 139psi
>Cylinder 2 – 129psi
>Cylinder 3 – 84psi
>Cylinder 4 – 30psi
>
>As I understand it this could mean three things:
>
>1) The head gasket has failed on the right-hand side of the engine as
>the values slope that way. Could this be due to the bike being parked
>on its side-stand for an extended period (oil starvation of some
>kind)?
>2) The piston rings in cylinders 3 and 4 are worn and require
>replacing.
>3) Adding oil to cylinders 3 and 4 did not bring back sufficient
>compression, so a valve service (lapping valves to give a better seal)
>is required. Would adjusting the valve clearances give any benefit?
>
>Can anyone confirm my diagnosis and recommend where to go from here? I
>imagine a leak-down test would be beneficial to pin point the exact
>source of the lack of compression.
>
>Any advice would be much appreciated. Thanks.

You're right that a leak-down test it the next step. Anyway, if it's
valves, if it has hydraulic lifters, it could be insufficient oil
pressure to the lifters to open the valves. If that's the case there
will be no leak-down. Maybe excessive oil pressure holding them open.
Maybe deposits on the valve stems, again holding the valves open. Did
you check the oil level? Is it good oil? Also, did it run okay the
last time it did run?

Bill Vanek <(E-Mail Removed)> wrote:

Learn to snip....


> You're right that a leak-down test it the next step. Anyway, if it's
> valves, if it has hydraulic lifters, it could be insufficient oil
> pressure to the lifters to open the valves. If that's the case there
> will be no leak-down.

Someone with this much ignorance of the bike in question shouldn't
really be trusted, IMHO.

> Maybe excessive oil pressure holding them open.
> Maybe deposits on the valve stems, again holding the valves open.

Not a problem since about 1920.

>Did
> you check the oil level? Is it good oil? Also, did it run okay the
> last time it did run?

<Holds head>

--
BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple
Suzuki TS250ERx2 GN250. Only seven bikes now.
Try Googling before asking a damn silly question.
chateau dot murray at idnet dot com

Rabbit <(E-Mail Removed)> wrote:

> I have a 1985 GPZ600R that doesn't want to start. I put it away just
> before Xmas and it wouldn't start again in January. I have charged the
> battery, put a backup one in parallel, cleaned out the carbs, put new
> fuel in the tank, tested the spark (big blue spark when against
> engine), replaced the spark plugs, checked the engine isn't seized
> (can be turned over from rear wheel in top gear). I have also tried
> using brake cleaner, carb clearner and easy-start in the engine with
> the air filter removed. It currently turns over but does catch/start.
> I am convinced the ignition is OK as the spark looks healthy.
> Similarly, I believe it is getting fuel as I can smell fuel from the
> exhaust pipes and it goes bang/backfires if I try to start it for too
> long.

<Snip the rest>

One cylinder does look rather low, and one looks worryingly low, but it
should start anyway.

Your problem is stale fuel in the carbs; jellied fuel that's blocking
key passageways and jets.

If you dismantled the carbs yourself to clean them, the chances are you
made the problem worse unless you *really* know what you're doing.

And this:

>Why does the strength of the battery affect the compression reading? Is
it due to the greater inertia of a faster moving piston?

makes me worry. As does your worry that leaving a bike on a sidestand
could cause a head gasket to fail.

Look, get SWK to strip down the carbs properly. Best solution is
ultrasonic cleaning, but proper professional-style cleaning plus
cleaning out all the jets with tiny strands of copper wire and lots of
compressed air will, if you're patient, do the job.

Don't start tearing down the engine.

