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Post by backhill on Mar 4, 2009 11:58:25 GMT -5
I've been contemplating a 70cc upgrade and have read up on several big bore kits. The question posed to anyone who can answer it is what exactly are all of the differences in reliability, performance, and quality of all of the big bore cylinder kits out there. I've searched this forum and a couple others using several kit names and different terms but only came up with a few posts on this forum that merely mentioned the setups people were using.
It's obvious a racing application would add more performance than a milder one but by how much? (how much with no supporting mods? how much with a few basic ones?). How reliable is each application for every day riding (how frequently would you need to rebuild?)
The specific ones in question I'm personally curious about are the partsforscooters kit, and various MRP, Polini (Sport or Contesta, Corsa), Stage6 (Streetrace, Pro Sport, Racing), and Malossi (Sport, MHR Replica) kits. If you have information and/or experience regarding other setups please feel free to add to the conversation.
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Post by rapidjim on Mar 4, 2009 12:18:49 GMT -5
There have been several posts regarding performance upgrades and these kits, I can only speak for MRP, I have yet to hear of a problem with that kit. Make sure you upgrade your jetting in your carb. Any other questions feels free to PM me.
Good Luck
Jim
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Post by rapidjim on Mar 4, 2009 12:21:51 GMT -5
Enviromoto also has a great kit.
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Post by medman1952 on Mar 4, 2009 12:22:07 GMT -5
Most of the conversations here are regarding the kit that Enviromoto sells. I think in general the 70-72cc kit does not have a dependability issue, when you get into the 80+ cc kits the stress on the stock bearings and crank becomes a reliability problem. Most of the smaller kits come with either no new head or a head that is no different than a stock head, You can get a head with bigger valves for more flow but your only going to get so much power out of these things and you have to decide just how much money is enough to spend.
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Post by Enviromoto on Mar 4, 2009 13:36:30 GMT -5
I've been contemplating a 70cc upgrade and have read up on several big bore kits. The question posed to anyone who can answer it is what exactly are all of the differences in reliability, performance, and quality of all of the big bore cylinder kits out there. I've searched this forum and a couple others using several kit names and different terms but only came up with a few posts on this forum that merely mentioned the setups people were using. It's obvious a racing application would add more performance than a milder one but by how much? (how much with no supporting mods? how much with a few basic ones?). How reliable is each application for every day riding (how frequently would you need to rebuild?) The specific ones in question I'm personally curious about are the partsforscooters kit, and various MRP, Polini (Sport or Contesta, Corsa), Stage6 (Streetrace, Pro Sport, Racing), and Malossi (Sport, MHR Replica) kits. If you have information and/or experience regarding other setups please feel free to add to the conversation. Is your scooter a 2 or 4 stroke?
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Post by backhill on Mar 4, 2009 14:09:47 GMT -5
I think in general the 70-72cc kit does not have a dependability issue. I'm assuming you're speaking of the Enviromoto setup then? How would you compare it to other 70cc upgrades? Are the differences minimal or can you really tell the difference in price when you go down the street? Is your scooter a 2 or 4 stroke? I'm rockin a 2T Keep the feedback coming guys
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Post by Enviromoto on Mar 4, 2009 15:08:55 GMT -5
All the kits I sell are for the 4 stroke.
I hear the stage 6 kit is best. Thats what all the racers in my area use.
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Post by medman1952 on Mar 4, 2009 15:16:01 GMT -5
If it is a 2 stroke, check out the two stroke forum, 90GTVert has a lot of good info there and is our resident 2 stroke authority.
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Post by 90GTVert on Mar 4, 2009 17:47:13 GMT -5
I've posted info about the 70cc MRP kit I used for quite some time in many threads answering similar questions, I'm feeling lazy so I'm just going to quote another post of mine for that info...
