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Only the gt750 was water cooled. The rest had that ram air head. The gt's weren't necessarily the most popular, but 40 years on, they're the best.
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Feb 5, 2014 13:19
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| # ? May 5, 2024 07:37 |
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Jim Silly-Balls posted:Only the gt750 was water cooled. The rest had that ram air head. The gt's weren't necessarily the most popular, but 40 years on, they're the best. forksludge.jpg 
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Feb 6, 2014 08:52
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Yeah the gt750's were pushed as sport touring bikes and are crazy reliable for any older bike, let alone an older two stroke
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Feb 6, 2014 19:38
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What makes them better than the Kawis/Yamahas?
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Feb 6, 2014 23:19
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Mostly that the oil pumps inject oil right into the crank bearings. Yamaha just threw it in the carb Venturi, so whatever oil was lucky enough to splash onto the bearings was all you got. Kawasaki eventually went the Suzuki route but suzukis cci was a more mature product.
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Feb 7, 2014 02:20
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That's actually a really good idea, I'm surprised more bikes didn't do that.
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Feb 7, 2014 02:51
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Why do you need to inject it into the bearings? All the non road going bikes have is pre-mixed gas and their crank bearings seem to hold up just fine assuming you're running normal ratios.
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Feb 7, 2014 02:58
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n8r posted:Why do you need to inject it into the bearings? All the non road going bikes have is pre-mixed gas and their crank bearings seem to hold up just fine assuming you're running normal ratios. They don't hold up at sustained high rpm. Sustained like "hours on the highway" sustained. You generally need to do RD top ends and sometimes bearings within 10k. Bikes like the gt750 can hit four stroke rebuild intervals. Bikes that run premix or inject like an RD aren't hand grenades waiting to blow up, but they won't do Suzuki cci mileage. Kawasaki in their weird agreement with Suzuki basically lifted cci for their own bikes, called it something else and ran it a bit differently. E: the later suzukis called it something other than cci, the name of which escapes me, but it was the same basic philosophy Beve Stuscemi fucked around with this message at 03:48 on Feb 7, 2014 |
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Feb 7, 2014 03:44
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Not all of the credit can go right to the CCI setup that Suzuki ran. When you couple that with an engine that had triple the cooling capacity that it really needed, it will last a drat long time. My Yamaha TDR has 30086km on the stock top and bottom end at the end of last season. The injection system on that is the simple oil pump to venturi with nothing lubricating the bearings directly. I never got why people pulled the injection system in lieu of premix if everything was in order. I have seen more seizures because of "hurf durf lovely autolube / oil injector" than I have from legitimate pump failures.
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Feb 7, 2014 08:10
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The TDR is also much more advanced than your average early-mid-70's two stroke. It uses better metals, cooling is better, tighter tolerances, better rings, timing, everything.
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Feb 7, 2014 17:24
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I'm somewhat familiar with the idea that if you sustain high RPMs for long periods of time you will 'burn off' the oil lubricating the crank bearings. I have no idea how much truth there is to that idea because lots of stuff on the forums is BS. I do know that the RDs I've ridden are pretty impossible to sustain high RPM for long periods because they vibrate like a motherfucker. I would say that from a number of bikes out there the Suzuki is the least common, the RDs are the most common and the Kawis are in between the two. My preference is for the smaller/lighter/sportier bike which really is the smaller displacement RDs. I'm sure the Kawis and Suzukis are fine bikes but I think in general the RDs are the most common and most well supported.
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Feb 7, 2014 18:05
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Yeah there is no question that back then and today, the RD's are the most popular.
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Feb 7, 2014 18:26
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I drained 3 gallons from this thing, how was this still holding fuel? The seams look just as bad  There have been more horror stories than ones of salvation from using Kreem tank liner kits so I'll be staying clear of those. I have never had to coat a tank before, only de-rust ones. Everyone seems to have their favorite tank liner product, but the two that I have seen mentioned more than others are RedKote and the Caswell epoxy tank sealer. http://damonq.com/red-kote.html http://www.caswellcanada.ca/shop/epoxy-gas-tank-sealer.html I remember seeing a few poster remove rust from their tanks, but do not remember them lining them. Has anyone used either of those two with success?
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Mar 3, 2014 21:31
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I am curious about this as well, as I need to save a tank from the brink of destruction.
