Unusual loss of power
 

Hi All,

Hoping you can help me. I have a 99 (T reg) SV650S (curvy) which I'm currently commuting on (only bike, etc, etc) from Bradford to York (45miles, 95% motorway). In the first 15-20 miles of the journey, the bike behaves itself, giving power throughout the rev range.

However, sometimes, after that initial 15-20 mile stretch (sometimes shorter if its not been idling for long before moving), I'll suddenly lose a truck-load of power, and I have trouble getting it over about 5k RPM (and this morning, it felt happiest at about 4k RPM). It doesn't matter which gear I'm in, as it'll do it in any gear, so dropping down a gear to get the speed back up won't work.

It feels like the front plug is flooded, but its dry on the roads, so no chance of water getting up there, and feels fine in the 0-5k RPM range.

I thought the bike could either be too cold, or too hot, so this morning, I pulled over on the A64, engine off and waiting 5mins for the engine to settle a bit before heading back off. That didn't work... so, pulled over a few miles later, and let the engine idle for a few minutes, but that didn't seem to work either.

The engine oil was changed about 2000miles ago (though looks like it could do with another change), and the coolant was topped up about the same time (need to check that properly).

Any ideas? Could the spark plugs need replacing / cleaning? The bike has done about 35k miles, and I've done about 3k of those since I got it.

Any help greatly appreciated.

Could be carb icing leading to fuel starvation. Is it worse when it's coder (like this morning)?

Yeah, it was alot worse this morning, and get steadily worse the colder the ground seemed to get (snow on the ground in York, but nice and sunny in Bradford).

I'll have a search of the site for 'carb icing' and see what I can do :)

Cheers

I had a similar prob (eons ago) with a car. As LP suggests, in my case it was true too much cold air into the carb, but with only one carb it would just cut out. had to do a mod to the air intake but obviously a bit trickier to do with a bike. Apparently it can vary between same make/model vehicles. Sorry I haven't got a solution though. :roll:

Carb'icing... try using super unleaded (2 ppl more then unleaded at Sainsburys) or by a tin of Silkolene Pro FST, designed to help carb'icing, but its rather expensive.

Thanks for your replies people :) I'll fill up with super-unleaded at Tescos tomorrow and see how that goes :)

Cheers again

I used Wynn's dry fuel last year. Easier to find in your local Halfords.