Engine Loses Power after 1.5 miles Resolved..Float Stuck

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jchesshyre
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Re: Engine Loses Power after 1.5 miles

Post by jchesshyre »

Have looked in Haynes and ignition coil resistance specs are as follows (don't know where they got these from, perhaps by measuring a new one?):

Primary winding resistance: 0.4 to 0.8 ohms @ 20˚C

Secondary winding resistance
With plug cap: 17.0 to 19.0 k ohms @ 20˚C
Without plug cap: 12.0 to 14.0 k ohms @ 20˚C

Plug cap resistance: approx. 5 k ohms
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sirch345
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Re: Engine Loses Power after 1.5 miles

Post by sirch345 »

Wicky wrote: Tue Mar 12, 2019 2:21 am Yes the angle on the reassembled vacuum spigot plate could possibly be interfering with the proper action of the diaphragm.

Definitely worth swivelling around to rule that out so its pointing horizontal. And a chance to check its sited well and doing its job.

Image
That is exactly what I was wondering.
Peeb wrote: Tue Mar 12, 2019 5:41 am
sirch345 wrote: Mon Mar 11, 2019 11:24 pm
Peeb wrote: Mon Mar 11, 2019 5:45 pm Image
Unless I'm mistaken the take off spout for the rear cylinder vacuum hose on the petrol tap is normally at 90 degrees to the vent spout, not sure if that would make any difference :eh:

Chris.
High Chris, I can clock the fuel valve so the vac is 90 degrees to the vent. I did flow test the tank on a bench by applying vac to the valve and the fuel drains out the two supply pipes so fast it's empty from 1/2 full in just over a min. Thanks for thinking and helping. Peeb
I'm not sure which way you applied the vacuum to bench test the flow, but it could be worth bench testing the flow again using the pipe from the front cylinder with an extension (if you didn't do it that way of course) so you're getting a true picture of what happens on the bike. Also as Wicky said worth checking the diaphragm when you spin that plate it around,

Chris.
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Chris58
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Re: Engine Loses Power after 1.5 miles

Post by Chris58 »

sirch345 wrote: Tue Mar 12, 2019 1:47 pm
Wicky wrote: Tue Mar 12, 2019 2:21 am Yes the angle on the reassembled vacuum spigot plate could possibly be interfering with the proper action of the diaphragm.

Definitely worth swivelling around to rule that out so its pointing horizontal. And a chance to check its sited well and doing its job.

Image
That is exactly what I was wondering.
Peeb wrote: Tue Mar 12, 2019 5:41 am
sirch345 wrote: Mon Mar 11, 2019 11:24 pm

Unless I'm mistaken the take off spout for the rear cylinder vacuum hose on the petrol tap is normally at 90 degrees to the vent spout, not sure if that would make any difference :eh:

Chris.
High Chris, I can clock the fuel valve so the vac is 90 degrees to the vent. I did flow test the tank on a bench by applying vac to the valve and the fuel drains out the two supply pipes so fast it's empty from 1/2 full in just over a min. Thanks for thinking and helping. Peeb
I'm not sure which way you applied the vacuum to bench test the flow, but it could be worth bench testing the flow again using the pipe from the front cylinder with an extension (if you didn't do it that way of course) so you're getting a true picture of what happens on the bike. Also as Wicky said worth checking the diaphragm when you spin that plate it around,

Chris.
+1 to this. Although you have already ruled out the petcock it is worth looking into again. It may work if you suck with your mouth on the bench, but when you open the throttle on your bike there is not much vaccum causing it to not work properly (maybe a pinhole, or not sealing properly). At an idle there is a lot of vaccum, and it probably works fine.
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Pete.L
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Re: Engine Loses Power after 1.5 miles

Post by Pete.L »

I’d check for splits in the vacuum lines too. They are all getting a bit old now and they may be fine when they are cold and a bit stiffer but start to leak when they warm up. I’ve had a couple go like that on me.
I also like the idea or a sticky choke plunger. Either the cable itself or the needle valve at the carb end


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Peeb
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Re: Engine Loses Power after 1.5 miles

Post by Peeb »

RESOLVED!!! After new coils, leads, rubber caps, carb bowl gaskets, and the big rubber isolators between carbs and intake (this time around) After new vacuum lines, fuel lines, fuel diaphragm (a couple years ago) the bike would run fine for 1.5 miles then barely run. The rear cylinder was going cold, the problem was not common to both as I originally thought. I get the dumb mechanic of the month award! The rear carb had a small bit of grit causing the float valve to hang up in the tube it slides in! What a dope! Had I just emptied the bowls and blown in the fuel tubes this would have been solved weeks ago! Enough fuel got by the float valve to idle indefinitely but not enough to pull a load.

The good news is the VTR runs, smells, and idles better than ever because this process discovered a leaking front bowl that made the garage smell like gas after every ride. And the new isolators and one other vac leak from the deleted pair system really helped the idle.

Thanks for the help

Peeb

1998 VTR1000 SuperHawk
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sirch345
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Re: Engine Loses Power after 1.5 miles Resolved..Float Stuck

Post by sirch345 »

I'm pleased you got there eventually, well done :clap:

Thanks for letting us know :thumbup:

Chris.
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Re: Engine Loses Power after 1.5 miles

Post by thised »

Peeb wrote: Mon Mar 11, 2019 5:45 pm
8541Hawk wrote: Mon Mar 11, 2019 3:02 pm I doubt it is an issue with the pulse generator. When they go bad you usually see erratic running at higher rpms and it slowly gets worse and lower in the rpm range as the generator degrades more.

I would take the advice of trying to open the tank when it is happening and see what that does as it does sound like you either have a tank vent issue or the vacuum line was inadvertently attached to the wrong nipple. :thumbup:
Mr 8541 Hawk. Thank you for the reply. I think you were the guy who got me going on the Pair Delete, the 48 pilots and TPS adjustments that really made this bike sing.

I did try opening the tank and tried running with it open with no change in symptoms. I was CERTAIN the vent or screen or diaphragm or vac source had to be causing a fuel delivey problem, it just makes too much sense. I also bench tested the tank and valve by providing mouth vacuum to the valve. I'm aware of the similar but incorrect nipple on the fuel valve that is the vent for the diaphram. Photos of the tank bottom and fuel valve are attached with comments. I welcome your suggestions, there are plenty of times I have missed something and the symptom is so indicative of a fuel problem.

Commented Under Fuel Tank.jpg
Commented Under Fuel Tank.jpg
Thank you for the pics Peeb. Was struggling with similar symptoms but thanks to your notes on the tap realised I put the vac pipe on the vent so the carbs were just running dry. Cheers Ed
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