RPM Cap out at about 5k

[amontyg]

My bike has been having some issues lately, and I am hoping that you guys may have some suggestions for diagnostics before I tear down my carbs and start looking for blockage.

My bike is having a lot of trouble starting and idling. When I can get it to start it, runs rough and will only get to about 5000 RPM before it acts like it is starved for fuel. Also, when accelerating it responds slowly. It may take three or four seconds of stuttering before it actually takes off. I haven't had a chance to ride much all summer and it sat all winter, although all fuel was drained from the system during winter months.

I recently had the carbs off while diagnosing an electrical problem, the bike ran almost perfectly before that. I believe that the electrical problem is fixed, as the bike will run and each spark plug fires when out of the socket and grounded to the engine.

I completely cleaned the carbs and installed new o-rings about four years ago. My intake boots are less than a year old, and my petcock is also about four years old. Everything else involving the fuel system is stock.

[Crankthat]

Give the carbs a full inspection while still on bike everything connected well? Clamps all centered? open up filter housing check filter condition and see if filter setting in correct. You might get lucky and mabye pulling to much or to little air.
Let a few others chime in with their thoughts before pulling carbs off.
Might help if knew what eletrical proablems were fixxed as will let others know what replaced or disconnected. Good luck.

[amontyg]

My regulator rectifier went bad and had to be replaced. I replaced it with a used R/R from a honda of some sort. I took the opportunity to solder almost every electrical connection in the bike and freshen all others. I had the carbs off during this process, so I could remove and clean the main ground to the crankcase.

What filter housing are you referring to? the one attached to the petcock?

[gustovh]

Change the carb mount O rings.
V

[Crankthat]

Sorry, Air filter. Not saying the problems not the petcock, and have heard people have alot of problems with fuel filters., I run a dirt bike style filter and have no problems on a 750. petcock - 2 inch hose peice - fuel filter - 8 or nine inch hose to carbs. Didnt know you had one. (fuel filter) Try running without one if tanks not bad, mabye clogged fuel filter? If tank has rust then make a reserve tank = One clean water bottle with a peice of fuel line through bottle cap then attached to fuel line that had filter on it will need to make a fitting to attach the hoses together dont know if part of a writeing pen would work or not? cut bottom of bottle off and make a couple of holes to tie some string through hang above bike fill with gas and start bike. Was hoping for the easy fixx with to much air to your carbs making it seem as if starved for fuel. Easier to check then ripping off carbs.
Pretty sure can check petcock by putting on prime and seeing if will run in higher rpm range just dont forget to switch off prime when shutting bike off as can fill cylinders with fuel.

[amontyg]

Thanks for your suggestions so far. The comments from gustovh made me think a little, and last year when I replaced the intake air boots, I destroyed the stock screws that were holding them on.

I replaced them with some steel allens that I had lying around as a temporary fix, but I noticed that they were rusting, and replaced them with stainless steel this last time the carbs were off.

Could the rubber o-rings under the intake boots have hardened enough in under a year to cause them to not seal properly if removed and re-attached?

[Crankthat]

Worth checking out.

[OldVet66]

How often do you ride your bike? If it sits for long periods of time, another carb rebuild might be in order. Check float bowls for evidence of rust sediment, it can clog the carbs and block the tank screen reducing fuel flow. You might just need to start at the beginning, but your O-rings should still be good. Fuel today goes bad real fast.

[amontyg]

It has been sitting quite a bit this summer. If it is that gas has gone bad in the carbs, has anyone had luck running a high concentration of sea foam through a few tanks and cleaninng it up without opening the carbs?

[Crankthat]

It has been sitting quite a bit this summer. If it is that gas has gone bad in the carbs, has anyone had luck running a high concentration of sea foam through a few tanks and cleaninng it up without opening the carbs?

I have never used seafoam, but i have used STP carb cleaner gas additave 5.25 oz to a tank of gas with a splash of marvel mystery oil in my bike then ran the **** out of it. Wont work to clean any hard particals but will loosen up jelly from most surfaces. Only do on a cooler day.

You would be better off pulling carbs though if none of the other things mentioned work. I think someone mentoned looking in a float bowl? you should be able to pull one on outside of carb rack while still on bike, and inspecting it.

If you do pull carbs off there is a trick for the 550. The plastic fender part that flows into rear fender has a couple of tabs that hold onto the frame.
Pull the tabs away from frame and slide past so you have a little more room to slide airbox back. It only gives you a couple of inches extra to work with but it makes a huge diffrence with pulling them off and getting them back on.

There are a couple of posts on it. I dont seem to have much luck with the search on this site but it can be found.

[OldVet66]

It helps as a preventative maintenance and fuel stabilizer, but after the fact, who knows, you might get lucky. The recurring theme of this site is, "there are no shortcuts", but it's your bike, do with it as you will, but that path most often leads to "there are no shortcuts". At least spot check the float bowls for sediment. You could also break loose a lot more stuff if it is a tank rust problem.

[AJ]

It sounds to me like your pilot jets are clogged.

For added spice to the forum, I recommend using a pin drill to clean them.