Idle not steady

[gregorious77]

Hi,

Just picked up an AR and once warm and off the choke the idle hunts rather than staying steady. If I put the choke back on the idle settles out to a nice steady one.
Is this just an air screw adjustment or something else? I havnt tried anything yet as it is dark, wet and windy out.
It has a DEP spanny and different silencer and is apparently jetted to suit.
There is no top end rush which is normally associated with a 2T motor with powervalve is this normal? mid range is strong then it sort of goes flat.
Cheers
Greg

[fallenmikethebike]

Oh dear where to start,perhaps have a read in FAQ, almost certainly covered in there at some point.
Power valve adjustment.
Idle jet= clean.
Plug check.
PGM brain on the blink? ouch, £450 or repair? Check for signs of being buggered.
Mike

[fishtail]

what mike said.. altho a bit pessimistic to mention the PGM so quickly?

I also found the main jet / needle height could affect "warp mode" - I had to bogger around wit me jettin quite a few times after stickin my DEP on

[gregorious77]

I have literally pages and pages of history to go through.
Jetting was done to match the pipe and the jet sizes are written down somwhere as I saw it when browsing through at purchasing.
The PGM has been repaired in the past I saw that in the receipts too.
Ill have a poke around when I have some time on my hands.

[fishtail]

check pv action first,, cable alignment..

try raisin needle 1 notch? thats easy to do - no need take carb really..

I had a similiar flat spot, and that sorted mine las year

[fallenmikethebike]

Unfortunately there are literally dozens of reasons for a the lack of top end punch.
Gearing? This can make a dramatic difference.
Jetting?
Servicing? Is the filter clean and oiled?
Is the pipe clean? Has the exhaust been repacked lately/ever?
Are there any odd pronounced noises? When the throttles cranked open especially?
What plugs in there?
What colour is it?
Have tried a plug chop test at high RPM?
The reeds could be not sealing?
Compression, is it low?
Have you checked the power valve is operating by verifying it's movement with the cover off.
Is it adjusted properly?
Then there's throttle position sensors, and vacuum valves.
Does it rev out in all lower gears?
I can say when I owned an AR, the one thing it would not do despite any amount of fettling was tick over.There is a school of thought that attributes this to the Active Radical system, as when it's running on tick over it's virtually using no fuel, but using up partly burned exhaust and crank gasses, there's generally a pronounced rising and falling of RPM, but a reluctance to settle to an even RPM.
Mike

Mike

[helisupp]

It should idle all day long..........if your plug and coil is in good nick, no crap in fuel bowl.

I would:
Fit new plug and check HT lead
Clean carb, tubes and solenoids (2 solenoids), check tube is on carb rubber securely.
V Regulator check
Powervalve motor check and adjust
ECU swap if nothing fixes it


A carb swap, it eliminates many things. They are not a simple carb as they have vacuum system and throttle position sensor included. You need to check the pipes and solenoids to make sure the vacuum system is working correctly at idle speed. Even the gear position sensor feed into the ecu can be a problem.

If you were local to Gloucester we have every spare for an AR, from complete overhauled engine, every single engine part including crankshaft assy, ECUs, solenoids, ignition parts, V regulators, carbs, full harness, swiches etc. If it cannot be cured by swapping parts nobody can cure it.

Sorry but we do not loan anything out, and if an electrical part was fitted and your bike destroyed it (ECU at £460 for example) it would have to be paid for.

Mark

[helisupp]

FMTB is right, as far as most are concerned the AR is too complicated (reason I like them).

The ARS I have, will idle superbly it seems, I had them all idling end of this year at the same time, getting drunk on the fumes, 3 idle perfectly with no rising and falling, but 2 do rise and fall, and 1 of them threatens to die but never does. Lowest mileage bike idles crispest, highest mileage bike idles worst, even though they were all stripped to last nut and bolt and inspected.

They run so lean that any wear in the engines or components will show up very easily at idle and top end due to gas flows.

My IT175J starts easier, will idle forever on an even note (but is has only done 250 miles since new). As its uncomplicated and not an engineers bike it may have to be sold in the new year. But seat height is 2 inches higher than the CRM...............outrageous.

[gregorious77]

Power valve is intermittent. All wiring in the servo unit is OK, the PT is OK and the motor runs.
Some times the power valve operates other times it does not or it turns to fully closed and stays there.
The PGM was fixed in Dec 12 by a guy called Nick? as there was a power valve problem! Its pointing to the PGM I think.
I am going to see if I can find out who this Nick is and contact him first.
Greg

[andrew19]

Could it be the Nick at

http://www.twostrokeracelab.com/

[fallenmikethebike]

^^^^^^ Undoubtedly, and the fault that killed the PGM first time around seems to be still present. as it sounds uncannily like the same fault.
It is possible to reset the PGM by switching the ignition off- then - back- on quickly. If this is the case then that's classic goosed PGM behaviour .
Check the p/v cables for free movement, ditto servo motor, a duff or dying voltage regulator will take down the PGM.
Check it for crud, it lives in a really stupid place, under the air box it works better if it's not covered in mung.
If it was an Ebay purchase, you have rights to recompense, as the product might be duff,talk with the seller initially, perhaps independently tested.
Mike

[gregorious77]

Power valve cables were the wrong way round at the servo end!!

[fallenmikethebike]

Ah, push-me- pull -me syndrome, yea that'll put a kibosh on the top end hit.
Now sorted then? For the top end hit, and the erratic tick over issue?
Mike

[fallenmikethebike]

From memory,on the AR the needle has to be changed for alteration to carburation as it's fixed in one position. Others?
Quite often changing the pilot jet is the only cure as well, even if the one in there looks clean.
Mike

[gregorious77]

Wheelies at will now!
Idle still hunts up and down. Idle adjusting knob has no affect on idle speed whatsoever.