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Post by 90GTVert on Sept 3, 2010 10:06:33 GMT -5
Yeah. That's what my last piston kit was. (The wrist pin bearing was separate.) The Hoca was $28 and the Koso was $30 something.  |
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Post by 90GTVert on Sept 3, 2010 16:02:33 GMT -5
I got the transmission back together (with a 1000RPM contra spring now) so I could use the kick starter for a compression test. I got 185psi, and there might be more in it. I quit because on a good kick, I knocked the engine into my shin and it made me curse it :swear: lol. I usually use electric start and a jump box for compression tests, but this thing has no e-start. It jumps all around trying to crank it and I didn't have anyone here right now to hold it down. At any rate, that's about 45psi higher than before. ;D
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Post by 90GTVert on Sept 3, 2010 19:44:07 GMT -5
I got the engine all set up and in the scooter again. Once again, I have mixed results to report.... I started off with 9g sliders, 1K contra, and 1.5K clutch springs. I fired it up and it took off hard and revved way too high still to do much. I swapped to a stock 50cc contra (the softest I know of) and stock clutch springs. I could still get the front end to pop up on a launch if I really wanted, but nothing like before. I tried running it in the yard, but the grass is still a little wet from hurricane Earl making it's way by earlier and all it wanted to do was spin the rear tire. I got my helmet on and headed out to the road. I left my driveway and went to my little test distance that I always use. The test distance is somewhere around 1/8 mile and I let off at 50MPH earlier than normal because the rear brake wasn't hooked all the awy up just right. lol I turned around and stoppped on the shoulder of my 50MPH road. I had some cars coming, pretty close... maybe 1/10 of a mile behind me when I took off. The never caught me until I let off to slow down for my driveway. I came back out of my driveway (just couldnt get enough) and went into town real quick. I just took a quick little lap around my small town and headed back. Coming out of the 30MPH heading towards a 40 and a 50 zone I slowed to let cars pass me while I was on the shoulder instead of pacing them. At part throttle I started hearing spark knock. The cars passed and I was into the 50 so I gassed it (spark knock disappeared as I thought it would) and caught up to the cars. I was pacing them , sitting up, at 54-55MPH before I turned in to my house. This thing has gone 53MPH before with the 70cc and that was full tuck and stretched out for long time. I did 55 pretty easily in a short distance. I pulled into the garage and shut the key off. It ran for about 30 seconds before it finally died.  Obviously, it's getting pretty hot and I probably almost soft siezed it. I went back to it 5min later because I was gonna get you guys a quick takeoff vid, but it wouldn't even start yet. I will probably move the squish clearance up over 1mm to help a little bit. I suspect the 70cc SP3 is choking the engine and causing all of the heat though. It took me a long time to figure that out on my first 90. I wish I could find a Phongeer or some other pipe intended for 90ccs that would actually fit and not be loud. I might go stock exhaust  or I guess I could mod the MRP as was discussed before. I just don't really want it loud at all. I'd like it to stay stealthy. You would NEVER expect this fat man on a quiet scoot to take off like this thing does. I am impressed considering I know it still needs tuning. I'm not saying I should go drag race and take home a trophy, but "it's no slouch" as my father likes to say. Now, that noise I was hearing. It's still there, but less. The only times I heard it were letting off after it was overrevving with the heavy contra or when it "chugs" after I let off. I'm sur eyou 2T guys will get this... you gas it for a moment and then it kinda chugs when you let off. Well every chug is accompanied by a knock. I dunno if I'm gonna need to replace the cylinder or if it's just a stronger noise than I'm used to. I still think it sounds liek metal but I haven't found those signs of contact I expect to see. |
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Post by 190mech on Sept 3, 2010 21:17:28 GMT -5
