Help I found something weird... 3LN3

chucked the ex valves in the ultrasonic tub, splash of vinegar and a bit of my favourite, sulfamic acid (scalex, bunnings, freaking aweesome for cleaning out radiators!) and the scunge basically fell off. look nice now.

neway sadly doesnt make a cutter to this size... noone makes a cutter to this size!

ummed and ahhed over getting neway inserts and making cutters...
finally went cheap and searched aliexpress.

got a few 30, 45 and 60 (58) cutters on the way, with the intention of turning them down. debraze em if need be, can always regrind and sharpen them. not meant to grind steel with diamond... meh. its a one off!

just like the neway site says... its the BODY of the cutter thats the issue. and that exhaust valve has enough clearance for a 17, or maybe 18. smallest i found was 20...


then the stem is... 3.5. smallest arbor from neway is 3.8.

aliexpress arbor, found a 3.5, but its taper only suits the 30 degree cutter...
so had to order a (pair of) 4mm with the intention of grinding it (one for practise!) down to deal with the rest...

setting up the toolpost grinder on the lathe. along with replumb the coolant. yay. thats been a side project for 10 years out of the way...

so now its twiddling thumbs as i contemplate flycutting, waiting for bits to turn up.

a bunch of carbide burrs cus i wanna clean up the ports a bit while im in here. and clean the combustion chambers up a bit. nothing extreme, just blend out the sharp edges. if this works, extreme comes later!

yes, shaving a head on a chinese mill is a scary prospect. i can just get enough travel for a full pass, but how sure am i that the ways are even flat/square? anyway, got a gymweight sitting here waiting to have a tooth stuck to it...
i dont think my surface plate is big enough to try the sandpaper trick.

when you consider the gains that can be seen on things like 350 chevs etc from doing the valves properly, where the tolerances and errors are only a small percentage, it makes sense that doing a good job on an engine this small is going to make a HUGE difference... efficiency always falls as machines get smaller and inaccuracies get bigger.

once these things arrive and as long as they modify as desired...

reface all valves. vee block, jig on the bench grinder, pretty easy. fiddly.
cut seats to 45, aiming for full contact. aim for consistent depth across the lot of course.
60 to bring contact in 1/2mm or so from outer edge.
30 to bring contact out to 2/3, which is slightly more than oem... every bit of cooling helps.
backgrind valves to blend in and match contact line.

the dreaded re-assemble and re-shim...

pop these chinesium pistons out and see how theyve held up. new set was only 10 more than a set of rings alone.

sigh. anyone looked in their carb throats yet?

 

Spotless now...

Carbon seats? Can see where theyve been riding...


17mm bar. No more room capn!

Taking the "hump" off is meant to be of some benefit... can see why at this angle...


Lol.
Low
Ry
Der...

 

very interesting... i see the edges of the carbide have been ground back a bit to fit in there but hows the body? ... second look... oh yeah. mc19. thats why it looks... odd.

neway did have lil 5/16 8mm teeth listed, mention "honda power equipment" that leads to nowhere...

iunno. i want all three angles. call me fussy?

whilst 3 teeth from neway would probably do it, the mounting screws and space just means its easier to order a set for each cutter, braze them in, and you need five minimum. can probably get away with one 30 degree cutter... 15 teeth? was about US200 all up... naw.

take the cheaper route for now and see if it ends up costing more! about 70 so far...

apparently theyve "cleared customs"...

 

Well, they aint neways, but theyll do.
Plenty of teeth to play with now!
Couldnt help myself, had to try the 45... seeing as its the only one that will work as is...

Chinese arbor... 3.38. Not exactly 3.5...
So i gotta grind the 4mm down, regardless. Or 3.96, i should say. Lol. A bit less to remove.
They cut. All i wanted to know. Surprisingly well actually. Not touching them again until i get the arbor sorted.
Sigh. So much to do for what takes five minutes once tooled...
Debraze. so i gotta go buy gas...
Set up the mill to cut them seats closer in to the center.
rebraze, regrind...
Seriously?

One thing i noticed about neway is they stagger the teeth. Its done on purpose, stops them chattering and making "roleaux triangles"...

Getting closer...

 

Grinding paste...
Knew i had some dust somewhere. Making lil granite surface plates...
Forget how theyre graded but w0.25 is like talcum powder... maybe a bit too fine.

Diamond sounds wrong in an engine...
But it burns. Unlike virtually every other abrasive.

 

update time i guess.

done sweet eff all but let rust grow

except. an experiment has been performed upon a 3ln1 suffering the dreaded chugs... not mine.

if its the valves and carbon clogging seats... what if we set the clearances so damn sloppy that the valve has no choice but to hammer it away, ensure its at least seating better?

enter sloppy clearances. aimed about 25 inlet, and 40 exhaust. 10 over max spec...

so. seemed good at first.

a nightmare peak hour ride at dusk through epping, as the clutch decided to start doing stupid crap, whjilst fighting the dreaded chugs whilst splitting and stopping at every freaking traffic light...
ive had clutches that dont disengage... snapped cables... but to have a clutch go from grab grab to nothing at all? i cant blame the owner (ha ha!) for bad adjustment as theres no way it can do that.. i suspect it dropped the linings off a plate... havent looked yet... only got home as i could pull the lock nut off the adjustor on the lever and was just enough grip to baby it...

so it seemed better at first, then got worse.

then got better. to the point that its absolutely perfect... gunna have to redo the clearances a bit. the last two rides have been flawless, or at least, it did it once but we have also worked out that just cranking no throttle until it starts seems to do the trick...

everything still suggests the valves, and only the valves, is the issue. everything else regards carbs or floats or filters is all just chasing wild geese.

a very interesting experiement was to unplug the EXUP servo when its wide open.
i didnt believe people when they said it needs it... the 2kr doesnt, and its fine...

