Losing Power (title edited)
 

Why do I loose power around 80 mph? I've even stalled out once and had to pull over I waited about a minute and fired it back up with the choke pulled open. Almost like it's not getting fuel. Has this happened to anyone else?

if you have had the tank off you have bent the breather tubes to the tank so no air is getting in to let the fuel run check the two breather pipes

Taker a look here for pics:

https://www.superhawkforum.com/forum...ad.php?t=22048

JB

That or the vacuum line is on the wrong nipple of the petcock.....

Diaphragm in the petcock could be toast. Mine acted a lot like you are describing when mine went out.

everything is connected properly... If it is the diaphragm in the petcock do I replace the petcock or just the diaphragm?

I definitely prefer tight power myself, loose power being much more unpredictable..... :)

I finally got around to rebuilding the petcock seeing that riding season is at the doorstep... well up in Minnesota anyways. Sure enough the diaphragm was shot so I replaced it with the new one that came in the rebuild kit. Got a chance to take it out for a run today to see if she would loose power at highway speeds and still :( the same thing is happening. Any other ideas of what it could be? I've made sure all the lines are attached correctly... so no problem there.

Dammm, I thought that there was "loose" power going on, not that you were losing power. Going back to what I was doing...

Does it happen only at 80 or at any sustained highway speeds? Sounds like fuel starvation. Could be something as dumb as dirty or watery gas. Try dumping the tank & starting fresh.

Dang, you beat me to it!

Loose Power... I guess I would prefer tight power as well:)

I guess any sustained highway speed I've noticed. I dumped the tank and put fresh octane in... well see what happens in the next couple days.

The other thing that could cause a high speed cruse issue would be if the holes in the emulsion tubes are clogged.

If the fresh fuel doesn't help, then remove the float bowls. Remove the main jets and then remove the piece that the main jets screw into.

These are the emulsion tubes. There is a front and rear so don't get them mixed up. There are a series of holes around the body of the emulsion tube. Make sure that these are all clean.

Attachment 11199

Ok I haven't dug into the carbs yet. figured I'd ask this question before I did....Would the cold weather (mid 30's) have anything to do with it? I've noticed the temp gauge is running quite cool. Just thought this could throw off the air/fuel mix?

The cold will not cause the problem.

After re reading your original post it sounds like a tank breather line issue.

If it happens again, open the fuel tank. If you hear vacuum when you open it or the bike fires right up after you open and close the tank, then you need to check the breather line.

Look at the lower part of the line and make sure there are no bends or low spots in the line. These can trap some water and cause the tank to vacuum lock.

yep...reading through the posts, I'd vote on breather too.

Ok silly question... which one is the breather line? Can you see it in these pics? https://www.superhawkforum.com/forum...ad.php?t=22048

it'll be a hose running off the under-side of the tank and runs down to the bottom of the bike. it'll be open and not connected to anything.

Found this post by RK1

"Should be five lines connected to the fuel tank- the fuel lines to the carbs- one on each side. the vacuum line from the rear cylinder manifold to the fitting on the rear left of the petcock and parallel to the ground- plus a drain tube and a breather tube for the fittings which point down from the tank itself in front of the petcock. The piece pointing down from the petcock doesn't take a hose."

Now I took a look under the tank and found only 3 line connected... both the fuel lines and the vacuum line. Looks like I'm missing the drain line and the breather line. would this make a difference?

That brings to question where the breather line went? If your tank does not breathe it creates a vacuum and no fuel will flow regardless of how much suction you put on it. I think you know what happened to the diaphram in your petcock now.

wouldn't the tank be able to breathe regardless of a breather line? I found the line... looks like it was cut:( there's still about an inch of tube connected to the tank. I'll remove that portion an replace it with the rest of the line that's just sittin' there doing nothing.

Make sure it isn't plugged, also make sure overflow isn't missing/plugged. Also make sure you are not a victim of PVLIR.

Checked
Checked
and Checked...

Not sure why the drain and breather hose were just hangin' out not hooked up:confused: Checked to make sure both lines were not plugged. Going to take it for a spin later to see how wonderful a job I/We did solving this issue:D

I conjuntion with this the SH has a tendancy to get vapor lock if you over fill the tank (up the fill neck) even under normal circumstances. I have had to coast off the Brooklyn bridge yanking the ignition key to open the tank to let it breathe then restart the bike & go on.

Remember, if it starts to sputter, pop the filler cap to see if this solves the issue. Leave the other key in the lock. If not, time to pull the carbs for cleaning.

I'll remember to do that when I take it out for the test run. If I pop the gas cap and it does solve the sputtering and popping and lack of power what does that mean? Something still plugged up?

It means the vent line is blocked.

Ok, so I decided dive in this weekend and clean the carbs...the emulsion tubes were in fact plugged up. Also while i was in there i noticed something that I wasn't too thrilled about. Anyone notice it?...

http://img39.imageshack.us/img39/688...3110645686.jpg

Uploaded with ImageShack.us

Yes you should change the pilot jet...... :shock: