Inlet upgrade?

Clive · Apr 12, 2021

Vernon240 said:
Normally you might entertain upgrading injectors as far as flow is concerned if you were on a dyno, max revs and your injector is close to 100% duration and you are still weak. so you are 'running out of injector' You could up line pressure, which can work, or look at new higher flow injectors. Changing pressure while mapping can cause an issue, but there are tricks around this...but you may well end up repeating the process if you started from low to high revs.

Yes with EFI you shouldn't need to but we are locked to a map so all you can do is fool it by meddling with sensor inputs (temp/ TPS/MAP), but without the program it's all a bit unpredictable, so fuel rail or injectors will give you a nice percentage increase across the range. I considered changing the rail pressure which is easy on a nice big engine bay with a replaceable pressure regulator but for the 961 it's a challenge and the injectors are designed to work at 3bar so spray patterns would change introducing another variable. The injectors are very common so I have picked up a couple of s/h low mileage ones for a few quid. Might get them ultrasonically cleaned if it all looks promising.

Vernon240 · Apr 12, 2021

Clive said:
Yes with EFI you shouldn't need to but we are locked to a map so all you can do is fool it by meddling with sensor inputs (temp/ TPS/MAP), but without the program it's all a bit unpredictable, so fuel rail or injectors will give you a nice percentage increase across the range. I considered changing the rail pressure which is easy on a nice big engine bay with a replaceable pressure regulator but for the 961 it's a challenge and the injectors are designed to work at 3bar so spray patterns would change introducing another variable. The injectors are very common so I have picked up a couple of s/h low mileage ones for a few quid. Might get them ultrasonically cleaned if it all looks promising.

Fair enough, if the injectors are cheap enough, worth a try I guess. Bloody frustrating that Omex force you into this when you have an ECU that is capable of being tuned!

iwilson · Apr 12, 2021

Clive said:
Thanks for this great info but I think you sent Nigel's brain open loop . So is the answer a knock sensor? Looking at the Omex site it looks like it is possible to add a knock sensor but again we are into the realms of a DIY dabbler trying to program an ECU which I have come to the conclusion of being very difficult. I'm thinking if I manage to get the bike running on the dyno with a AFR reading that looks ok, which should be possible thanks to open loop mode, and I'm not too worried about economy - more preserving the engine - then I should not be too far from getting the best from the engine. First 'dabble' is a pair of alternative higher flow injectors.

I think back to when I was at Lucas with the mechanical fuel injection systems on cars such as the TR6 which were crude in the extreme but economy and fuel emissions were not such big considerations.

No the answer isn't a knock sensor since you don't have a programmable ECU to make use of it. They're just a little microphone that listen for the 'ping' when an engine knocks and immediately start to retard the timing.

Bear in mind your engine only runs in closed loop when the engine can run at lambda 1 which is low load conditions. If the load goes up cylinder temperatures increase requiring a richer mixture to reduce the possibility of knocking, something a narrow band sensor can't deal with. So don't worry about closed loop it's not really relevant as its only used when the engine is plodding along.

I think fitting a Power Commander is probably the simplest and most cost effective way forward for you. I have also found the probes dyno operators insert inside the exhaust can sometimes falsely show the engine is running lean. Because they don't go far enough up the exhaust to prevent a little bit of air skewing the reading to lean. I ended up welding wide band o2 sensor bungs in place of the narrow band bungs to guarantee I was getting good data and yes the readings were different compared to the exhaust probe!

iwilson · Apr 12, 2021

Clive said:
Yes with EFI you shouldn't need to but we are locked to a map so all you can do is fool it by meddling with sensor inputs (temp/ TPS/MAP), but without the program it's all a bit unpredictable, so fuel rail or injectors will give you a nice percentage increase across the range. I considered changing the rail pressure which is easy on a nice big engine bay with a replaceable pressure regulator but for the 961 it's a challenge and the injectors are designed to work at 3bar so spray patterns would change introducing another variable. The injectors are very common so I have picked up a couple of s/h low mileage ones for a few quid. Might get them ultrasonically cleaned if it all looks promising.

