1984 Katana 7/11

[Guest]

Interesting comment on the instructions there Dave... I've read similar, but it seems they're just the standard warranty/liability coverage type things which don't translate to the real world so much. You're spot on in the real world... I've never heard of any vehicle with a separate switch to turn a sensor on/off although I guess it could be controlled via the ECU or whatever. Either way for me also this is only temporary to get the fueling close, then it will go back to my mate. I've postponed getting my own as I need to get the head rebuild done sooner rather than later.

Are you using a wideband O2 sensor along with this AFR gauge?

Yeah, same as Dave the AFR gauge works with a Bosch LSU 4.9.

 

[steve murdoch]

Cheers mate! I still grin every time I ride it

Apparently I now have an incurable disease... I'd like to get a 750 Kat to replace the 450 as my commuter...

Let's not get greedy there, Pete. haha.

 

[Guest]

Why not? hahahaha

'Tis nothing but a pipe dream at present, there's that annoying little thing called money getting in the way

Forgot to get a photo of the repaired and painted horn bracket but it's back on, and the VM33's are all set to go as well.

Hit the go button very briefly last night and she fired although I needed both choke and throttle to get that happening, either I haven't got the idle wound up enough or the pilots/air screws are possibly too lean. Time to get tuning...

Untitled by starpoint73, on Flickr

 

[Guest]

Why not? hahahaha

'Tis nothing but a pipe dream at present, there's that annoying little thing called money getting in the way

Quite annoying isn't it?

 

[Guest]

Sure is! Only need two things for this stuff... time and money... for some reason they're very rarely available together

I hit the go button again yesterday and no way are those 17.5 pilots big enough, just refuses to start even on choke unless throttle is added, so I've gone up to the 22.5 pilots.

Before getting the slides modified, the 22.5's were too rich no matter what I did, and if I recall correctly the AFR was showing numbers in the 11's and 12's which is why I went back to the 17.5's, and had to have the air screws at half a turn from memory. I don't have 20 pilots at the moment.

With the air screws out another quarter turn to one turn out and the 22.5's, the AFR is now showing mid 13's. Admittedly that isn't with the motor warmed up properly yet as it was only a couple of minutes idling, but definitely a noticeable difference in behaviour with the slides modified.

Will get it out this morning and see how it really is, can't wait!

 

[Rob S.]

... I'd like to get a 750 Kat to replace the 450 as my commuter...

But you had a 750 Kat, didn't you? And you put an 1100 motor in it, right?
So now you want to get another 750 Kat, and what motor will you put in it? 1200 Bandit? Hayabusa?
I must sound like your wife.

 

[Guest]

Sure is! Only need two things for this stuff... time and money... for some reason they're very rarely available together

I hit the go button again yesterday and no way are those 17.5 pilots big enough, just refuses to start even on choke unless throttle is added, so I've gone up to the 22.5 pilots.

Before getting the slides modified, the 22.5's were too rich no matter what I did, and if I recall correctly the AFR was showing numbers in the 11's and 12's which is why I went back to the 17.5's, and had to have the air screws at half a turn from memory. I don't have 20 pilots at the moment.

With the air screws out another quarter turn to one turn out and the 22.5's, the AFR is now showing mid 13's. Admittedly that isn't with the motor warmed up properly yet as it was only a couple of minutes idling, but definitely a noticeable difference in behaviour with the slides modified.

Will get it out this morning and see how it really is, can't wait!

What's been your experience with using the AFR gauge to help get your carbs tuned? Has it made it easier and what AFR range does your bike like best?

Also, what circuit did you tap into to power the O2 sensor as to avoid popping fuses?

 

[Guest]

But you had a 750 Kat, didn't you? And you put an 1100 motor in it, right?
So now you want to get another 750 Kat, and what motor will you put in it? 1200 Bandit? Hayabusa?
I must sound like your wife.

Hahahaha yes well... technically I had a 750 frame not a complete Kat

I was thinking just a 750 would be good, but, well, you just never know right?

The 1100's a bit wasted on the commute though...

What's been your experience with using the AFR gauge to help get your carbs tuned? Has it made it easier and what AFR range does your bike like best?

Also, what circuit did you tap into to power the O2 sensor as to avoid popping fuses?

I'd be lost without the use of a wideband sensor and O2 gauge! I discovered with the 450 that I haven't a clue about diagnosing symptoms by feel/sound, and I'm useless when it comes to accurately reading spark plugs while doing plug chops. Having a number on a gauge in front of my eyes takes all the guesswork away, and it makes it a world easier.

The "idea" for gasoline engines is 14.7:1 AFR, but in real world (street) riding and with the compromises that carbs give, as long as I'm somewhere between mid 12's and mid 13's I'm happy. Running leaner means hotter, and where I live it gets a bit warm and the last thing I want is to be running a bit lean, get stuck in traffic, and start having cooling issues!

