xander450

Hoping one of you transmission gurus can help me out with this one. I just got an RZ350 tranny that I planned to drop into my shee motor this weekend. All was looking pretty good until I came across this: a little nick in one of the shift drum grooves that seems to bind up the fork when it passes through that part of the channel. Thoughts? Any hope for it? It doesn't seem to be raised, so not sure if filing would get me anywhere.

I think it's your jetting, yes.

Well, oil can only come from two places - either from your premix or you're sucking up oil from your trans. If you've done a leakdown and you're good there, it has to be your jetting/mixture. Jetted correctly, I've never seen a 2 stroke fail to burn oil as a result of a mixture ratio as high as 20:1. Surely some oils are more resistant to combustion than others, but I doubt that's where the problem is. Moral of story, I'd work on dialing in your pilot until you're able to do some plug chops for the mains. Something else worth contemplating... things that cause inefficient/incomplete combustion can produce some very confusing symptoms. I recently had a setup that was spitting oil out of the exhaust at the cylinders, but also had bone white plugs. Turns out i had a massive air leak - fixed that and both problems cleared up.

Nah, it wasn't a bad idea, or a particularly hard one to accomplish. You could drill and tap a low send and high return fitting on your clutch cover, add reservoir, electric pump and inline coolers and you're there. But as said, not really necessary - it was done on GP bikes, but they run WOT for long periods. Btw, not sure your oil is the best idea - wet clutches don't get along well with synthetic motor oils, which is why there are bike-specific trans oils. If your clutch starts slipping, you might try klotz, bel-ray, even ATF.

Do these cranks require professional installation?

I'm a little unclear on your plan here - is the banshee motor going into the ZX6RR frame, or is the ZX6RR motor going into the banshee frame? Or both?

Myself and a couple other people have been asking about those g-115 rods - so far no one has brought up a known failure. Would love to hear people's experiences with these - thus far mine has only run for about an hour's worth of tuning.

Stupid question I'm sure - but it looks to me like if the coolant level's not all the way up (which would be a likely cause of overheating) it wouldn't reach these rad cap temp gauges, which strikes me as a serious flaw in design. Am i missing something?

Perhaps you're thinking in keihin jet ranges? Stock jetting is in the low 200s. Plenty of ported stockers are running 300+ mains on stock vm26's.

Anyone? I tested for a short while today at 440 main, 40 pilot - a bit lean which surprised me, that was my surely-too-rich guess. Next shot will be 480/50.

Radar, was that jetting for a 421 serval? That seems way low - I tested for a short while this afternoon on 340 main/35 pilot with needle in the middle and it was definitely lean (and tested with leak down, motor is tight).

Aren't the stock banshee carbs mikuni vm26's?

As title says - just put together a serval 421, need to jet. I'm using a pair of VM32's, mostly just because they're what I've got around. I know they might not be ideal - let's skip the bit where we talk about why PWK 28's would be better. So, on to jetting - setup is: serval 421 w/ 24cc domes at 500ft, squish at .042", uni pod filters, stock timing, mixing Motul 800 at 32:1. Anyone got a ballpark on jetting? Thanks!!

Unfortunately not... their shit turned out to be vaporware. http://www.customfighters.com/forums/showthread.php?t=51542

Fair enough - i, for one, plan to carve my next crank from brazilian rosewood. It'll probably fail, and will also be expensive, which i understand means i have chosen wisely. Neat.

Personally i don't think a built motor can be expected to last as long as a stocker. You ever wonder why Yamaha didn't set the stock timing a few degrees up, or the carbs a little closer to stoich? I've never owned a bike with carbs that wasn't rich with stock jetting. Those things alone amount to several HP that the Yamaha engineers left on the table. Also, it's not as if they don't know how to design fast cylinders (see tz, tzr). When you look at it that way, they could've made the banshee about twice as powerful for basically the same cost... and didn't. In fact, there's an RZ350 series that makes 67 HP stock, about twice the banshee. That power was the margin that they left for the sake of reliability. So that wasn't my point. My point was that if a stock motor will run reliably for 500 hours, a 4 mil with a Hot Rods will go for 150 hours and a Vitos will average 70 hours, I'd like to know that (an example only, not meaning the slur on Vitos cranks). And it makes sense to care, ESPECIALLY if our motors are all grenades. So when i said it was silly, I only mean that it's silly to say basically "these motors are grenades, so you can't expect your crank not to fail." You're right, it will fail, so i want the best part on the market to increase the life of the motor before it fails.