You might find the bike becomes more of a pig to start. The ECU uses a fuel enrichment table that adds extra fuel when you do a cold start. If you fit bigger injectors you might find the engine floods in a heartbeat....

Clive · Apr 13, 2021

iwilson said:
You might find the bike becomes more of a pig to start. The ECU uses a fuel enrichment table that adds extra fuel when you do a cold start. If you fit bigger injectors you might find the engine floods in a heartbeat....

I keep looking for the sensor which detects when people are watching me try to start it when its hot and cuts the spark until they wander off muttering about British bikes....

Ok we'll see how things go with the starting, which is why I haven't gone crazy with the nozzle upsizing, but, as you may have gathered, the engineer in me likes to measure and test so your comment about the misreading probes is a bit concerning as everything is based on the assumption that the dyno AFR readings are accurate - I will have a discussion with the dyno guys.

iwilson · Apr 13, 2021

Clive said:
I keep looking for the sensor which detects when people are watching me try to start it when its hot and cuts the spark until they wander off muttering about British bikes....

Ok we'll see how things go with the starting, which is why I haven't gone crazy with the nozzle upsizing, but, as you may have gathered, the engineer in me likes to measure and test so your comment about the misreading probes is a bit concerning as everything is based on the assumption that the dyno AFR readings are accurate - I will have a discussion with the dyno guys.

With all due respect to the dyno guys... Of course they’ll tell you it’s accurate! Secondly it’s good for business if it reads a little lean! Did your engine melt or knock on the full throttle max load dyno run? This would suggest the timing is very conservative or it’s not that lean.

Not suggesting there’s any funny business going on but sometimes people just ‘assume’ without digging a bit deeper. Unfortunately I’m a little ocd so just have to know 100%. Annoying yet useful.

Al's#5 · Apr 14, 2021

Clive said:
I keep looking for the sensor which detects when people are watching me try to start it when its hot and cuts the spark until they wander off muttering about British bikes....

Ok we'll see how things go with the starting, which is why I haven't gone crazy with the nozzle upsizing, but, as you may have gathered, the engineer in me likes to measure and test so your comment about the misreading probes is a bit concerning as everything is based on the assumption that the dyno AFR readings are accurate - I will have a discussion with the dyno guys.

Just had a negative reply from Dynojet, pity, here's hoping the incremental increase of the injector is the way to go. Tweaking and riding an alternative at the moment but planning to resurrect the 961for the summer, looking forward to some refinement ref my basic mods.

iwilson · Apr 14, 2021

Al's#5 said:
Just had a negative reply from Dynojet, pity, here's hoping the incremental increase of the injector is the way to go. Tweaking and riding an alternative at the moment but planning to resurrect the 961for the summer, looking forward to some refinement ref my basic mods.

Don’t get to cut up! There’s not much really wrong. I haven’t heard of many if any engines exploding due to fuelling issues.

BLIGHTYBRIT/SF · Apr 15, 2021

Now this guys got 10 of these to shift , on eBay atm ??? Amazing in it when a bunch of new parts end up on eBay , & oh , don’t get too excited, these ones don’t have the idle motor mounts cast underneath I have just been reliably informed , only suitable if u remove the idle motor apparently!

comet · Apr 15, 2021

BLIGHTYBRIT/SF said:
Now this guys got 10 of these to shift , on eBay atm ??? Amazing in it when a bunch of new parts end up on eBay , & oh , don’t get too excited, these ones don’t have the idle motor mounts cast underneath I have just been reliably informed , only suitable if u remove the idle motor apparently!

Looks like TonyA used one of these as part of his new air-flow setup. I wonder what the story is with the missing mounts. Was the idle motor mounted somewhere else at some point?

TonyA · Apr 15, 2021

comet said:
Looks like TonyA used one of these as part of his new air-flow setup. I wonder what the story is with the missing mounts. Was the idle motor mounted somewhere else at some point?

