[Clumzi]

I haven't been able to run my bike in a while. Too busy, whether is... well, exactly what you'd expect from Portland in Oct/Nov, 40 degrees and raining everyday, and I was more than a little worried going out to start the bike this morning. I think she's been ridden twice since I moved down here in September. Old gas, gummy carbs, sitting in the rain for months on end, trying to start her when it's below 40 out.



I had to keep on the started for a second, but she fired up. I let her get warm and then took her 25 miles or so down to Damascus. After ten miles or so, the idle was damn near perfect, throttle pull was perfect... she ran as if I'd been riding her daily. By the time I got home after putting about 50 miles on... unreal. I stopped to get breakfast and read the paper, came back out, pipes were warm but not hot, I gave her zero choke, just hit the starter, engine spun once and started.



The bike has 55,485 on it and I've done NOTHING mechanical to the bike in about a year.



So, that all being said, there was one problem. Once I picked up the DSL modem I went out to Damascus for, on the way back when I let off the gas she started popping real bad, like she does when she needs gas. Luckily, I was right next to a gas station so I pulled in and filled up. She only took 1.2 gallons. Hmm. Didn't need gas. Even after getting gas she kept doing it when I let off the throttle. Hard and big pops too. The idle got a little low as well but she didn't stall. Then, poof, it when away.



Now, I have a hunch. Someone at some point apparently lined the tank without removing the filter inside the tank. Once I figured that out I removed the in tank filter and just put an exterior in line filter on. It's worked fine ever since but she tends to start popping and gets thirsty long before she should actually need gas. Then today, I'm guessing something got stuck near the petcock inside the tank and blocked fuel flow.



Does that sound reasonable? Does that sound like a likely culprit? If so, where do I go from here? I was reading the long distance build up thread and read how Larry put gravel in the tank and all that. Should I look into doing something similar? Gravel, muriatic acid, coke, water and a new liner? Is that the idea? Or am I on the wrong path and this is likely being caused by something else? -Nick

 

[Blue Fox]

It sounds like your ACV valves are not operating properly. Their function is to enrich the mixture on deceleration to prevent backfiring and popping. You may have a bad diaphragm in one or both valves. They can be defeating by replacing the O ring under the ACV cover with a small rubber disk cut from a inner tube. Leave the spring and diaphragm in place. Then open up the idle mixture screw a half turn and test. You may be able to turn it back in a bit until you are satisfied.



The EPA mandated such a lean mixture setting for these that those valves were developed to solve the backfiring problem.



It probably doesn't have anything to do with your tank or petcock.

 

[Clumzi]

Either you or someone else mentioned th ACV valves once before. If I understand, you replace the O ring with a rubber disk to cut off or bypass the ACV? Then enrich the mix by upping the idle? Do I have this correct? I need a picture or diagram, I'm assuming this is all part of the carbs, yes? Is this a carb out fix or can it be done while the carbs are still on the bike?



I need to make a spring 'to do' list for the bike. Nothing is getting done until the weather clears up or I find a friend with a garage I can fiddle with the bike in

. -Nick

 

[ki4radiocom]

If I am not seeing it, what year and modle bike? Do I go with the picture?

 

[phantomcxmenance]

carbs out of balance and need a tweek on the mixture settings

 

[marshallf3]

They're cheap enough and seeing you're likely to be in there anyway you may as well replace them.



Tricky design as to the entire engine, there for a reason.

 

[Shep]

Also check for exhaust leaks anywhere in the system.These engines are a very lean-burn engine and any leak in and around the carb boots and or exhaust will cause problems.



HTH

 

[kingston73]

Either you or someone else mentioned th ACV valves once before. If I understand, you replace the O ring with a rubber disk to cut off or bypass the ACV? Then enrich the mix by upping the idle? Do I have this correct? I need a picture or diagram, I'm assuming this is all part of the carbs, yes? Is this a carb out fix or can it be done while the carbs are still on the bike?



I need to make a spring 'to do' list for the bike. Nothing is getting done until the weather clears up or I find a friend with a garage I can fiddle with the bike in

. -Nick

It's mostly a carb out deal. You can get to the left side easily but the right side carb would be pretty tricky to get the ACV off unless you take the carbs off. I can't post pictures at work but it's the little bump on the side of the carb, held on by a couple screws. When you take it off, you'll see the penny-sized rubber disk with metal center. Below and to the side is the little rubber o-ring, it'll sometimes fall out as you're pulling off the metal cover.