Project Linkins 3LN6 - The Pink Lady

I was scouring the internet last night, you can get replacement slides for BDST 38 carbs for Ducati and Cagiva models, sadly nothing available for the 28mm that I could find.

Worst case if I need replacement slides I could use earlier 3LN ones with the Zeal 2nd spring and plastic spacers or the Suzuki spacers again

 

The retainers are on the vacuum/air side of the carb so little if any fuel should get there.

It was 2-part metal epoxy like JB-weld type stuff.

I know what it feels like when a needle clip has come off (happened to my 3LN1 carbs using keyster clips on the needles - no good), the needles get jammed in the tube and then pop all the way up at wide open throttle once the slides lift up enough.

 

Coil connectors arrived today (after waiting 2 weeks - remind me to order locally!), straight onto it after work finished.

Just bare wire and zip ties for the build stage until I finalise lengths etc then heatshrink or lecky tape

 

Coils went in without much drama. Clearance is a bit tight around the radiator fan on the inner two, but this is a good thing. I have not yet sorted something to hold the coils in place. On test fit, they were a bit loose. Worried they would pop off, I slid the larger seals down all the way. This means that they just make contact either side of the cam cover acting as support. They are stable but not rigid. Good enough for testing.

Once again I was on a time schedule, so no heatshrink or electrical tape just yet, but wires are routed clear of obstructions. The factory coil connections on the harness side had seen better days, as had the coil mounting bolts etc. Rust and corrosion, so chop chop and make new connections with the stuff at work. Just your standard open barrel pins (spades in this case) with the clear insulators slid over the wires. They have worked for decades and will do just fine for now. Eventually I will re-do all of it with weatherpack connectors and heatshrink.

The good news is they work as expected without any issues, fired straight up. The bad news is that they haven't solved my problem. Which is what I expected. At least now I can move forward with, you guessed it, the carburettors. Again.

That said, I was a bit weary of where the mixture screws where set because my boss did them 'by ear' listening to the engine while adjusting them, wind in until it isn't happy, then wind out until it isn't happy, and set them in the middle. So with the tank and airbox off I got in there and checked them, they were at 4-4.5 turns. Not hugely out like my 3LN1 was at 6+ turns out, but still too much in my book. Now as far as the pilot circuit is concerned it was running alright but I could tell it was rich. Loads of carbon on the exhaust tip. The plugs looked more or less perfect, but still I reset them to 3 turns as a baseline.

It definitely runs better 3 turns than 4-4.5. I filled up on the way home and reset the trip meter so will recheck in 100km and see what fuel consumption is like. The on-off-on-off throttle transition has improved noticeably down low, but still isn't perfect in my problem area, around 5,000-6,000rpm. Incidentally, on an FZR in standard gearing, that is about where you sit in 5th or 6th doing 60km/h, which is most of my riding at the moment.

Makes me think that my problem is definitely the transition area from pilot jet to needle and tube, but not in the usual way of worn out needles/tubes. I'm thinking that the exhaust pipe is very open for the standard setup. On my previous FZR's I had a JRE exhaust pipe on it, and the exit diameter was about half of what the LCI one is.

So my current plan is to do 100km to check how it runs now, check fuel consumption, then refit the baffle I dug out of my toolbox today, refuel & do another 100km to compare to that.

If it still isn't good at that point, I have the keyster kits ready to go. I will replace all the brass in the carbs. The only meaningful changes would be going from #12 to #10 on the pilots, and the needles/tubes. The rest is all the same.

Wish me luck

 

Best I ever got on the old 3LN1 bitsa was about bang on 4L/100KM and that was long stretches of motorway sat at 100km/h in top gear.

Worst was Grasshopper's 3LN3 with totally worn out needles and tubes, 10L for 77KM, after keyster kits back to what my 3LN1 was like.

Throttle balance makes a big difference too, once you get the balance spot on fuel economy improves, especially if they were way out of balance.

Pity it's not as simple as float seat o-rings like the Kawasakis.

 

Well it sounds like my patch on the exhaust I did back in February has failed. I was riding around the city and then heard a strange noise and the exhaust note changed. Then I noticed the distinct sound of an exhaust leak, plus the gassy smell.

I think I will do it properly this time, blast the whole exhaust system and weld up and suspect spots.

 

Got the exhaust off at lunch today because we had some other stuff to take for welding, after finishing up for the day I decided to get the bike on the bench and and knock a few jobs off the list.

First up was cam cover gasket and the rubber plugs in the cam caps. No time to check or do clearances sadly, but they were done a few years ago before it went into storage and has only done a few thousand KM since then, should be good for a while.




Here you can see the new gasket fitted and the still temporary coil arrangement. I threw a new set of CR8EK's in. The standard plug is CR8E, but the EK only denotes the double ground strap, they are supposed to last twice as long before replacement. The electrode sticks out a little further and isn't as shrouded by the ground straps, which I think is good.

I would have stuck Iridiums in, but only had CR9EIX instead of 8. No need to change heat ranges when running well. Next set of plugs I will try the NGK Laser Iridiums in CR8EIA-9. Lots of modern bikes with coil on plug systems use CR9EIA-9. They are an even longer life version of the older EIX plugs apparently.




The old rubber plugs were still in good condition, though some were partially popped out. To my surprise, some of the new ones didn't want to stay in and kept popping out just trying to fit them. This was due to oil pooling in the caps, causing a high air pressure. Sometimes get this with solid dowel pins on engine side covers too. So I used a piece of ziptie wedged alongside them to relieve the pressure while fitting them and had no problems doing that.





Since I had to drain the coolant and remove the radiator, it was time for an oil & filter change too, and not a moment too soon as the level was below the sight glass (oops) and black in colour. New HF303RC racing filter. Delo 400 is long gone now thanks to Caltex branding no longer being a thing, all changed to Ampol Their new range of oils are basically just Mobil1 stuff but there is no direct replacement for the Delo 400 that contains the good anti-wear additives and none of the emissions related shite.

So I stuck the only mineral oil in that we had at work: Motul 3000 10w40. I am generally not a fan of Motul but we will see how it goes. Nothing can replace the Delo 400 though. Of course, when undoing the oil filler cap it promptly split into 2 pieces. I had wondered why I had an oil weep around it. Must have been already fractured. Luckily we have stock of aftermarket bits so a nice billet alloy replacement with 10mm allen head was fitted.

Still got a few things to do:

Adjust steering bearings as they have loosened slightly since installation, normal occurrence, but over choppy surfaces you can feel the movement in them.
Replace the swingarm and linkage bearings, still need to order parts for that job.
Refill coolant and bleed the system

 

I'll get mine welded up again for now, I should have checked it properly in the first place, but I will grab a spare set off you at some point.

Please evict the redbacks first

 

OK, all back together once again and rode it home today.

XV250 needle sets will be here soon, then I am into the carbs once again.

 

Looks like they will work.

 

Fuel consumption update: 6.5L/100KM

Could be better but has improved. Have not done any highway cruising with constant throttle, so usage a little bit higher is expected. My ZXR would do 5-5.5L/100KM commuting and it was in a great state of tune. Still a little bit to go with the FZR to get it right.

I have spent a lot of time thinking about the cause of my main problem, and it finally came to me that it feels and sounds like an air leak. As I have not yet split the carb bank to replace the fuel seals and the t-piece o-rings, I will do that first.

I could change the needles and fit the proper retaining plugs at the same time, but then I won't know what actually fixed the problem. So I will do that after the o-rings. At least the carbs can stay on the bike for that. I will try the 5CT7 and 5CT9 needles in the correct arrangement.