Do GS1100s naturally run rough at low speed?

[Paul.S]

Well the new carbs did not make any difference at all. I sure wish I could find out what it is.

[Paul.S]

I think I am going to try another brand of spark plug gapped at 40 thousandths like Dyna recommends. Suzuki want 28. I am currently running NGK Iridium plugs. Because I basically have a steady rythymic misfire when cruising at lower speeds. And everything on the ignition is brand new Dyna stuff. And the problem was also there with the old ignition system too.

[Paul.S]

Update: new plugs did not help at all. Now, I am thinking it has to do with not enough exhaust backpressure. One of my freinds rode my bike and said it runs perfect but he was flooring it everywhere lol. Anither friend rode my bike and says his gsxr-1000 does the same thing but worse without the baffle in muffler. If you stick your hand over the tail pipe of my bike it will actually almost suck your hand in as the valve overlap pulls in some exhaust gas. My dad has the same bike with same brand Kerker exhaust but his muffler has a much smaller outlet due to a bigger baffle inside the pipe so I am going to swap mufflers to see if it makes any difference.

[radbassist]

I'm wondering if you need the "KISS" system at this point. Sometimes you need to slow down and start thinking the obvious. My friends bike had a rattle at certain RPM's and thought it was a connecting rod knocking or something in the crankcase......Turns out the rubber cushion fell off his kickstand and was rattling against his frame. My bike rattles a bit too but I fixed that with a carb sync. The noise was coming from the clutch basket and my crankshaft was SO out of wack due to the bad sync I have(had), was causing my stuff to rattle in the clutch basket.

When U hear the rattle, may want to slip the clutch a little and see what happens. Could be a vibration from something at a certain RPM that gets magnified at a certain "frequency" because of something being out of balance.

But I would start with the KISS system and look for the obvious - I overlook it ALL the time then I kick myself.

Heck, it could be your pipe hitting your frame at a certain RPM ! KISS man......KISS.

[Paul.S]

Update: I found the problem. I was not propery syncing the carbs. They are Mikuni VM33 smoothbores. Sudco just says to sync with the drill bit method. Well, that only gets you somewhat close as I have found out. I then synced the carbs with an Emgo brand sync tool with the 4 individual needle gauges. Still, did not help at all. The gauges showed a perfect reading. I then bought the Morgan Carbtune Pro 4. Best decision ever! I hooked them up and found out I was 4cm of mercury off from high to low. I then synced them again with the Carbtune Pro 4 and now she runs perfectly smooth! The Carbtune has 4 mechanical manometers that move stainless rods inside of glass tubes. It never had to be re-calibrated and you can store it however you want as there is no liquid to spill out. And yes, everytime I synced the carbs with both tools I allways had the carb hats on to prevent any vacuum leaks around the slides. Thought yall could use that info.

[posplayr]

Update: I found the problem. I was not propery syncing the carbs. They are Mikuni VM33 smoothbores. Sudco just says to sync with the drill bit method. Well, that only gets you somewhat close as I have found out. I then synced the carbs with an Emgo brand sync tool with the 4 individual needle gauges. Still, did not help at all. The gauges showed a perfect reading. I then bought the Morgan Carbtune Pro 4. Best decision ever! I hooked them up and found out I was 4cm of mercury off from high to low. I then synced them again with the Carbtune Pro 4 and now she runs perfectly smooth! The Carbtune has 4 mechanical manometers that move stainless rods inside of glass tubes. It never had to be re-calibrated and you can store it however you want as there is no liquid to spill out. And yes, everytime I synced the carbs with both tools I allways had the carb hats on to prevent any vacuum leaks around the slides. Thought yall could use that info.

I'm glad it is sorted, but no reason to believe the pressure gauages could not have done the same job if properly calibrated.

BTW along with carb sync, balanced head porting helps to improve the moothness of the engine

[Paul.S]

I'm glad it is sorted, but no reason to believe the pressure gauages could not have done the same job if properly calibrated.

BTW along with carb sync, balanced head porting helps to improve the moothness of the engine

Correct I should have put them all on a hand vacuum pump to about 10" and set them all the same and it would have been better than just adjusting the needles to 0 like I did with no vacuum hooked up. But even then, they would allways return to a slightly different spot on the gauges probably since they only cost about $60.