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Author Topic: blowin' smoke!  (Read 2241 times)

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cherry bomb

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blowin' smoke!
« on: April 03, 2009, 10:05:56 PM »
I have noticed that my 1 and 2 are blowin' some smoke...I know its burning oil...this means my valve seals/seats or something of this nature is bad or going bad right?
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Offline bender01

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Re: blowin' smoke!
« Reply #1 on: April 03, 2009, 11:39:59 PM »
How poorly is it running? Can you bear it or not. How often do You ride this bike? Can you find someone young near you thats into classic bikes? If so get them to help you tune it up. As they learn about classic bikes and you as nearing 90 years old will have passed on the knowledge and drive that our younger than I (genx? label) needs to bring this country around. What bike is it also would help.
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Offline 750goes

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Re: blowin' smoke!
« Reply #2 on: April 03, 2009, 11:43:40 PM »
What colour is the smoke ?

White/Blue or Black ??
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cherry bomb

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Re: blowin' smoke!
« Reply #3 on: April 06, 2009, 06:33:13 PM »
im not really that old...ha ha...but sometimes after working on the thing it feels like I am!

the smoke is blue...its burning oil...there is some wet oily deposits on the inside of the pipes.

its running pretty good...for a 30 plus year old bike...I can tell it hasnt been ridden for quite awhile so im sure the seals are bad but who knows...it is a 77 cb750f2...ive ridden it a total of 3 times since i got it running...im planning on riding it a lot more though...do you think its going to be more than just annoying? im sure eventually ill have to fix it but how soon?
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Offline OldSchool_IsCool

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Re: blowin' smoke!
« Reply #4 on: April 06, 2009, 06:39:03 PM »
Run compression tests, first without oil then again with a tablespoon of oil poured into the plug hole first.  This will help to determine if its valve seals or rings.
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cherry bomb

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Re: blowin' smoke!
« Reply #5 on: April 06, 2009, 07:06:48 PM »
what am I looking for...with oil and then with out oil?
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Offline OldSchool_IsCool

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Re: blowin' smoke!
« Reply #6 on: April 06, 2009, 07:13:56 PM »
The oil will seal the rings better.  If the pressure tests change significantly with oil, then your rings are suspect.  If the oil makes little difference, then your valve guides look like the culprit.
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Can I have a motorcycle when I get old enough?
If you take care of it.
What do you have to do?
Lot’s of things. You’ve been watching me.
Will you show me all of them?
Sure.
Is it hard?
Not if you have the right attitudes. It’s having the right attitudes that’s hard.

cherry bomb

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Re: blowin' smoke!
« Reply #7 on: April 06, 2009, 07:23:20 PM »
good deal thanks...ill check it out and report what i find...if it happens to be the valves what will I need to replace? it seems pretty obvious what to replace if the rings are the problem.
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Offline 750goes

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Re: blowin' smoke!
« Reply #8 on: April 06, 2009, 08:33:50 PM »
cherry bomb,

before you run a compression test - adjust all your valves to make sure they are set properly - that will give you a good start for reading properly.

For a more definite answer on whether it is rings or valves - a leak down test will provide more information.....basically you lock the cylinder being tested at TDC and apply air pressure through the spark plug hole with a threaded adapter, and then measure the drop in pressure .. sometime it is easily heard coming out the exhaust (exhaust valve), or the carb throat (inlet valve) or through the crankcase vent (rings).. or all 3 occur...

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cherry bomb

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Re: blowin' smoke!
« Reply #9 on: April 07, 2009, 10:19:08 AM »
i guess all three would be a bad thing! thanks for the heads up.
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Offline bryanj

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Re: blowin' smoke!
« Reply #10 on: April 07, 2009, 10:22:11 AM »
F2, 110% certain exhaust valve guides and seals are shot
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cherry bomb

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Re: blowin' smoke!
« Reply #11 on: April 07, 2009, 10:30:32 AM »
yeah ive been reading about the vavles and those seem to be the weak link in the motor...if it is the guides and seals, on a scale of 1(easy) to 10(hard) what are we looking at? should i just go with OEM stuff or is there something out there better...ive been looking at cycle x.
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Offline MRieck

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Re: blowin' smoke!
« Reply #12 on: April 07, 2009, 11:44:06 AM »
Quote from: bryanj on April 07, 2009, 10:22:11 AM
F2, 110% certain exhaust valve guides and seals are shot
That's a sure bet.
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Offline MRieck

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Re: blowin' smoke!
« Reply #13 on: April 07, 2009, 11:44:58 AM »
Quote from: cherry bomb on April 07, 2009, 10:30:32 AM
yeah ive been reading about the vavles and those seem to be the weak link in the motor...if it is the guides and seals, on a scale of 1(easy) to 10(hard) what are we looking at? should i just go with OEM stuff or is there something out there better...ive been looking at cycle x.
OEM valves are not available.
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Offline UnCrash

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Re: blowin' smoke!
« Reply #14 on: April 07, 2009, 11:49:26 AM »
Quote
yeah ive been reading about the vavles and those seem to be the weak link in the motor...if it is the guides and seals, on a scale of 1(easy) to 10(hard) what are we looking at? should i just go with OEM stuff or is there something out there better...ive been looking at cycle x.

OEM valves are not available.

What is the solution then?  I have the same problem with my 78F.
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Offline MRieck

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Re: blowin' smoke!
« Reply #15 on: April 07, 2009, 12:29:13 PM »
Quote from: UnCrash on April 07, 2009, 11:49:26 AM
Quote
yeah ive been reading about the vavles and those seem to be the weak link in the motor...if it is the guides and seals, on a scale of 1(easy) to 10(hard) what are we looking at? should i just go with OEM stuff or is there something out there better...ive been looking at cycle x.

OEM valves are not available.

What is the solution then?  I have the same problem with my 78F.
Dynoman sells them. CycleX may have them too.
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