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Blipping Stumbles

Started by Matnique, April 25, 2008, 01:39:12 PM

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Matnique

Lately, when easing off the throttle from 4-6K to idle and blipping the throttle, I get a no-response hesitation as if the engine just wants to stall out; sometimes it backfires softly. I'd have to ease on the throttle to get the revs back up and not blip it. It only happens when coming down from higher RPM's and then blipping the throttle to downshift. I haven't removed my carbs for dipping yet and have been postponing this since I am quite new to doing this; although I did get some practise removing the carbs out from one of my parts bikes(2).  Other than this blipping issue, it's been trouble-free and I've been really enjoying the ride, especially with new tires.  Is this the Vision stumble that I've heard about?

Lucky

1) do you have a fuel filter installed?
2) try running a can of Berrymans or Seafoam fuel injector cleaner thru a tankfull of fuel.  NOTE: do not use these products if you have a tank coating like Kreem (PVC vynal).   POR-15, Caswell or unlined tanks are fine.
might simply be time to resynq & set adjust pilots.

--Lucky
1982/3 XZ550 Touring Vison, Gold on Black

QBS

What Lucky said.  Plus, there is the option of doing a pure Berryman or Seafoam carb soak.  This consists of draining the carbs, refilling them from a pony(aka auxilary) tank with Berrymans' or Seafoam and then starting the bike and letting it idle for about 5 minutes.  Next, turn off the bike and let the cleaner filled carbs soak for two days.  Then, reconnect the regular fuel line and start the bike as usual.  Let it idle for minute and then go for a test ride to check for improvement.  I've done this to my '83 several times over the last 24 years with no ill effects.

If a carb dip can be avoided by doing this procedure, it's a major win.

Matnique

Great.  When I run the carb cleaner through, do I just bypass and replace the fuel coming from the tank with the carb cleaner on a separate line while detaching the vacuum line? 

QBS

#4
This procedure can be done with or without the tank in place.  With the tank in place, put the fuel petcock in the ON position and disconnect the fuel line from the tank.  Then use some type of large syringe or turkey baster to inject the cleaner into the carbs via the bikes' fuel line, or splice the fuel line from an auxiliary tank onto the bikes' fuel line.

With the tank off, carb access is much easier.  The procedure is pretty much the same except that you don't have to splice the auxiliary tank line onto the bike fuel line.  Instead, remove the bike fuel line from the bike where it Ts off to each carb and replace it with your auxiliary tank line.

Remove the air cleaner if you think it'll make the job easier for you.  The bike should start and run fine without the air cleaner in place.  However, do not ride without the air cleaner on.  The bike will run but not very well.

YellowJacket!

Will it fire up with pure berrymans or seafoam?  Last year I put too much seafoam in my tank and I couldn't get it to start for anything.  Had to drain it out and add more gas to finally get it going.

David


Living the dream - I am now a Physician Assistant!!   :-)

QBS

Haven't done it with Seafoam.  Have run it on pure Berrymans' numerious times.  Suggest it be run with ample ventilization.  Exhaust smells pretty bad.

Lucky

just seems like a bad idea...
1982/3 XZ550 Touring Vison, Gold on Black

Rick G

#8
I have  a "83 Honda Night hawk, in right now , and just dipped the carbs , The tank was supposed to have been cleaned by others.  Instead it was  half full of rusty water and contaminated my newly dipped carbs, trust no one!!first I opened the float bowl drain screws and drained the carbs, then used a small funnel to pour Seafoam  in the the fuel line and filled all four carbs  with it. Then I hooked up my Hang tank with gas in it  and ran some gas in with the  SeaFoam.  I fired it up and it barfed and popped , but after a bit of choke , it blew a large cloud of smoke and cleaned out. One thing I didn't want to do, was go through a set of four carbs again , for free.
Rick G
Go soothingly on the grease mud, as there in lurks the skid demon
'82.5 Yamaha XZ550 RJ  Vision,
'90 Suzuki VX800, 1990 Suzuki DR350.
'74  XL350   Honda , 77 XL350 Honda, 78 XL350 Honda, '82 XT 200 Yamaha, '67 Yamaha YG1TK, 80cc trail bike

