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Bike Problem this morning - Ideas?

Joined
Aug 2, 2005
Messages
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Location
Allen, TX
First Name
Mike
Last Name
Napurano
Okay... I haven't ever had any problems with the bike, but this morning on the way in, coming up 75, the bike just lost throttle response, and eventually died.

I was able to exit and pull into a parking lot. Turned off the key, pulled off my helmet and gloves (30 seconds?), and then tried to restart it.

Well, it started (although a tad hesitant), but was running rough and with a low idle. Rev'ing the engine made it sound like (via exhaust) it was missing or something.

It sat like that for not even a minute, and I hit the throttle again... sounded fine (back to normal?). I was able to ride it on in to the office with no issues.

If it's relevant (probably), I've put about 14K miles on the bike since last July, so I have about 16.5K on it now. Other then tires, oil, and a K&N air filter (which probably needs to be cleaned), I haven't done anything major maintenance wise.

Ideas?
 
Sounds like you may have experienced fuel starvation caused by a temporary blockage somewhere, so I would start by checking the fuel filter and work from there. If it was an electrical fault, it probably wouldn't have resumed running normally again.
 
Fuel or vent line kink or obstruction? Cracked vacuum line to the carb from the petcock (Assuming it has a carb and not EFI)? Bad diaphram in the petcock?
 
I agree with scratch. Maybe water in the gas? Stop at a local stop-n-rob for gas lately (instead of one of the big brands)?
 
Had the tank up or off lately, my guess is vent line kinked, if it happens again
open the gas cap and see if you get a rush of air, a sure sine a vent is clogged or pinched
 
budzrex said:
Had the tank up or off lately, my guess is vent line kinked, if it happens again
open the gas cap and see if you get a rush of air, a sure sine a vent is clogged or pinched
Great suggestion - check the easy stuff first.
 
I would be more prone to believe the one idea about the vent hose. This is a very common problem and often troublesome to diagnose. A pinched/loose fuel line or vacuum hose to the petcock.

H2O in the fuel is somewhat unlikely, for it to have started up again. The fuel valve stand pipes are typically much higher than a small amount of water in the tank can reach (not impossible, just unlikely).
 
If we're taking bets....put me down for $20 on the gas cap vent.

If (or when) this happens again, try opening the gas cap. If you get a loud 'thunk' (or the cap is sucked down so tight you can't open it)....I win.
 
Try ELECTRICAL.

I had (what sounds like) a similar issue on my RC51, and after asking around it seemed they were notorious for the battery connection (+/-posts) vibrating loose....loose enough to let it get connection, but irratic.
It happened twice to me before I locked all those connections up good.:pound: No issues since.

just get in there and secure, resecure all your obvious connections.

Don't try to think too technical with it, just step by step...spark and fuel being the two main points.
 
Last edited:
I have ridden the bike with a dead battery (push start) so doubt that's it. And Voltage looks fine (have volt meter).

I went ahead and changed the oil (time anyhow), and then pulled the tank. Didn't see any problems, but went ahead and replaced the fuel filter, and also pulled and cleaned my K&N Air filter (dirty, but certainlly not clogged).

Oh... and not that it matters much, but I am fairly low on gas, but not low enough for the low fuel light to come on.
 
Ok you mechanical whizzes... try this one one for size.

1978/79 - a ride from Tucson to Kitt Peak (6500 elevation). I'm on my KZ650 and a good friend and his wife are on his new touring bike. I think it was a Kawasaki KZ1300 but I don't remember when the bike first came out; that was a LONG time ago. We make it to the top okay, get the rags out and clean the crud and bugs off the windshields (I ran a full fairing on the KZ), take the tour, walk around for a while and then head for home.

On the way down the mountain he was having some intermittant roughness; almost to the point of stalling. As we hit the flatlands it got worse but what he noticed was that if he stood on the pegs it would run fine. Sit down and it would run rough again.

What's your diagnosis?
 
I would tend to think electrical , fuel problums usally dont fix thereselves with something being done , ie open fuel tank cap , wiggle gas line or take the spring out of the vacume fuel petcock so it is disabled and works manuel only , does not apply to FI bikes . VTX were famous for loose bolts mounting the coils to the frame , that doesn't help preformance . the loose battery cables should cause starting problums . If you pull the plastic check every electrical connection you can get to , any signs of green corrision inside a plug should be cleaned out then coat all plugs with dielectric grease before reassembly . Good luck SEYA
 
I had a '78 KZ650. Similar problem that only happened on the hottest days. Never exactly figured out what it was but I believe it was the coils overheating. Pull over, check it all out and restart it and it would run fine.

As long as I was moving at 50+ it was fine, but stop and go traffic on a hot day and it would act up. Only once did it completely stop running. But after a short time of 5 minutes or so it fired right back up.
 
My guess would be a loose battery connection that was compounded when the seat was depressed...
 
