testing throttle response
 

I was wondering if anyone can tell me about something I came across with 660 XT 2011 model, I was running it the other day and after it warmed up a bit I check the throttle response with a "snappy" twist of the throttle , from idle, and I hear a tinny 'clunk' and then the motor catches up ...of course I don't keep the full throttle revs up...just a snap on and off of the throttle to check the responsiveness....but the tinny 'clunk' bothered me ..is it just the intake of fuel / air being too much for the motor so quickly.....? I noticed again that if I do a couple of rapid "snap on / off " throttle twists.....the motor cut out. What is the reason for that ...does anyone know.....? Is it not recommended. I am thinking it is that the introduction of the fuel /air is too fast....could that be it.
I would appreciate anyone's comment on this....( if you understand my dialogue)

My 2005 X does the same when it's warm despite having the better ECU and a brand new TPS, new filter, good plug and correct idle speed (1500 when hot) (all stock apart from MTC cans). Happened to me a couple of times yesterday in traffic - I have a tendency to blip the throttle. Have also had the engine cut when blipping to downshift. I think it might just be a trait of it being a big single, although it wouldn't surprise me if it's related to the bikes being lean, in which case maybe a Kev mod would fix it.

Kev mod will certainly contribute to adjust the correct A/F flow, however if the throttle body is not being fed at shut throttle, then a simple solution is to raise the idleing speed to at least 1450-1550 rpm.

A slack chain and worn rubbers in the hub also need to be spot on, i.e. the chain not too slack and the rubbers not too worn that will give the hub too much play and contribute a "delay" between giving gas and final motion response.

I have the chain slack set within spec and have done the innertube mod to my cush drive, made a big difference with the surging effect, though my engine will still surge anyway. I think the 'clunk' OP might be refering to is the engine misfiring when blipping - mine does the same. Not quite a 'clunk', but kind of.

Next thing I will try next is increasing the Co. Failing that, Kev mod!

Thanks for the reply...some good advice for me there.

Yeah, I have heard alot about them being a tad lean @ standard factory.

Out of interest, have you had your bike cut out whilst riding?

That happens to me every day. It is very annoying, especially in traffic while I'm shifting trying to get out from all the vehicles around me. I just have a single MTC can, the rest is all stock (as far as I can tell).
I adjusted the idling speed a bit last night and that seems to have done the trick so far but I'll have to wait and see tonight.

I only really get it in traffic, but particularly when the engine gets around operating temp and beyond. Had it happen twice or three times over a 10 mile ride yesterday whilst in town - the engine misses and bump-starts itself. I also find the idle speed seems to get lower as the engine gets hotter, only slightly, and this makes it more prone to stalling. I pull over and increase it to 1,500, and it still seems to drop to my ears (don't have a tacho on the X unless in diag mode, so can't really tell)

Do you find your problems get worse with heat at all?

I somehow missed your reply, sorry. Do you still experience this?