Matnique

Okay, ran some Berryman's carb cleaner through the carbs and let it idle for about 5 minutes and then kept the carb cleaner in for 48 hrs.  I drained the float bowl and then had this idea of blasting some air through the fuel line into the carbs with the float drain open. With the carb cleaner drained out, I put the fuel line back on and started her up.  Okay, no problem there.  Took her out for a trial to see if any improvement.  First thing I noticed was that when I rolled off the throttle, the engine went down to about less than 1K idle, slog, slog, throaty sounds.  She didn't stall but I had to give it some throttle to keep the revs over 1.5K.  Back on the throttle riding and then she started bucking a bit, revs behaving very erratically, up and down.  I decided to ride back home out of concern that I might stall.  Hmmm, what have I done?

Anyway, I wanted to see about adjusting the pilot screw(s). Now, as they are factory sealed, what's the best approach to removing these seals to get to the pilot screw? Also, the Haynes manual is not to clear in the diagram as to where exactly these suckers are. Correct me if I'm wrong, there are two brass colored bolts on the left side (10mm) left of the drain screws. Am I getting warm or am I way off here?  When I do find them, do I drill them out?

YellowJacket!

Ur getting warm but not quite there.  the adjustment s are a little futher back behind a plastic pplug that will have to be pulled out. 

I'll let some of the others more experienced tell you how to do that.  also dont have access to my bike at the moment to show you what it looks like.

David


Living the dream - I am now a Physician Assistant!!   :-)

kwells

oh the factory plugs
you probably have to take the carbs back off.  I used a drywall screw and screwed down into the cover about 1/4 inch...just enough to grab it.  And then have to pull them out.  It might be a bit tedious.  Some penetrating oil will help to loosen them too.
...a vision is never complete.

www.wellsmoto.com

h2olawyer

WAIT!!!!

Before you remove the plugs (if they're still there), get a piece of paper & pencil.  Take them out to the bike.  Then remove the plugs.  Get a screwdriver & turn the screws to the right.  Count the turns (th the 1/4 turn) until the adjustment screws seat.  Write down the count for each carb.  Let us know what you discover.

It's been done a couple times before, but this type of factory data is RARE!

Thanks & I hope I'm not too late!

H2O
If you have an accident on a motorcycle, it's always your fault. Tough call, but it has to be that way. You're in the right, and dead -on a bike. The principle is not to have any accident. If you're involved in an an accident, it's because you did not anticipate. Then, by default, you failed.

kwells

ah yes...obtain the scientific data
inquiring minds want to know
...a vision is never complete.

www.wellsmoto.com

Matnique

Okay, I'm not there yet. A little further back? If I'm looking at the float drain screw, is it left of that or is it at the bottom of the float bowl itself where there is a fairly large screw. I took that off and this leads to a brass ring (it does not have a groove for a flat head screwdriver though).  Does it mean that the carbs have to be off to make the pilot screw adjustments?  Yikes.

jasonm.

the Yamaha carbs I have worked on always had brass plugs. At least my '83s and my Venture that's the case. This requires drilling very carefully w/1/8" bit, then pulling out with a dry wall screw. Often they just comeout while drilling.  All carbs are differently set at the factory. So the original settings are only valuable the carbs they came from.  But don't forget, there always exists a possible issue with a vacuum leak.
looks aren't important, if she lets you play by your rules

h2olawyer

The pilot screws are down closer to where the carbs enter the rubber boots.  The rear one can be a real pain to reach without a long, skinny screwdriver.

H2O
If you have an accident on a motorcycle, it's always your fault. Tough call, but it has to be that way. You're in the right, and dead -on a bike. The principle is not to have any accident. If you're involved in an an accident, it's because you did not anticipate. Then, by default, you failed.