I didn't measure the squish to be honest, I may pull it back apart this weekend and check it for you all to see. I had to repair the engine brace so I want to pull it for inspection anyway. I'll let you know what I come up with. So far the engine is pretty responsive and I was able to give it a start to a good break in through the morning traffic as as its a lot of stop and go with varying engine loads.
it’s all good Fidy, this is all a part of finding weak links and ways to improve. I’m lucky I don’t run one of those ankle biter type things, that could have ejected in any direction. I’ll be keeping this trophy for sure. This gives me a chance to run an engine I got a while ago. A beast of an engine from our good friend Dan, the NCY engine. I was able to buy it when he liquidated. I have to check the piston to valve clearance to be sure we are good to go, but as it stands now there is no binding, but as rpm increases we all know what happens. Dan I’ll do my best not to grenade this engine.
Man I knew something cut loose cause I heard it tearing itself apart. After seeing the failure I realize I underestimated two things, the first being having the crank unsupported with the weight of the variator assembly, additionally don’t know why I never thought about the lateral load the shifting of the variator causes on the crankshaft when the belt pushes on the fixed face, until it slides up. I have to do a few more videos for you guys.
I should be able to change the crank, so I’m looking at either getting a 2.2, 4, or 6 over stroker crank. The issue will still stand with the lack of support, but I’m pretty sure rpm has a lot more to do with the failure than the lateral loading of the crank. I’ll probably do a bearing surrport with an extension on the nut or something to control the free end of the crank.
Sooo hmmm, not sure how to say this. I couldn’t get a photo so here is a video. Anyone want to take a shot of what caused the failure lmao. With the increase in rpm, im pretty sure the stock crank couldn’t take it. Well now I can get a striker crank.
Not too sure how much damage as yet unitl I get it apart, I'm seeing shards of variator fan coming out the back. I also windowed the clutch to try to get some more cooling of the cvt. I'm 100% sure at least the sliders ejected, I also cut a mini window under the vartiator, I can see a slider through the cut out. I'll get her back together by tonight. Doesn't seem that I added a window in the engine case which is good, so I'm sure I can fix the CVT.
just went out for a frickin fun run around the savannah and blew the cvt apart. And today is the last day of work for the year. Lesson here, don't relieve the ramps in the variator too much, lol especially if you have one that doesn't follow the roller/slider to the end of the travel.
That sounds like a great build, I've toyed with the idea of just adapting a straight up centrifugal clutch and shoot for one ratio, but obviously it has its draw backs compared to a varied setup. I do prefer my odds with a chain compared to a belted CVT though, I'm not sure exactly how much we lose with the belt. I'm no go kart expert but I believe Noram and Bully make some mean clutches that are tuneable. I even thought about either making my own or adapting a manual clutch to run a single ratio.
Damn these guys are rootless in here just machining the bore a bit, they didn't even taper it in. CV's are some of the smoothest transitioning carbs ever. I'll never trade it for a slide carb though, lol. Hey Kachi, that exhaust looks killer and since you said it has the baffles inside, I won't mind throwing some cash at it for some kicks.
Got damn, its been a while and I have done some poo. trying to wrap up work and do some business on the side has stripped my time to a minimum. I grenaded a belt on the highway doing about 125km/hr. Was on a long downhill. lets pull back 2 days before. I took a head from a 125cc engine, ported it and matched the intake and exhaust. just blending etc. The valves are much smaller and I dont care. the valves also sit closer to the piston and I rushed the job. started it and slapped the poo out of the piston with the exhaust valve. No worries, I just pulled it back down and shaved her some clearance. Valve didn't bend and it was back together. I unshrouded the valves to try to maximize the flow and ease the compression. It knocked once the CDI brought in timing so I limped to the gas station and poured a full bottle of octane booster and topped up with 95. Gave it a little jiggle and went on my first group ride. I dont have a working speedo on my scoot so I sometimes us the gps on my phone. I have realized that it isn't calibrated well and alomst all the times in a number of vehicles reads 8-15km/hr low. Anyway, we hit the southern highways and my buddy had his water cooled 150cc scooter CPI GTR with 17" wheels. He normally hits 135-140km/hr at the top. we had a few fun runs, I thought he was pulling back and later found out he was flat out and I was right on him. The quickest downhill run we did he said he hit 145 and I was next to him, so I'd call that a good 130-135 for me safely. The engine did ping with the excessive rpm on the downhill runs, so I had to pull back. Man it was fun, the guys with the bigger bikes were amazed that we picked up and moved like we did. I did pull the silencer from my can to lean out the mixture, I know I am normally rich at the top. I had to leave the group to head back home and fragmented the belt on a downhill, i didn't take into consideration the amount of heat and abuse the belt took on the way down. Futhermore I previously abused the belt by using a NCY non-fan fixed variator face and over heated the belt. This more than likely lead to the failure. Anyway, it briefly locked the back tire until it was able to shred the belt and free wheel. It was definitely a skid mark worthy moment, lol. Had to get her home on a van and changed the belt out for a Gates. The belt was less than 5 months old Bando brand. But I ride everyday, so I know its my own fault. PS dont be like me. So even now the higher compression engine is soo much more enjoyable in the mid range. I can still kick start it. I did fabricate and install a new kick start stop, since I broke the old one off the case. I have pictures of everything, I'll try to upload later tonight. Even with a full tank of 95 I cant run up in the rpm's without spark knocking. It doesn't matter right now cause I am stil able to pull up to 110-115 without knocking. I just have to be really careful with the throttle. I will try to get some video and sound of it for you all to hear. I also sent a 150 head to the machine shop and got it shaved a few thou to raise compression while still having the big valves for better flow. will see how that turns out. The goal is to find a good balance of compression and performance without reaching the limits of knock and fuel. I'm also trying to get a water injection system to help with the knock up at the top, but I dont want to get too complicated. we dont have E85 and methanol is expensive down here.