As for the circuit, my harness is completely hand built from scratch, and I added a 5 amp accessory circuit which is what I'm using to run the sensor and gauge.



As for the test riding yesterday... Wow I've missed those carbs, I feel like I've unleashed the beast now!

I ended up doing about 170kms of test riding yesterday after remembering how much fun it is to open the throttle with the VM33's... I really like that arm stretching feeling!

Generally they seem to be set reasonably ok, idle is mid 13's, 1/8 throttle or thereabouts at cruising speed is between mid 12's to low 13's depending on the RPM's, and 1/4 to 1/2 throttle is in the low to mid 13's, so I'm pretty happy with that.

Once the throttle gets towards 3/4 and beyond though they're still way too rich, quickly getting to 11's then 10's, so I need smaller mains yet. The big question is how much smaller? I'm going to need to buy them so anyone got tips on a way to guestimate how far down to go?

As for the lag that was there, well that was bad initially until I realised I hadn't adjusted the throttle cable properly (fixed), but there is still a little there, but only when the RPM's are up a bit, and given the few curvy bits I tried I don't think it will be confidence killing any more. I did bump the idle up a bit as well which has helped again.

Current setup now:

Pilots - 22.5
Air screw - 1 turn out
Needle - 3 (middle notch)
Mains - 115

 

[Guest]

Generally they seem to be set reasonably ok, idle is mid 13's, 1/8 throttle or thereabouts at cruising speed is between mid 12's to low 13's depending on the RPM's, and 1/4 to 1/2 throttle is in the low to mid 13's, so I'm pretty happy with that.

Current setup now:

Pilots - 22.5
Air screw - 1 turn out
Needle - 3 (middle notch)
Mains - 115

Good information for sure, thanks for sharing! I recently purchased an AEM wideband sensor/gauge (might be the same kit as yours?) and am excited to try it out. Having a wideband on my GSXR made tuning so much easier - that bike is smoothest and makes the most power in the 13.0-13.1 range. Curious to see if that AFR holds true on the GS as well...

 

[Guest]

Could be, this one's an AEM also (it's my mates, I have yet to procure my own). It's a panel mount gauge which is why I had to make the enclosure for it.

13.0 - 13.1 is awesome, would love to get the VM33's like that across the board, will require a bit more time yet to get closer to that. While I'm no expert on this, my understanding is you should find that pretty much regardless of the bike for real world riding. If you're looking for pure economy, up towards 14 will be better, all out power I believe something like mid 12's is better? My preference is always to err on the rich side and run the motor a bit cooler.

 

[Guest]

I've ridden it to work both Tuesday and yesterday and the idle is a bit too lean for my liking as it gets to low 14's, so I wound the air screws in a quarter turn last night. Only thing there is if it richens the 1/8 throttle cruise up too much I'll likely need to put some bigger pilots in which from what I've read is not unusual for these carbs. See how it goes today.

 

[Grimly]

Got mine installed in a temporary fashion today. Just a quick and dirty lash-up that can be removed in two minutes.
I'll make a better enclosure for it; as the one I made, while it does the job just looks totally trashy.

It's not showing mega-lean, that's just it running through its setup routine. Earlier on I warmed the bike up and got some figures from it at least while sitting in the workshop unloaded. It's sitting at 13.1 at any steady rev state up to 3K. Interesting to see the SU enrichment process working when I open the throttle.

 

[Guest]

Got mine installed in a temporary fashion today. Just a quick and dirty lash-up that can be removed in two minutes.
I'll make a better enclosure for it; as the one I made, while it does the job just looks totally trashy.

It's not showing mega-lean, that's just it running through its setup routine. Earlier on I warmed the bike up and got some figures from it at least while sitting in the workshop unloaded. It's sitting at 13.1 at any steady rev state up to 3K. Interesting to see the SU enrichment process working when I open the throttle.

Which AFR gauge is that with the blue numbers?

 

[Grimly]

Which AFR gauge is that with the blue numbers?

14point7.com
It's the Spartan 2 with the 52mm gauge (extra).

 

[Guest]

Good stuff Dave, how big is the Spartan unit itself? The 14.7 SLC Free is still on my list but that'll now be next year ready for when I rebuild the head.

The quarter turn on the air screws seems to have sorted the idle out nicely without screwing up the 1/8 throttle cruise. It sits nicely at low 13's now with 1/8 still at that mid 12's to low 13's, at least on the commute anyway.

