Not VW hesitating in top gear/full throttle

[Ian and Lins]

I've bought a SFM ZX 125 motorcycle (Suzuki GS 125 engine copy) as Winter transport. Pretty pleased with it. But, there is a bit of intermittent hesitancy on full throttle in top (fifth) gear. Seems ok in 4th. At the moment I've changed the plug and cleaned up the HT side of the electrics. I'm thinking it may be a carb issue but a lot of 'advice' on tinternet assumes fuel injection and ECUs. Any thoughts? (oh, and 'full throttle' is used quite a lot of the time. It is S L O W)

[Highroller]

other likely culprits could be a dirty air filter or an air leak at the manifold.

[bigherb]

At the moment I've changed the plug and cleaned up the HT side of the electrics.

Change the spark plug cap as well.

[Ian and Lins]

I've just done the air filter; it was pretty clean and fitted properly. Good idea about the HT cap BigHerb. Checked the float chamber and no water or crap.

[kevtherev]

What sort of carb is it?
Needle jet?
Is there any adjustment on the needle setting?
If your on full throttle everywhere I would suggest you get a license to ride a bigger machine.

[300CE]

Try putting some super unleaded in - i had a hesitancy spot on my scoot at mid/full throttle about 3 months ago - changed the plug, cleaned up all the sensors and the filters to no avail. A pal said put some super in - did this and it cleared almost immediately. Filled back with unleaded afterwards and it returned but was nothing like it was previously, filled up again with super and back again with normal and it's been fine since (touches wood).

I can only assume i'd filled up with some cr4ppy fuel.

[Ian and Lins]

What sort of carb is it?
Needle jet?
Is there any adjustment on the needle setting?
If your on full throttle everywhere I would suggest you get a license to ride a bigger machine.

Not delved into the carb yet. The bike runs fine on all other gears and up to 'red line'; it's just top in fith. As for getting another bike, I have already. Recalled highest speed (on a track, of course)

[Ian and Lins]

Try putting some super unleaded in - i had a hesitancy spot on my scoot at mid/full throttle about 3 months ago - changed the plug, cleaned up all the sensors and the filters to no avail. A pal said put some super in - did this and it cleared almost immediately. Filled back with unleaded afterwards and it returned but was nothing like it was previously, filled up again with super and back again with normal and it's been fine since (touches wood).

I can only assume i'd filled up with some cr4ppy fuel.

This one worked! Changed plug cap and cleaned/silicon greased everything else, but filled up with BP Premium (so it says) and hesitancy has gone and managed to get the little 125 up to 65 mph!. Handling’s a bit vague on full trials tyres. Thanks 300CE and everyone else.

[300CE]

No worries mate! Nothing like a nice easy fix!