I can confirm that is what impex is saying and I just ordered and obtained a set of 8 via the most helpful @maelstrom through impex https://en.impex-jp.com/catalogs/mo...ne-white-ck-japan-6242/crankshaft-363765.html
Impex are very useful, although I have two browser tabs open, pull the part numbers from one tab and search them on the other
Been bashing my head against the wall over these stupid wrist pins. I'm certain I can reuse the ones I have if it comes down to it, but if I'm doing a rebuild why stop here? I did a bit of research and found the mc31 uses the same conrods. That being said the little end diameter has not changed. What has changed on the 250 hornet is the wrist pin part #, as well as the piston part #. Might they work? How the hell would I know. What does the hive mind have to say on the subject? I'm not opposed to finding something of the right diameter hand having it chopped down to size if I can't find a direct replacement. CMSNL is insisting I provide VIN/engine # so they can cross reference. Pretty sure I've done the same thing they would at this point...
Probably the length will be different. With any luck the MC31 pins will be longer and you can shorten them.
I've found plenty of non-JDM pins that could be cut down, just trying to save machining costs/time (HAHAHAHA) if possible
These are an incorrect part number: https://www.ebay.com/itm/175370373050 However searching 13111-KT7-000 does yield one informative and useful result https://www.cbr250.com/threads/so-this-is-where-i-belong.16759/page-2 Also note Dave Moss' second post with this additional part number for the wrist pins; 13111-KT7-751 So might be worth asking that ebay seller if they can take a length, external diameter and I.D. measurement - price seems reasonable
ebay listing is "made in japan" but ships from china so I'm highly suspect. That part # is for 1986 cbr250f per CMSNL https://www.cmsnl.com/products/pinpiston_13111kt7000/#pageproductModelfit (mc17) pistons from the same seller look like trash, could be their potato camera but I'm skeptical of anything coming out of China https://www.ebay.com/itm/175441681962?hash=item28d9239e2a:g:by8AAOSwYcNjQUwK 13111-KT7-751 I is the wrong part # (fat fingered would be my guess). The only reference I find on the webs to it are the post you linked. 13111-KT7-750 is the correct part # for mc22, mc17, mc19
Found OEM wrist pins finally! I didn't post about this when I found them so there wouldn't be a wrestle with someone else since they were on yahoo japan auction... Anyone in the US needs OEM rings or wrist pin clips? Hopefully going to have the cranks checked out this week. If they aren't in bad shape, going to buy crank bearings. Going to plastigage the rods after dinner tonight to make sure they are still in good shape. If the plastigage says they are install in good shape, going to have them checked out too to make sure they aren't out of shape. Fingers crossed the rests checks out! Otherwise it's probably going to take me a long time to find the rest of the parts. If everything checks out, sending the cases and pistons to have the cases re-sleeved! In due time though. The woman wasn't too happy coming into my house to find 2 engines on the table We usually cool off around 2-3 weeks from now, that will make it a lot easier for me to get things done and her not eating in the living room. It's not like the cases are dirty, they are just stained, but I digress.
Interested to learn of the re-sleeving process, somewhere in the mists of time, someone was attempting to pull the sleeve from, IIRC, an MC19 or MC22 case. It wouldn't budge IIRC I pointed them to a document which has brilliantly written info https://www.electrosil.com.au/pdf/KS.pdf Anyway, the sleeves may be cast in with a rough outer surface, so eccentric boring a small groove may be necessary to collapse one edge and "pull" the sleeve. I just added that document to the resources https://www.2fiftycc.com/index.php?resources/aluminium-engine-reconditioning.454/
I talked to Millennium Technologies (US company) about it, knowing the sleeves are cast in place. I stated my concerns (bore size, thermal expansion, etc...) and they threw a price (quote) at me. I'm leaving the details and alchemy up to them. This is well outside of my wheel house, and they are a very reputable company I trust to do the work. I talked to the local machine shop thats re-bored my klx110 motors and they wouldn't touch it due to the bore size. They had to use a hone to get the klx110 cylinders to size, so I was not surprised. Tempted to troll millenium tech when I do send it by sending them a tiny RC motor a day in advance.
Millennium are top of the list with that type of work, if they've said they can do it, then I' trust them. Out of interest are you going for C.I. sleeves or plated aluminum (Aluminium for the locals)? Reason I ask is because Mike Norman from MNGForce said somewhere in one of his blogs stated IIRC that if he was to overbore an RVF or VFR400 that's what he'd do, go for plated alloy sleeves, or did he say just ditch the sleeves altogether an plate the cases, anyway perhaps food for thought...
I'll go with Milleniums suggestion on materials for the sleeve. If MNG was going with plate the cases, it's likely because he has oversized pistons available, 414&428cc kits. If I were going with chinese oversize pistons it would be a simple bore job.
In full ADHD mode today so haven't really gotten anything done, but I did have an "ahha" moment and pulled out the 1-2" mitutoyo mic and made an attempt at measuring the crank. I was surprised, to say the least, that I was getting repeatable results. I use these things about once every 14 blue moons or so. I also realized why I'm not a machinist! Measuring things accurately and consistently is a pain in the ass! There was less than .001" difference on the 1 I measured at 2 different spots 90 degrees apart from each other. I might mess with it again tomorrow and use the vernier scale to really annoy the hell out of myself and screw it all up when I convert to metric. Would be faster and easier to drop them off at a machine shop, but I keep having scheduling conflicts that prevent me from dropping the parts off. The shop that pulled the first rotor has closed, so now I need to track down another rotor puller before I have the shop measure it
I like using cubits when working on the house, but for motorcycles, metric is the go because 0.001" is too big and 0.0001" is too small. My two cents, buy your own metric Mitutoyo, you know you want to.
FWIW - Honda goes down to the smallest resolution between their bearing shell thickness tolerances which is 0.003mm, equals 1 poofteenth or very close to as 0.0001" = 0.0025mm and the crankpin diameters are in 6 micron increments = 2.36 poofteenths - their measurement resolution and accuracy is quite something to behold - most impressive! So a metric Mitutoyo of at least 0.01 resolution does fit the bill, the higher resolution 0.001 isn't appreciably more expensive and makes reading between adjacent 0.01 marks easier. Another option is the Shahe made ones on Aliexpress, I've got the 0.001 resolution digital ones and they're accurate, very well manufactured (cross referenced and checked against the equivalent 0.001 Mitutoyos ), repeatable measurements, much less expensive also.
Okay, okay, butter me up a sh*t sandwich. 0.0001" micrometer would be fine. However, if you want to start talking microns then 1/ Temperature is critical. For example, a 30mm length of steel with a 10°C change = 0.0039 difference in length, and for Al that number is 0.0066. Since most mics are calibrated at 20°C, I better build myself a cold room. https://goodcalculators.com/thermal-expansion-calculator/ 2/ You rely on you ratchet to have exactly the correct amount of closing pressure. My two cents, I am not going to trust a Chinese jobby for that.