dummy question

how long does your bike have to run with gas in the oil to hurt it? would 40 seconds hurt it?
I got a petcock that was fine but now it leaks

 

If the float needles and their seats are good, and the float height is adjusted correctly, a leaking petcock is not a problem.

Do you know that one or more of the carbs were overflowing, or do you just know that the petcock was not shutting off when vacuum was removed?

BTW, unless it was under high load (accelerating up a hill, etc), no, I don't think 40 seconds would cause any major damage.

 

As SQL stated. Unless it was under a serious load, I would not expect any damage in 40 seconds of running.

Change the oil, and filter, Look for any metal chunks, or shavings in the oil. If you find anything that looks more than metallic paint (small specks are reasonably normal). Pull the bottom cover (oil pan) and check further.

Was the motor knocking?
Sniff test at the oil fill hole?
Did you notice the fuel leak, and shut it off?

Ghost

 

If it was a lot of gas, you might want to change the oil a second time after a short run just to get the residual gas out.

 

The gasoline in the crankcase isnt good but its actually the least of your worries.

One thing that CAN happen is if a fuel leak was washing gasoline down a cylinder for a period of time it will act as a solvent and "fuel wash" all the oil from that cylinder down past the rings. Then when you go to start it you get in essence a "dry" start which can damage the cylinder walls and/or rings. Do this enough and you will end up with low compression pretty fast in that cylinder.

Its more applicable to new engines that still have lots of crosshatch in the cylinders, but it can still happen if the wash was drastic enough.



Find your fuel issue first (as was stated, the issue is in the carbs, probably a bad needle) and change the oil immediately, then do a proper compression test just to verify that you didnt have any fuel wash damage.

 

ok gonna do a compression test in a few minutes (just got home) now Im not sure if thats the deal or not. I had a flood of gas in the oil before I tore it down. when I did I drained the oil and stuck the plug back in. whats the chance the gas Im smelling is residual from then? I drained it all out and its nothing like it was then, but the smell is still present. since the rebuild and new oil its had say 15 starts none over a minute and 3 short rides about 700 feet. last night I waent to look things over and noticed I left the gas on, Thats when I smelled in the crank case and faintly detected gas and drained it immediatly and just blamed the petcock. Im gonna fill it with more oil and do a compression test but I cant chang the filter yet cause I have to grind the bolt off and replace it and I cant get one just yet it'll be a few days before I can get one, but Ill change it then and probably the oil again too

 

Remove the fuel line from the carbs and attach a spare length of line to them (plug or clamp the loose end from the tank if its leaking); then blow into the spare length. You should not be able to blow, because the float needles should be sealing the bowls. If you can blow through the hose, see if you can tell which carb(s) are bubbling....

 

That is a good posibility. Until you can change the filter, and get a good run on it to get it up to temp. You will not be able to get the system flushed entirely.

Make sure you disconnect the TCI when doing the compression test!!

Ghost

 

thanks guys I'm paranoid about her I guess

 

Skw- That is infinitely better than not caring at all.

 

Does any body have good luck with those compression gauges the have the rubber "slide in" tip? I just tried to check mine and it was all jumpy and blew out. Couldnt even get a decent reading. this thing sucks. If I had low compression would it even start and run so easy? I mean this thing fires right off

 

My experience with low compression is that they will run up the point that they dont run anymore. Meaning, if there is enough compression to fire it will run and still even sound ok, but once it drops below a certain point it wont even fire anymore.


I seriously doubt you've done any damage. The recommendation for testing it is more of a precaution and a "peace of mind" test.

 

but shouldn't the gauge "hold" at a reading? it jumped to 60 and right back to 0 with every "stroke" I could feel the hose pulsing but the gauge move up and down so fast I couldnt tell what it really went to, my eye kinda coaght it near the 60 anyway. I mean it was fast, eye blinking fast.
so.. two questions: #1 if I go buy a real screw in gauge, do they "hold" at a reading? #2. whats that "low" number where it stops firing? (generally speaking I realize it's got to be variable)
oh .. and this gauge is borrowed and the warranty paper in the case is from 03/03/1977!

 

yes, they are supposed to hold at the peak, then there is a release valve that you press before you unscrew it. If yours is moving the needle but then immediately dropping to zero, then you dont have it seated in the plug hole right or the release valve is stuck...or the gauge has gone tits up.

 

teah Im thinking the tits thing. Well I need one anyway. so what is the lowest compression you ever seen or heard of that still ran?

 

Tits? I like tits

Try to see if the guage really sets right.... but it might be shot though. 60's definitely not right..... or you have some SERIOUS problems (as in time for a new motor) my moneys on the guage.... at 60 you probbably wouldn't be running anyway....

