Idle problem solved

richard-7 said:
We think some problems are from joined exhausts. When you replace with the catless pipes that are completely separate the bikes runs a lot better.

My dad and Tony separately made a manual choke. Works great. More to come.
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So a decat x pipe makes it worse?
 
Pretty much yes. It was quite a revelation to discover an engine that was formerly a bit of a pig to get to idle could be so docile with a relatively small change. So docile in fact it will start and idle at 850rpm from cold. Also no more black plugs. Bear in mind I also have the Delta 400 ECU so could tell the ECU there was no idle air control motor. No idea what will happen with a stock ECU. But it’s the kind of thing you can try in a morning and is fully reversible.
 
Voodooo said:
So I have a Domi with megaphone and a commando with a decat x pipe. Are you saying this can only be done with the megaphones?
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No, this was only a comment regarding measuring the AFR using probes inserted up each silencer. The best way to do this is to weld a couple of wide band o2 sensor bungs in well before the x-over. This was something I did to my bike in order to diagnose the cause of the poor idle. You can’t get an accurate AFR reading if there is a Cat in the way and you obviously can’t get a look at what an individual cylinder is doing if there’s an x-over pipe mixing the gases from each cylinder together.
 
ok Guys, mission completed! I newly set a bit more the screw for zero position of the butterfly in the TBs and close the IAC intake from the aribox tube. And yes...thank you Iwilson, Tony, Richard and whoever more sponsored this solution, after the bike was tested a lot I never more got a stall and had on the other hand a completely nice and stable idling.
But even more important a predictable behaviour of the bike in the twisties (not the usual random working at throttle grip closing approaching a curve).
My opinion: definitely do this mod if you want to improve a lot (a lot!!!) your Commando 961.

Now again my question to iwilson: given that simply doing what I've done you get the expected result in idling, which further improvement could I expect closing the link between cylinders in the throttle bodies and so not allowing the stealing? Might be a more smooth running in the 2000-4000 rpm range? or whatever else?
 
The stealing takes place at idle speeds only where there is a relatively small amount of air flowing into the cylinders. At higher RPM's the flow of air between the throttle bodies is insignificant relative to the overall flow.

What you have done is solve one problem. That is the inability of the idle air control motor to control the idle speed. Problem two is the fuel stealing which over time leads to poor starting performance. This is fixed by blocking the tube between the two throttle bodies. If you do that one thing (and adjust the idle screw) then you solve problems one and two.

There is more going on in terms of explaining why the idle air control motor struggles but I don't want to write a novel. Most of this has been covered in previous threads.
 
Whilst I've come to this thread quite late, I appreciate all the research that everyone has provided. It's good to come it late yet get all the benefit :D

Can I ask - in regards to the balance pipe allowing the cylinders to rob charge and therefore lean one cylinder - has anyone considered a solution via an altered camshaft grind?
 
Gojuu said:
Whilst I've come to this thread quite late, I appreciate all the research that everyone has provided. It's good to come it late yet get all the benefit :D

Can I ask - in regards to the balance pipe allowing the cylinders to rob charge and therefore lean one cylinder - has anyone considered a solution via an altered camshaft grind?
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I get the idea but think that most owners would prefer to find an 'external' solution without opening the engine. My thoughts were that if you could replace the connector ferrule on the throttle body with one split into two having a little plate to extend down into the balance tube so there wasn't an easy flow between the two sides.

You could make it into a 'y' piece and have two pipes to the air control motor to separate further but my gut feeling is most gains would be from the first mod.
 
Clive said:
I get the idea but think that most owners would prefer to find an 'external' solution without opening the engine. My thoughts were that if you could replace the connector ferrule on the throttle body with one split into two having a little plate to extend down into the balance tube so there wasn't an easy flow between the two sides.

