Forum Donations
Search
VTF Google Search
 Click Here

Bike lost power about 5 min after starting it

  • Advertisement

Post a reply

Bike lost power about 5 min after starting it

PostAuthor: 96virago750cpt » Wed Apr 15, 2020 7:12 pm

Lost power twice on my way home thought I forgot to turn the petcock on, that wasn’t it felt like it was starved for fuel. Battery is brand new a little confused not sure what it could be I replaced the petcock with a manual one I bought off amazon this bike has never done this to me since I bought it about a year ago. Any ideas?

96virago750cpt
Junior Membership
Junior Membership
 
Posts: 49
Joined: Wed May 29, 2019 5:15 pm
Location: Huntington Beach Ca Flag
Bike year & model: 1996 Virago 750
Sex: Male

Re: Bike lost power about 5 min after starting it

PostAuthor: Cusstout 1100 » Wed Apr 15, 2020 8:17 pm

I've found in the past that the bikes will run for quite a few minutes, depending on speed, acceleration, etc on the fuel in the float bowls. So with that thought in mind, I'd probably check to see if the tank cap vent is partially plugged, or maybe a kinked fuel line....or maybe that petcock isn't flowing properly to keep the bowls full. You could check that by taking the outlet line off while the petcock is in the off position and then see how it flows when you turn it to on, and then to reserve. Check for the tank vent by running with the cap open. I bought a cheap manual petcock off Amazon a while back and it wouldn't shut off, so it was pretty much useless; glad I tested it before I changed oil!
My Ride, '97 XV1100, +14, 10" over forks, progressive rear, Jardine forward controls, cobra slip-ons, K&N Filter, Dyno Jet Stage 1, Kuryakin grips, heat demon heaters, custom fabricated seat, chrome side covers, bullet signals, risers, custom modified rear fender with modified FZ1 tail light, sectioned and reversed front fender, custom paint...

Image

Cusstout 1100
Silver Membership
Silver Membership
 
Posts: 1077
Images: 7
Joined: Mon Oct 17, 2011 4:37 pm
  Flag
Bike year & model: 1997 xv1100 Virago
1987 xv535 Virago
1985 xv1000 Virago

Re: Bike lost power about 5 min after starting it

PostAuthor: mark75 » Thu Apr 16, 2020 5:54 pm

:yup:

start at your last 'action' / 'alteration' /'repair' / 'fix' / etc. the last thing you did, and make sure it's working as planned.

if so you'll need to start systematically diagnosing (one system at a time, please) - your symptoms are also sound like from dropping one cylinder ...
"Over the Mountains of the Moon,
Down the Valley of the Shadow,
Ride, boldly ride" ... E.A. Poe


Time flies >>> whether you're having fun __ :bike: or not :fan: ---

Any day above ground is a good day.
so Laissez les bon temps roulez. just roll safely --- Semper Vigilans...always watchful

"I hear and I forget, I see and I remember, I do and I understand." ... Confucius*

If you don't read the news you are not informed.
If you read the news you are misinformed.
... Mark Twain


-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
The views, opinions, and experiences expressed in this post are mine and may not necessarily represent views and opinions of other VTF members, so feel free to agree, disagree, or ignore them.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
User avatar
mark75
Mod
Mod
 
Posts: 16132
Images: 15
Joined: Sun Apr 02, 2006 3:57 am
Location: Republic of Texas Flag
Bike year & model: 1982 - XV750
2013 - FXDC Super Glide Custom
*
Sex: Male

Re: Bike lost power about 5 min after starting it

PostAuthor: OnlyJoshin » Thu Jul 30, 2020 11:53 pm

Did this happen right after you installed the petcock? I had similar issues with losing power after five minutes. Turned out to be the tci box
Image
1996 Xv1100 in a hard tail 1986 Xv750 frame :cl:

OnlyJoshin
Junior Membership
Junior Membership
 
Posts: 8
Joined: Wed Jul 29, 2020 9:49 pm
  Flag
Bike year & model: 1986/96 xv1100 hardtail

Kamloops, BC, Canada
Sex: Male

Re: Bike lost power about 5 min after starting it

PostAuthor: faffi » Fri Jul 31, 2020 4:04 am

As said already, fuel or spark is your likely sources of trouble. If fuel runs too slowly, the engine will eventually run lean and you will lose power. But unless you increase load quite a bit after 5 minutes that will make the bike drink more fuel, electrical gremlins seems more likely to me. Note that it could still be a partially blocked fuel cap vent, so you could simply try and ride with the lid just resting, not locked in place - but only if the fuel level is down a bit in the tank, or you risk flooding your noble parts with petrol. If the bike now runs nice, you have found your culprit. If you close the petcock after every ride, it is unlikely that is your issue, but if you leave it open it can be that the petcock restrict fuel flow.

If electrical... It could be a coil, the TCI or the pickups that lose internal contact when things heat up. Easiest way to check is to have a strobe timing light hooked up if you can find a good way to secure it until the engine start to lose power. Check immediately for a reliable spark by operating the strope lamp. If the strobe flashes fine, move the pickup to the other cylinder and repeat. If one is dead or very intermittent, you at least know you have some trouble-shooting to do.
User avatar
faffi
Silver Membership
Silver Membership
 
Posts: 3067
Images: 10
Joined: Sun Feb 15, 2015 3:11 pm
Location: Norway Flag
Bike year & model: Relevant machines for this forum:
Current: 2001 XVS650 Drag Star Classic
Former: 1982 XV750SE with XV1100 engine and electrics, XT600Z shock absorber, 18" Seca rear wheel
Sex: Male

Re: Bike lost power about 5 min after starting it

PostAuthor: chrismalm » Fri Jul 31, 2020 12:41 pm

:yup: :yup:
You could do a float level check while the bike is running using the clear tube method. If the float level drops while it's misfiring, see the above recommendations for petcock, fuel inlet needle & seat, etc...

If a timing light faulters while it's misfiring, see the above recommendations for electrical gremlins.
Chris Malm
User avatar
chrismalm
Mod
Mod
 
Posts: 1373
Images: 28
Joined: Mon Dec 11, 2006 11:00 pm
Location: Laguna Hills, CA Flag
Bike year & model: 1982 XZ550H
1982 XZ550H (project)
1982 XV750 (project)
1982 XV920 (project)
Sex: Male



Post a reply


  • Advertisement

Return to Yamaha Virago XV750

Who is online

Registered users: faffi