"I was very happy with the MRP cylinder. There are a lot of cylinder kits out there that would make more power but the MRP kit was extremely reliable for me. I used my stock carb, stock jets, stock airbox, stock intake, and stock reeds with an MRP 1500 RPM torque spring, 4g rollers, and MRP 2000 RPM clutch springs along with an MRP pipe. At 285 pounds, I could cruise at 50+MPH aside from when there was a good headwind. I rode for 100+ miles in a day on a few occasions and screamed the engine to cruise 50 or above a good bit of the time and never really had any issues with it. Acceleration was way better than stock. I definitely didn't have to put my feet down and push off in town to avoid being ran over when leaving traffic lights anymore lol. I believe I put 3,000 miles or so on the MRP kit and never really had any problems related to the cylinder kit."
I don't really have experience with other 70cc kits to give you any good info regarding them. I can give you a small bit of info about MRP vs some eBay kits that I've owned. This information is regarding 52 and 54mm cylinders and not the 47 or 48mm cylinder kits for 70cc engines, but I believe it applies. I paid $170 for a 52mm MRP cylinder kit that lacked a cylinder head and then bought a kit from autotech355 on eBay for $140 that came with a high compression head. Both cylinders appeared to be nearly identical in design. The MRP 70cc kit does come with a cylinder head and it is going for $179.99 at scootertronics. Autotech355 is selling a 70cc kit for $140 w/free shipping. Just looking at them now I am noticing that the MRP uses and o-ring head gasket and the autotech kit uses a metal head gasket. I see that the partsforscooters kit uses an o-ring as well, it looks just like the MRP kit and it sells for $149.99. I have never seen a Malossi kit, but I have heard that the sport is very similar to the MRP kit's design as well. They're all basically mild cast iron cylinders. I know stage 6 has a good reputation, and I know Polini's high end kits can make great power.
Aluminum cylinders will be lighter and should dissipate heat better. I would think the even better side of the aluminum cylinder would be the expansion rate. The pistons in all of the kits that I have seen are aluminum. The heads in all of these kits are aluminum. If you use an aluminum cylinder shouldn't all of your parts be expanded at a more similar rate when everything is heating up? I may be wrong on that, but it sounds like a good thing to me. Iron cylinders should be more durable and may actually make more power (with the same specs) because it retains more heat inside the cylinder. I would imagine any power differences for iron and aluminum would be minute for this type of engine though.
I really haven't pushed it enough to tell you the limits on 70s, but more performance is going to mean less reliability from heat and stress. With a mild cylinder you shouldn;t have to do rebuilds very often at all. Even if you do need a rebuild you may be able to get by with just a new piston, rings, gaskets, and cylinder honing. It shouldn't be that expensive or time consuming, once you're used to it.
Another huge part of reliability is tuning. You can put a mild cylinder kit on that should be hassle-free for thousands of miles, but if you run it lean you could destroy a piston in no time. Whatever kit you get, take your time and do spark plug checks.
One more note, if you are looking at all these kits for the minarelli engine be aware that they come with either a 10 or 12mm wristpin and you need to get the correct one for your engine.
Sorry it's not the comparison of every cylinder you are looking for, but hopefully something here will be helpful.
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Post by rapidjim on Mar 4, 2009 17:52:02 GMT -5
Check out my site for the MRP kit. I give a discount to Dawg members so PM me before you order if you decide to.
Jim
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Post by 90GTVert on Mar 4, 2009 18:19:52 GMT -5
Make sure you upgrade your jetting in your carb. If you are using the same carburetor and air filter the larger displacement engine will often use the same jet or a smaller one. The larger piston travelling down a larger cylinder actually creates more vacuum which draws more fuel through the carburetor.
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Post by backhill on Mar 5, 2009 9:00:45 GMT -5
Thanks for the feedback guys! I appreciate the timeliness.
I'm pretty sure I have the 12mm wrist pins, it being a 2005 model. Better to check though before any ordering happens.
I would imagine an 80cc kit would require some crank case work on a 1E40QMB (mine is a QJ1E40QMB). What's the max bore that would clear it? I've read mixed answers everywhere.
I haz the mod bug like no other. It's too cold to me working on the scoot right now but I'll do some more research and see where it gets me.