Glad the ATV swap is going well.Sounds like the dreaded part throttle lean condition is trying to fry another cylinder for ya!I remember when that pretty Nikasil one melted down.If you've got a good carb stash,might want to find a thinner needle,here is a chart of different needles; www.motorcyclecarbs.com/Mikuni_Jet_Needle_Dimension_Ch_W121C37.cfm#Series%206You can measure your stocker and find a richer one (part throttle) on the chart and order one or chuck your needle in a drill and sand it to a richer dimension. Could be the exhaust,but Ive seen ATV's that had awful small tail pipes.. |
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Post by 90GTVert on Sept 3, 2010 21:53:43 GMT -5
I will try to get the carb doing better, but it's not all that I promise. I kept it WOT most of the time or off throttle. That detonation and part throttle doesn't indicate a lean condition necessarily from my experience. Any time I run higher compression the ping is worse at part throttle. I wnet through something liek this for a very long time with my first 90cc. Not sure if you were watching back then?, but I swapped to a big carb, then a bigger carb, and changed cylinders, and changed cylinder specs, and changed this and that... then I changed froma 70cc pipe to a 90cc pipe and ran for a very long time without issues. I'm not doubting that there are other factors at play, but I have seen first hand (I bet I soft seized 25 times on my first 90cc) how devastating the wrong pipe can be. The fact that this one i not only for 50-70cc but restrictive enough to be nearly silent really worries me. Maybe I'm all wrong, but this is bringing back old memories. IIRC I sanded this needle some time ago when the Airsal burnt a piston to richen it up. Squish is easily handled. Still not quite sure about the noise I hear. Wonder how slow it would be with a stock pipe? It feels so fast it's really depressing to think about losing speed. Remember, this is exciting to me because I'm fat and it's hard to make a little engine take off like this with me on it. T2 wasn't this fast taking off on it's best day I don't think, and like I said... it's barely got any tuning done at this point. |
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Post by 90GTVert on Sept 3, 2010 22:27:54 GMT -5
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Post by 190mech on Sept 4, 2010 5:25:55 GMT -5
Youve got a bunch of hours tuning 90+ scoots,Try the stock muffler and see if the knock goes away..
Ive looked at all those pipes too,seems like all are from the same company or copies?I found a nice 1" OD bent tube off an exersize machine while dumpster diving a while back.Can send you a U bend and a big core muffler for the MRP if you want to go that route(dont know if it'll be whisper quiet though)..
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Post by 2strokd on Sept 4, 2010 7:49:04 GMT -5
I had a metal sounding knock when i let off the throttle on my first 70cc.
It was because i put the base gasket upside down tho!
It would surge, chuck, and knock when i let off... More of a bang, bang, then a ping, ping!
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Post by 90GTVert on Sept 4, 2010 9:03:45 GMT -5
VT Cycles got back to me already. Talk about helpful people... this is honestly one of the best replies I've ever got when inquiring about scooter parts. I'm gonna post it here because it has a little info about minarelli exhaust fitment that I never knew. I can see why DioSpeedDemon speaks so highly of them in his YouTube vids. "Hey Brent, OK, I have two different ZUMA / BWS 100 exhaust. One is a All Black tuned performance exhaust. Muffler looking Phongeer made exhaust with a carbon fiber heat shield. The other is a Expansion Chamber I get from Phongeer but made by his friend YMS. It has a carbon fiber silencer. I can offer you either one for $145.00 (plus shipping). I need to ask you a few questions to help you get the right type of exhaust for your needs. 1. Is the engine a Jog or a Zuma (called BWS in Asia)? The reason is you can bolt a Zuma exhaust on a Jog engine, but you can't bolt a Jog engine on a Zuma engine. The Zuma side muffler mounts where you bolt the muffler on is farther out than the Jog cause the run larger / wider wheels. The Jog runs smaller / narrow wheels, so the side mounts are closer to the engine. If you you try to bolt the Jog muffler on a Zuma it won't fit. The case where the side muffler bolts goes sticks out too far. But if you try to stick a Zuma muffler on the Jog, all you need are spacers to take up the gap. I seen guys run roller weights with the right size hole in the center to fill this gap. Maybe with a washer or two also. 2. Do you plan on installing a larger cylinder later on and maybe a larger carb set up also? This will help on