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Post by 190mech on Jun 13, 2010 5:38:47 GMT -5
A sharp pencil will do,guys use a felt tip pen as a dye to mark the cyl bore then use a razor knife or scribe to lightly scratch the cylinder wall for a fine line..Tiny scratch wont hurt anything...
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Post by drawkward on Jun 15, 2010 22:42:07 GMT -5
A sharp pencil will do,guys use a felt tip pen as a dye to mark the cyl bore then use a razor knife or scribe to lightly scratch the cylinder wall for a fine line..Tiny scratch wont hurt anything... Thanks for the tip, a pencil worked great. I got it measured down 5mm from the exhaust height and 5mm from the port heights. Came up with 181/131. If I cut 6mm and raised the exhaust port I'm sure I could come up with 181/127. I went to the closest machine shop to get a quote. The owner said he didn't want to put my cylinder on his small lathe, and his big lathe was too big for my cylinder... He recommended me to a place a little farther away. Going to check them out tomorrow. |
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Post by 90GTVert on Jun 16, 2010 8:02:40 GMT -5
I would suggest getting the degree wheel out again and make sure what you think will work will actually work the way you'd like. I know you can add spacers if too much is cut off, but if you take the time now you can have a simple setup where you just install it with one base gasket and don't need to worry about the extra gaskets and spacers all the time.
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Post by drawkward on Jun 16, 2010 10:26:12 GMT -5
I would suggest getting the degree wheel out again and make sure what you think will work will actually work the way you'd like. I know you can add spacers if too much is cut off, but if you take the time now you can have a simple setup where you just install it with one base gasket and don't need to worry about the extra gaskets and spacers all the time. I used the degree wheel for the 5mm cut down, but I'll double check for the 6mm cut. I'm pressed for time though. Have a million things to do today, and have to take a 1 hour ride to go get it milled (hopefully). I have Bell's book but I haven't had a chance to sit down and read it yet, so I'm really relying on these example numbers you gave me. What is more aggressive (Steeper power curve) - Having a lower transfer duration and a higher exhaust duration, or what? I'd like to know, so if I decide to let it go one way or the other that it'll still be ok, and maybe have an idea of how it's going to run. |
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Post by 90GTVert on Jun 16, 2010 11:27:25 GMT -5
Longer durations in general are more suited for high rev power. Lower durations will usually make more bottom end power. Too low and the kit will feel weak up top or all around. Too high and you won't make any power until you get the revs up which can make the scoot kind of a pain to tune and ride on the street. If you get the transfer durations straight, you can open up the exhaust port a little to make the duration you are looking for like John said. Modding the transfers and boost port is tricky because of their entry angles and the ability to reach them with anything but expensive porting tools.
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Post by drawkward on Jun 16, 2010 13:37:55 GMT -5
Nice. That's what I needed to know. So If I can't get it exactly right, it's ok. I'm not really into the whole bottom end power thing. I love having a steep power curve.
I went to the next closest machine shop. They are a real metal fabrication facility in an industrial park. Wanted too much money to shave it down for me. He recommended I find a highschool or friend with a lathe...
So, anyone on here that can do that for me?
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Post by drawkward on May 28, 2011 18:29:11 GMT -5
Updates: This project took a back seat after I got my first 70cc Minarelli Running on my other scoot. After that, school started up, had an accident, and the scooters started collecting dust for a while. Been slowly putting the pieces back together. Started first the RX8, since it is my first scoot. As most of you probably know, this scooter came stock with a Linhai-Yamaha 1E40QMB-A Engine sporting a 1E40FM top end. Most of you probably already know that these engines come stock with a 42mm stroker crank, and the clearance to bolt on a 54mm cylinder - all while using JOG 50 components (flywheel, variator). Unfortunately, the stock piston pin in these motors is almost always a 10mm. To my knowledge, there are no 54mm BBK that come with a 10mm piston pin. Oh well. Found a cheap 42mm Crank, OEM style, with a 12mm pin that happened to be used with 50cc parts. Sweet. Later on picked up 54mm BBK from Autotech355@eBay. Nice. Everything sat around for a while, since I never really felt like busting into it. Don't ask me why, always seemed like there was plenty else to do around here. I always say it - there just isn't enough time in the day! Got so tired of looking at this...  Eventually decided to start putting things together - but first I wanted to try my hand at matching and case modding. I mean, why not? Might as well get the most from the upgrade.  Stock  Did some light trenching.      Did some lousy port matching.     Glued the cases together with my trusty Threebond 1194.   After getting them together, I used a drill to tighten all case bolts as quickly as possible and to a uniform torque. Got a little binding after, so I had to tap the flywheel side of the crank with a light mallet. Freed her right up... Pushed in my fresh seals... But, wait! Damnit! I think I might have pushed the large CVT side seal in too far! What do you think?  Got the intake, stator, flywheel, fan, matched copper-coated base gasket, and the new 54mm kit installed in about an hour or so.  Installed the final drive gears and used some Threebond 1194 to glue the mission case on. Fresh 90w followed.  Found the original cylinder air shroud for this engine (thankfully). This engine is literally a downsized 90cc. Even the cylinder shroud allows clearance for a 90cc jug. Funny thing is, the shroud for the fan is actually the same size as for the 50cc - go figure.  Installed a newish clutch, unmodified with stock pill springs, Autotech355 Red Torque Spring, almost-new Bando 788, and a stock painted bell.  Unfortunately, I got held up because I didn't notice that my mount's bearing wasn't installed on my right case half. It's sitting in the freezer right now while I use my free minutes to type this up.  Whew. That was a lot. Bearing should be frozen by now! Back to work! P.S. - The RX8 is sitting outside with a blown motor. Just pulled off the cover to let her get some fresh air before I yank that block out from underneath 'er.  |
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Post by 90GTVert on May 28, 2011 22:15:17 GMT -5
Great update! Glad to see you getting this done. I think that seal is OK. A pressure test would tell you for sure.
