Slight surging at cruise speeds - Help

[DjPete]

I have had this prob for about 4 mths now.
Very slight annoying surge at any cruising speed.
Mainly around the 2.5 to 3.5rpm area when sitting on 60kph but I even feel its not right when at 100kph in top gear.
Apart from that no issues. No flat spots or anything.

I have just had a full tune, plugs, new air filter which was pretty bad apparently and fuel pressures etc checked. All good.

I am thinking it may be one of the fuel filters. I have heard there is a small one in line with the fuel pump on the 02 model which is inside the fuel tank.

Can anyone give me more info on how to get to it and fix?

I don't want to throw any more money at the prob if it ain't going to make a diff so will have a go myself...

[ohdear]

That would be the $450 one DJ ?

[ohdear]

That would be the $450 one DJ ?

DJ you say "Full Service" dyno with A/F readings ? As this will tell you instantly if you have a fuel supply problem. I note also you say checked fuel pressure ............. just as important if not more so what about fuel pump volume ? You can have plenty of pressure but no volume. To get at drain tank and remove from underneath, pump and filter comes out as one. You can either buy the filter on it's own $450 + or the whole assembly $900 +
Cheers

[ohdear]

Probably wouldn't be in to much of a hurry to replace filter as a cure DJ as fuel supply issues will usually be more evident in high fuel demand areas rather than light throttle / cruise situation.
Cheers

[DjPete]

No, I am not so sure it has to do with the pump.
To me maybe more of tuning the fuel injection map?

Someone else mentioned it could even be regulator not putting out enough at low revs.
I do have battery charging issues the battery is flat quite a bit.
I have it on trickle charger.

Once its going for a while its fine though.

Second battery since I have had it.
Changed about 3 yrs ago I guess.

This is not a major issue just a pain annoyance.

[BabyBusa]

Hi DJ

Maybe check TPS and look at balancing throttle bodies. We had this problem on the 00 for a while, now have done a D service and it's gone.

[DjPete]

Any tips on checking the TPS?
I wouldn't know where to start

[1hotbusa]

Hello DJ

There are two ways you can check the TPS, the first way is to bridge out the dealer plug on the ECU, and then look where the clock is. There should be a readout that looks like -C00. The - to the left of the C00 is what you are looking for. If it is not in the middle then the TPS is out. It is on the end of the throttle bodies on the LH side after lifting the tank, you'll require a Torx bit to adjust it, and this needs to be done with the engine running at idle.

If you have the service manual then refer to page 4-30.

[DjPete]

Sounds involved, but thanks.

[DjPete]

Well you won't believe it but guess what fixed my problem?
I put a tank of the highest octane petrol I could find.
The Shell red pump stuff.

It is now so smooth.
Like a new bike again.
I am soooo rapt.

A joy to ride again!!!!!!


I used to only use premium Unleaded but stopped doing that about 6 mths ago and I think that's when my probs started.

Anyone else have this problem?

[BUSGO]

Well that was an easy fix DJ.
Vpower is good but I reckon BP Ultimate is even better.
For a GEN 1 bike you might find going back to regular will be ok in hot weather.
The high octane stuff vaporises quicker in hot weather and may cause vapour lock.

[Maj]

Probably an indication your fuel mapping is slightly lean in that area, the higher octaine fuel may have a higher specific gravity or greater density and richen the a/f slightly

[DjPete]

Thanks fellas.
You may be right there Maj.
But for the moment its going really well so that will do me.

Until the next episode!