Hey hey, what is this I'm seeing here, is that a TOCE style exhaust I see up there, and you didnt put a link...... lol I'm diggin it for sure, do they have silencers in them?, If not they gonna be loud as...... I doubt you'll need such a big main jet, and I agree no need for the 30mm carb. Do you plan to try a round slide carb? or back with the CV carb.
SD you sure do know your CVT systems and appreciate all the feedback from everyone, this is exactly what we need. To add to your previous post about grinding ramps and slider "channels" I also use it to manage the mechanical limits of the CVT. Also note that every almost every setup is different and has to be hand finished accordingly. I guess I should cut to the chase and actually put mods in. The first step I take is removing the variator faces and putting them together, I prefer to take it off the scoot. I place them face to face centered and put the belt on. Almost all the time for unmodified systems, the belt will not sit to the top of the tapered faces. here we see our first obstacle, this will limit our maximum attainable final drive and potential top speed. Conversely, with the CVT fully installed, if the belt doesn't rest on the boss (deepest between the faces), (not sure if this is ever the case) we are not able to achieve the lowest attainable ratio that will give the greatest torque. Ok so after typing up a storm with modifications I did, it is confusing to say the least without having a visual guide to make sense of things. I will have to prepare a few photos and add some arrows etc before I continue. My apologies for the delay.
Hey guys, I pulled the from the crank key and added back the timing from the pickup coil. No more knock. Its funny when we use the term knock, cause it sounds almost like a low crackle, anyway will let you guys know what I do next. This weekend I have ti install a homemade fixture to replace the kick start stop for the transmission. It literally ripped right out the case. I tried expoying it back in place and it held for about 2 months. The plan is to do a bolted sumtin sumtin to stop the kic starter cam. left uncontrolled, it allows the secondary gear to over spin and not reset, rendering the mechanism useless, ask me how I know.
I agree fully with you guys, the last set of rollers I had turned into a flat spotted slider with a big loss in performance, I was pissed. It happened in under a month. So I always run sliders. I've even modified the sliders at one point. The face that is closest to the perimeter of the variator, Ive shaved about 20 thou off of it as thats what comes into contact and stops the travel of the slider outward. I only saw an increase of about 3-4 km/hr. I'll continue the thread with some actual modifications a bit later today.
We have 93 octane standard, and 95 as our premium. The combination of the two timing advances was a bit too much. I could hear her knock and ping once the rpm increased and the highest advance on the cdi came on. I pulled back some timing on the pickup coil this morning and it seems to like it. I have to fill up today so I'll buy some premium fuel and throw the timing back in. It takes me less than two minutes to make the timing change. To adjust the timing using the crankshaft key take less than 5 mins, once I have my tools. The engine responds well at lower and midrange with the timing increase. I think the best option would be to get a proper programmable cdi and make a nice curve.
Quick update for you guys, turns out the stator is bad, well at least the ignition winding is, it gives inconsistent voltage to feed the cap in the CDI. Sometimes it gives around 50 volts AC and then drops off to 14V, so thats a no go. Luckily I had the stator from the last engine so I threw it on and rewired it into the harness. The old stator was wired in bad so I had to cut the wires. Anyway, I couldn't help myself as I already had the flywheel and stator off. So i modified the flywheel key, I have to fully verify the timing advance as I didnt have a degree wheel or my timing light. I would estimate a 6-8 degree advance + the 2-4degree advance from the modification I did on the pickup coil. I haven't had chance to load the engine as yet. I'll do that tonight to see if it knocks. If it does I'll pull timing from the pickup coil adjustment. It is snappier from low down from the ride to work this morning. I am using the stock CDI.
This is some good write up as well SD, this is exactly what I hoped for, some good discussion. I agree that most scooter owners dont run at WOT. I on the other hand have a bad habit of doing what I'm not supposed to, so I ride a bit harder than I should. The explanation of the lighter weights will give more acceleration is correct as you mentioned, the misconception I dont like is when guys think that because its a lighter weight, they wont get as much top speed as if they used heavier weights. Dont think I explained enough, lol. The part you explained about the ground speed and condition is exactly what needs to be spoken about for the shifting of the transmission or "torque sensing". I'm having a hard time continuing the write up right now, we are getting flooded again, so I got to head out of work early today. I'll try to continue the modification section over the weekend. Please feel free to add the shifting characteristics and mechanical principal of the CVT dependent on load demand/ road characteristics, I know a few of you can explain it well. I think more discussion like this is what the scooter community needs