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Discussion Starter #1
I just bought me one of these beauties and brought it out of long term storage. it was definitely properly stored as far as I can tell. but on cold start up it will do this weird hiss thump noise from under the gas tank a couple of times and then go away. it also did something weird the other night when I decided to take it to redline for the first time since waking it up the speedometer cut out completely and it started to run really rich. back firing and wouldn't idle I did manage to get it home. so when I woke up this morning and started it up it did the hiss thump thing again but it has since ran perfectly... anyone have any Ideas. Thank you in advance!!!
 

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Could you get a recording of it and we can diagnose it from there. There are lines coming off the carbs that feed a vacuum diaphragm that control the petcock. you may have a ruptured diaphragm there. Check your oil level if that is leaking it will dump raw fuel into the crankcase. If it's reading high or smells of fuel DO NOT RUN the bike untill you change the oil and the filter and find the fuel leak. Check plug colors as well make sure they are all chocolate brown.
 

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Discussion Starter #3
eww... Ok I will definitely check that. Dangit I did run it a little bit to get it home. I'll definitely check this stuff out and get back to you. Thanks!!!
 

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Discussion Starter #5
Well I most definitely have a fuel leak because there was a ton o gas in the crank case. Where should I go from here?
 

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Let me see if I can direct you correctly.

You will need to lift the fuel tank. So remove seat. Undue the hold down bolt at the rear of the tank. Remove or provide access (unhook) the gray tank surround in fill panels...then you can tilt the tank up. You can support the tank at the rear with a block of wood of some sort..or use the tool kits wrench and slider handle as a prop to hold the tank up. Do not remove the tank if you were thinking of doing so. At least not yet. O.k. that's phase one.

Phase two: Click on my link above and find the petcock and the vacuum supply line I have identifiec on the front face of the petcock. follow that vacuum supply line down to the nipple which should be below/between the #2 cylinder area on the cylinder head. Again..see my link and pictures which identifies the nipple. If you pull the small hose off that nipple at the cylinder head it is possible (hopeful) that fuel will run out of it or at least be present in it to some degree. If this is the case, fuel is present, it will mean that the diaphragm in the petcock is perhaps holed out and fuel in pasing directly to the crank case via that vacuum supply hose. There is a repair kit available for the petcock. Part # follows:

COVER SET, PETCOCK

16953-ML0-014

Partzilla list them for approx. $33.00 https://www.partzilla.com/product/honda/16953-ML0-014?ref=76fef1f3721864eb100e581869fd76628a1d7fb6 your cost will vari with your local dealer.

HTH.

T.
 

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After you have the leak fixed pull the plugs and drain the oil and change the filter. Refill with regular oil and roll the motor over, plugs out to blow out the cylinders. Put the plugs back in fire the bike up let it warm a bit and then change the oil and filter again. You should be good from there. You could find an oil pressure gauge and tee off the oil pressure switch and check running pressure for a piece of mind. Here is the factory spec, if you in that area you can have some assurance you didn't hurt anything

490 kPa (5.0 kgf/cm 2 or 71 psi) at
5,400 rpm / (176 °F/80 °C)
 

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In addition to the good advise by Tigrest and Beestoys it might be agood idea to check the cut off valves in the carb float chambers in case they are sticking or leaking.
As you say it was stored so the gas may have turned to varnish and jammed one or more of the valves.
A bit of a PITA job but I think you need to dive in and do it!
Good luck!
 

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Discussion Starter #9
I think I found the problem, my question is how was the bike running without the vacuum line connected? Thank you all again for the amazing advice. I'm definitely sticking around here and maybe someday will be able to hand down some of my own knowledge. Talking to my dealership about it and they don't think I was running it long enough to do any major damage...
 

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I think I found the problem, my question is how was the bike running without the vacuum line connected? Thank you all again for the amazing advice. I'm definitely sticking around here and maybe someday will be able to hand down some of my own knowledge. Talking to my dealership about it and they don't think I was running it long enough to do any major damage...
Sounds like your petcock is FUBAR then if there was no vacuum to it because without the vacuum it shouldn't be opening to allow fuel through ;)
Maybe it had a pinhole which was enough initially to allow it to run but with the full throttle run it split wide open and dumped fuel in :huh:
If you disconnect the fuel line to the carbs in that pic does fuel piss out the petcock? The fuel is probably just running straight through the petcock and into the carbs flooding the bike :idunno:
 

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Discussion Starter #15
I just turned the petcock on and after about a minute the left side fuel line started leaking...
 

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Discussion Starter #16
I know I'm going worse case scenario but about what would it cost to rebuild this engine? The bike itself is in amazingly good shape with only thirteen thousand miles?
 

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Discussion Starter #18
13000 miles? She will do ten times that when you got the fuel leaks sorted.
Thank you for the vote of confidence. I'm just hoping that the almost gallon of gas that ended up in the crankcase hasn't done much damage.... Thank god I didn't ride it that far
 

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It will be just fine! Change oil and clear out cylinders as advised.
Get the leak sorted but bear in mind that you might still have problem with float cut off valves.
This is a common problem and easily sorted but may take a few attempts.
It is one of the joys of biking and once you have cracked it you have tens of thousands of happy riding miles ahead.
Enjoy!
 

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Discussion Starter #20
Let me see if I can direct you correctly.

You will need to lift the fuel tank. So remove seat. Undue the hold down bolt at the rear of the tank. Remove or provide access (unhook) the gray tank surround in fill panels...then you can tilt the tank up. You can support the tank at the rear with a block of wood of some sort..or use the tool kits wrench and slider handle as a prop to hold the tank up. Do not remove the tank if you were thinking of doing so. At least not yet. O.k. that's phase one.

Phase two: Click on my link above and find the petcock and the vacuum supply line I have identifiec on the front face of the petcock. follow that vacuum supply line down to the nipple which should be below/between the #2 cylinder area on the cylinder head. Again..see my link and pictures which identifies the nipple. If you pull the small hose off that nipple at the cylinder head it is possible (hopeful) that fuel will run out of it or at least be present in it to some degree. If this is the case, fuel is present, it will mean that the diaphragm in the petcock is perhaps holed out and fuel in pasing directly to the crank case via that vacuum supply hose. There is a repair kit available for the petcock. Part # follows:

COVER SET, PETCOCK

16953-ML0-014

Partzilla list them for approx. $33.00 https://www.partzilla.com/product/honda/16953-ML0-014?ref=76fef1f3721864eb100e581869fd76628a1d7fb6 your cost will vari with your local dealer.

HTH.

T.
This is exactly what I needed. Going to go get the repair kit from my local dealer. "I get a serious discout that even partzilla can't beat" I'll keep ya'll informed of my progress. I was definitely being paranoid last night. Boy this stuff is frustratingly fun.. lol!
 
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