MY GOD!!!! is this the only engine in the world that REQUIRES a certain amount of backpressure? it is the doggiest boggiest heap of junk i have ever tried riding... until it hits about 10k. then WEEEE!

what did those loony engineers do?

its the valves.

they pushed cams to the limit, carbs to the limit, and then had to compensate with exhaust pressure to make it... workable. as soon as ONE element in that chain of carefully balanced chaos isnt quite right? the whole lot collapses and we are left chasing carbs as EVERYTHING IT DOES feels carb related...

its not carbs. its valves. insufficient vacuum or contaminated air fuel or just some weird back looping in the exhaust... but it aint carbs.

one experiment not done is to swap carbs from a "full working" to a "chugger" and vice versa... i suspect the chugger wont care which carbs it has, nor will the runner. as it is not the carbs at fault.

or, the carbs are at fault, because theyre bigger than what the 2kr runs, and they made it require a freaking EXUP to fill in the blanks...

so, on my lil project...

finally got the toolpost grinder working. sideproject #3,412... waiting on proper belt n pulleys. guards? pfft! (naw... its getting one. i may be crazy but i aint stupid. or vice versa? wait... are those 3d printed drive washers? on a freaking grinder? lol.)

and mounted the flypress... unrelated side project #26,005.2. freakin beast, bend a bit of 1 inch bar no sweat. this is related to further projects involving pistons... ie, cast em into a mold, wait til theyre soft n pliable, smack em with the press, semi-forged pistons.

and the english wheel... shrinker stretchers next...
ive been... scraping my cnc mill, rebuilding a pc, rebuilding concrete saws, log splitters, erecting walls... all the fun stuff that doesnt get arbors ground...


right. distractions aside... nearly in the position i can actually make a freakin arbor... without screaming. this was a ten minute job when i used to have access to a proper toolgrinder.

the chinese arbors... they seem to sell two tapers, 8-9 and 10-11 iirc? the 3.5 was the small taper, and the 4 was available in both. theres a lot of sellers, and aliexpress has the worst search of any site?
the cutters just drive on, i remember seeing someone asking "why the useless nut in kit?"... um. you put it on the arbor so you can get the cutter OFF! cus that taper will lock up.

the 4mm arbor, (3.89ish) i cant reuse, the choice of center drill leaves no meat to support or grind... meh, its only a bit of steel turned down. and considering everything, its best to use the same arbor when sharpening cutters, keep the concentricity. use a tiny 1mm centre drill rather than a 3...

the cutters themselves are sintered crap. i wouldnt trust them anyway, so im sticking to the plan of simply making my own. the teeth are the bit i needed.

 

been a while. sidetracking!
no idea what happened with the clutch... hasnt been an issue since... couple of tanks through it now.. we popped the cover, nothing suss. shrugged. whatever, got new plates on the way?

the chugging... the odd moment here and there, but basically cured. probably getting time to check those clearances again... it idles, it starts, it just occasionally chugs out if idled for a few minutes, and it starts straight back up with no throttle and a few seconds of winding. this is acceptable, if it dies at lights its no real stress. it hasnt? and considering we didnt pull the head or actually do anything besides be...erm...brutal? im pretty damn pleased with the result! dont think its even had carb cleaner or any of that BS...

once again, the whole carb/fuel thing is a wild goose chase in my opinion...

so. mine... in between finding another one (3ln1, thats four fizzers now!) and yeah... life. the shed, the garden, and other things took priority. i got my rego papers the other day. its been a year? omfg...

so, my toolpost grinder was a stuff up. couldnt live with it, rebuilt it with precision angular contacts and an er16 collet... far better.



arbors ground, more of a "lets just have a go", randomly hit the dimension spot on... didnt harden it. hell, i didnt even use a center! i was looking at my tailstock and came to the conclusion its about 1.5mm too high and could i REALLY be stuffed sidetracking AGAIN? so gave it a go and im glad i stopped to measure it when i did...

for now i dont think i have to harden. pretty easy to remake anyway... just that final dimension is a matter of luck rather than skill... lathes arent really suited for this... and im not about to do a centerless grinder.

today spent on the mill, note the broken flute on a 2mm. sigh.

got my lil cutter bodies ready to go,




gotta go get some carbide tomorrow and braze them up. then sharpen. aw hell!

60@16,
45@18 and 20
60@18 and 20.

and then its a matter of a few minutes to cut seats, dammit...




pulled the dremel out, looked at my burrs... shrugged... roughed out one combustion chamber.
oh yeah, my cameras stuffed, gotta use 0.5, wont focus on the normal lens. and its all gunked up still
looks better in person, though its only roughskies yet... only the lightest of nibbles.



no plan to port mad but yeah, clean up the edges, smooth the flow a bit. casting flash an stuff.

 

wohfuh? naw, i silver solder carbide... 650C, hard pressed to get that hot! dont press so hard! reminding me i better get a wheel or three, all i got is SiC.

just hope the internal taper dont distort too bad as i meant to grind a reamer up from a broken endmill whilst the compound was set... oops.

no fancy neway cutters. just go my old work, carbide tooling. grab some 2x3mm strips, solder them in and grind back to angle. 58 apparently rather than 60 on the last one. pretty well much copy the chinese ones i got but skinner carbide and only 3 flute. really im meant to use the index head and go for 5 at uneven (not 72) spacing... but that just makes setting the lathe up with the grinder, arbor, and hitting the right clearance a complete *****... a tool grinder would be real handy... one of the reasons the old work is the OLD work... lol. long story.

and i still gotta dress the valves themselves! that... should be easy.