suggesting what pipe to go with. 3. Is noise a factor where you will be riding your scoot? Cause a full expansion chamber with an outer silencer will be noisy. If you know it is a Jog engine, I do have exhaust that will work with it at lower prices. These are made to run on 82cc up to 100cc. But will only fit the Jog engines, not the ZUMA. What kind of 70cc pipe do you have now? And when you bought it, did it say made for JOG? OK, I just measured a ZUMA and a Jog exhaust. I measured from the inside of the top side mounting bracket to the center of the exhaust hole ( the inlet hole). Here is what I got: JOG ------ 4 and 5/8 inches ZUMA ---- 5 and 1/2 inches This is give or take about a 16th of an inch. But that is almost an inch difference. So you can see what I mean. I don't want you getting the wrong exhaust weather or not you order one from us or someone else. I used the corner of my desk and put the top side mount bracket flush to the the desk edge and ran a ruler thur the center of the inlet hole of the exhaust pipe and marked the desk. Then I measured the edge of the desk to each mark I made from the Jog and Zuma center inlet hole. You can also do this with a carpenters square. It would be even better. I don't have one here at VT Cycles. Well answer some of my questions and take a measurement and we can go from there. Sorry long response. Just trying to help you get the right part for your needs. Talk to you soon, Steve VT www.vtcycles.com" |
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Post by 90GTVert on Sept 4, 2010 13:06:37 GMT -5
I went out and test fitted the exhausts I have this morning. I ws kinda surprised at the results.... Here's the pipe John made for T1. I can't even get it near the mounts.  Here's T2's stock pipe. Definitely gonna hit the fairing when I sit on it.  Here's the Leo Vince from T2. Not bad. I stuck with this one. It would still hit with the fairing on, but it's the lesser of the evils at this point.  I fired it up went out in the yard for a sec. I got on my sidewals and picked the wheel up enough that I had to let off, then got on it again and did the same thing. I went out to the road and made about the same route I did last night. First time I took off I had to lean over the front to keep it fromt coming up far. By the time I was in town it was getting weaker taking off. Leaving town it spark knocked again. I got it up to 57.7MPH sitting up with a crosswind blowing me sideways since I was clear of traffic and after that I couldn't touch the gas or it sounded nasty with all the ping. Luckily I was at my house. I pulled in and it took about 10 seconds to die after I killed the switch.  It might have been close to in tune before, but it must be off with this setup and I still do beleive the squish is too tight. Obviously I overreacted about the pipe, but I would still like to have a pipe intended for a 90-100cc on it. I went to check the plug (wow is it hard to get out with the tighter clearance) but it was an older iridium that I had stuck in, so it tells me nothing really. I do think the ring aroudn the plug was dark, so it might be really lean, but I'm not sure. The piston would give me a better idea.  I pulled the top off of the carb and I had moved the needle back to the center to get the Polini kit in tune on the 70cc. I moved it to the richest position again. Then I lost the clip somewhere in the scooter that holds the needle in. I had intended to do another pass after it cooled down, but I guess next time I mess with it I'll just pull the motor and look around since I gotta pull it out or panels off to figure out where tha tclip whent anyway. I'm suspecting it needs a main jet change as well. I still hear the knock so I'm getting very tempted togo with a new cylinder. I dunno. |
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Post by 2strokd on Sept 4, 2010 14:40:46 GMT -5
WoW! Sounds mean for sure :twisted: ! Once you get her good and tuned im sure it will wheelies of fun :rockon: ! I gotta build me one of these 90cc+motors i keep hearing such good things about 
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Post by 90GTVert on Sept 4, 2010 14:54:09 GMT -5
Honestly, once I felt the real takeoff power, I quit caring about the wheelies. lol It's doing what you little guys are doing finally, but that makes me wonder what will happen when I put a little guy on it. When it's all setup, I gotta get two of my small friends to race the 150 vs this and see how it fares. I might even take the 150 with me on this. Should be a good race anyway I think. ;D Where the hell is that kid that wanted to race when I've been through town the last 2 times.  Actaully, last night when I was trying to start it to make a vid for you all, a scooter went by. I was mad. |
