carb #1 leaking, oil burning
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- Posts: 24
- Joined: Sun Sep 24, 2006 12:09 pm
carb #1 leaking, oil burning
Just as the title says. I just had the carbs rebuilt and suddenly(as in I drove it for a week with no problems) carb #1 starts leaking fuel out of the drain on the bottom of the bowl. I'm taking it back in to be looked at tomorrow but thought I should pose the question to you experts on this particular bike. Any idea what is wrong here?
My boss (works with carbs more than I do) believes something must have gotten caught in the needle or the float is stuck. He also pointed out that I have no fuel filter in my system. I didn't realize that and I really would like one. It is supposed to go on the bottom of the fuel selecter switch right? Which fuel selecter switches are compatable with this bike so I can do a little swap.
Also, the same shop did a compression test on the bike and said that it is downright fantastic. However, it has been blowing a little smoke at idle (warm or cold) and when I checked the oil today, it was really low even after getting an oil change when it was serviced a week ago.
If it has really high compression how would it be burning oil?
My boss (works with carbs more than I do) believes something must have gotten caught in the needle or the float is stuck. He also pointed out that I have no fuel filter in my system. I didn't realize that and I really would like one. It is supposed to go on the bottom of the fuel selecter switch right? Which fuel selecter switches are compatable with this bike so I can do a little swap.
Also, the same shop did a compression test on the bike and said that it is downright fantastic. However, it has been blowing a little smoke at idle (warm or cold) and when I checked the oil today, it was really low even after getting an oil change when it was serviced a week ago.
If it has really high compression how would it be burning oil?
Is the above comment is complete idiotic or ignorant please attribute it to the alchohol.
Is the carb actually leaking from the drain, or is it just dripping from there? (since it's the lowest part on the carb, gas may just be collecting there and you may have a leak higher up instead). A sticking float valve is the likely suspect. Try tapping (hard enough to break a glass, but not hard enough to dent your car ) on the bowl with a screwdriver and see if it stops leaking.
The in-line filter would actually go on the fuel line between the tank petcock and the carbs. Just go to an auto parts store (or dealership) and pick up a filter, cut the line in two and put the filter between the cut. Make sure you put the filter on in the right direction, since they have a flow path to them.
It is probably smoking with good compression numbers because of your valve stem seals. They get old and start to leak oil around the valves if the bike has been sitting for a while. Bad News: the smoking will only get worse, and the only way to fix it is to tear down the top end and replace the seals. Good News: it's not hard to tear down the top end, and it's an engine-in job (I did it in about 5 hours a few weekends ago to fix the very same problem. No more smoke for me!). Just find someone who can put the valves back in for you, and you're good to go. It's definitely a weekend job, though.
If you don't know much about engines or carburetors (like I did when I started), you'll certainly be close to an expert by the time you're done with this bike!
The in-line filter would actually go on the fuel line between the tank petcock and the carbs. Just go to an auto parts store (or dealership) and pick up a filter, cut the line in two and put the filter between the cut. Make sure you put the filter on in the right direction, since they have a flow path to them.
It is probably smoking with good compression numbers because of your valve stem seals. They get old and start to leak oil around the valves if the bike has been sitting for a while. Bad News: the smoking will only get worse, and the only way to fix it is to tear down the top end and replace the seals. Good News: it's not hard to tear down the top end, and it's an engine-in job (I did it in about 5 hours a few weekends ago to fix the very same problem. No more smoke for me!). Just find someone who can put the valves back in for you, and you're good to go. It's definitely a weekend job, though.
If you don't know much about engines or carburetors (like I did when I started), you'll certainly be close to an expert by the time you're done with this bike!
Just a tip about checking the oil level. It should always be checked with a warm engine, not cold. The oil will expand a litte when it gets hot and if you check it when the engine is cold, and fill it up to the top mark on the dipstick, the level will be too high when the engine is warm.
Otherwise I agree with Dan and your boss, if the fuel is flowing from the drain, the float or float valve is the problem. And like Dan said, if the compression is good, the valve seals are the most likely cause for the smoking.
Otherwise I agree with Dan and your boss, if the fuel is flowing from the drain, the float or float valve is the problem. And like Dan said, if the compression is good, the valve seals are the most likely cause for the smoking.
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- Posts: 24
- Joined: Sun Sep 24, 2006 12:09 pm
DammitDan wrote:Is the carb actually leaking from the drain, or is it just dripping from there? (since it's the lowest part on the carb, gas may just be collecting there and you may have a leak higher up instead). A sticking float valve is the likely suspect. Try tapping (hard enough to break a glass, but not hard enough to dent your car ) on the bowl with a screwdriver and see if it stops leaking.