Keep us posted!
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Post by drawkward on May 29, 2011 2:39:16 GMT -5
Thanks for the encouragement, Brent. It's not that I didn't want to update - it was just the amount of typing and uploading from all the archived photo albums seemed too daunting and time consuming a task. Plus there's always plenty to read on here. I get sidetracked quite often, to be honest.
I was too lazy after going hard on this for most of today to do anything else. I'm going to do a pressure test en la manana. If there are any leaks, I'm probably not going to worry too much - if it's only around the cylinder. Shouldn't be anything major - used copper spray coating on my fresh base gasket. All mating surfaces were absolutely spotless. I used copper rtv silicone from a tube on the intake - I know, it won't last due to the silicone vs gas. Not using 1194 on anything but the cases, though. Still can't free one of my intakes from my reed block that I sealed with 1194 last year! I would do a compression test, but I can tell this baby is good to go just by turning the crank. Don't think I need to do a squish test just yet. I just experienced my first holed piston, so I know what to look for now with detonation. I'll notice it right away.
For now the goal is to get this up and running smoothly, then move on to the new 47mm kit with single ring piston I've got coming for that holed piston in the RX8's current 1E40QMB. I've got two 1E40QMB's to get up and running after this build, lol. One is split, the other needs to be. I'll update another thread for that, though.
I'm actually about to move, so I want to get them all mobile ASAP. Once they are all up and running, then I can move on to parts modding and swapping.
I want to show you guys my little shop area soon! It makes working on the scooters much more enjoyable. I think you guys might approve.
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Post by 90GTVert on May 29, 2011 3:48:59 GMT -5
I don't think I'd overlook any leaks. Now is the time to handle them for sure. Otherwise you might get it all "done" and swap it in and never get it to run the way it should. You're not likely to have any with how everything is sealed. I've never used copper RTV on the intake stuff, but I've noticed Luke using it so it might be fine. I use Ultra Black RTV or The Right Stuff on all of my reeds now.
Even though you're used to hearing detonation, it's not a bad idea to take the 5 minutes to check squish. I'm not even saying you need to be picky about it, but if it's much under about 1.5mm you might need to use a thicker gasket or multiple gaskets and if it's much over 2mm you'd probably wanna eliminate a gasket somewhere. That should get you in a good safe range for a street engine. Again, it's just faster and easier to do this stuff before it's in the scooter.
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Post by lshigham on May 29, 2011 4:00:07 GMT -5
I agree with Brent, a leakdown and squish test would be invaluable now to save time and money later.
Yeah, I've had no problem using Loctite copper RTV in the intake manifold. I use the grey version, as it's less conspicuous.
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Post by 190mech on May 29, 2011 5:24:36 GMT -5
Great Work! :thumb: Thought this project went to the recycler!!
Ya gotta do those simple checks to have peace of mind about the build.
Also the LV has a verrry small stinger and muffler,it'll need to be increased to keep the piston from overheating..
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Post by drawkward on May 29, 2011 13:06:37 GMT -5
Checked out on the leak down tester. Even though I knew I was very thorough with my seals and gaskets - I still expected some sort of leak somewhere. Nope. Held steady at ~7psi passed ~10 minutes (I lost track of time  ).  Did my squish. Hows this? Sounds pretty mild to me. (I don't have any solder, so I had to improvise with some foil.)  I suppose I could do a compression test - but again, I'm quite sure I don't need it. If you guys think it's necessary, I'll bolt up a starter and turn 'er over to get some readings before putting the bike on top of her. |
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Post by 90GTVert on May 29, 2011 13:15:31 GMT -5
Sorry to make a suggestion that kinda wasted your time, but it's just best to know there aren't leaks when you build 'em from the cases up.
If the squish is accurate (never tried foil) that's certainly plenty of clearance. I'd consider assembly with no head gasket and just copper spray if you have no issues and are looking for more power at some point. It would probably be fine that way now, as that should put you around 2.2-2.3mm squish most likely, again assuming the foil is accurate. I just wonder if it may expand a little?
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Post by drawkward on May 29, 2011 13:48:38 GMT -5
Oh, no worries, Brent! I kind of knew you guys would suggest it anyways. I knew it needed to be done. I took the time to build the tool - why not use it?! Plus it does help with the added peace of mind. No worries, brother - always good suggestions coming from your end! What is an ideal squish for my set up? I know it depends on fuel type - but lets just assume I use pump grade 92 octane.
The variator nut for this crank was not included. I must not have noticed before, but it is much smaller than all of my other vari nuts. I think the other's I have are M12x1.25, this one is a M10x1.25. Hopefully my favorite local hardware store is still open!!! This is the "normal" size M12 nut over the new crank's threads. 
I got my bearing in with some hot and cold.  Believe it or not - I've never had mount bearings that allowed me to do this... ... Hopefully I don't hit too much holiday traffic. I'm dying to get this block mounted and smokin'! |
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