 

yeah I think so too but now I got to know. like I said it don't hold the reading. it's from 1977, and its just a "universal" rubber tip, and it blew out the hole once.

 

my toyota 20R just barely fired a cylinder that had 90psi when I had some shattered rings, and Ive seen those things run with holes in the block and no oil in it. Our Yamahas arent that forgiving. Im guessing below 100PSI and you would notice its not running right.

 

yeah so 60 or even 90 has got to be wrong then but now I got to know. Was just looking at engines on ebay, why? because Im a dnam worry wart I guess. around 400 bucks? about the same as a rebuild? getting a real gauge tomorrow

 

Priceless.

BTW, I drove about 150 miles with gas in oil from prime left on by PO. Oil change then another oil change after 200 miles - all was good.

 

see now I feel better, but still gotta see what my REAL compression is. its funny- I got a truck, an suv, 2 cars and a minivan and anyone of them died Id just replace it. This bike is not like that. I have so dnam many hours in it trying to bring it back from the forgotten dead its like my child. She has to be healthy!

 

Geezlouise.

Just get a proper screw-in compression gauge already. Run you less than $30 at Sears, AutoZone, Advance Auto, Home Depot, K-Mart, wherever.

The press-in kind never seem to be very accurate anyway.

 

The rubber tipped press in guages can barely check tire air pressure. Let alone any kind of real compression.

Get a proper screw in guage. You will need to turn the motor several revolutions until the reading tops out.

As we are progressing into diagnostic stage.
Make sure the valves are in spec. or the compression readings might well be incorrect. You have already taken care of this correct?

It is interesting how something like a faulty petcock can stretch into affecting other areas of the bike. You can't touch one part without having it affect other parts of the system!


Ghost

 

proper gauge obtained, just got home with it. testing will begin within the hour.
what you dont like my buddies 1977 press in gauge? (I didnt have the heart to tell him it sucks)

oh.. the valves are great, did that BEFORE I ever got the battery, and she has the
'happy tick'

 

ok can some one tell me whats going on, hear are the readings I got thus far: #4--60psi #3--35psi #2--10psi got the battery charging now, all pugs out, throttle open, tci unplugged, tank off out of the way.
all valves are in spec, whats up?If these readings are right it shouldnt even run I thought? but it does, very well too and fires at the first touch???

 

well dig this #1 with the gauge and the adapter 30 psi
#1 withe gauge and no adapter 40 psi
#1 old 1977 rubber press in gauge 60 psi
taking the auto zone loaner back and going to sears in pensacola and buy a dnam good NEW one.
I guess the real dummy question is... can you get a decent loaner gauge from autozone?---- probably not.
Im enjoying this right?

 

Key word "loaner".

How many times has it been used by joe nobody who let it be used as a toy by the 2 year old?

Ghost

 

That motor wouldnt fire if those were the correct readings.

There may have been an o-ring missing from the bottom of the gauge and/or you had the extension on and it wasnt sealing correctly. It may also be necessary to clean the spark plug seat area to get a decent seal.

this is the exact gauge I have and the extension isnt needed to test our motors, but those o-rings DO need to be intact.




just screw it in as tight as you can by turning the rubber hose by hand. Thats should be more than enough to seal for a reading.

 

that is the gauge I just came home with. battery is charging now. I didn't think it would fire at those readings either. I thought you had to have at least 90? and the bike dont smoke-nada-none. if I had bad rings it would smoke right? if my valves were not seating would I be in spec? if my rings are good and valves are good (reasoning not assuming) what's that leave? head gasket?
ok besides the fact I cant get a freaking reading on my compression what am I missing?
so far the 1977 rubber job gave the best bad reading that is just outstanding.
who was it had the thread "I hate autozone, O'riely's..."
GOOZFRABA

 

I should post a pic of mine; it's like 35 years old and was made in the USA. But I also have one of the oriental imported kits as shown above (I like having a "second opinion" available) and the o-rings are important.

To review: Battery fully charged, all plugs out, TCI disconnected and throttles held wide open. With the gauge in place, crank the motor until the gauge stops rising, about 5~8 "cranks" usually does it.

 

You can also double-check your gauges on your car/truck - you should see 150-175.

 

ok Im really ready to do this now just got home (again) with yet another gauge. This one I bought so its new. not another loaner. It seems I like it the hard way ( kind of helps me understand why I got 2 ex wifes come to think of it)
and a new float charger and a new stethascope.
I swear you guys are great.

so now Im going to do this with good stuff.
post results when Im done (soon as I get back from the post office gotta send something I thought got sent till I found it in back of the SUV this morning)

 

what a difference a good gauge makes! #1 to #4 dry no oil with a battery maintainer hooked up: 130 130 130 135 maybe a point or two off but thats the jist (135 was more like 136.5)
I know thats lower than spec but I am HAPPY!
2 IMPORTANT LESSONS LEARNED HERE:
#1 compression check before you get to end of the build, or even before you buy that way you dont end up looking at engines on ebay all night kicking yourself
#2 dont EVER EVER EVER try to use loaner stuff like a compression gauge, just get the right stuff and do it right.
got it. Thick headed student has got it through his thick head. Next?
Thanks guys

 

no redo the test with a little squirt of oil in each cylinder and report your results.

