Thanks for everyones input. I was going to start with fuel. I have a glass fuel filter i will be installed to see if the fuel runs out when this occurs.I just wanted some other opinions to see if this has happened to anyone else. I will try it out this weekend. Thanks again to everyone.

 

Not a good idea. I did it some time ago, accel pump spitted fuel to the carb and around the pump jet, engine backfired (lack of air filter) and all gas on and around the carb starded to burn. "killed" the fire with my bare hands, got burned a bit but at least I saved my bike from burning. If the diaphragm was damaged it would not rev up.

Your problem is somewhere round the fuel line. Had this same problem last summer. Fuel line was bent, fuel flow was restricted, when I held the engine on higher revs for a moment it started backfiring etc. Check Your bike if it does this same if You hold it on higher revs on 3rd or 4th gear, not only 5th at 70MPH. If it does it`s gotta be fuel starvation. Check fuel tank vent, if it`s clogged it will cause this same problem. Also check for leaks around the manifold and choke piston using WD40 or "cold start" spray (or whatever You call it in US).

 

If the petcock fails, you won't always find an empty fuel filter. It's just like when you put your finger over a straw, the fuel stays there because there is no vent to let air in. When you find an empty fuel filter it is because the tank is empty and air allows the level to drop.

 

Should I try loosening the gas cap to see if the vent is the problem. What else can I try before replacing parts ? Thanks for all the help !!!

 

I'd get rid of the vacuum petcock Replace it with the old off /on style You might be loosing vacuum for some reason Bad rubber diaphragm ? Also the CV rubber diaphragm (as stated ) might have a small rip It definitely sounds fuel related

 

Yes, you can eliminate fuel tank vent/filler cap source of problem by loosening the fuel cap and see if it still does it. If not it's the tank vent or cap if cap is vented type.

 

I had some extra time tonight,so I installed a vacuum bypass kit. I will test it out as soon as I can and update. Thanks for all the input.

 

These symptoms are similar to a problem I had with my old lady some years ago. It would always start, but 'fluff' every now and then, hiccup, call it what you will! Can't say it restricted speed, but was unpredicatable. Eventually the bike cut out on a busy hiway, with me in the outside lane! Engine still ran, but wouldn't pull any load or get me going again.

Turned out to be the ignition sender in the cam cover. Once replaced all was sweetness and light. I have to admit I had a mechanic look the bike over and he eventually found the problem, so I am not sure what he tested or how he diagnosed it. But it is worth considering that as a candidate.

 

If it is a fuel supply issue there would be signs of trouble while going through the gears and accelerating which draw more gas quickly and would give "stalls" at the end of the rev before shifting. Traveling 70 down the road is where you get some of the best gas mileage so if the filter is plugged and starving the engine it would (should) occur at some other given times too.

I'm thinking the issue is just starting and 70mph is when you notice it the most.

Ignition problems get really quirky. Just when you think it's a cam sensor it turns out to be the ignition module. Just when you think it's a coil, it's actually a cam sensor, or module, and so on.

There's no logic to this stall unless it's in the ventilation of the tank. Building pressure, actually vacumn, until while cruising long after starting the flow begins to reduce over the long hall at highway speeds.

I found critter shards plugging up my tank vent, and the factory hose had aged to the point of being so soft it collapsed so I upgraded and replaced that too.

When it turned out to be an ignition module the bike ran perfect, until at times it didn't. Dieing completely at the oddest times, early issue could be resolved by turning off ignition and the it started right back up. AS the issue turned from a nuisance to prolonged shut downs it became more obvious. OF course by then I had replaced the least expensive parts first and essentially overhauled the entire ignition system with new parts, only to find the module did the trick.

Start with the easy, and least expensive items first.

And it could even be a cracked intake manifold, or the other components in that area. As those components heats the leak often will expand. So cruising over a period of time, at any speed could gradually bring on an issue of loss of vacuum / fuel flow.You'd start by reading your spark plugs condition to know if it's a "lean" issue brought on by a leak.

A funny story about tank filters. If you think about it, if there is enough debris that it plugs the filter ... then when you take off the tank is sloshing it all around. After you cruise on flat road the debris settles and is drawn to the filter (flow) and can collect, and then stop the flow.

 

I took the bike out yesterday after removing the diaphram fom the petcock. I loosened the gas cap. I thought I had it resolved . I ran up to 80mph in 4th and then 5th no problems. Road about 5 miles then it at started acting up again.It shut off when coasting to a stop. It will start back up and I can ride about 100 ft before it acts up again. It seems to rev ok in neutral. I removed the air cleaner and checked for fuel. With the engine off I have no vapor spray,when the engine is running and I rev it up the slide moves and I see fuel spray. I rode home with the aircleaner off and almost got there and it started acting up again. I removed the carb today and disassembled it. No bebris in bowl or float. I noticed a bend in the accellerator pump diaphram.I ordered another rebuild kit and go from there. It very well could be ignition. I've had coils work fine cold,but once warm quit working. Like its was stated earlier start with te cheapest first. Tanks again for the imput and will gladly take more.