Announcement

**strom** · 04-15-2005, 02:25 PM

I would definetly replace the air filter. Original yamaha cost a lot and that paper stuff... well...

I got a question tho... if I change the guts of my mufflers so the exhaust gasses pass more freely (open it up a bit), would I have to make the fuel/air mixture leaner or richer?

LP

**hollywoodxs11sf** · 04-15-2005, 06:51 PM

You'd want to make the mixture richer.

**skids** · 04-15-2005, 08:16 PM

Re: Restricted Airflow?

If it is a K&N filter, it will look like it has a plastic fine screen element enslosed on both sides by wire mesh screen. If so, it is washable with warm, soapy water. You should spray it when dried with a light coat of filter oil on the inside of the oval's surface.

Question...are you maintaining oil level through the site glass with the bike on the centerstand or on the side stand? You know where I was going with this, and I hope you are not offended, but some newbies did not know better in the past!

If you are running rich, someone following you would definately smell it. 25 mpg is pretty poor.

Keep in mind that other things can cause this besides a dirty filter or a bad carb setting. Broken pipes can cause a similar problem and the specials are notorious for this at the locations by the foot pegs under the heat shields at the welds.

The dealer may have put in some non stock pilots which flow way more fuel at idle than stock, but at highway speed, say 55 mph, you should be getting about 35 mpg because you would be running more on the midrange needle positions and mains jets.

I would chech that filter first. I rerouted all of my crankcase breathers away from the airbox to keep the carbs clean, but if yours is puking out oil, you may have some other problems(?)

Originally posted by hollywoodxs11sf

The air filter was once saturated with oil/gas mixture (long story that ends with LOTS of gassy oil spewing through the crankcase breather assembly... almost 10 quarts of gas/oil in the case). Would oil saturation cause the filter to restrict airflow? This filter cost me a fortune (at the dealer). Can I clean it? With what?

When the carbs were rebuilt, the slides were replaced. Is it possible that the needles on the slides are not adjusted properly? Would that cause an overly rich mixture?

How can I tell what size my jets are? I have an extra bank of carbs from a '79 special, and it looks like the only marked jets on it are marked "180". That seems higher than the numbers I've seen mentioned here by quite a bit. These jets were on the airbox side of the carb.

Also, I only get about 25 mpg. I've got new bearings around and my brakes don't seem to be dragging, either, so I assume it's definitely a carb/gas mixture problem.

**hollywoodxs11sf** · 04-15-2005, 08:39 PM

Mine only puked oil out once, right after I got the bike. The electrical system was totally dead. I finally traced the problem there to the fuse box. I replaced the fuse box with inline fuses, and was checking to see that everything worked. I hit the starter, and she kicked over and fired right up, spewing gassy oil through the airbox. I took the carbs off and changed the oil. There was 10 quarts of gassy oil in the case. Had the carbs rebuilt at the dealer. Reassembled, and the next day the same thing happened. Turns out debris from my rusty tank had held one (or more) needles open, and all the gas drained into the engine and the airbox. It spewed up the breather hose and through the oil spouts. It soaked my air filter.

I had the tank cleaned, carbs cleaned again and all has seemed well except for the sooty plugs. If my pipes were cracked, wouldn't I have a lean mixture instead of a rich one? My left pipe was cracked for a few hundred miles, but I had it welded.

**skids** · 04-15-2005, 09:07 PM

Cracked pipes or shot muffs can give you wierd plug readings. You are right, the plugs do not look sooty, they look either bone white or GLAZED brown, or can even get aluminum deposits on the electrode, but I was getting about 24 mpg when normally at those speeds I should have been getting 38mpg.

Check the air filter, make sure that the seat flange is not sitting on the air snorkel (some said that this was their problem), and see if the header pipes are all hot when running. I guess you have to figure out which range of throttle is giving your bike fits before you get into carb adjustments. Also, make sure your compression is OK. I used to have a good link for constant velocity carb tuning, but I lost all of my favorites when I upgraded my computer!

Originally posted by hollywoodxs11sf
(snip) I had the tank cleaned, carbs cleaned again and all has seemed well except for the sooty plugs. If my pipes were cracked, wouldn't I have a lean mixture instead of a rich one? My left pipe was cracked for a few hundred miles, but I had it welded.

**TopCatGr58** · 04-17-2005, 08:45 PM

Hey HollywoodSF,

Those 180 jets you were alluding to that were on the INTAKE/filter side o fthe carbs are probably the AIR jets, not fuel jets!

You also stated that you had the carbs rebuilt by the dealer, what parts did they use/replace?? They could have gotten some bad K&L pilot jets which are notorious for overly rich conditions. Sorry for the repitition, just re-read Skids reply!

What are the floats set at!? A light hazy smoke could be unburnt fuel, overly rich vs. the blue/black oily smoke!?
T.C.

Announcement

Restricted Airflow?

Restricted Airflow?

Comment

Comment

Comment

Comment

Comment

Comment