My 81R is almost back together! what ratio should i mix at for break in?

[Deathrocket]

so lets see owned this thing for over 2 years.. it has been down more than ridden, first it was the axle bearings, then the piston circlip let go and poked through the rings, then the machine shop screwed up, or i didn't have enough oil in the mix (was at 32:1) and it locked up again, got the top end redone once again, and the carb would not tune to save its life, so to the big bin of used parts it went, and a neeeew carb got ordered, while it was apart i did crank seals, and decided since the rollers in the swing arm bearings were now flat, it was time to bite the big one and swap from bearings to polyurethane bushings, which are now waiting for me to pick them up at the machine shop, then its time to assemble everything resolder the throttle cable ferrule, and tune her in.. woo! also slated to be done are rear shock bushings, and rebuild the forks.. then i will have a completely new trike.. woohoo.. lets hope it holds together for the rest of the season lol

[yamaha driver]

what kind of oil you run depends on the ratio. I ran 32:1 when i broke in my 250r. And i used any t3wc oil (i think thats it). if you mix it richer rember you are leaning out the gas which is hard on it also.

[Deathrocket]

well then i still blame the machinist, the 2nd machinist i went to knew what was up and has only been working on bikes for the last 30 years lol...

[yamaha driver]

yea thats a good machinist to go to. i get my cylinders done by a same type of guy and he can get the clearences PERFECT. what sounds like happened to you is they didnt leave enough clearence for the piston to expand, causing it to sieze. Or not trying to be mean you didnt let it warm up long enough

[4x4van]

Run a good quality oil at the Oil manufacturer's recommended ratio. I run Golden Spectro at 53:1, have for over 3 decades now. Don't run a richer premix ratio for break-in than what you are going to run normally, because that leans out the carb jetting. Read my post here for the explanation.

[manbearpig]

It really comes down to picking a ratio and sticking with it. Honda recommends 20:1 (according to the sticker on the frame) but that was based on stock jetting and an older caster based oil technology. With today's synthetics and ethanol free race fuels, you CAN run as lean as 100:1 with the right jetting. I would not recommend it though, cuz that's lean as for an oil mixture. Ultimately I've found that 32:1 with amsoil synthetic works best for my 82R. I run 100 octane and a 138 main on my keihin PE.

DO YOUR PLUG CHOPS and use what you know about jetting to dial it in. All this theory about mixture and jetting is secondary to what the plug says

[Deathrocket]

hey guys! picking up my swing arm bushings from the machinist on friday! and yeah, my take on the 2nd blow up is just that, weisco recomended .002 piston to wall clearance, the machinist bored the bore .002 over the size of the piston.. now correct me if im wrong but fpr .002 clearance one would need .004 overbore. not 002. also i found that the crank seals were leaking too, so it was a combination of my fault and the machinist so call it what it is, the lower end has all new seals, with the exception of the output seal, which i will do when i put a new sprocket on. but for now i wanna get this silly thing back in one piece so i can play with it instead of working on it lol....

[bkm]

hey guys! picking up my swing arm bushings from the machinist on friday! and yeah, my take on the 2nd blow up is just that, weisco recomended .002 piston to wall clearance, the machinist bored the bore .002 over the size of the piston.. now correct me if im wrong but fpr .002 clearance one would need .004 overbore. not 002. also i found that the crank seals were leaking too, so it was a combination of my fault and the machinist so call it what it is, the lower end has all new seals, with the exception of the output seal, which i will do when i put a new sprocket on. but for now i wanna get this silly thing back in one piece so i can play with it instead of working on it lol....

A few things here. Did you put the rings on the piston and slide it into the bore and measure the clearance or did you just take the shops word for it? If you didn't measure the clearance and then admit to the crank seals leaking how can you blame the machine work also? A lean condition will seize a piston regardless if the machining was spot on. Also is there cooling holes drilled into the exhaust side of the piston where it rides on the exhaust port bridge. The air cooled R's are notorious for seizing at that point due to lack of cooling and heat buildup at the bridge.

[yaegerb]

Breaking in procedure on my 82 R, I played it safe and ran two tanks of 20:1. Then, after break-in I ran 32:1.

[bkm]

Breaking in procedure on my 82 R, I played it safe and ran two tanks of 20:1. Then, after break-in I ran 32:1.

Brendon, you do know that by increasing the ratio without changing the jetting, you are actually leaning out the mixture. The increased oil let less fuel though the jet causing it to go lean. There is nothing wrong with running at 20:1 as long as the jetting is set up for it and the engine is ran hard enough to use the oil being supplied. A lot of shifter cart engines run as high as 15:1 but they run at a very high rpm at all times so they actually use the oil being supplied.

[yaegerb]

Didn't know that Bryan. I was following what the Honda shop manual said to run for break in procedure....at the time, i figured it was the closest thing to the truth.

[bkm]

Before I knew any better I also did the same thing with a fresh top end and never had a problem with babying it through the first tank or so, but now that I know its 32:1 for everything.