Bored Room
I suspected the ignition on my 900SL but issue was those kehin flatslides and lack of choke.
With rejetted stock carbs back runs nice ( does however need new float valves, which two months later I haven't bothered to do)
Currently funds diverted to the more usable R90s
I was going to bin the ignition and fit one of these
http://www.fastbikegear.co.nz/index....&cPath=706_787
DeMyer's Laws - an argument that consists primarily of rambling quotes isn't worth bothering with.
Learning
Yeah, I'd got curious and did a spot of reading about them. They do sound pretty sweet - check this youtube of the Fastbikegear Frankencati wringing its nuts off:Originally Posted by Voltaire
https://www.youtube.com/watch?v=l6u5wi9Mvjo
Of course that's a very highly modded bike, I expect that the muffler has a lot to do with the sound.
The downsides so far seem to be:
- price
- sensitive to EMI emissions from the coils so relocation of CDI to tail might be needed and / or shielding on all electrical lines
- won't work well with CA Cycleworks coils
- can have problems with corrupted firmware (OK, once in a blue moon, but it's happened)
- doesn't like the battery getting a bit flat
Full credit to Liam, he's completely open about these issues and welcomes discussion of them.
In terms of reliability of the OEM Kokusans, they actually did let me down once, in the worst rain I've ever ridden in. Bakeout (at 50 C, fan bake oven) and silicone seal grease got them going again.
For now, I'll keep going with the Kokusans, since going to Ignitech is going to cost $$... need coils, Hall sensors, TPS as well as the programmable CDI.
Bored Room
Yes it does seem to add up.
I've run one on my track R100 BMW for a few years total loss with a non hall sensor with no issues. Must be a Ducati thang...
DeMyer's Laws - an argument that consists primarily of rambling quotes isn't worth bothering with.
Learning
Could raise a few bob for the Igni gear by selling the old CDI's on TM, especially if they're still going just fine... cost at the dealer's for these dinky little black boxes is crazy numbers. Even ex Stein Dinse they're $250 or so each landed.
Learning
Getting back into it after the recent midwinter ride to Castlepoint and back... the engine started running rough on the return into Masterton. It kept running rough the whole way home. A quick check on the plugs showed both with carbon deposits, the vertical plug worse than the horizontal. I swapped the plugs out and the issue disappeared.
Carbon fouling would happen if:
Weak ignition system and therefore weak spark;
Plugs were a grade too hot and therefore never got hot enough to self-clean;
Liquid fuel was being drawn into the engine and burning onto everything.
It's been a few years, I've tried a few things, and I'm inclined to think that the bike has a design issue with the placement of the carburettors and the length of the inlet manifolds. Thinking is one thing, though. Knowing is another. So I had a think about how to measure what's going on, got the thermal imager out again, and this time I marked surfaces with bits of masking tape so that the imager had a decent target.
A quick note about thermal imagers or radiation thermometers: they don't like shiny metal as a target. Oxidised is fine, so is painted, but any bare metal is basically a mirror to a long-wavelength IR device even if it's dull grey in the visible. A single layer of masking tape applied though and that's it, problem sorted. The tape is thin enough to match the temperature underneath it, but IR-absorbent / emittent enough to make a clean target.
So I got the tape out in a few places on the carburettor flank and along the lengths of both inlet manifolds. I warmed the bike up at idle and then started playing with the throttle while checking temperatures. The images nicely show a gradient along the left-side inlet manifold, about the clearest data from this night's work. It was getting late by this stage so I halted proper testing, but I did find something worth checking further: the inlet manifold temperature will drop with the throttle being opened, but recover with the throttle closing. It makes sense. More throttle means more air, more fuel, and thus more evaporation, pulling heat from whatever surroundings it can. The only heat source for the inlet manifolds is conduction from the cylinder heads. What was instructive was seeing the indicated temperature ticking down on the imager. It went from about 35 C with idle throttle (at the boot insulator end) to approximately 13 C with 1/8th throttle and revs at around 4000. This took a few seconds to happen after the throttle opened. Ambient was around 12 C.