Gilk51 said:
My guess would be a loose battery connection that was compounded when the seat was depressed...
Nope. The hint you need was in my original post. It's a well-hidden hint, but it's there. ;-)
 
Texas T said:
Ok you mechanical whizzes... try this one one for size.

1978/79 - a ride from Tucson to Kitt Peak (6500 elevation). I'm on my KZ650 and a good friend and his wife are on his new touring bike. I think it was a Kawasaki KZ1300 but I don't remember when the bike first came out; that was a LONG time ago. We make it to the top okay, get the rags out and clean the crud and bugs off the windshields (I ran a full fairing on the KZ), take the tour, walk around for a while and then head for home.

On the way down the mountain he was having some intermittant roughness; almost to the point of stalling. As we hit the flatlands it got worse but what he noticed was that if he stood on the pegs it would run fine. Sit down and it would run rough again.

What's your diagnosis?
That rag covering the intake?
 
I think it had something to do with "walk around for a while"... :roll:
 
Texas T said:
Ok you mechanical whizzes... try this one one for size.

1978/79 - a ride from Tucson to Kitt Peak (6500 elevation). I'm on my KZ650 and a good friend and his wife are on his new touring bike. I think it was a Kawasaki KZ1300 but I don't remember when the bike first came out; that was a LONG time ago. We make it to the top okay, get the rags out and clean the crud and bugs off the windshields (I ran a full fairing on the KZ), take the tour, walk around for a while and then head for home.

On the way down the mountain he was having some intermittant roughness; almost to the point of stalling. As we hit the flatlands it got worse but what he noticed was that if he stood on the pegs it would run fine. Sit down and it would run rough again.

What's your diagnosis?

I had this happen on a Z-1 Kawi.

The Old Kawi's had hinged seats that opened up sideways to the Airbox, Battery, and Storage compartment. The Airboxes didn't have snorkels on them like nowdays, they vented to the top. If you weren't careful how you stowed your rags, closing the seat on top of them, and then sitting on them, you would close off the airway to the airbox. Get up... it would breathe... sit down... Choke!

One other thing the old Kawi's did. The crankcase vented to the Airbox. Also the Oil pans didn't have baffles in them. Most models called for 3.5, 3.7, or 3.9 US Quarts for an oil change. Lazy people (me) would go ahead and pour the whole 4 Qts in. If you accelerated too hard and/or lifted the front wheel, oil would slam against the rear of the pan and get sucked up into the Airbox, down the carb throats, and into the motor. Mosquito Sprayer type clouds would erupt from you pipes. First thought??? I've blown my motor! :eek2: Nah! Drain a Cup of oil out, and you're good to go. :rider: (Maybe with a change of plugs too.)
 
Did he happen to have pod style filters on the bike, some bikes show strange
carburation when you move your legs and change airflow or encounter big crosswinds, or did he get a rag covering the air intake
 
Mike,

:tab My 01 VFR 800 did this. It turned out to be dirty contacts on one or more of the sensors for the FI system. I disconnected all of them, cleaned the contacts, reassembled and never had a problem again. In the VFR, when you turn on the ignition, the FI light would blink. Count the blinks, compare to a chart in the book, check whichever sensor matched the number of blinks. I think I had more than one sensor that was dirty. I road in the rain often so road grime eventually worked its way up inside the fairings. Of course if your F4 is carbed... nevermind ;-)
 
Texas T said:
Ok you mechanical whizzes... try this one one for size.

1978/79 - a ride from Tucson to Kitt Peak (6500 elevation). I'm on my KZ650 and a good friend and his wife are on his new touring bike. I think it was a Kawasaki KZ1300 but I don't remember when the bike first came out; that was a LONG time ago. We make it to the top okay, get the rags out and clean the crud and bugs off the windshields (I ran a full fairing on the KZ), take the tour, walk around for a while and then head for home.

On the way down the mountain he was having some intermittant roughness; almost to the point of stalling. As we hit the flatlands it got worse but what he noticed was that if he stood on the pegs it would run fine. Sit down and it would run rough again.

What's your diagnosis?

Sounds like a mis-routed vent or fuel line that's being pinched by the seat....you know...after you got the rag that was stored under the seat. :scratch: But I think that's a bit of a reach.

Again, if I had to put my $20 on one, I think there's a carb float or fuel pick-up problem that is affected by the 'attitude' of the bike...nose up=okay, nose down= bad.
 
Kent, Stephen and Bud all nailed it. After cleaning the shield he tossed the rag back under the seat but it was partially blocking the air intake. When he sat down on the seat (he was a large US Marshall) it was enough to choke off the air flow. It wasn't hard to figure out once we pulled over and he described what was going on; we just lifted the seat and saw the rag covering the intake.

Good analysis guys! :thumb:
 
So, Hey Mike - have you been stuffing rags under your seat lately?
John
 
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