They must have used a different mounting system for the Idle Motor early on at Norton . I have not used the ebay MCT throttle bodies yet and can't mount my idle motor without designing another bracket which will mount up. The mounting ears are MISSING from these throttle bodies. BUT , these should work great if you remove the idle motor and plug it like iwilson did . This is why I haven't posted about them yet.

iwilson · Apr 15, 2021

TonyA said:
They must have used a different mounting system for the Idle Motor early on at Norton . I have not used the ebay MCT throttle bodies yet and can't mount my idle motor without designing another bracket which will mount up. The mounting ears are MISSING from these throttle bodies. BUT , these should work great if you remove the idle motor and plug it like iwilson did . This is why I haven't posted about them yet.

Although you can block it just as easily without shelling out 225 pounds for a new throttle body! I'd like to get my hands on a 'cheap' throttle body so I could modify it with the intention of putting the IAC back on but without the shared air supply.

TonyA · Apr 16, 2021

iwilson said:
Although you can block it just as easily without shelling out 225 pounds for a new throttle body! I'd like to get my hands on a 'cheap' throttle body so I could modify it with the intention of putting the IAC back on but without the shared air supply.

I did bid it down from 225 , but it wasn't a giveaway for sure. I want to try the throttle body boring service eventually and I don't want to mess up my originals. I may even get a Power Commander to add on simply because the tuning centers work with these. Once a good map is developed and I get some numbers we can really see just how good or bad the 961 air box is. I think I already know my answer ! I am contemplating asking SCS Delta to do this (inlet upgrade) to their 961 and develop their own ( 961 race cans high flow intake ) . But I doubt they will comply and until I can find a dyno center that will work with the SXTune Delta 400 its power commander time. The piggy back system the PCV uses will allow me to switch between Delta 400 base map and PCV enhanced with a switch.

BritTwit · Apr 16, 2021

TonyA said:
I want to try the throttle body boring service eventually and I don't want to mess up my originals. I may even get a Power Commander to add on simply because the tuning centers work with these. Once a good map is developed and I get some numbers we can really see just how good or bad the 961 air box is.

Tony,
If you find a dyno shop that tunes drag race m/c they will know how to use SXTune software.
Anyway, anxiously awaiting your results!

Vernon240 · Apr 16, 2021

I wonder if SCS here can map a bike..maybe I could go and see them...and then exchange the revised map for fame, fortune and beer. Mostly beer.

TonyA · Apr 16, 2021

Vernon240 said:
I wonder if SCS here can map a bike..maybe I could go and see them...and then exchange the revised map for fame, fortune and beer. Mostly beer.

That would be a grand idea ! If you brought your bike to them already fitted out with the K&N's ? YES , that's just the ticket ! Then this map you and they develop could be used by others with the same set up ? Is that what you're thinking ? We wouldn't need the power commander ! If this is agreeable to you of course . I would be willing to help pay the costs for this .

Vernon240 · Apr 16, 2021

TonyA said:
That would be a grand idea ! If you brought your bike to them already fitted out with the K&N's ? YES , that's just the ticket ! Then this map you and they develop could be used by others with the same set up ? Is that what you're thinking ? We wouldn't need the power commander ! If this is agreeable to you of course . I would be willing to help pay the costs for this .

I need to get my bike running first. I'll see if they have a bike dyno...I would assume they have..or have access to one, to develop the maps in the first place. Could be an idea, huh?

TonyA · Apr 16, 2021

Vernon240 said:
I need to get my bike running first. I'll see if they have a bike dyno...I would assume they have..or have access to one, to develop the maps in the first place. Could be an idea, huh?

Clive · Apr 19, 2021

Got new injectors (on left) and oooooh spot the big difference;

So a quick trip to Mr Ebay;

All fitted with existing airbox and the bum dyno feels like its pulling really well from 3000rpm but could be fake news....

So make a start on the new inlet bits;

Build delayed sorting out rust on swingarm;

Vernon240 · Apr 19, 2021

Looking cool!

Inlet upgrade?

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