You've got some time available, what about going though and checking what clearances you need with the 158 - 160 shims, I think that may be insufficient to get a read on a few valves - then machine down one or two of the 160's to say a 155 and a 150 to get some measurements on the others with 0 clearance. And now that I've typed all of that, you've obviously got skills and the necessary tools, what about cutting some shims yourself from the back end of a 7.5mm or a 19/64 drill bit, or machine down the O.D. of a piece off of the back of a drill, trimmed down to 7.48mm could be used to go into the chuck jaws to seat the current shims against and hold them square for machining
My attempt at machining down the shims was a fail, the first one I faced worked beautifully, then when I wanted to turn the second one it immediatly blunted my tool, i only have HSS bars from which you grind a lathe tool which seems to be too soft for the shims, except for one which by lucky chance was the first one i put in, i've tried slighty sanding the surface to remove the shiny surface and then facing, that didn't work, grinding a slot through the shims to get the cut started, also didn't work, those things are hard . So think i'll just move on to the cosmetics and order shims after lockdown. Thanks for everyone's input and words of advise, I appreciate it alot, will keep you posted
There is a way out even in lockdown.Back in the day, at the first WSB round in NZ, a local had an OW01 with the soft kit valves. He lost clearance every time he took it out - as those valves were known to do. The pit counters were thick baulks of dressed timber. I watched them place a shim on the bench, then hammer it level with the surface. Then pull out a disc grinder and attack the shim....Then check with a micrometer. After the meeting, they pulled the top off the bench and turned it over - clean wood. I must confess that a couple of times over the years I've done this myself. If you want to make shims - again, I've done this. Use silver steel round bar. It's soft and can be machined and filed/ground to thickness. Once you've got what you need, it's heat to cherry red and drop into some old oil. This hardens them nicely.
AH, that makes sense, they have the darkened colour of a heat treatment and now that I think about it, every time you see valve tips and faces being machined it's with grinding wheels obviously to deal with the hardened tips and stellite faces, so sensible that the shims should be appropriately hardened also Gregt just beat me to it - what about a dremel with a drum sanding attachment and the shim installed into the lathe at a slow rotation - that will ensure that they are even at the circumference, then face them gently on some 400-800 wet and dry on a sheet of glass You could try a thin cutoff disc in a 5" or smaller grinder/polisher with a speed control and the shim spinning in the lathe, don't know if I'd attack one with a 10K RPM grinder and expect any control though Makes the bought ones seem like such good value when you consider the work needed to make them yourself
So I managed to machine down some shims to get clearance, all cylinders have clearance now but I didn’t check the exact clearances, just stuck a 0.15mm gauge under each one to check for clearance, so I got pretty excited when all showed clearance..Then when it got to that moment to see if she will fire....nothing, swopped the coil connectors then I got some pops through the carb and a nice flame out of the exhaust, swopped back the wires and no signs of life, The cams are in the correct position(will double check tommorow) and timing is correct, I got spark(also just checked on cylinder 4)will also trim leads tomorrow..Must the valve clearances be in exact spec?.. but im feeling that I screwed up somewhere, gonna do compression test as well tomorrow, any thoughts or suggestions?
OK, so we've had a few play up recently and not start after having cams out for one reason or another You've already tagged the cams in the incorrect positions, then there was someone else that had just done the valve clearances, replace everything with crank aligned to the incorrect mark on the flywheel - there are multiples marks of the flywheel, I think @Linkin spotted that error - that one wouldn't spin through by hand, it encountered resistance https://www.2fiftycc.com/index.php?threads/fzr250-project.10828/page-5#post-131645 Final suggestion is to check that each coil is driving the correct plugs - plugs 1 & 4 on one coil with plugs 2 & 3 on the other This thread has the plug swapping on the coils as well as coils connected incorrectly whilst we were in the process of discovering that the cams were in the wrong spots https://www.2fiftycc.com/index.php?threads/first-bike-the-fzr250-3ln.10816/page-2 https://www.2fiftycc.com/index.php?threads/first-bike-the-fzr250-3ln.10816/page-5 hope this helps
I’ve got good news and Kak news, good news, I found the problem, put some oil in the combustion chamber, compression felt loads better, cranked it, and she barked at me for 2 seconds, so the kak thing is now I have to strip everything off again to get to the rings which is the cause of the problem, im guessing their seized to the pistons again as they were the first time I took off the block...The reason I didn’t replace them is because when I order stuff on alixpress, it takes 3 months to get to me, but I think I did a **** job on cleaning the piston grooves as I never took of the rings to properly clean them
If you contact the seller you should be able to get them sent by Express. Normal shipping is just dead at the moment.