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Post by 90GTVert on Mar 5, 2009 9:33:57 GMT -5
I would imagine an 80cc kit would require some crank case work on a 1E40QMB (mine is a QJ1E40QMB). Can anyone verify that? Some say it clears and others say it doesn't. To make 80cc with a 39.2mm stroke (stock minarelli) you'd need around a 51mm cylinder. I think there are 50mm kits out there marketed as 80cc (should be 77cc) though. I actually bought a 52mm cylinder to put on my Triton. It will not fit stock. In fact, the piston is even too large to fit in the crankcase, so you know the cylinder is a good bit off. Mayber there are kits out there that have thin cylinder walls at the base to allow for more clearance? You'd probably be just as well off to stick with a 70cc kit that will clear for sure unless you feel like splitting the cases to grind them out and then reassemble everything or you find out that there is a kit designed to fit. It turns a small job into a much larger job that requires the use of specialty tools. There are a ton of 70cc kits that can probably achieve whatever you are looking for without needing to do the extra work associated with crankcase clearancing. The smaller, lighter, pistons are actually better for reaching higher revs too.
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Post by backhill on Mar 5, 2009 11:06:12 GMT -5
That's why I asked. I don't personally have the tools to work on the crankcase like that.
What I'm aiming for is a solid commuter that has balls in the low-mid range. Higher up isn't a concern. I intend on keeping it registered as a 50cc so I can park in certain places downtown. Exceeding 35mph in Michigan automatically violates the state's Moped Laws which require a 50cc displacement, 35mph, and a single gear.
With performance there comes more wear and tear but I'm not too concerned with upkeep and rebuilds. These little 2T motors are cheap to work on compared to my car. It's already burned through the stock tranny, and the upgraded version (clutch plates, limited slip, etc.) is starting to go now. I'm actually amazed at how relatively inexpensive it is to work on this motor.
In the end I want it to have lots of low and mid range power with a decent top speed. If it can reach 55mph I would be more than pleased.
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Post by 90GTVert on Mar 5, 2009 13:43:34 GMT -5
From your last statement, I think you'd be happy with one of the MRP style 70cc kits. The racing cylinder kits are usually tailored more towards high RPM horsepower rather than low end torque. The larger displacement kits with similar porting will make even more torque, but it really doesn't sound necessary for your needs. The more mildly ported 70s make much better low end power than the stock 50. Being such a heavy rider, it was night and day taking off with the MRP 70cc kit vs the stock cylinder for me. If you only want to get to 35mph faster you may be happy with the cylinder kit and no other modifications. If you get a mild 70cc kit and decide you still want a little more low to midrange umph there are other things you can do after that that wouldn't cost too much like changing the contra spring, stiffer clutch springs or lightening the clutch, using a reed spacer, etc...
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Post by backhill on Mar 5, 2009 14:43:49 GMT -5
I already have 2000rpm springs, belt, and a variator in. I'm just looking for a bit more.
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Post by 90GTVert on Mar 5, 2009 14:56:04 GMT -5
Even better.
If you don't care much at all about top speed you could also use a spacer in the variator, like some scoots do stock to limit top speed. It depends how yours is setup now. With no restrictor/washer in my variator my belt can't go all the way down. I bought an assortment of washers that looked close to what I needed from the local hardware store and used one as a spacer between the front sheave and the bushing over the crankshaft splines. The belt can ride lower now so it takes off a little harder. There are 2 down sides to this on my scoot. 1) I can't use a kick start gear anymore becase the splines are no longer showing that far out. 2)My top speed is around 50-51mph because the belt can't ride as high now.
To be fair, if you really want to hit 35mph fast you can still get one of those high end kits. You can put on a pipe, lighter clutch, bigger carb, heavier contra spring, carbon fiber reeds, etc... and try to tune it to hit the pipe off of the clutch or close to it. If it's done right you can probably do wheelies. I just think that's overkill for what you are looking for. It will end up being much more expensive and less reliable.
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Post by backhill on Mar 5, 2009 16:14:56 GMT -5
I kind of need my kick start when the battery is drained, but it sounds like a good idea otherwise.
I still care about top speed. A cruising speed of 55mph would be ideal. If it can get up a few more mph that would be awesome.