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Mar 3, 2014 21:53
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I hear good things about caswell. I've done a couple POR15s myself. It's pretty highly regarded in the vintage BMW community, I know. Our shop has done a bunch of Kreem. I think the problem with Kreem isn't so much the sealer as that it's easy to do it wrong. That said, though, I haven't like waited 5 years and tested the condition of any of the above sealers personally.
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Mar 3, 2014 22:55
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Everyone I talk to has a different trick or magic snake oil that will turn rust into gold. gently caress it, going with the Caswell 2 part goo.
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Mar 6, 2014 06:41
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You going to electolysis the tank first? Im thinking I might need to do that on mine.
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Mar 6, 2014 08:01
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5:1 dilute of Phosphoric acid after scraping it as clean as I can get it. Last time I let that stuff sit in my rusty RD tank, it went from rust to perfectly bare in 10 minutes. I wouldn't mind giving reverse electrolysis a shot, but what kind of current would one have to pass in order to get a clean tank?
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Mar 6, 2014 08:24
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DefaultPeanut posted:5:1 dilute of Phosphoric acid after scraping it as clean as I can get it. Last time I let that stuff sit in my rusty RD tank, it went from rust to perfectly bare in 10 minutes. I wouldn't mind giving reverse electrolysis a shot, but what kind of current would one have to pass in order to get a clean tank? Standard car battery charger on the "jump start" mode is what I did. Worked great, I've done it with 4 tanks now
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Mar 6, 2014 16:04
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I got my caswell kit in the yesterday, and carb parts today. The instructions are very clear on stating that it needs to be at room temperature for at least 24 hours for it to properly cure. Or 120c for 4 hours. A heated shop is in short supply and no way could I bring that inside. Artsy bullshit picture http://imgur.com/CcIGNT2
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Mar 20, 2014 08:12
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This is really awesome, I admire the attention to detail. I've always been scared of carbs but when you lay them out like that they are pretty ok I guess.
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Mar 20, 2014 14:53
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I never take more than one carb apart at a time - just in case you forget how something should go you can check the other one(s).
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Mar 20, 2014 18:29
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LOL if you don't have the layout of all carbs memorized 
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Mar 20, 2014 18:39
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wish me luck, guys I'm going to look at an 81 KDX420 today so that I can taste the sweet oil smoke for myself
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Apr 1, 2014 14:11
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Oddball of oddball there. Time has not treated those well for the few I have seen in person. I had a KX420 and it was beat to hell but still a pretty fun ride.
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Apr 2, 2014 05:47
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DefaultPeanut posted:Oddball of oddball there. Time has not treated those well for the few I have seen in person. I had a KX420 and it was beat to hell but still a pretty fun ride. unfortunately it was a bag of poo poo, so I didn't buy
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Apr 2, 2014 06:25
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Anyone know anything about a 1987 Can-Am 406? There's one that pops up on CL around here every once in a while. It looks to be in decent shape, but I imagine that parts would be a pain to find. 
Dellikose fucked around with this message at 12:12 on Apr 2, 2014 |
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Apr 2, 2014 12:10
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Dellikose posted:Anyone know anything about a 1987 Can-Am 406? There's one that pops up on CL around here every once in a while. Where would you get parts though?
