News:

We rely on our supporters to help keep us running. Thank You!

Main Menu

Restoring Vision, what needs to be done?

Started by b_racuda, March 10, 2015, 07:27:07 AM

Previous topic - Next topic

b_racuda

Actually the German low power version has different carbs, different intake manifolds and different cams. All these are changed to full power version. Somehow the site won't give me attach the dyno curve here, it always goes to some error. Anyhow, with words:

Given values for Vision as new:
65 hp (48 kW) @ 9500 rpm
50 Nm (37 ft·lbf) @ 8500 rpm

My Vision currently (with +15% more):
42 hp (48hp) @ 8456 rpm
39 Nm (44,9 Nm)@ 6452 rpm

The dyno curve is rising nicely and steady to 6500 rpm, then it drops and starts have waves. So there is not enough power in the upper end. I have to check all the fuel and vacuum lines ones more. They are all done with new parts.

Just checked electric fuel pumps available at Ebay, I may just order one of those because the price is cheaper than the repairing set for the original pump.

Walt_M.

That does sound a little like fuel starvation a good fuel pump would help solve that. You could actually remove your existing pump, fill it with fuel and let gravity take care of it. If the power is improved you have found the problem, fix the pump, electric or rebuild and you should be ok. You need the pump for the lower fuel levels. I just proved that on mine this morning.
Whale oil beef hooked!

QBS

#142
Do you have an exhaust gas anylizer available?  If so, look for anomalous results (rich or lean) above 6500.  Is any part of the intact track obstructed?  Are you running a flapper air box?  If so, is the flapper operating correctly?  Remember it is vacuum actuated.  Check to make sure that you are using the correct vacume source.

b_racuda

Actually at the dyno there was analyzer attached and that shows that mixtures were rather little rich than lean. But the mixtures curve is quite nice for the whole time, nothing dramatic. The dyno guy said that it can be anything, not getting fuel enough, not getting air enough or the exhaust is limiting. He also said that it is not the carburetors, they are now workint really well, the problem lies somewhere else. If I only can that dyno picture attached here...

I have flapper box,  earlier style which does not have the update. I have to check it also that it is still ok.

The Prophet of Doom

I was having similar issues on the Black Bastard from hell.  Turns out the TCI was sparking but not advancing with increasing revs.  A long shot, but you can check that easily with just a timing light.

b_racuda

Finally the dyno curve, now I got it attached!!

b_racuda

Checked also all the connections, still the same problem exist. I will put electric fuel pump during the winter.

Ken Williams

As Walt_M indicated previously, it is easy to temporarily plumb the fuel pump out of the system to see if it is the source of your problem. 

b_racuda

Little progress, ordered a electric fuel pump as planned. Looked on Ebay several different pumps but decided to go with some known brand, so I ordered K&N fuel pump 81-0400 http://www.knfilters.com/search/product.aspx?prod=81-0400 Hope that will work fine, at least they promise 5 years warranty.

I have now 5 months time to get it installed before the driving seasons starts. I hope this will solve the lack of power issue. I also remembered that the problems with no response when turning the gas started when the fuel tank was half full, they did not appear with full gas tank. So maybe the problem is with the original fuel pump...at least I hope so. Well at the spring time I will go to dyno again with newly installed electric fuel pump and will see what happens  ::)

QBS

#149
The half full tank, lose power condition was, for me, indicative of a failed oem fuel pump.  Installation of a fuel pump rebuild kit solved my problem.  Very modest cost and no new plumbing to devise.

b_racuda

I understand that I spend more bucks to electric pump than buying a repair kit for oem pump. Also at Ebay there was electric pumps under 10€ from China but I wanted better quality so I thought to put more money on it. But I also wanted to upgrade my bike and I think electric pump helps cold starting.

Next step is to have new exhaust system, I want something like 4-2-1, I don't have skills to do it by myself so I have to find someone to manufacture it. This is maybe something for the future, first I want to see my Vision to work one summer with no problems before putting more money on it.

Walt_M.

The fuel pump looks good. As for exhaust, Predator in UK still makes one but they are expensive at 756 euro
Whale oil beef hooked!

b_racuda

Well eventually the sun started shining and the snow is melting. So that gave me inspiration to start changing the fuel pump. I read the manual and it says that new electric fuel pump preferred installing position is in 45 degrees angle. So I started to see where to instal it and how. Well with help of piece of cardboard I got a position where the fuel pump is so that it is in 45 degree angle and I can check it easily. I tested and it is not in a way when driving.

I also noticed that there is a minor leak of coolant. One is coming from the rear cylinder bolt, the one which is meant to open when taking all the coolant away. The other one is coming from the thermostat cover. I purchased a new o-ring or should I call it seal to thermostat cover, some new old stock but it seemed better and more elastic than my original one.

Well, after looking that new Harley Davidson Street Rod 750 and it commercial which says "Color-Matched Speed Screen" so I finally took my Visions Speed Screen to painter so that it matches to color of the rest of the bike. Also the tail part where the tail light is located, that is at the moment at painter. So after these the bike has more BMW Oxford Green.

The exhaust is still open, I don´t have money to spend on that at the moment. First I get this Vision running again and buy a new helmet.

b_racuda

Wish me luck, I am going to try if my Vision starts today and hopefully there are now leaking gas or cooland. Yesterday I drained the coolant and started opening the water pump cover. After I opened the water pump cover I did go through every surface with a fine sandpaper, just to make sure that they are clean and that is not the problem for leaking. Also changed the gasket. Also the fuel pump is now finally installed properly.

If everything seems to working and nothing is leaking then I also change oil and filter and go for a test drive. In Finland the weather is very cold, the April is colder than normal. Even when the sun is shining it is only 6 degrees of Celsius and in the nights it drops under zero. 

b_racuda

WOW! 50km test run completed, everything worked and no leaks. The bike performed great, no hesitation when accelerating, when stopping no stalling but nice idle. Only complain is when I stopped to refuel, it took quite a long time to get it started again. But maybe it is just the 7 month old gasoline which is causing this. Also maybe I need new spark plugs. But so far so good.

Walt_M.

Good job on the ride. These bikes do have vapor lock issues at high temperatures but I don't think that is the problem. Does it start easier if you leave it on the center stand? Mine had that problem with the standard carburetors so I always put it on the center stand. I  think it is a float level issue but rather than fight it I just used the center stand.
Whale oil beef hooked!

b_racuda

#156
I took some pictures of my bike at the moment. The color is BMW Oxford Green, unfortunately with my Photoshop skills I can't get the color shown right in the picture, it was so bright day light when I took the photographs.


b_racuda

The starting issue remains but the otherwise the bike works great. When it starts warm it don't allow to twist the throttle at all and it was in center stand. I don't have a clue what is the problem. Maybe I adjust the idle a little bit higher, now it is around 1000rpm, maybe round 1300rpm is better.

Rikugun

That's a sharp looking bike. I like the color, rim treatment and flyscreen. The two-tone seat is also different.
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

b_racuda

Well, one story ends. I got it running, solved that starting issue and rode quite a lot this spring. But I want to go for a long motorcycle trip and maybe ride some gravel roads, the Yamaha Vision is not my choice for that so I listed my bike for sale. Now it is sold and I already purchased a new one, BMW F650GS with that 800cc twin engine.  I did learn a lot from this site and by repairing it. Thank You for help and keep those Visions running.