BTW I just saw a picture of your scooter. Real similar to my UM Xpeed 50. I wouldn't be surprised if mine was just a rebadged version of your Vento.
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Post by 90GTVert on Mar 5, 2009 16:34:00 GMT -5
I know mine looks like a CPI Hussar and Strada RX8 as well. There are prob tons with the same body style.
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Post by backhill on Mar 20, 2009 13:16:51 GMT -5
Whelp ... I got bored earlier this week and decided to strip down the motor to see exactly what the pin size is. It is in fact a 12mm wrist pin. I ended up ordering the Polini Sport kit. I'll keep you guys posted.
I also found a sticker underneath the seat stating that my United Motors X-Peed 50 is actually a rebadged CPI JR 50. Go figure.
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Post by 90GTVert on Mar 20, 2009 14:27:20 GMT -5
Good job backhill, it's always nice to be confident that you are ordering the right part rather than guessing. Keep us posted on your upgrade.
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Post by 2strokd on Mar 21, 2009 21:37:42 GMT -5
You are going to love that Polini kit backhill! I read this and its perfect for what your goals are. I just put that kit on my CPI yesterday and im lovin it already. It provides lots of low, and mid range punch. I hope you have a pipe though.?. Other than that maybe some jets, and your gonna be poppin wheelys soon too!!! j/k
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Post by backhill on Mar 22, 2009 8:26:28 GMT -5
That's good to hear. There's already a pipe on it. I don't know what displacement it's tuned for though. Jets are on the way as well.
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Post by backhill on Apr 19, 2009 21:42:58 GMT -5
Whelp ... I've had the kit for a few weeks now and I found some time this weekend to finally get around to installing it. Everything went smoothly. Fired up on the second kick. Excited is an understatement.
I flew around the block once and was grinning from ear to ear. Like 2strokd said, lots of low and mid range power. Everything I wanted. I threw in a new plug and it seems to be running slightly rich at the moment I haven't been able to rip it to top speed or fine tune it since it's been raining all day. But for once something has gone right for me on this scoot.
I highly recommend a 70cc upgrade to anyone who is only considering it. Best $150 I've spent on this thing.
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Post by 2strokd on Apr 19, 2009 22:05:53 GMT -5
Im glad to hear it worked out well for you too. Pretty cool how much more punch you get with 70ccs huh? Ive had mine on for about a month and im really happy with it. I need a new back tire now lol. I was running a long shank plug(champion N2C) like Pollini suggests but i had bad spark knock, so i ended up using the short shank NGK 8R8ES. That solved the problem thankfully because it was nasty, made me grit my teeth. Now i gotta remind myself to quit smiling while riding, its getting warmer and the bugs are out now.
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Post by backhill on Apr 19, 2009 22:26:48 GMT -5
Haha thats one of the first things I tried when I let it warm up - see if I could smoke the rear tire (best way to break it in is to beat on it so what the hell right?) . I can't wait until it stops raining and I can go for a cruise.
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Post by 2strokd on Apr 22, 2009 15:14:24 GMT -5
Just watch the real high revs until you got a tank or two ran through(i did anyway). Until then short full throttle bursts are the best for thing for it, and a good tune of course. My scoot will light up the tire easier than i thought, and wheelies lol thats pretty easy now too.
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Post by jefe on Apr 24, 2009 9:14:31 GMT -5
backhill.. can you post a link to the kit you bought?
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Post by backhill on Apr 24, 2009 14:56:56 GMT -5
I can't really link it because of the way the site is set up but I bought the kit from scooter-attack.com. It's the Polini 70cc Sport Cylinder (it's also called the Contesta kit by others). The part number for the kit is P166.0105 if you just want to google that. Scooter-attack was the cheapest I could find it at about $145 shipped. Ebay was around $225 shipped IIRC.
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Post by amirny on Apr 26, 2009 21:37:43 GMT -5
hey guys!! Im upgrading my fueling system with oko 28mm carb and new intake/reed valve. it has 2 nipples in it which I dont know how to connect to my carb. these parts are from scooterparts.com can you help?? thanks!
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