These numbers are anything but solid. The engine wasn't properly warmed up, I didn't properly check throttle position or RPM, air temperature was guessed at being equal to the imager reading off the garage floor, and any change in ambient air temperature would affect these results anyway.
What does matter is the pattern of the behaviour. The drop in inlet manifold temperatures corresponds with a behaviour I'm monitoring on the AFR gauge during sustained runs at 100 kph. Initially the mixture is perfect, then the ratio increases, indicating lean conditions. It takes a few seconds to start moving and then stabilises to a value which seems to be set by ambient temperature. I think that what's happening is fuel dropping out of vapour – or never vaporising in the first place – immediately in the throats of the carburettors and over the walls of the inlet manifolds. There simply isn't enough heat getting into these to ensure proper running of the engine.
Learning
And now for the fix... a while ago Kickaha had suggested shifting the oil cooler upwards, putting the carburettor bowls into its slipstream. I'll leave that possibility open, but for now I'll try something harder, namely applying controlled heat to the carburettors and the inlet manifolds.
It has to be controlled heat. It has to cope with changes in:
ambient air temperature
fuel temperature, as delivered from the tank
engine temperature
throttle position
slipstream velocity
The thermal load will vary enormously. I'm not yet sure if setpoints can be fixed, or need to be tweaked to match changes in ambient – I need the carburettors hot enough to vaporise the fuel properly and without icing, plus the inlet manifolds hot enough to prevent vapour condensing out. The two setpoints will be different. It's already clear that the manifolds will have to run hotter than the carburettors.
Adding to the fun and games... the system can't load the electrical system of the bike too much, there aren't too many more watts spare after the AFR gauge. Whatever I build has to work despite dirt, vibration, oil, heat, condensation or rain, gravel, tar, and bugs. It would ideally be simple enough to fix or patch up while on tour, and if it fails, it shouldn't take the rest of the bike down with it. The setpoints should be precise and adjustable, too – chances are that I'll need to spend a while tuning these. I'll also need the temperature indicators visible so that I can see what's happening while I'm riding.
So, how to do this. I spent quite some time thinking about the problem and trawling the web. The short answer there is that nobody appears to have done what I want to do, or at least nobody's bothered going public with it. There are passive, semi-controlled solutions:
heating the inlet manifolds by engine coolant
heating the inlet manifolds by heat stove over exhaust manifold and using a heat riser
using electrical heaters in the carburettor bowls
directly running exhaust over the inlet manifolds
running fuel lines past exhaust manifolds
The heat stove option offers thermal control by either wax pellet motor or bimetallic spring. These turn a butterfly valve on the heat riser, the whole thing transfers energy by rising hot air, and that's about as sophisticated as any control gets. Most of these solutions are from the car world and are designed to work under a bonnet.
Cutting a (very) long story short, I've decided to use heat stoves on both exhaust header pipes, electrically controlled fans to draw air despite slipstream, and heat jackets placed over carburettors and inlet manifolds. The system will work via on/off hot air. Temperature control will be via the fans and some of the thermostat boards used earlier, with sensors placed on the carburettor bowls and the inlet manifolds.
I spent way too long trying to think out every feature before I realised that it isn't possible to design this in advance. This is going to be one of those jobs where it's learned as I go. I'll have to build, test, modify, or possibly build again. I went out and bought some stainless steel dairy tube and elbows, and have started hacking up some rough first-try heat stoves and jackets.
Learning
A couple of quick notes about the dairy-grade 304 welded seam tubing that I'm using for the heat stoves.
It's extensively cold-worked. When the tube is made, it's rolled up from sheet metal and then seam welded. The elbows are then swaged straight out of bits of that tubing. The process leaves the material bright, but rather hard from cold working... I took the points off a few drills before I realised what was happening and that the material needed to be annealed before being drilled.
