Cutting out/bad idle
 

My 748 sp has started to miss and splutter on tickover. When it's cold this results in it stalling and when warm just alters the idle rate. The bike hasn't been used too much of late but has just had a mini-service (oil, fuel filter etc).

The bike's relatively new (to me) but the power delivery feels very 2-stroke like (i.e weak until 7k rpm when it takes off). I'm not sure whether this is a symptom of the same problem or just a characteristic of the wilder cams on the sp.

Could anyone offer any suggestions as to what this could be or should I be booking it in at the local dealer?

Thanks in advance.
DJ

Did you change the plugs as part of the service?

I believe so (I'll check the receipt). I was thinking that the HT leads breaking down could possibly cause this. It could tick over nicely for 20-30 seconds then misses about 5 times in the next 30 seconds so it's not at all predictable.

I actually plan to have it blueprinted and given a 'full monty' service over winter which should sort but just want to have some fun whilst the sun's shining!

D

The power band thing is quite normal mate, mines the same!
Have you got the right chip in for your exhaust? Mine was terrible when I got it and that was why, but having said that mine is reminiscent of a bag of nails at tickover too. :(

I need to check the chip really (or change the exhaust back for a day). Someone mentioned getting it RR'd and mapped correctly so I may do that, but just wanted to make sure I wasn't going to have to spend a fortune sorting this problem out first :) Is the chip easy to get and/check it's non standard?

thanks,
D

Yep, it should have a code on it, you just ring one of the specialists (JHP or someone like that) who should be able to tell you if you have the right one or not.
Could be also that your tickover is just a tad too low?

There was a thread on here a month or so ago with all the chip codes on them and what they should have been fitted to.

In fact it's here

http://217.199.188.40/xmb/viewthread...=9814#pid79924

Jason


[Edited on 9-9-2004 by Mr_S]

I don't have plaster restricting my typing though :P

Thanks guys! I don't actually think it's the chip though! I've just had it start with the 'choke' i.e 2k revs and you can still hear it missing occasionally.

I'll check the chip regardless, but this has got to be something to do with fuel/spark surely?

D

What do you think the chip does? Lol :lol:

I know, I know :). I meant it was probably something like the leads/plugs which will cause the seemingly random behaviour rather than the chip that should (assuming all the sensors are giving true values) either work, or not.

Could be, and probably am wrong though :(

Update: I went to Baines this morning (who obviously know there stuff) and the opinion was that the bike needs the valve clearances setting (the exhaust is wet with upburnt fuel, the bike 'sneezes' intermittently and it's very lethargic when starting).

Whilst I don't doubt the diagnosis, I then set off back up north (200 mile trip). I immediately filled the bike with the BP Optimax alternative (can't remember its name) and set off up the A1.

I gave it a good run (and got to maximum speed a few times on my private test track). When I got close to home and onto the back roads I noticed that it sounded a little better.

I've left it ticking over for a few minutes and it settled into an even idle with no evidence of the original problem at all! I then left it to cool for a few hours, started it cold and it's still fine.

I've no idea what to make of that, other than it'll be nice when I get proper compression back after the service, it's damned quick as it is!

D

BP Ultimate's the stuff. It's that or Optimax I use all the time (unless I can't get it). It's chock full of detergents as well as other things which may have helped clean out injectors / valve stems etc.

During the mini service, did you do the air filters as well? Even the foam undertank ones need a bit of attention...

I always use optimax, it may be placebo, but I swear she runs better on it.

Obviously you just needed to give her a good caning DeeJay, they love it! ;)