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Discussion Starter · #1 ·
Decided to sniff my dipstick for some reason and I noticed it smelled a little like gas, from what I read it could be a variety of issues but not sure about the severity. I know the previous owner rebuilt the carb before it was sold but I don't know when the oil was changed. I only notice black smoke on high revs and since I replaced the air filter and gas it seems to have gotten better, still bogs on full throttle so something seems off on the mixture.

If I change the oil and it starts smelling like gas again where should I start, Oil type is 10w-40 right?
 

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JASO MA rated 10-40W oil is correct. Automotive oils are wrong.
Fuel in the oil is due to carb flooding from a sticking float needle, incorrect float level or continued starting attempts w/o spark. Otherwise there's no path in.
I'd adjust the valves, replace the plugs, check the points and set the timing before I ventured into the carb. Old fuel could also cause running issues.
 

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Any gas in the oil is serious, it can trash the engine in a very short time. Since you suspect there is gas in the oil you should change the oil and filter before starting the engine again. Not knowing how long the oil has been in there is another good reason to change it.

One way to get gas in the oil is to leave the petcock on when the bike is not running. Even at their best the float needles provide an imperfect seal which can allow the carbs to overfill and fuel can get into the intake, through an open valve, past the piston rings and into the crankcase where it dilutes the oil. If the PO rebuilt the carbs with aftermarket kits there's a good chance the needles are not the right length which could also contribute to the problem. Looking at your spark plugs can tell you if it is running rich (extremely rich is another way to get gas in the oil). Correcting carb problems or re-jetting may be necessary. Browsing around the SOHC fuel and carburation section can be very informative.

Which oil to use is the most common topic in this and probably many other motorcycle forums. I suggest a large cooler full of your favorite beverage and a weekend searching the topic on the internet (or even just the HondaTwins forum). Short answer is you need an MA rated oil in a viscosity suggested for your bike. 10-40 is fine for your bike though quite a few of us use 15-40.

Just in case you don't have the factory service manual I'll send you a PM on the subject.

Welcome to the group. How about a post in the member introduction section complete with pictures?:p


Edit: Or what Jim said.
 

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Discussion Starter · #4 ·
Well some good news is I've done alot of the bad stuff, cranking and giving it gas without the choke pulled to flood the carb, leaving the fuel on and maybe dropping the bike during transport... If anything I'm suspecting the PO put some 5w in there
Thank you on the manual! I'll read it over at work some night, Is it just me or are carb rebuilt kits hard to find?

I'll do a member intro tomorrow hopefully


This oil should be good right?
https://www.menards.com/main/tools-...commendationsAvailableContentDescription=true
 

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That's a passenger car oil, its got stuff in it that will probably make your clutch slip. You need a motorcycle specific oil (Valvoline, Castrol 4T), or a heavy diesel oil that has a JASO MA sticker on it somewhere (check out the Rotella line at your local hardware/auto store).

For carb kits you only really need the o-rings plus accelerator pump and air cut diaphragms. The original float needles, jet needles, jets etc. that are metal are much better kept original. Check the sohc 400 carburation/fuel section for the sticky on "rebuilding VB carbs".

That manual will help you very much, along with the "Rebuilding VB carbs" sticky as your supplemental carb rebuild service manual
 

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Discussion Starter · #7 ·
Its now running much smoother. Can i reuse the gasket on the filter pan?
 
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