The bike is running much better since running a fresh wire to the coil.

But, ocassionally the thing still feel's sluggish through the midrange , moment's later it flies.

I'm baffled again, just as I thought I'd found the cause of the problem.

Went over to the Yorkshire dale's today, with the TPS disconnected from the carb's, and altering it's position from time to time.

About 1/3 open the bike struggles through midrange.
With the TPS about 2/3 open the engine run's better and stronger, with a little kick at about 8ish.

Bingo, found the problem (again).

The first good stretch of open, dryer road, I gave the bike a 'good bit of welly', next thing, the bike loses power in the midrange and goes all soggy again.

Bugger.

I've since been playing with the powervalves, disconnecting the powersupply and setting the pulley in different position's.

Result's;

1; midway, bike surges at about 5500rpm, feel's very strong, v. noticably kick at 8ish, run's out of puff at about 10500rpm.

2; Hi, Bike feel's ok low down, through midrange feel's exactly like it does when it loses power and goe's all'soggy', twisty road's so couldn't be botherd waiting for power to come in!

3; Lo; Bike feel's strong low down and through midrange, very usable, run's out of puff at 9ish.

I'm now wondering wether my TPS AND p. valve motor's dodgy.

Is there any thing to look for inparticular inside the servo housing when it's in bit's?

Funny how thing's are fine for hour's on greasy little dale's road's and suddenly goes AWOL when given a bit of stick.....

Powervalve's move fine when you pull up and blip the throttle.

Thanx,
Regard's Phil

Sorry for ANOTHER essay...

Im sure youve checked this before but.. when ever i suspect more than one electrical fault on a bike i head stright for the earths. I know youve been thought most of the harness but just have a look at the engine earth and the colour of the main earth lead. If the one wire you replaced to the PGM was green then there's a good chance theres some others. A bad earth will cause hell on a bike.
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If I have to take the carbs off once more...

Yup. And due to the manufacture process, all the earth requirements go through one point - it's easier to make the harness that way.

It'a real eye-opener when you strip a loom for racing to see the crazy route some of the earth wires take, just so they can get to the one earth stud.

You could do worse than fitting an extra earth just to be sure...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Seems I am having a very similar problem since my 21 come back from the dyno. One minute its running fine, the next its holding back at about 5-6000rpm for about 3 seconds then bang it goes properly again.

Powervalves are all turning properly, carbs are all clean, bike is standard apart from re-jet, airbox mod (which I want to put back to standard if I can find a standard airbox lid - anyone got one?) and wire splice.

Its the same in all gears so doubt its the splice causig the problem, at least not the gps one. The dyno session gave a power output of 54bhp but had a little flat spot at 9k rpm which had 40 bhp and the torque also dropped slightly at the same time.

Anyone know if/how snagger fixed the problem? I am guessing its an electrial problem somewhere but just wondered if anyone has any ideas where to start.

Cheers

Leigh

Just a thought, but have you checked your powervalves are properly setup? I think Matt has done some testing at Tyga, and found that wrongly set PV's will mess with power quite a bit...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Yes I have checked the powervalves, maybe I should check them again as the hole in the pulley is worn a bit and looks a bit bow tie shaped.

Although if this was the problem I would have thought it would be a consistent fault rather then sometimes working fine then another time holding back.

Cheers