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Post by 90GTVert on Sept 4, 2010 16:12:59 GMT -5
I puleed the engien once again and opened it up for another look. Here's the head and piston crown.  I think the compression may be way high with just the one base gasket. Even though the squish isn't bad, the crown does go a good bit above deck. The 185psi comrpression probably shoulda clued me in. I forget the numbers, but T2 wasn't that high and it was on the edge of spark knock on premium fuel with my decent setups.  I inspected again for any signs of contact. I found a little mark on the crank where it would be possible to hit the piston skirt if there were some issue at BDC...  I inspected the skirt, but I'm pretty sure that mark was on the crank before and nothing to do with this piston.  The cylinder doesn't look too sporty for something with 5ish miles on it.  Just for kicks, I checked the piston ring end gap. Once again, it's over .025" in just a matter of miles. I had set id just a tad low at .008" since I'd been having such wear issues.  I guess it's time for a new cylinder. I don't know why else I'd wear out 3 sets of rings almost immediately even after light honings. |
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Post by 190mech on Sept 4, 2010 17:59:05 GMT -5
Ive read elsewhere how the 90+ motors dont like a tight squish and spark knock if done so,Have you tried the T2 carb on it yet?Even if they're the same size the needle jet&jet needle,slide cut away may be tuned for a bigger engine.I think a 90+ needs a bigger carb as an aircooled engine uses fuel as well as air to keep it cool.Cant understand why the ring is getting so sloppy,hows the air filter/box?Maybe getting it real hot cooks the ring?I'd think it'd run fine on .0045",just a bit of clatter.Did the lower ring wear also?Once the bugs are worked out I think this is THE lowbuck/high power swap!!!
Edit;I remembered you hung a nice Delorto carb on T2,EVEN BETTER!
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Post by 90GTVert on Sept 4, 2010 19:20:47 GMT -5
I don't think I'd ever fit the big carbs in this small frame. Maybe with a backwards intake or some crazy configuration? Not even sure about the backwards intake because I had to squeeze the big rear tire in. I agree that a bigger carb is not a bad thing, I'm just trying to figure out it it's necessary. If it will run alright on this small carb, I could probably get relatively good mileage. I got 40MPG out of T2 with a 25mm. Add to that I cant really use the stock airbox easily, and the cost of another carb and intake, and I'd need a different throttle setup. When I looked the 50 and 90 carbs over, they were the same as far as I could tell. I don't have the 90 carb anymore, it's running on a 50cc somewhere.
It's not a horrible noise in the engine, but I really have no desire to ride with any improper engine noises.
I'm quite sure the heat doesn't help the rings, butr here's what throws that heat thoery off... It did the same thing (ate the rings, not the hear) with T2 and the big carb/intake and the smae setup it ran for lots of miles before with. It's just since the rod failure, it's ate rings. Maybe there's an odd spot or shape in the cylinder somewhere that I can't tell with my tools or knowledge? I dunno. I think there's more to it than just heat though.
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Obviously, it's getting pretty hot and I probably almost soft siezed it. I went back to it 5min later because I was gonna get you guys a quick takeoff vid, but it wouldn't even start yet. I will probably move the squish clearance up over 1mm to help a little bit. I suspect the 70cc SP3 is choking the engine and causing all of the heat though. It took me a long time to figure that out on my first 90. I wish I could find a Phongeer or some other pipe intended for 90ccs that would actually fit and not be loud. I might go stock exhaust 
or I guess I could mod the MRP as was discussed before. I just don't really want it loud at all. I'd like it to stay stealthy. You would NEVER expect this fat man on a quiet scoot to take off like this thing does. I am impressed considering I know it still needs tuning. I'm not saying I should go drag race and take home a trophy, but "it's no slouch" as my father likes to say. 
Actaully, last night when I was trying to start it to make a vid for you all, a scooter went by. I was mad.