Top Speed 60mph?

[srwalters]

I have been riding back and forth to work for the last two weeks with no issue, except for having to rev up some to not putter into traffic. I went out onto the Interstate today and my top speed was 60mph, throttle pegged then came to an off ramp and bike died, but fired right back up, ran at 2500-3000 rpms until I got home and reset back to 1100+/-.
I recently used a mercury tuner and all seems to be running fine.
History: Had a low idle problem, cleaned the carbs didn't change jets (original).
I didn't put the original air intake back on, individual carb filters.

[GARTHXS]

jet

You are not providing enough fuel , with the pods you may need to change the main jet and pilot , and don't forget to check float level that is a crucial step, you are better off with the stock air box, - I have pods on the 78 but trust me you lose bottom end power

[Montreux_Blue]

I didn't put the original air intake back on, individual carb filters.

Easiest fix, put the original air box back on. Also what kind of pod filters did you put on, Emgo or K&N?

[srwalters]

I have the K&N filters you oictures on the right

[Ken Talbot]

Spritz the header pipes with a bit of water to see how many are hot and how many are cold. I'll bet two are cold. Then when you tell us which those two are, we can start closing in on the cause.

[Montreux_Blue]

You will more than definitely need to change jets because of the more air flow.

[srwalters]

I will try to check to see if one side is running cool first the maybe reinstall the old airbox. If this works I will rejet.
I will let you know the results of the heat test tomorrow. Thanks

[oldyam80sg]

I had a similar problem with my ZRX last weekend except for the speed and it did not die.I did not use it in 2 months time and was sitting in my storage unit resting.Started it up 2 weeks ago and it was fine.Went to drive it to my Moms house last weekend because I'm in the process of moving and needed the room.Bike didn't want to keep running and it would die when i gave it some throttle.Finally ran on its own and pulled out of unit.Stumbled for a few seconds then i punched it.Literally was going 100 mph in 3 gear before i realized that it is not ok to speed on the road and went the speed limit.Sprayed the pipes with some water and they were all hot.Blamed it on crappy gas.Put some Berrymans Chem-Tool in the tank and will ride it more often.

[srwalters]

Ken Talbot

I let my bike warm up and sure enough after spraying water on the pikes, 1 and 3 let the water stay and just run down 2 and 4 evaporated instantly.
question now is, what does this mean. I thought it would be on one side only? Thanks

[TopCatGr58]

Hey Walter,

Your signature says 80SG/sf, which is it, or is it mixed parts, ie. SF engine in 80SG frame??

What's the history on the bike maintanence? Have you ever taken the carbs off and cleaned by disassembly? You say you synched the carbs with a mercury stick, but where are your pilot screws set at? If they are the 79 carbs, the tips easily break off clogging the pilot circuit.

The 1-3 cyls being faulty points towards carbs. 1-4 and 2-3 are linked with ignition, 1-2 and 3-4 linked with fuel supply, but with your pairing, it's more likely individual carb tuning.

There is a more rare condition of the main spark plug wire for each coil pair to be firing, but the other wire of each coil not having enough spark to function properly due to reduced volts to the coil's primaries.

Also, could be corrosion between plug wires and plug caps, or damaged internal resistors in the plug caps. A volt/ohmeter will help you diagnose that.

Okay, several things to check out, I would start with spark eval 1st. What do the plugs look like in the nonfiring/cool cylinders...wet or dry?? Dry=carbs, wet = spark problem...probably!
T.C.

[tarzan]

Well if it was fuel starvation from petcocks it would not fire on 1+2 or 3+4.
If it was coils it would have problems on 1+4 or 2+3.
It sounds like to me that you have some type of restriction in the two offending carbs.
Maybe idle circuits or those little orifices in the side of the bowl.
Rick

[srwalters]

SF engine in 80SG frame
Pilot screws are set to 1 1/2 out
When I pulled the plug wire from 1 or 3, it didn't make a difference in the way the bikes idle and it looked kind of wet, but didn't smell like gas. It did have a good spark, because I grounded myself and let go real fast.
Have taken the carbs off and cleaned by disassembly and soaked in a carb bath.
Do you think that the floats need to be adjusted?

[DiverRay]

Have taken the carbs off and cleaned by disassembly and soaked in a carb bath.

Did you soak the CARB BODIES?!?! I hope NOT. you may have a vacuum leak in the shaft seals if you did.
My take on this would be to pull the carbs, and do a "bench test". Set them up on a rack and put a fuel supply to them. Wait about ten minutes to see if there are any leaks. If there are no leaks, shut off the fuel, pull the fuel lines off the carbs, and then pull the bolt on the bottom of the bowel to see how much gas is in each carb. Remember the first carb you check for each pair, 1&2, or 3&4, should have just a little more gas than the second one, about 1/2 ounce. If the gas level is the same, and all the internals of the carbs are clean and the same, it would be time to check for other problems.
When did you last check the valve clearance? This engine will TIGHTEN as it wears, and can cause the valves to NOT CLOSE. You may also want to check the spark plug CAPS with a VOM. They should ALL be 5 K Ohms, +- 10%. If you have one that reads 7.5K or higher, it's bad. You CAN buy new caps from almost any import parts store, as they are NGK. I have the "0" Ohm on my bike, and run resister spark plugs.

[srwalters]

I bought the bike last year and have never checked the valve clearance. It has now 13,000 original miles.
I checked the spark plug gap, it is set to .032.
Swalters

[dbeardslee]

Might check your gas lid vent too. Might be shutting of the flow from the top. JAT