 

[Grimly]

The controller is barely a bump on the wire, actually narrower than the connector it's attached to.
Caused me a moment of acute anxiety when the damn thing wouldn't disconnect from the sensor lead, and I was worried about damaging the body of the controller.
Moving on... today's results were mixed.
I quickly sussed the default settings I'd been running with were far too rich, but that was good, better than too lean.
After a warm up of around ten miles I jacked the jet up by a turn on the screw and got an idle reading of about 13. Taking off down the highway, it was immediately obvious the bike was breathing better and mid-range responsiveness was improved.
Things aren't right yet, but this was just a settling-in exercise while I did some shopping.
Steady cruise at 4K is around 13.9 to 14.1, cruise at 5K is 14.5, while 6K is getting leaner at around 14.8. I didn't push it too hard into the top end, as the rear tyre feels a bit squirrelly, so that's for later. There seems to be a tendency to lean out as speed rises, so a different needle will be needed. Otoh, the instant reading of the acceleration mix was an immediate drop to 12-ish, which is good.
All in all, I'm quite happy with this purchase, so hope it lasts. I wasn't reading good reports of both AEM and Innovate gauges crapping out, which is why I bought this one.

 

[Guest]

Good stuff Dave, sounds like success is on the way! I'm still keen on giving the SLC Free a go when I get to that point, but it'll be interesting looking at the pure lambda number as opposed to the stoichometric ratio, not sure if I'll choose to use a gauge or just stick with the standard display yet.

These things may be obvious but were things I've discovered along the way... CV carbs are best tuned by steady RPM's as opposed to throttle position which is different to what I'd kept reading, but of course makes good sense when you think of how they work. When tuning the stock loaner carbs I took note of the idle mixture, ~2500 to 3000RPM cruise, ~5000RPM cruise, and then WOT.

With the VM33's though, everything has been done on throttle position... idle, 1/8 cruise, 1/4, 1/2, 3/4, and WOT. The hardest readings to ascertain have been 3/4 and WOT, and the reason for that is purely due to the numbers in red circles posted on our roads here It's really hard to hold 3/4 and WOT throttle long enough to get a good consistent AFR reading and stay in those legal speeds. In fact 1/2 throttle was hard enough in that regard...

In both cases, what I found the most challenging was resisting the temptation to take note of instantaneous number changes on the gauge. You always need to hold steady RPM's or throttle position for probably 10 seconds or preferably more to really get a good accurate assessment. It sounds like a short time, but 10 seconds at WOT on an 1100cc bike is a challenge when trying to obey road rules! My experience says both the VM33's and CV's will lean out noticeably when first changing throttle positions (the VM33's quite dramatically) but the AFR will quickly change once the throttle is steady again. I hope that makes some sense!

Going by your numbers there, definitely seems like something needs richening in the needle department. Over here, our needles from the factory have 5 E clip positions, meaning we can raise the needle very easily by moving the E clip down one notch. Do you have that option or do you only have one notch? If you have one notch, it's possible to insert a shim above the E clip to have the same net effect of richening the needle up. Not sure if I'm telling you something you already know there though.

 

[Grimly]

This is on the SU, so no fiddling with clips and notches involved.
Instead, there's a world of pain awaits if you go heading in the wrong direction and change the wrong things.
There's the obvious, like the needle profile, then there's the dashpot spring which determines just how much of a venturi you get for a given throttle opening - there's a choice of three or four, although the vast majority of applications usually need one of two. Of course, the venturi opening given by the spring lands you in a different pattern of fuelling on the needle... and so it goes on.
It's entirely possible to think you've got it, but you've gone down a wrong turning and should have done something else. It will work, but not quite right.

At least, that was the case when I was playing it by ear and doing the odd plug chop. It worked ok, and I never did any damage, but I always knew it could be better. Much nicer to see some figures dancing around, showing me exactly what's going on.

I'm going to sort out this 38mm carb for once and for all, then look at putting the 44mm back on, and with the aid of the AFR gauge be able to tame its rough idle and slow-ish mid-range response. The big carb delivers enough fuel for the factory's 80hp, just getting it to do it neatly and cleanly is the challenge.

 

[Guest]

Ah ok, I have zero experience or knowledge of SU carbs. I've heard of them but that's as far as that goes... sounds complicated!

A mate handed me a set of 107.5 main jets on our ride yesterday so I'm hoping to get out for some 3/4 and WOT tests today and see where they put the numbers. Gut instinct tells me it's going to be on the lean side as that's three sizes down from the 115's, but it'll give me a good reference to make a better decision on which size to buy.

 

[Guest]

Test ride observations from this morning's ride with the only change being the mains dropped from 115 to 107.5...


Steady quarter throttle has become a bit leaner, seeing up to low 14's now, 1/2 throttle still good, steady 3/4 and WOT are in the low 12's now.


That would say I could possibly go down another size, not sure why steady 1/4 has changed though.


The standard VM33 issue of cracking the throttle and watching the fueling go lean is now beyond just noticeable, the gauge max's out and the engine basically stalls until the throttle closes a bit.


Given 99% of the time that I use 3/4 throttle and up is for short bursts of acceleration only, I'm going to do what I think is the sensible thing and go up to 110 mains. Steady 3/4 and WOT will be a bit rich but I'm fine with that, will still be much improved over the way too rich condition it has now.