Warning lots of offensive content, well as much as I can cram in. The Plan: Well here I go again. This one is off to a very slow start because I don't have the bike to start with, but you get that here in Thailand. The flip side is that I don't plan to do a lot to it, so once I get the donor bike it won't take an eternity like the others. The poor FZR is always ragged on, so of course, since I support the underdog, I just have to do it. Plus all the snooty MC22 owners give me more incentive. If I get it done before I am dead, I will line up a local on the new shitbox R3 so we can have a drag race. Now I know that I am offensive, but I am a grumpy, old bastard, and I think all new bikes look like ****, so take your tail tidy and your pointy bits of plastic and stick them where the sun doesn't shine. Now that we have the 'Rant of the Day' out of the way, let's start with the goal, which is based on this family of Yamahas. Bodywork: Solo seat similar to YZF750SP Headlights sourced from 4JH (already have those) Fairing: Undecided, will merge 4JH upper with something. Front guard to match forks rear hugger Chassis: Perhaps change forks to USD at a later date Lighten parts Fit Ohlins from late model Honda CBR250 Alloy subframe Engine: Replace gearbox output bearing with custom double row ($$$$$$$$$$$) Superfinish gearbox (they are hideous) Work on big end issues Fit oil cooler? Attempt the 300cc conversion with 52mm bore Try 28mm OKO's or 26mm OKO's or even simpler like 4 VM's Bin the stupid water pump & fit electric. Exhaust: Make one from Ti, if it doesn't pan out then bang up a stainless version.
The 300cc Dream: All this can be blamed on @ruckusman. Plan is to go out to 52mm bore = 297cc. This should be finished, or canned, well before I expect to find a bike, since I already have a cylinder block and have started on it. Has to be at least 300cc anyway so we are on a level playing field with the new pile of Yamaha ****. R3 pffft, blasphemy, should call it XS300.
Cylinder Block Part 1: Got this on Jauce for 158 Yen then had to pay about 6000 yen to get it delivered, and took the sleeves out. I will send it off to be vapour blasted and then comes measuring and drawing.
What pistons are you proposing to use ? Sleeves in close to correct size might be hard to source, I made mine from solid CI. I'd recommend making the top flanges thicker than needed as a finish cut over the top surface of the block is good practice.
I have seen a couple RC162 replicas with FZR250 motors. https://www.jl-exhausts.com/honda-rc162-quotreplicaquot-parts-558-c.asp
@Tigger996 What is your point? @gregt Well that is where things go into the twilight zone. I am going to try making a sleeve from a one piece Yamaha cylinder. All the details will be forthcoming in a few weeks when some more parts arrive. Yes, I will leave some extra height for a top cut.
Not quite twilight, lol. If you can source 52mm bore nicasil cylinders cheap enough to use as your liners, great stuff. But if that is it, be careful about how much you take off the top. I'm told nicasil doesn't like being cut across and can flake. I did consider it. If i'd made my liners from aluminium I could have had them nicasil'd locally at NZ Cylinders. The drawback is that for a one-off, the cost of the necessary mounting plate made to suit is about $NZ1000. Which would be about 2/3 the cost of the job. On the other hand, It's possible you've found 52mm bore cast iron cylinders. Again, if the price is good, why not.
Well I'm going to go for 54mm for 316cc Now if I can only get those chaps at Dayton pistons to send me some data on their forged pistons, life would be simpler BTW - we both blame Project Binky
All this talk of big bore makes me want to go through with getting my xr650r custom plated with 'xr250'. Sounds like a fun project, but I'm years away from such a build!
It's like that. I swore off engine mods a long time ago, but fitting alloy sleeves as wet liners is really going out on a limb, so it has to be done Worst case scenario is trashed engine. Hey, I found a donor bike. What a gem. Somehow I don't think I will be buying it.
I wouldn't think it's as big a risk as you might imagine. The iron ones in mine don't have much metal surrounding them so only have about .003in interference fit. Any tighter and I'd have stretched the block walls. It's run a little - and sat a lot - with water in it all the time. No water in the oil so far. Painted copper head gasket too. You'd use about the same interference but the benefit of alloy sleeves is that they'd expand more than my iron ones. Not so much more as to be dangerous - but it would help sealing under pressure. There's always high temp epoxy.....
Yes, all valid points. Because they are so thick, I am thinking to run the liners as slip fit, otherwise they will walk axially to the adjacent hole. This leaves me with three issues, cavitation, deck and fretting. At the moment I am thinking of o-rings or epoxy. When I have the block cleaned and some drawings done I will think about it some more. I am in my usual waiting mode at the moment.
Mine required flats on the adjacent top flanges. They won't rotate. As you probably know, in the experimental stages of the Royal Enfield 250 race single, they used slip-in chrome plated alloy liners to easily change the port timing. Slip-in at room temp, as soon as it was running they expanded to lock in place. The top flange should expand quite quickly to lock the head joint. Any O ring should only be there to seal when cold. It must have metal to metal contact under the flange when running or compression pressure will drop the liner.
No, it will be a hornet's nest of rubbish, lost parts and butchery. Better to pay the money to get a good one. Also it can never be registered.
Found this seller who has complete decal sets for various bikes, including the 1994 YZF750SP https://www.etsy.com/listing/741037966/yamaha-yzf-750r-1993-1994-complete?ref=shop_home_active_72 All a bit special really.