 

If those numbers came from a cold motor I would say you're fine, and not out of spec. Book says warm it up slightly, and Spec is 128 minimum, 156 "standard" and 171 max. You're still within spec, although at the low end, but the biggest consideration is your comparative numbers and from that aspect, they look great.

Those cylinders are fine, especially for a motor with 36K.

 

PTS- I was wondering if I should or not. but with dry numbers like that and the way I worry like an old woman I really want to leave well enough alone! I guess for a real picture I should though

Fitz- I wouldnt say COLD, I read that it should be warmed a little.
I let it Idle with fans on it for about 5 or 6 minutes then let it cool off some cause the plugs was a little too warm for comfort so I let it cool till I could hold the plugs without them being too hot to handle, so not really warm but not cold either

so redo the test with oil huh? ok I can do that, should I maybe do leak down test too? ( I just read about that but I have no idea what it even is)

 

doing the test with oil certainly wont hurt anything, it just burns right off the next time you run it. The reason for doing it however is that since you ARE on the low end of the scale it would be nice to know where your losing it. If the oil test significantly improves your numbers (like near the top of the scale that Fitz outlined) then you know your rings/cylinder walls are showing their age. If the numbers DONT significantly increase then you know your valves are beginning to show their age. If its somewhere in the middle then you can assume you have a little of both. Its just good information to have.

Another reason to want this data is for future comparisons. Lets say a year from now you notice some performance loss and you repeat the test and it points to a valve, you will know what your numbers were like today and it may be diagnostically relevant.

Besides, if you are like me, its an excuse to spend more time touching your bike.

 

Good Point. Thats a sunday date.
post results tomorrow

 

Note - your engine has something like a 23 CC combustion chamber, and an OZ of oil is 29 CC's. You should try to measure out 10 CC exactly, or your higher measurements will be all over the place (and then you'll worry).

 

10 cc = 1 teaspoon? Id read 1 teaspoon so thats what I did but the employment of a childs medicine squirter would work good though and probably pretty clean too, but I used my wifes measuring spoon from the kitchen. When she asks if I seen it I'm gonna pretend I didnt hear her maybe.
moving on-- re did the test, this time stone cold ( I know book says warm but the tank was off)
anyway cold cold like cold to the touch-- dry and with oil:
dry -- 125 125 125 130 ( all within a few points )
wet -- 135 135 135 140
As I said above all mnumber were within a few points, the gauge goes by 5's so I called it whatever it was closest too.
The oil did increase it but the differences between the cylinders stayed pretty consistent.
she has almost 37K on her now so I expect the wear should be "normal"?
I'm probably looking at a ring job around the 60K mark and some other stuff anyway so I was thinking just keep the oil good, dont dog it and just ride.
My job is 100 miles round trip and I'd like to take the bike, actually thats my plan. If you guys got an opinion on that Id love to hear it.
Also, I get that warn metal expands but how much difference DOES it make testing cold and warm? 5-10 psi?

 

Probably oh, 5~10 psi.

The fact that it didn't change much by putting oil in the cylinders means that other things are worn, or other things are worn too. If you were to pop the head off and do a valve job, the numbers would probably come up a bit. My Norton's had 2 valve jobs in 45K, but the second was more a case of "since I have the head off, why not?" after a valve stem seal let go.

Your bike still makes compression numbers that are within spec. Make sure everything else is up to snuff, and RIDE IT. That's what it was made for, remember? Make sure it stops, and always starts, stay on top of the battery and other maintenance and ride it. My job is a 120+ mile round trip commute, that's one of my reasons for owning the XJs.

 

cool! yeah I plkan to stay on the maintenance, and outside of tune and sync she really runs great. actually pretty good even without the sync yet, kinda rich though sorta bogs before bringing the power, but thats due to me turning the mix screw a full 3/4 turn out when iy had a "lean pop" it went away but I went too far.
thats another subject but the short is Im finally to sync- tune -ride time.
so between now and the future ring/valve/whatever else job I'll be looking for another one to ride whilke this one is down. (dont think the KZ will be ready by then THAT one is a wild child project and gonna be slow)
NEED a 550 Fitz, I want that extra gear!

 

Yep, acceptable numbers given the mileage and indicates mostly valve issues with a little ring wear as well. Again, all within reason given the miles. Treat her right and dont hammer on her real hard and she should last you a good long while.