The LPG torch did work, but wasn't quite hot enough used as pictured - next time I'd like a hearth of firebricks to surround the work and keep some of the heat in. It'll help to raise the temperature a bit. What I'd found courtesy of the web was that annealing temperature for 304 is supposed to be 1010 to 1090 C, followed by rapid air cool to room temperature. There's no way this is getting to that peak temperature. By eye, I make it 900 to 950, which is the zone where stress embrittlement can become a problem. It did shift the material from not drillable to workable, though... The other thing was that there were a lot of problems with material springing closed on the blade while being hacksawed. I had to take the half-elbow cut in stages and work my way around, resorting to a Dremel for the inside curve.
Most commercial (automotive) heat stoves are stamped out of one piece of plate, after doing this work I can see why.
Bogeyman
Aye, some stainless is hideously poorly treated ex factory, literally unworkable. But those bends, (Ultibend?) aren't bad, it's far more likely you've work hardened it with the initial drill friction.
The trick is, firstly to use decent quality drills, 'cause most of the sets you buy at Mitre10 et al are shit. Secondly halve the rpm you'd use on mild steel, (and if in doubt halve that again) and double the pressure. Use a cutting agent like Rocol RTD.
But yes, there's a bunch of stress built into any cold worked stainless, and you have to be bloody careful cutting stainless tubing with a grinder in particular.
Go soothingly on the grease mud, as there lurks the skid demon
Forum whore
Wouldn't it be easier (and probably cheaper) to build the prototypes using plain old exhaust tube ('muffler moly") and then go for the nice stainless once the design has been worked out? (or what I would probably do, design the prototype in exhaust tubing, shoot it with some flat black rattle can and call it done)
it's not a bad thing till you throw a KLR into the mix.
those cheap ass bitches can do anything with ductape.
(PostalDave on ADVrider)
Learning
Yep, gotta go shopping. Sutton / P&N / Evacut ? I'd been using Bosch drills (yes, off M10) since they'll sell single sizes OTC on a Sunday, but you're right, it's time to order in a decent set of drills.
Slowing down and pressuring up is going to require purchasing a drill press. I'd been putting it off for a bit but thinking about it now, a pedestal drill press would actually go in to the garage and avoid taking up space on the bench.
Cutting tubing with a grinder: agree, death on wheels, literally. The tubes that I was cutting were springing open (no problem) or pinching shut (big problem), it's why I was using a hacksaw rather than powertools. I can see a lot of exploding cut off wheels from that sort of thing.
Learning
Weelll... at the moment the only source I've found for stainless muffler pipe is Redline Performance and they wanted $99 plus delivery for a 1 meter length of 2.5" diameter. It was $99 for a single elbow too. It was much cheaper to go to Steel and Tube and buy 304 ss OTC for full cash. That said if you know where I can get 2" / 2.5" stainless tube / bends etc for reasonable coin then I am all ears
I hear ya on calling the prototype the finished item!!
Learning
A wee bit more work tonight - I'd wanted to be able to mount / dismount the heat stoves without any need to take the bike's exhaust system apart. The plan was to split the heatstove down the centerline, use stainless steel hose clamps to assemble as well as hold heat wrap tape on, but the halves need to be spaced and centered on the exhaust pipe. I've decided to use cap screw heads as the spacers / locators. M4 cap heads had about the right height for the job.
So tonight's effort has been to cut some M4 cap screws down a bit, put them into place, and rivet them in by crushing the threads in the vice. I'll probably weld them in properly later, for now they look a bit medieval.
Bogeyman
Yes, I keep an eye out for sales on any of those brands.
There's times you can't use a drill press. A good speed control helps, so does a short series drill, (or a rivet drill, double-ended). And getting the cutting edge shape right, in this case just minimum trailing edge clearance.
I cut stainless tube with a 5" grinder regularly, you just need to be aware of the potential issues. The big divots up my RH wrist are from putting the grinder down too quickly and not paying attention, broke the disk on the edge of the vice.