--
BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple
Suzuki TS250ERx2 GN250. Only seven bikes now.
Try Googling before asking a damn silly question.
chateau dot murray at idnet dot com

On Fri, 8 Apr 2011 07:18:44 +0100, (E-Mail Removed) (The
Older Gentleman) wrote:

>Bill Vanek <(E-Mail Removed)> wrote:
>
>Learn to snip....
>
>
>> You're right that a leak-down test it the next step. Anyway, if it's
>> valves, if it has hydraulic lifters, it could be insufficient oil
>> pressure to the lifters to open the valves. If that's the case there
>> will be no leak-down.
>
>Someone with this much ignorance of the bike in question shouldn't
>really be trusted, IMHO.

So I guess you missed the "if" in my reply?

>> Maybe excessive oil pressure holding them open.
>> Maybe deposits on the valve stems, again holding the valves open.
>
>Not a problem since about 1920.

It still happens on cars, so why not bikes? Reminds me of the
"ignorance" comment.

>>Did
>> you check the oil level? Is it good oil? Also, did it run okay the
>> last time it did run?
>
><Holds head>

As am I. Sarcasm work best if you know what you're talking about.

On Fri, 8 Apr 2011 07:18:45 +0100, (E-Mail Removed) (The
Older Gentleman) wrote:

>One cylinder does look rather low, and one looks worryingly low, but it
>should start anyway.
>Your problem is stale fuel in the carbs; jellied fuel that's blocking
>key passageways and jets.

That explains what is essentially no compression in one cylinder? That
is an issue that needs to be addressed, don't you think? BTW, if you
had actually read the initial post, he said the bike sat for about a
month - that's all. Stale fuel? That's an interesting theory.

>Look, get SWK to strip down the carbs properly. Best solution is
>ultrasonic cleaning, but proper professional-style cleaning plus
>cleaning out all the jets with tiny strands of copper wire and lots of
>compressed air will, if you're patient, do the job.

Right, that should get the compression back up.

As they say, when the only tool you have is a hammer, every problem
looks like a nail. I guess when you have some special carb cleaning
aptitude, that's where the diagnosis always leads.

On 07/04/2011 11:18 PM, The Older Gentleman wrote:
> Rabbit<(E-Mail Removed)> wrote:
>
>> I have a 1985 GPZ600R that doesn't want to start. I put it away just
>> before Xmas and it wouldn't start again in January. I have charged the
>> battery, put a backup one in parallel, cleaned out the carbs, put new
>> fuel in the tank, tested the spark (big blue spark when against
>> engine), replaced the spark plugs, checked the engine isn't seized
>> (can be turned over from rear wheel in top gear). I have also tried
>> using brake cleaner, carb clearner and easy-start in the engine with
>> the air filter removed. It currently turns over but does catch/start.
>> I am convinced the ignition is OK as the spark looks healthy.
>> Similarly, I believe it is getting fuel as I can smell fuel from the
>> exhaust pipes and it goes bang/backfires if I try to start it for too
>> long.
>
> <Snip the rest>
>
> One cylinder does look rather low, and one looks worryingly low, but it
> should start anyway.
>
> Your problem is stale fuel in the carbs; jellied fuel that's blocking
> key passageways and jets.
>
> If you dismantled the carbs yourself to clean them, the chances are you
> made the problem worse unless you *really* know what you're doing.
>
> And this:
>
>> Why does the strength of the battery affect the compression reading? Is
> it due to the greater inertia of a faster moving piston?
>
> makes me worry. As does your worry that leaving a bike on a sidestand
> could cause a head gasket to fail.
>
> Look, get SWK to strip down the carbs properly. Best solution is
> ultrasonic cleaning, but proper professional-style cleaning plus
> cleaning out all the jets with tiny strands of copper wire and lots of
> compressed air will, if you're patient, do the job.
>
> Don't start tearing down the engine.
>

