Hi

would anyone have any ideas what might cause a minor but sudden drop in power on hard acceleration.  My bikes being doing this for a couple of weeks, other than that its perfectly fine.

Could it be my iridium plugs betting a bit crusty maybe?

Ta

Rutger                                                                                                                                                                             

Does it pick up aftetwards? Does it only happen when the throttle is cracked open fast? Is it as soon as the throttle is opened fast or is it at certain revs?                                                                                                                                                                             

hi first thing is check the silencer ,could be the stuffing is moving around and blocking the system .    chris                                                                                                                                                                             

Hi, wont be your plugs. Need more info.                                                                                                                                                                              

All, thanks for the replies.

It does re-pick up in power.

It happens rarely, but when it does, it starts when the revs drop eg on changing gear, not when you hold the throttle open.

If you stop for a bit, get off, give it a while, restart the bike, its completely OK.

Confused....I am.

Interesting thing about the silencer, hmmm.  Could a small hole cause this sort of thing occasionally too?  Bloody titanium mid section has a wee hole.                                                                                                                                                                             

what bike is it ?                                                                                                                                                                              

Hi Nev

re the drop in power, its an R1, 02, the injected sort.

I had a lot of expensive looking at it, but it hasn't solved the prob.  It seems to happen more often in warm weather...?

I've got it going in for an hrs diagnostic next Thurs.  Maybe that'll find the prob.    (I bet it won't but I'm sure they'll tell me this and that and the charges of course - what can you do though.  I'm not 3 mechanically minded and worse at electronics.

I was half hoping   someone local, you know a kind friendly knowledgeable soul  would offer to help me look at it... HINT HINT maybe maybe...(hopeful dog look)   .  I'd like to learn and don't mind getting my hands dirty, but haven't got the dosh to make mistakes.  

If Thurs turns out crap, I might repost with the above as a title.    You can only try can't ya.

R

                                                                                                                                                                             

The drop in power in hard acceleration could be , are you ready. The fuel pump, intake temp sensor, intake air pressure sensor, throttle position sensor, coolant temperature sensor, pressure regulator, atmospheric pressure sensor, lean angle sensor, speed sensor, exup servo motor. The self diagnostic should show the problem with the F1 light.  With no F1 light illuminated on the dash it could be throttle position sensor, 1-4 ignition coils, 1-4 injectors, Air induction solenoid, if its none of these then its probably internal parts of the engine.

Have you checked your air filter, air induction hose collapse.?                                                                                                                                                                             

I haven;t, but will add it to the list, ta.

Bloody hell, at the rate it'll take me to get through all that,  think I'm going to have to get out my old space hopper at this rate.  Boing.                                                                                                                                                                             

Hi Rutger, any luck yet?                                                                                                                                                                             

A definite maybe! (They say its good to be positive ;-)). Sorry about the delay, although i cleaned the fuel pump and had the exup valve serviced and a new cable.

But since i havent actually had the problem recur. It didnt happen on windey back so much as on full blown fast roads. Anyway fingers the fuel pump/ exup service have solved it.

Thanks to all for suggestions.

SUMMARY for Future Reference

02 R1 sudden drop in power

It happens rarely, but when it does, it starts when the revs drop eg on changing up a gear, not when you hold the throttle open.

After dropping power, it does re-pick up in power.

If you stop for a bit, get off, give it 5 mins, restart the bike, its completely OK.

SUGGESTED REASONS
From the diver, bingwing, christof

1 could be the silencer stuffing is moving around + blocking the system

With dash F1 self diagnostic light lit, the problem could be:

2 The fuel pump*
3 intake temp sensor
4 intake air pressure sensor
5 coolant temperature sensor
6 pressure regulator,
7 atmospheric pressure sensor,
8 lean angle sensor,
9 speed sensor,
10 exup* servo motor.

With no F1 light lit, it could be:

11. throttle position sensor**
12. 1-4 ignition coils,
13. 1-4 injectors,
14. Air induction solenoid,
15. None of the above, then its probably internal parts of the engine.

Additionally
16 air filter, air induction hose collapse

ACTIONS TAKEN (so far)
Local mechanic
*serviced exup valve and replaced cable.
*Cleaned electrical all connections.

I
*cleaned fuel pump
* washed out fuel tank and
* renewed fuel line filter

Full Yamaha garage ( Metropolis, Vauxhall)
* serviced the throttle position sensor(tps).

The problem hasnt recurred since.
I think the root cause was the tps.

Big thanks to:
Metropolis Vauxhall for their expertise in diagnosis + solutions; though you have wait 1-2 weeks for an appt!
My brother, whos van was a helpful transport. I appreciate an R1's is no goldwing or blackbird, but if you got push it for 2 miles you'll loose a stone in sweat on the flat
Bikermatch contributors- thankyou very much indeed for all clarifying questions and suggestions. Much appreciated.

Best regards