Prime vs on when riding

[oregonjake]

I have noticed a few posts on this thread with questions on reduced power in the mid-range when accelerating. I too experienced that problem, but may have found the answer.

I noticed the other day that the vacuum line from the petcock to the manifold spigot was bent/folded almost to the point to where the hose is actually kinked enough to reduce vacuum enough to reduce/stop fuel flow. First is this possible? Second, I decided to run the bike in the prime position and noticed the mid-range hesitation is gone and she runs normal throughout the entire RPM range. Now I am assuming the vacuum line is causing the problem, not the petcock. I am going to find a small 90 degree bend pipe that will fit the vacuum hose in order to eliminate the bend in the hose. Would that effectively solve the problem, if it is indeed the vacuum hose?

Also on a side note I have been running Seafoam through every second tank and found the idle much smoother and consistent. Is it okay to run Seafoam through regularly and if so, should I be concerned with any future problems because of the Seafoam?

[Gorminrider]

I think it's possible especially with weak walled tubing... Just an idea or two from the MrHaywire that inhabits my brain but you might be able to fit a tight-wound spring over the vacuum line to stop it kinking. Or if you can find better thicker tubing...there's maybe a size of car-fuel/vacuum-line to suit. cars are all injector now so the fuel-line is awfully thicknugly..but won't collapse easily...maybe even a large size of this slipped over your vacuum line?

[phydeauxmutt]

It's possible that your kinked line is just a little bit too long. Examine the routing, you might be able trim an inch or so of tubing to ease the curve and remove the kink. It also helps a lot if you have proper-size tubing. Not going to find it at the local auto parts store, best to get OEM hose from Suzuki.

[oregonjake]

Phydeaxmutt and Gorminrider, thanks for your advice, I had not thought of the spring or a larger size hose over the offender. I did a bit of trimming but that didn't change it enough. I have wondered why the petcock vacuum spigot is pointed to the rear while the manifold spigot is in front of the petcock. The hose has to go backwards and then curve 180 degrees to come back to the manifold. Weird to me, anyway.

[phydeauxmutt]

I have wondered why the petcock vacuum spigot is pointed to the rear while the manifold spigot is in front of the petcock.

Sounds like someone might have replaced it.

[hillsy]

Most of the diaphragm covers are symmetrically screwed so you can rotate the inlet to whichever side you want....

[oregonjake]

Is that it? You know, as I get older my higher functions seem to be slowing down, and if not for the collective brains here I would have problems even getting out of bed. It started raining here in the Willamette Valley so tomorrow I will check the petcock and make the needed adjustment. I will report back tomorrow as well with an update.

[oregonjake]

Turned the plate with the vacuum spigot on the petcock so it points toward the manifold spigot and she runs fine now. No more keeping her on prime. Thanks for the help.