The in-line filter would actually go on the fuel line between the tank petcock and the carbs. Just go to an auto parts store (or dealership) and pick up a filter, cut the line in two and put the filter between the cut. Make sure you put the filter on in the right direction, since they have a flow path to them.
It is probably smoking with good compression numbers because of your valve stem seals. They get old and start to leak oil around the valves if the bike has been sitting for a while. Bad News: the smoking will only get worse, and the only way to fix it is to tear down the top end and replace the seals. Good News: it's not hard to tear down the top end, and it's an engine-in job (I did it in about 5 hours a few weekends ago to fix the very same problem. No more smoke for me!). Just find someone who can put the valves back in for you, and you're good to go. It's definitely a weekend job, though.
If you don't know much about engines or carburetors (like I did when I started), you'll certainly be close to an expert by the time you're done with this bike!
It is leaking from the actual drain line on the bowl and not at all from any of the carbs or tank. If the shop doesn't fix it then I'll just remove the bowl and see if I can jostle loose the debre myself. I don't like the idea of tapping too much on carbs.
That sucks about the valve stem seals. I was hoping it was something simple like the head gasket (stupid I know). Unfortunately I don't have a weekend for about 2 months and it can't wait that long. Anyone in the Bremerton, poulsbo, or tacoma area (washington) that has done this before want to make a little money? If not then I may be forced to take this thing to the shop again.
Thanks for identifying the problem though.
Is the above comment is complete idiotic or ignorant please attribute it to the alchohol.
Oh, I rode mine smoking like a corncob pipe for about 3 months. It won't HURT the bike (although you may get a little glazing on the bores, but not likely from a light stem seal leak), but it will make you embarassed to ride, spitting smoke at the cars behind you... That's the only reason I finally got around to fixing it. That, and remembering to put in a quart of oil every 400-500 miles got to be tiresome.
The bike may be clean, but if it smokes it just hurts the image, ya know?
The bike may be clean, but if it smokes it just hurts the image, ya know?
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- Posts: 24
- Joined: Sun Sep 24, 2006 12:09 pm
Yea, I know. This thing looks pristine but smokes quite a bit. I figure I'll drive it for another month and then remove the head and take it in. Might as well get a 3-angle valve grind while I have it off. Another head work I should have done while its off? The only things I can think of is:
Port and Polish
3-angle grind
camshaft if possible
stiffer or just new springs if it'll help
Port and Polish
3-angle grind
camshaft if possible
stiffer or just new springs if it'll help
Is the above comment is complete idiotic or ignorant please attribute it to the alchohol.
I would think that with such low milage, and good compression you shouldn't need a valve grind. If the valve seats were worn, your compression would suffer. So I'd say your valve seats are fine. I'm not much of a bike mechanic, but on cars there's a neat little trick for doing valve stem seals without removing the valves... fabricate a fitting for the spark plug hole and use compressed air to keep the valves up while you change the stem seals Another really old school trick is to stuff a bunch of rope into the cylinder to hold the valve in the closed position(in case you don't have access to an air compressor). Both methods save removal of the head As for tapping on the carbs LIGHTLY with a screwdriver handle... everybody does it sooner or later and I've never heard of any damage coming from it. Could save you some cash. Good luck.
1980 CB650c
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- Posts: 24
- Joined: Sun Sep 24, 2006 12:09 pm
I would only do the valve grind for performance. A three angle valve grind gives better air flow at both low and high rpm. This means a very decent improvment in power.
I didn't know about the valve stem seals. I need to really read up on the procedure for pulling the seals. I would much rather doing that myself.
As for the leaky carb bowl...already brought it in and the guy pulled the bowl and cleaned it for me. He also put a fuel filter in line before the carbs to help prevent this from happing again. Didn't really charge me for it either. By all means he should have charged me at least an hour's work for it. Still not going back to them again. They're too pricey.
I didn't know about the valve stem seals. I need to really read up on the procedure for pulling the seals. I would much rather doing that myself.
As for the leaky carb bowl...already brought it in and the guy pulled the bowl and cleaned it for me. He also put a fuel filter in line before the carbs to help prevent this from happing again. Didn't really charge me for it either. By all means he should have charged me at least an hour's work for it. Still not going back to them again. They're too pricey.
Is the above comment is complete idiotic or ignorant please attribute it to the alchohol.
Too pricey is the problem I've had with every shop I've been to.
I wouldn't do anything to the bike that may change it's performance. I believe it already has a 3-angle valve grind on it, and re-cutting the head also means cutting the valves, doesn't it? You can do all the non-machine work yourself (including removing/lapping/replacing valves) but you need a valve compressor tool to do it.
Ah, if only I had known it would cost me $150 to get my valves installed, I would have bought the tool and done the damn work myself. Stupid overpricing motorcycle shops! He charged me 3 hours labor for 25 minutes of work (considering he quoted me $35-$50), and there wasn't shit I could do about it. Well, lord knows if I ever need machine/heavy duty work done I'll find another damn shop.
I wouldn't do anything to the bike that may change it's performance. I believe it already has a 3-angle valve grind on it, and re-cutting the head also means cutting the valves, doesn't it? You can do all the non-machine work yourself (including removing/lapping/replacing valves) but you need a valve compressor tool to do it.
Ah, if only I had known it would cost me $150 to get my valves installed, I would have bought the tool and done the damn work myself. Stupid overpricing motorcycle shops! He charged me 3 hours labor for 25 minutes of work (considering he quoted me $35-$50), and there wasn't shit I could do about it. Well, lord knows if I ever need machine/heavy duty work done I'll find another damn shop.
Re: carb #1 leaking, oil burning
frankinstyn wrote:Just as the title says. I just had the carbs rebuilt and suddenly(as in I drove it for a week with no problems) carb #1 starts leaking fuel out of the drain on the bottom of the bowl.
Is the drain plug screw not seating properly, and therefore allowing fuel to escape??
.....to be myself, a pattern for others.
1979 CB650
1971 Norton Commando
1968 CB175
1979 CB650
1971 Norton Commando
1968 CB175
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Re: carb #1 leaking, oil burning
First you should check your airbox for oil, maybe it is not burned but deposited there. Piston wear would mean white smoke in your mirrors at high revs. If it does not depend much on revs, it could be valve stem seals. Some guys do this kind of job with air pressure in the cylinder to avoid head removal.
No need to do anything else to the head, maybe it makes sense to smoothen the surface of the grooves of the 5x2.5mm O-rings in the head to increase the time until head leaking occurs. I will try this next time, if I do not forget again.
Do not remove the cyliders without need. It is much work to remove the old black bottom gasket and its tricky to re-install the chain tensioner correctly.
No need to do anything else to the head, maybe it makes sense to smoothen the surface of the grooves of the 5x2.5mm O-rings in the head to increase the time until head leaking occurs. I will try this next time, if I do not forget again.
Do not remove the cyliders without need. It is much work to remove the old black bottom gasket and its tricky to re-install the chain tensioner correctly.
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- Posts: 24
- Joined: Sun Sep 24, 2006 12:09 pm
Re: carb #1 leaking, oil burning
Volker_P wrote:First you should check your airbox for oil, maybe it is not burned but deposited there. Piston wear would mean white smoke in your mirrors at high revs. If it does not depend much on revs, it could be valve stem seals. Some guys do this kind of job with air pressure in the cylinder to avoid head removal.
No need to do anything else to the head, maybe it makes sense to smoothen the surface of the grooves of the 5x2.5mm O-rings in the head to increase the time until head leaking occurs. I will try this next time, if I do not forget again.
Do not remove the cyliders without need. It is much work to remove the old black bottom gasket and its tricky to re-install the chain tensioner correctly.
I am getting fuel in my airbox. It happens more often when I forget to close the fuel petcock when its not running. But that is definetely fuel. Not oil.
As for the oil. It does it at all revs but I can only really see it at idle. I found out it did it at all revs when I took it in to dyno.
So I definetely don't need to remove the head to replace these then? I just have to hold the valves up as I'm replacing the seals. I'm not sure I understand completely. I still need to remove the camshaft and rocker arms right? This means that I still have to deal with the timing chain. I suppose that isn't that big of a deal. Now that I look at it the only thing holding the camshaft in it the chain. Wierd. The only thing I don't understand is how the rocker arms are attached to the head. I need to remove those as well before I can start compressing spring and replacing seals.
So after all that I suppose my questions are....
1) How do I remove the rocker arms?
2) How do I compress the springs?
3) Should I replace the springs and keepers while I have them off?
4) I will need to regap all the valve clearances when I'm done right? This is a solid lifter head?
Unfortunately the book I purchased is
Is the above comment is complete idiotic or ignorant please attribute it to the alchohol.
If you are planning on replacing the valve stem seals, the first thing you will need is a workshop manual. A Clymer manual will be fine:
http://www.repairmanual.com/catalog/M336
I also posted a few pics when I had the cylinder head off and replaced the cam chain tensioner:
viewtopic.php?t=74
And Volker posted this:
viewtopic.php?t=52
http://www.repairmanual.com/catalog/M336
I also posted a few pics when I had the cylinder head off and replaced the cam chain tensioner:
viewtopic.php?t=74
And Volker posted this:
viewtopic.php?t=52
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