I think she has a cold.

[jamespayne]

Greetings brain-boxes, I think my '98 twin is a bit poorly, and I'm running out of ideas of how to cure it. It feels like fuel starvation. It will rev to the red line when out of gear, but under load, it struggles around 3-4000 rpm, making it judder like its in a high gear at very low speed. Strangely, it does it when the bike is cold, AND when its hot. It also does it after I have been riding at very slow speeds. If I can get it up to motorway speeds without shaking it to bits, it runs fine, then its fine again, until I do a lot of slow speed stuff. As I'm teaching CBTs at the moment, its a pain in the a*se having 16 year old pull away from me, HELP PLEASE!!!!

[StumpyFingers]

Have you checked the air filter?

[jamespayne]

I gave it a full service a few months ago. Plugs, air oil and fuel filters, and before anyone asks, I also fitted a Facet pump I bought from the forum shop! These problems are all recent, after the service it ran fine.

[BobA]

One thing you can be sure of is that it is either electrical or fuelling.

I would check the colour of the spark plugs in the front AND rear cylinders. This will give you an idea of whats going on.

If a spark plug from 1 or both cylinders is black, I'd suspect the choke assembly. If one plug is OK and the other wet, I'd suspect electrical and possibly the 12v connections to the coils. The front one is more prone rain and the elements.

All worth a check


Good Luck


Bob

[jamespayne]

Thanks Bob, but I was thinking that a fueling/choke problem would be showing its self all the time? My problem happens intermitently, but is more prominent at the times I have stated. What do you think?

[BobA]

I think checking the plugs is a good starting point.

I fancy maybe only one of the choke plungers might be stuck, or one of the coils has an intermittent connection.

Start with the basics.



Bob

[jik1219]

Another thing you can check is the ignition wires. Some times the wires can develope a brake inside the insulation and will misfire under laod but not at low throttle levels causing a shudder or miss. Have had this happen and took fore ever to find. The coils can also cause the same symtoms if they are begining to fail.

[miss P]

I had re-occuring running problems of this nature caused by my choke plungers sticking. In the end we removed the choke completely - there are some threads somewhere on here, it's a common @ problem.

The only issue I had after removing the choke was that if the bike had been sat for a week or so she was hard to start as the fuel had evaporated from the carbs. We got around this by running a switch from under my seat to the fuel pump so that I can "tickle" the carbs before starting.

[jamespayne]

Another thing you can check is the ignition wires. Some times the wires can develope a brake inside the insulation and will misfire under laod but not at low throttle levels causing a shudder or miss. Have had this happen and took fore ever to find. The coils can also cause the same symtoms if they are begining to fail.

Interesting. Where did you wires break?
Miss P- I havent used the choke for months, due to me suspecting they might be an issue. Will the choke plungers still stick if the choke isnt being used?

[BobA]

Will the choke plungers still stick if the choke isnt being used?

The problem with choke plungers is if they haven't returned home since you last used the choke.

The lever may be back, the top cable may be back, but one or both of the lower cables (after the splitter) could be seized, stopping the choke plungers from returning home. It may also be one or both the plungers seized in the carb. It only has to be one half stuck to make the bike run like crap!

Careful when undoing the plastic knurled nut that hold the assembly into the carb. If you break one, and they can become brittle, they are not sold on their own, so it will mean a whole choke assembly!!!



Bob