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Discussion Starter #1 (Edited)
Re piston wt. - should I be concerned going from a ~412 gram piston/pin (stock 2001 - 883cc) wt. to a ~507 gm. wt. with my Buell top side 1200 conversion ?? I read on a different forum about a 'Zipper' light-weight pin being used to keep down the bigger piston/pin weight. Local mechanic said not to worry, unless racing. What's the take -- Am I ok for street use?? Are factory cranks balanced differently between 883's & 1200's??
Thanks for any info here.
 

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Discussion Starter #2
O.K.,here's the scoop, as I understand it talking with Jim (techline man @ Zipper) & more techs at local Harley shop.
For 2001 Sportsters -- crank/flywheel asms, w/ rods are the same for all models, 883 & 1200's. WOW!!
No one seemed concerned going with the Buell pistons with my setup. However, the Buell pistons, pins & rings weigh in at about 100 grams more per cylinder than the stock 883 ones. Don't know what stock 1200 ones would be, be probably a similar wt. difference.
Personally, I just didn't feel easy throwing a couple hundred more grams around with my conversion, because the bike has been smooth with no vibration problems. So, I ordered a set of Zipper forged pistons, thinwall pins, etc., that will weigh in at about half that difference.
Yea, I know, it costs me about $100 more, buy I'm trying to avoid any vibration problems which the bike doesn't have up to this point.
Below, hopefully, is a link to the Zipper page, in case anyone is interested. It's the third picture down and it's their p/n 521-685. Jim, at Zipper, was very helpful, knowledgable and took the time to answer all my anal questions.
I'll let post back here in a week or so when I get it all back & running again.http://www.zippersperformance.com/catalogue/showproduct.asp?cat=591&prod=1142
 

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I went with the thunderstorm set up (heads&pistons), that was about 14,000 miles ago, no problems with no more vibrations vrs 883. Everyone I talked to before I did the conversion said don't worry about it.
Good Luck
Drifter
 

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Discussion Starter #4
Thanks for the info, Drifter... glad to hear I'm in the green zone. BTW, what cams did you go with?? Did you find you needed to change any other components -- carb (other than rejetting), ignition stuff?? Fellows here say to just stay with stock items, initially. And did it REALLY sound better??
Thanks, again.
 

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I went with the Andrews N8 cams. I did the SE coil & ignition mod. later(as money and my wife would permit). I couldn't tell much difference when I installed them so save that for later.
I did go with the thunderslide with 185 main & 45 slow jet and cycleshack pipes. 85hp & 78t
Hope this helps
Drifter
 

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IronButt
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On the 883 to 1200 conversion wiseco makes a piston that weighs the same as a stock 883. There has been case's where they have had to replavce crank pins ... Kinda funny that they use a piston that weighs approx 4 oz more than stock. 3.7X 2 and you are at about 1/2 a lb now spin that to 6000RPM. That is a the flat top kit with stock 883 heads with enlarged chambers . That is the most way kits are done. At our shop we only use the wiseco piston as it is a direct swap and you dont have to mess with the heads. We are done a 1200 sporty now that is using Thunderstorm heads Buell wheels with a AXtell big bore kit. and red shift cams. Should break 105 hp
 

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Discussion Starter #7 (Edited)
The conversion's done & the bike runs. Below is the initial break-in procedure recommended by Jim Lewis at Zipper's. It's a little more detailed than other's I seen, but, makes sense to me -- I used it & all's fine so far.
Everything went pretty much as planned & it started right up after I first turned it over about 5-10 seconds with the plugs out. I really didn't notice much change in the exhaust noise, but it seems the bike actually runs smoother than before & stronger, as it should. I've just driven around the neighborhood & haven't had it over 3k or 40 mph. I'll take it out tomorrow for a longer ride. Thanks for all the input/info here.

The heat cycling process is as follows:
Start the engine in short stages. Perfect piston fit is a critical factor
for engine performance and long engine life. An incredible amount of heat
is generated between the rings, pistons and cylinders during initial
startup. It is at this point where clearances are the tightest and your
rings, pistons and cylinders will meet for the first time.

DO NOT ESTIMATE TIMES – USE A WATCH!!

1. 1st, 2nd, 3rd and 4th starts – Each of these starts should last only ten seconds each at 1250 – 1400 rpm, just above idle speed. After each start, shut the engine off and allow cooling to room temperature. Box or industrial type fans can be used to expedite the cooling process. Take your time with this. Your new parts need to get acquainted.

2. 5th, 6th, 7th and 8th starts - Again, start the engine and run for 15 –
20 seconds at 1250 – 1400 rpm, with time to cool to room temperature between each start.

3. 9th, 10th and 11th starts – Increase run times to 45 seconds, again at
1250 – 1400 rpm. Allow cooling to room temperature between runs, as before.

4. Next 2 runs – No more than 1-1/2 minutes each. Use the cooling fan
allowing the engine to cool to room temperature between each start.

These first few minutes of run time are critical to establish cylinder and piston wear patterns and to protect the rings from overheating. Remember – pistons don’t die, they are murdered!! The absolute worst thing you can do is to start a fresh engine and let it idle, while you kick back and watch it melt from the inside out.

During each successive cycle, check oil pressure to make sure proper
lubrication of the engine and pressurization of the lifters will occur.
Lifters may require two or three start cycles before pumping up completely.
In some extreme cases, lifters may not completely pump up until the
motorcycle has been ridden. Check to ensure oil is returning to the oil
tank.
J. Lewis
Tech Services, Zipper's Performance Products.
 
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