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Apr 2, 2014 18:39
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Skipped out on the electrolysis for this tank. I'll give it a shot on the Riva that was just dropped off. I took out as much large flakes of rust as possible by scraping it out, doing the shaking thing with screws and a magnet. Not the worst.  The instructions on the lining kit said to rinse it out with acetone and then move right onto the sealer I have one more step planned for it before that. Fill it with nasty smelling stuff and let sit for 15 minutes. RUST GONE.   About the only thing I would trust those stands to hold up. Mixing these things even at 20C yielded a fairly liquid result that poured in and spread with only one minor glitch. Half part A to half part B - 16oz.   After swirling the tank around for 20 minutes and being able to see a coating over the entirety of the inside I drained out the remains, about 4oz, and set it to dry.  I let it dry like that for a few hours and then put it inside to finish curing over night. There was absolutely no smell during any of the mixing or curing process. When I drained the remainder of the sealer, I pulled off the aluminum stopper and drained it through the petcock hole, thinking that the sealer in the small pinholes would somehow drain out if I pulled the tape off before it cured. The largest pinhole seemed to have kept an air bubble in it, because there was a pretty large void right in the middle. I mixed up the remainder of the sealer and made sure some oozed out of the hole before taping it off. Cured fine and the tank passes the fuel test! This stuff cures clear and is amazingly hard. Cleaning up the little bits that cured in and around the bolt holes took a good bit of effort. Tapping the holes clean gave about the same resistance as tapping fresh holes in aluminum and cleaning off the surrounding flat metal took a sanding drum on a dremel. Use this stuff. Its awesome. Also:  DefaultPeanut fucked around with this message at 09:24 on Apr 20, 2014 |
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Apr 20, 2014 09:19
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Whatever works 
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Apr 20, 2014 13:03
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Busy as poo poo lately working on everything buy my own bikes, but that's how it goes. A bonus from that - I will have a KX100 engine to rebuild and do some lite port work to. A KX250 to crack open and see why it is low on compression. Two CRF250 engines to do complete rebuilds on. I had never wet sanded before this and I was scared as poo poo to ruin the clear / paint. This:  To this:  The pipes were really coked up as far as I could see, which is not too far inside. Knocking them with a rubber mallet or block of wood gave a very solid reply. Not the hollow sound I was hoping for. A few times before, I had used an old cable with the end frayed up to scrape the carbon from the insides, but that was not yielding very much progress. One of the old techs at the shop said to torch that poo poo clean.  The smoke show these things let off was impressive and the smell lingered for hours. After cleaning out the two lower pipes and silencers there was a noticeable difference in the weight of the pipes. Next time I do this it will be at dusk to see the cool flames and the red hot ring move down the pipe. Once you get the front cherry red with O/A, shut the acet off and run pure oxy through it and the burning oil and carbon will sustain combustion until there is no more fuel. Install the pipes, mount the tank and she lives! 
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May 16, 2014 09:26
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The manual for my bike says to use an old chain to remove the buildup, but that's much cooler looking.
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May 17, 2014 18:01
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This happened in the fall and I finally got around to pulling the head off. I guess it ran a little hot at highway speeds. Gonna call a machine shop tomorrow and hopefully get the thing fixed this weekend or next. Would a richer main jet avoid that, or is sustained throttle pretty much gonna burn up a piston no matter what on a 2-stroke?
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May 22, 2014 05:10
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I am guessing that's the exhaust side based on the decompression hole. A little lean it would seem - I always jet my bikes a tad on the fat side if I am going to be running around on the highways. How is the intake side of your bike - are all of the rubber components in good shape? When was the last time you replace the crank seals, mainly the stator side one? When you get around to having the cylinder bored, have the machine shop cut the squish band to a better profile. Want to make your eyes bleed and learn some theory? http://justyamahard350.com/articles/dale_1.htm I had some time to pull apart the KX250 that a customer brought in. The story is that his buddy gave him the bike for free after riding it until it quit running. Apparently, the owner before that did a top and bottom end rebuild, albeit very poorly. The head gasket had been installed one stud off of where it should have been, cylinder base nuts ranging from "holy poo poo" tight to finger tight. A few stripped threads holding the exhaust valve covers on are no big worry, but the exhaust valve assembly being jammed closed is a worry. Here is how the head gasket was installed when I first pulled the head.  How it should be; tab in line with the exhaust port, and dowel through the hole.  Between the customer first getting the bike and me working on it, someone took a stab at working on the carb and tore the cap o-ring. The lovely thing about this is that the o-ring is not available separately. I'll have to buy the entire top cap assy just for the gasket.  Not why it died, but always funny to see a piston cracked to hell and back. A few hours more and the baby skirt would have left the nest to find its own home. Most likely between the crank and cases.  What actually brought the engine to a whimpering halt. A very light exhaust side seizure that stuck a ring and dropped compression below the point of running.  The fun doesn't end there - the bottom end bearing of the rod has noticeable vertical play and is therefore garbage. After I pulled the carb, I noticed sand in the boot coming from the air filter, so the engine had been sucking that in for a while. Couple that with the fuel in the tank is a very light blue makes me beleive that the PO was running a very lean oil to gas ratio - around 50:1 with most likely cheap premix oil. The customer says he wants to o a complete top and bottom end rebuild and bring the bike back into decent working order. He'll be getting lucky as the cylinder has been sleeved and can get away with a simple hone instead of needing to bore it to the next size and having to clearance the exhaust valves or install a new sleeve. At the same time, I will be doing a set of fork seals and consequential front brake pads.
