Nomad 1500 (carbed) hesitation

[zoom45]

Got a 2000 Nomad 1500 (carbed) bike that has developed a low speed hesitation (surging) feeling only at low speed cruising. I thought I may have picked up some bad gas so I drained the tank,changed the fuel filter and ran a can of seafoam through it but still no change. I changed the plugs but still no change. The bike idles fine and will get up and go if you roll on the throttle. I don't notice it cruising on the interstate at 70. If you cruise in the lower gears (say 40 mph steady speed in 4th) you can feel the bike like its hesitating. I even thought it may have a worn out clutch spring (and it was) so I installed a new one but that didn't affect the hesitation. What can make it surge at a low steady speed? I wouldn't think it would be the fuel pump since it runs fine if you get on the throttle. I haven't noticed any backfiring. Gas mileage is not affected either. It has about 120,000 on it so I was wondering if the spark plug wires could be breaking down but it run so good under throttle. Any ideas?
Thanks,
Zoom45

[jrecken]

My first thought was the accelerator pump has gone bad.

[gssbmm]

Have you checked the air filter.

[cnc]

Have you tried adjusting the air pilot screw?

[zoom45]

Air filter almost new. No on screw adjustment. Was running great before so why change adjustment. Maybe some trash got through and stopped up something that seafoam can't get out. It gets plenty of miles on it without sitting. Never had a gas problem in almost 120,000 miles. Had more electrical problems than anything.

[Bud2rat]

Sounds like you might have some trash in one of the jets.

[cnc]

Originally Posted by zoom45

Air filter almost new. No on screw adjustment. Was running great before so why change adjustment. Maybe some trash got through and stopped up something that seafoam can't get out. It gets plenty of miles on it without sitting. Never had a gas problem in almost 120,000 miles. Had more electrical problems than anything.

Cause you might have a bit of crap on the screw, or in a jet, but an adjustable jet or an air screw is just a screw with a spring on the shaft to keep tension on it. A bad bump, continual viberation and a weaked spring from being compressed for 15 years can slowly cause the screw to move over time till it show up as a flat spot or similar. Wouldn't hurt to back it out 1/4 turn and see if it helps, if it is worse return it a 1/4 turn then another 1/8- 1/4 turn.

[mick56]

Unlesse the carb has been apart before, there will be a blob of solder in the reccess where the mixture screw is,you will need to take the carb off to get at it.Take the right hand side dog bowl and backing plate off,then the speedo housing and tank.The jubillee clip that hold's the carb onto the inlet manifold has a tab on the top, it's supposed to slot into the top of the carb body,bend it upright and use it to put your finger on it to stop the jubille clip from rotating as you re-tighten it, because getting the carb back on is a pain in the arse unless you do. There is a hose on the bottom left hand side of the carb,you will need to remove that to give you enough slack to lift the carb upward's and to get to the mixture screw,(which is right at the back centre between 2 hoses) it's a bastard to get on and off because it's only just long enough and there is no room to get your hand's in there,i replaced mine with a longer piece. (after doing it 3 time's,slow learner ). When you take the speedo housing off,you need to unscrew the cable under it,stick that to the frame with some Gaffer tape,otherwise it will fall back through the hole in the frame, and that too is a bastard to thread back up through,it's also just long enough and is a pain to thread back on,i bought a 2in longer one,you might wish you had too.There are 3 electrical plug in's that you need to undo,and there is not much slack on them either,be carefull with the one that run's to the the fuel sensor at the back of the tank,it has a habit of coming adrift. If you decide to take the float bowl off to clean the jet's, which you should,DONT take the throttle cable's off the carb to give you more slack unless you are a sadistic contortionist with 9in swivelling finger's,you can remove the float bowl and get to all the jet's without doing that. Enjoy

[zoom45]

Thanks guys will give it a try.