I'd agree about the compression being a bit of a red herring, ie., if
everything else is okay it should start even though it would probably
run roughly. (eg., it should start even if the carb to cyl #4 is
blocked off.) But the OP didn't state whether he has ever been able to
start it so for all we know the plug wires are connected to the wrong
cylinders or the carbs are massively out-of-sync or the choke/enrichener
is not adjusted or a few other things. I'd say the only useful result of
a leak-down test, at least as far as getting the engine started is
concerned, would be to confirm that the valve timing hasn't been
reversed by somebody who's had it apart. The OP did say he had clean
gas but as you suggest the slow jets could still be blocked or the carbs
seriously mis-assembled after cleaning (the OP didn't say whether the
carbs are the slide type or CV type but either way it's not hard to muck
things up when there are four of them). Also, he didn't say whether he
had spark on the cylinders that have decent compression. Still, I'd
agree that it is kind of a waste of time to do a leak-down test when the
immediate problem is getting the engine started.

Bill Vanek <(E-Mail Removed)> wrote:

> >Someone with this much ignorance of the bike in question shouldn't
> >really be trusted, IMHO.
>
> So I guess you missed the "if" in my reply?

If (hah!) you have to speculate, you *really* don't know what you're
talking about.

>
> >> Maybe excessive oil pressure holding them open.
> >> Maybe deposits on the valve stems, again holding the valves open.
> >
> >Not a problem since about 1920.
>
> It still happens on cars, so why not bikes? Reminds me of the
> "ignorance" comment.

It is *such* a rare thing to happen on bikes built in the last 30 years.
The 'excessive oil pressure' thing we can safely discount. You're not
doing well here.

Apply Occam's Razor. The bike has been sitting for nearly four months.
It's reasonable to assume it was running before "it was put away", or
the OP would have said "it hasn't run since x", but it's not a given, I
grant you. Still, if it has been sitting for *longer* that only makes
the stale fuel likelihood even more likely.


> >>Did
> >> you check the oil level? Is it good oil? Also, did it run okay the
> >> last time it did run?
> >
> ><Holds head>
>
> As am I. Sarcasm work best if you know what you're talking about.

And you don't. Now, apologies for being curt, but there are times and
places when...

--
BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple
Suzuki TS250ERx2 GN250. Only seven bikes now.
Try Googling before asking a damn silly question.
chateau dot murray at idnet dot com

Bill Vanek <(E-Mail Removed)> wrote:

> That explains what is essentially no compression in one cylinder? That
> is an issue that needs to be addressed, don't you think? BTW, if you
> had actually read the initial post, he said the bike sat for about a
> month - that's all. Stale fuel? That's an interesting theory.

It seems to be the case. nine times out of ten, when somebody has left a
carb-fed[1] bike sitting for months without using it. A simple Google of
this and other groups will show you that.

>
> >Look, get SWK to strip down the carbs properly. Best solution is
> >ultrasonic cleaning, but proper professional-style cleaning plus
> >cleaning out all the jets with tiny strands of copper wire and lots of
> >compressed air will, if you're patient, do the job.
>
> Right, that should get the compression back up.

The compression isn't the issue here. It really, really isn't.

>
> As they say, when the only tool you have is a hammer, every problem
> looks like a nail. I guess when you have some special carb cleaning
> aptitude, that's where the diagnosis always leads.

I don't. But I've got a bit more experience with bikes than you have.

[1] Less of an issue with FI. I wonder if you can work out why?


--
BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple
Suzuki TS250ERx2 GN250. Only seven bikes now.
Try Googling before asking a damn silly question.
chateau dot murray at idnet dot com

All sniping and lack of snipping aside, have we determined whether or not this
engine actually has hydraulic lifters? If we're dealing with solid lifters and
adjustable tappets, it's entirely possible that two cylinders have tight valves
causing low compression.

And it's entirely possible that it was left sitting with 10% ethanol fuel in the
carbs, which has dried out and left the idle circuits plugged. Many bikes will
not start if the throttle is not at idle position (none of mine will), so if the
idle circuit is plugged, it's not going to start at idle position and opening
the throttle during cranking will not help.

It would help if Rabbit would come back and tell us exactly what he did when he
"cleaned out the carbs".

--
Futility Man