Maybe we can go about this a bit more scientifically. A couple thoughts here: one, this isn't about blame; I very much doubt the reputable builders here would knowingly sell inferior hardware. I realize they're also in an awkward position on this - if they give us the results of any serious technical analysis of the cranks or crank parts on the market, whether theirs or another company's, they're also handing that info to their competitors. On the other hand, "trust me" is sort of a tough pill to swallow when we're talking about exceedingly expensive motors. It's a given that correct installation and tuning is essential to crank longevity, but it's also a bit silly to pretend that the quality of a crank is an insignificant factor. All this "any crank can fail" stuff fully misses the point, i think, that some cranks will fail more than others. There's nothing unreasonable about trying to work out, as a community, which cranks those are. So, to the point, two proposals: one, that we set up a form similar to the jetting questionnaire to log crank failures, incl type and location of failure, type of rods and bearings, other motor mods, known contributing issues (air leaks, improper squish, etc), riding style and approximate ride time. This is essentially what dealerships do to know if a part has an unusually high rate of failure. Second thought is we could take a collection for independent metallurgical analysis of available cranks on the market, which could be posted here for the benefit of all. I have no idea what this costs but would be happy to look into it. Any engineers here want to pipe up?

I just put a motor together, not yet in frame, with a crank that has those g-115 rods, so i too am curious. Anyone have experience (good or bad) with these rods?

I just did a full rebuild last month - called Andy at m&m/no limits, and he talked me through everything i'd need and put an order together for me. i have no doubt any of the parts dealers who sponsor this site would do the same.

It stands to reason you're massively lean. Since you haven't done anything that would affect jetting, I figure there are a couple likely options here: one, that your now-clean carbs are not properly tuned (float height correct, air mixture screw correct, idle screws set) and synced, or two, that since your re-installation you've got an air leak around your carbs. There are other things that would do it too (i.e. an air leak anywhere else), but let's just rule out spooky coincidences for the moment. So I'd re-do the full procedure for carb setup. Then I'd do a leak down test and repair any leaks you might have. I just had a very similar experience - running like shit with chokes and not at all without them. Couldn't find the problem anywhere, had me stumped. Turned out to be a huge air leak in the intake manifold.... I was losing 5-6 psi/min.

Nope, most of the oil would never make it out of the crank area unless that motor is upside down. And don't even consider starting it with oil in there, you'd in all likelihood blow out your crank seals before the bike even started (which, of course because the fog path is blocked by motor oil, it won't anyway). This doesn't sound like a problem worthy of giving up on it - frustrating, sure, but only a few hours of actual work. Why not just accept that you learned an annoying lesson, do the work and then spend next weekend rocketing around on your newly rebuilt bamshee? Just my $.02.

Unfortunately the lowest open point on the crank side is the intake. If it were me i would pull the motor, drain the tranny (it would leak from the vents), pull the carbs, reeds and spark plugs and then completely invert the motor so it drains out of the plug holes. I would leave it to drain for a couple days at least. Even then, you're still probably going to oil foul your plugs for some days.

Wow. Gotta say, this has kind of put the fear in me about the 4 mil serval I'm building right now. Anyone familiar with a crank that has G-115 stamped on the rods? Came from M&M with their serval kit. Should I trust it?

Yeah, to my mind the benefit of taking it to a shop is that they'll check your measurements with better tools than you'd probably want to buy for occasional use. To my mind that's worth the relatively small cost of doing it professionally. On the other hand, a good set of mics is a pretty neat thing to have, so I say go for it but buy a good bore gauge.

Ok, just made my first (known) mistake, haha. I apparently overtightened my clutch screws - which is frustrating because I was following torque specs, and the screws were continuing to turn happily. Anyway, broke a spring retainer screw off in the clutch boss. I managed to back it out, but I had a look at the others - I had definitely stretched a few of those as well. So, questions. One, how are you guys setting those screws correctly? I wonder if the HD springs are making a difference in the torque value. And two, should I replace the clutch boss? The screws now seem to have a bit of wiggle when placed without springs in the boss holes. Clearly I need to replace all of those screws.