dimeadozen
dimeadozen Reader
10/24/10 11:46 a.m.

About 3 years ago, I purchased an '81 Yamaha XJ550H- at the time of purchase, the PO said he thought it needed a carb rebuild. The bike would start easily and idled fine, but if you opened the throttle in a normal manner, it would stall nearly instantly. Much to the annoyance of my neighbors, I discovered that by repeatedly blipping the throttle, I could get the RPM's up without stalling it. In the mean time, the bike has been setting at the back of the garage, and this morning I had the great idea to check the direction of the fuel filter. According to the markings, it's installed backwards. Could this have been part/all of the cause of the stalling problem?

I realize this is a stupid question, but in my web search, I found answers ranging from "The engine will run as normal, but nearly all of the crap will make it past the filter into the engine" to "The filter will clog very quickly and could cause the engine to stall/not start."

P.S.- I also realize that I have committed one of the cardinal sins of motorcycle ownership by letting the bike set this long, and that at this point, the carbs and fuel system WILL need to be cleaned/rebuilt. I'm just curious about a correct answer to file away for future reference.

Thanks!

MrJoshua
MrJoshua SuperDork
10/24/10 1:07 p.m.

You will of course reverse the flow of your fuel system causing the engine to fill the tanks with gasoline. All you need to do now is run a new line to the engine parallel to the old one with a properly installed filter and you will have a bike that runs forever on one tank of gas. And they said a perpetual motion machine was impossible!

Dr. Hess
Dr. Hess SuperDork
10/24/10 3:59 p.m.

Well, if there was any crap in the fuel filter, it will now be in the carbs when the thing got reversed. If it was new, I think it would probably not make much difference. A new filter, new gas, clean out the tank, see if it starts, check the timing, rebuild the carbs.

44Dwarf
44Dwarf Dork
10/24/10 8:06 p.m.

A new filter installed backwards will work fine for a while then start to stave the engine as it clogs. There's less surface area when installed backwards.

44

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