That's the domain of either threebdond engine conditioner if you can locate some Threebond is recommended by Subaru for unsticking rings and removing built up engine gunk or otherwise you can mix up the equivalent of seafoam, which I posted the formula for here https://www.2fiftycc.com/index.php?...-fzr-250-some-advice.10855/page-2#post-130958 There's a formula for something called seafoam which is either kerosene or diesel @ about 60% plus isopropyl alcohol @ 15% and shellite @ about the final 25% You can put small amounts down the plug hole, ideally the cylinders would be vertical,so engine out and propped up, but it's worth a try for a few days at least
Ok so I read this too late head is off, block is off and I got to the pistons, those rings are stuck pretty good and it takes some force to get them loose, the glands looks to be clean when I removed one ring, is it possible to put the wrong rings on these cylinders? I read somewhere 2kr rings are a bit thicker than the 3ln1? But my plan for now is to clean the cylinders and lighty sand the rings with 2000grit just to remove any high spots and check how they fit then
Pop the pistons off of the rods and clean the ring lands till they are spotless, if it's really gunked on in the ring lands, then I've used oven cleaner successfully, beware fumes, spray it on, then wait max 60 seconds, toothbrush to remove, otherwise gentler things like diesel, kerosene and shellite are great. Are they new rings? The ring land clearance should be in the manual, I don't know it off by heart, it's tiny, but they shouldn't jam in there. 2000 grit on glass should work to level them OK, I just spotted something, they look to be 2KR pistons because of the full round skirt at the bottom, the 3ln1 pistons are slipper pistons 2KR pistons don't go onto 3LN rods because they lengthened the rods by 2mm: 80mm 2KR -> 82mm 3LN They would hit the cylinder head because of the different compression height Compare - 2KR pistons https://www.aliexpress.com/item/32996977971.html 3LN1 pistons https://www.aliexpress.com/item/32276337915.html
Well thats intresting..I guess they put 2kr rods on it as well because its not hitting the head,but is the rods compatible with the crank? what else on this bike is then 2kr im wondering? I think the motor is a 2kr with 3ln1 head, on the inside of my stator cover its marked 2kr and also the magnets are the same as on a 2kr The rings are not new they are the ones that were on there..but that 2 seconds she barked at me gave me hope that all that is keeping me from getting it to run is the compression, so even with the 2kr parts then it should work...but with all the info I got so far my grocery list for this bike when lockdown is over is getting very long
Ok, then it's likely a 2KR motor, I don't think anything beside rod length and pistons changed between them. Stroke remained unchanged all through @34.5mm We can cross reference parts lists to check the cylinder head, but I've got a zeal cylinder head which is the same part I.D. as my 3LN1. I do know that 2KR, 3LN1 -> 3LN5 had the same power output, 3LN6/7 and zeal had lower output attributable to perhaps all of or some of cam(Zeal for sure), valve sizes, carbs 28mm I.D. -> 26.5mm I.D. and ignition boxes and timing. One thing to know if it's a 2KR head is that the valve stems are ~4mm, whereas later models used ~3.5mm, valve sizes did change somewhere through the series, I think they may have increased from 2KR -> 3LN1-5, then decreased, I definitely know for the zeal, unsure if they decreased for 3LN6/7 to reduce power output.
@ruckusman Thanx for that info, i’m 100% sure now it is a 2 kr motor, but with a 3ln1 head because of the screw holes for the radiator brackets, now I know for future reference. Besides that i’m feeling very positive that tomorrow will be the day that we get it running
While you've got the head removed, just for interest sake, measure the valve head diameter and stem diameter to know if it's 2KR or 3LN for certain. And as I mentioned I've got a Zeal cylinder head, same casting I.D. as 3LN1, although I get the impression that the Zeal could have been assembled out of bits to hand at the time, and I'd need to measure the valves on the Zeal head again to be certain of this detail, however IIRC - they weren't what's in the zeal specs but 3LN1/3/5 specs
What nobody has suggested at this point is for you to check piston ring end gap... this will give you a good idea if the rings or bore for that matter are worth reassembling. Simply take a compression ring (top ring) place it in its bore and using the piston make sure it is square around 1/3 to 1/2 way down and measure the end gap with feeler gauges... the specs are in the manual. You should also give the bore a light hone while you are there... it will help with oil retention initially which will provide a better compression seal. Please dont re-use the head gasket for anything other than just getting it going... as a water cooled engine it can mean disaster if you get a leak and in most cases you will.. you could try using the copper gasket spray but generally these gaskets are compressed to their limit after being on the there for umpteen years and will not seal properly... given the drama of having to pull the head off etc it is better to do these things once rather than multiple times...
Wondering if they are already new rings to be as ill fitting on the pistons as they are, IIRC, you did measurements on your new Chinese rings for the FZR400 and they came in in spec Forgot to mention, the reason for thinking that they are perhaps Chinese rings already is because that's paper cylinder base gasket in the photo with the pistons found it https://www.2fiftycc.com/index.php?threads/chinese-rings.7840/ Looks like a full set of measurements of the rings he has might be appropriate