You could make it into a 'y' piece and have two pipes to the air control motor to separate further but my gut feeling is most gains would be from the first mod.
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I'm pretty sure that was tried by iwilson (unsuccessfully)
 
Gojuu said:
has anyone considered a solution via an altered camshaft grind?
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That would not work, whatever gains you would achieve at idle would only be replaced by adverse changes at higher revs. Either going the Honda VTEC route or going back to a 360 degree twin would work but the engineering effort would be way too much compared to the solution already found.
 
cliffa said:
I'm pretty sure that was tried by iwilson (unsuccessfully)
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I have one of the ebay throttle bodies and may try that for myself, just out of interest....might even use a different idle control valve.
 
I excluded the idle control valve and made the compensation pipe closure modification, I am satisfied and the bike works great
 
cliffa said:
I think lcrken has also removed it ?
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Yes, and it still runs great without it. It does need a tiny bit of throttle to keep it idling when first started, but by the time I reach the bottom of my driveway it's warm enough to idle normally. I suspect I could cure it with some tweaks to the base mapping and/or temperature corrections, but it's not enough of a problem for me to put in the time and effort.

Ken
 
A non-961 owner would probably be totally bemused at the amount of effort and discussions trying to get these bikes to idle. Every other bike from cheap runaround to high end superbike seems to manage it. Even my 30 year old Kwakka with carbs can do it fairly well.

I'm not boasting here but my '17 Omex 961CR manages to do it reliably. So what the funk is the difference between mine and an apparently identical machine? I wonder if the ECU, sensors and Idle control motor were transferred to a problem bike whether it would idle correctly? Maybe there are a number of things which may be faulty and can affect it so if all the ducks line up on your bike then no one thing you change will solve it. It was only after I recently bought a 'normal' bike that I appreciated how this should really be one of those things that you don't need to think about: it just works. While carrying out their recent track and road testing of the 961 I wonder if New Norton saw any idling issues?
 
Definitely interested to see of Norton make any modifications, that's for sure.

bet the V4's idle ok! :D
 
Vernon240 said:
Definitely interested to see of Norton make any modifications, that's for sure.

bet the V4's idle ok! :D
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Bet you're right.
No one is paying $40K for a bike that can't start easily, idle or run properly.

The EFI on the 961 was a bargain basement unit for SG. It is crap, but kept the cost down.
And fixing it seems like a science project for owners, try this, try that, maybe it's better, maybe not...
Best fix is for Norton to swap it out for one half of a V4 system, or a Keihin EFI system, then be done with it once and for all.
Charge more for the 961 if necessary, but owners of any modern bike should have to start a science project to get their 961 to run properly.
Dr. Bob should think very carefully about this, if he entertains the notion of continuing 961 production.
 
Clive said:
A non-961 owner would probably be totally bemused at the amount of effort and discussions trying to get these bikes to idle. Every other bike from cheap runaround to high end superbike seems to manage it. Even my 30 year old Kwakka with carbs can do it fairly well.

I'm not boasting here but my '17 Omex 961CR manages to do it reliably. So what the funk is the difference between mine and an apparently identical machine? I wonder if the ECU, sensors and Idle control motor were transferred to a problem bike whether it would idle correctly? Maybe there are a number of things which may be faulty and can affect it so if all the ducks line up on your bike then no one thing you change will solve it. It was only after I recently bought a 'normal' bike that I appreciated how this should really be one of those things that you don't need to think about: it just works. While carrying out their recent track and road testing of the 961 I wonder if New Norton saw any idling issues?
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Oh Boy , This is opening a can of worms ! Some will complain , some others not. Some will say OMEX is better some others not. Well I have had success finally with my setup on the original SC Typhoon . The Delta 400 works very well and is best in my view and why not ? When I loaded the latest map it has been the best yet. If Norton were to replace the throttle with a syncro-servo type throttle body this will be solved. No more passage between the throats , a throttle stop screw adjustable from the side of bike. This is how my 2020 Kawasaki is. I can adjust my idle up or down 1000 , 1100 , 1200 rpm with the thumb screw.

I also think part of the problem may be how the Delta 400 is setup . As iwlson said there is a lot going on there and easy to mess it up.
 
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