If you keep an eye on tardme you often see those early cheap drill-mills that people bought years ago thinking they're some sort of mill, have since repeatedly discovered otherwise and have sat in the corner ever since. They often go for what you might pay for a half decent drill press and have some additional usefulness.
Go soothingly on the grease mud, as there lurks the skid demon
Learning
A spot of progress in bits and pieces over the last few days... no pictures this time sorry.
1) Carburettor jacket.
I spent some time tonight playing with bits of gridded paper and cardboard, trying to mock up a jacket that'd fit around the carburettors in situ while they're in the frame. Not much joy... lots of clutter in the way. Frame, hoses, wiring etc... it just isn't possible to simply drop a jacket in, as my original idea went. There's also no easy or obvious way to mount the thing to the frame.
The other option is to mount the jacket to the carburettors themselves while they're out of the bike, then drop the whole lot into position as a single unit. The issue with that idea had been mounting points. Tonight I finally realised that the carburettors are paired. There are three posts between the two bodies, with three cap screws on each side securing them together. It's possible to replace the cap screws with male-female threaded spacers. This will secure the two bodies as before, while providing threaded sockets for mounting side plates to the carbies. These side plates can then be the basis for mounting the jacket.
Because the jacket will be fitted to the carburettors directly, it can be mounted close and even be a wraparound design, I can duct warm air right around the carburettors instead of leaving the backs open. I think this is the way to go here.
2) Inlet manifold heater fan.
This will have to be run by a 12V dc motor and able to handle air at 100-ish degrees C continuously, possibly up to 200+ intermittently (especially likely on fan start during on-off operation while tootling around town). The inlet manifolds are really going to need this sort of heat, particularly under sustained running.
There aren't (as far as I can tell) any commercially available fans which can handle this requirement. Doesn't have to shift much air, doesn't have to generate much static pressure, just has to be able to cope with a lot of heat. Small, light, compact (don't have much room to fit it), doesn't draw much current either... these requirements don't make it easier.
Currently my best idea is to find an old turbocharger, strip it down to impellor housing and impellor, maybe keep the bearings and shaft, and fit a motor independently. I'll use a heat spacer of some kind if I have to. This idea has taken around a month or more of thinking... I just can't see anything else which has a chance, except maybe using a fan blowing cold air through a venturi and thus drawing superhot air through piping, without the fan itself ever being exposed. The venturi would not be an efficient way to shift air, though.
3) Hot air line filters.
I just realised that I really do need filters of some kind (probably wire mesh) in the hot air lines. I've got to protect those fans against bits of leaves, road grit etc. The heat stoves are both completely open to outside air, it's not a closed system by any means. This shouldn't be a big deal, some kind of inline canister should do the job.
4) Hot air line hoses.
Currently I'm thinking that I'll give radiator hosing a try, for both air lines, mixed with lengths of metal tubing where needed. There are very nice looking bits of braided hosing around, but that's for later. It's easy enough to fit.
5) Carburettor jacket fans.
I've ordered a pair of metal-bodied, long life at elevated temperature, computer fans. They're rated at 100,000 hours at 60 C, which should be more than enough for the job. Weather sealing may be an issue but we'll see if that can be sorted out by jacket design.
6) Heat stove slipstream insulation.
There isn't much point in a heatstove if it loses most of its heat to slipstream. Accordingly I've ordered some of the dreaded header tape. There'll have to be a lot of practical experimentation here in order to find what length of heat stove provides required heat while on the motorway, versus not cooking the exhaust header while rolling slow in traffic with both warming systems not drawing air.
7) Recirculating hot air in order to boost the temperature.
It can be a loop system if needed. It's unlikely that I can get much heat off the exhaust headers in one pass only, but this is one for practical experimentation first.
Anyway, slow progress, lots of metalwork to do over the next few weeks.
Bored Room
Is all this work from the original crack in the frame, leading to modified air box and flat slide carbs?
DeMyer's Laws - an argument that consists primarily of rambling quotes isn't worth bothering with.
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