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May 22, 2014 09:00
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DefaultPeanut posted:I am guessing that's the exhaust side based on the decompression hole. A little lean it would seem - I always jet my bikes a tad on the fat side if I am going to be running around on the highways. How is the intake side of your bike - are all of the rubber components in good shape? When was the last time you replace the crank seals, mainly the stator side one? When you get around to having the cylinder bored, have the machine shop cut the squish band to a better profile. Want to make your eyes bleed and learn some theory? http://justyamahard350.com/articles/dale_1.htm Yeah, exhaust side is where the aluminum started melting through. The intake boot and gasket are less than a year old, though I'm seeing surface cracks on the boot(reproduction, not NOS). It might be the ethanol in gas screwing it up, but last time I tested it it wasn't leaking. I might need to change the crank seals as well, but they looked good as new last time I saw them. Thanks for the reading, pretty cool information. I'll ask the shop about setting the squish, but unless it's something they're familiar with and can do without the rest of the engine, I probably won't mess with it. Thanks for the info!
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May 22, 2014 17:16
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Honed cylinder came back with the piston, so I finally pulled the old one off for a better look. New piston, rings, and gaskets in there now. I discovered a 3" crack in the bent downtube portion of the expansion chamber, so I'll need to get that welded up. Since I had the pipe off the bike for a while and had to do a respray anyways, I decided to do a poor man's version of the carbon burnout.  It made quite a bit of smoke.  ...flammable smoke.  Shook a ton of dust out when it was all done with. It made the paint flake off, but I've still got half a can of the high-temp stuff left that should cover the rest after the weld gets done.
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Jun 1, 2014 06:33
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Here, have a family photo I'll type some more words and post pictures after the blown up '08 VT750 is done, after the blown up RMZ engine is done, after the blown up 85SX is done, after the go fast scooter is done. You get the idea. I am actually pretty stoked to do the scooter - a friend picked up a awesome condition 88 Yamaha Riva 125 with ~6000km. We got it back in running condition and he has hauled rear end on it for 2000km before the top end gave up the ghost. Poor thing wouldn't even push my thumb off the spark plug hole when cranking. He has apparently tracked down a ported head, mondo cam and carb to match. I am not the most versed with scooter CV clutches / variators and how to make them handle more power. Any ideas?
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Jul 22, 2014 07:49
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If the power is made at (roughly) the same RPM, (probably) no problem. If the power is made at a different RPM, you really should change the weights (aka rollers) in the variator to allow a different RPM before the clutch housing starts moving. Depending on how thorough you want to be, you probably should change them anywho as the weights wear and sometimes are no longer their original weight. As they get lighter, they can't push the clutch housing to its highest position, therefore preventing the belt from reaching its highest gear and reaching its top speed. The belt itself can also be worn enough that it can no longer achieve this. As a rule of thumb, heavier rollers add a bit of top speed at the expense of acceleration, and lighter ones improve acceleration at the price of a slightly reduced top speed. NOTE: This is assuming the engines power remains the same. If you do a little online learning you might run across people talking about changing "ramps" or "springs", these parts are not exchangeble on your variator IIRC.
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Jul 22, 2014 20:03
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And now I really miss my 270 Beta. Time to recover it from the friends I lent it to I guess. It was a little odd to ride after hearing my Dad's impressions of racing an RZ350, but honestly the most fun I've ever had on two wheels, even just around the yard. I imagine a proper trials course would be even more fun, assuming I had the time to practice so as not to make a complete rear end of myself. Despite advice from a couple friends, one of whom rides competitively and is a far better rider than I could ever hope to be, I still lust after a street legal 250 2 stroke supermoto. It's such a stupid idea, particularly since I have a DRZ SM, but it's just slightly cheaper than the KTM or Husky SM offerings. The siren song of ruined wrists and shoulders, along with the smell of castor oil I guess. Really wish I fit on an RS125 or similar, but at 6' 2" I only manage to look thoroughly stupid.
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Jul 23, 2014 03:34
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A friend had this sitting on his shelf and said he had no more use for it. A case of beer later, it was driving home with me. Time to ruin some cylinders and heads. A coworker just bought a 1966 Suzuki K11 (80cc). It was his first bike when he was growing up in Saskatchewan and wanted to find another. When the weather gets better, in 6 months or so, we are going to (slowly) rip around town on bikes under 100cc. Another coworker has a plated CT90 and a somehow street legal EZ90.
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Oct 22, 2014 07:22
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