Sorry for my ignorance, but why do the 883s wiegh more than the 1200s?

Also, I heard that the 883s have a longer/heavier piston, and that if you keep the same piston (because you don't change the bore, just the stroke) when you go to 1200 or 1300+, you will actually produce more torque... is this true?

Basically, if you really want a hot-rod sporty, take an 883 and built it...?

Thanks

 

1200's have bigger holes in the engine, so they're lighter... maybe? [sm=biker2.gif]

 

I think most of the 883 to 1200 conversion include new jugs and new pistons because they are a larger diameter. Most kits you don't have to change the rods or anything on the botom end, so you keep the same stroke. The cubes come from the increased bore diameter.

 

the 1200s cylinders are made with less metal to hold a bigger piston and keep the same size on the outside. that little bit makes a difference.

 

correct answer.

 

The 883 cylinder has ALOT of meat to in. When i did my 883-1200 big bore conversion, i had the cylinders bored out to accept the larger diameter pistons. From what i recall it took about 28 cuts to get the cylinders bored out to the correct diameter. The rods, push rods,rockers, need not be changed. I also had my heads domed out etc.The 1200 pistons were about 1/2 inch larger in diameter from what i recall,which gives you a good idea how thick the sleeves are to allow you to shave 1/2 inch off and still have enough left for strength and future rebuilds if need be. The 883 motor and cylinders are built very well and you can do quite abit with one of them motors. I will tell you though that i did not realize an 883 weighs more. Thats interesting.

 

The weight difference is often ~5 lbs. Really negligible. The 883, 1000 & 1200 were designed to have just about the same everything by simply changing bore. Very economical to manufacture.

Due to same stroke, bigger bore yet still low rpm (under 7k) the 1200 does not get high hp values, when compared to something like the v-rod. Both the hp & torque go up due to the increased bore of the 1200 ... but don't forget larger valves allowing more air.

If you really want a hot-rod sporty you can get 79, 80, 88,90, 99 & 100ci bore & stroke kits. Including cast jugs for better heat retension on the 1/4 mile! Cost for the kits is often $3k and up.
http://www.axtellsales.com/
http://www.zippersperformance.com/ca...ts.asp?cat=865
http://www.sscycle.com/

The problem with many of the stroker kits is the piston to piston skirt clearance. The skirts often have to be machined to keep from coliding at BDC. This is why these engines have poor engine life compared to near stock displacements.

 

if you dont know then its not an ignorant question. I have an apprentice working with me and I tell him he is ignorant only if he dont ask questions. to answer your question there are alot of variables when doing a conversion , what alot of people forget is when you re-jug an 883 to what ever size you want unless you do head work then you are cheating yourself and leaving alot on the table, alot of people think they are generating more torque by simply re-jugging but in reality it is the transmission . an 883 is geared lower and gives the impression of the motor making more torque.

 

"But using the 883 heads increases compreession ratio" Yes it does but it does not flow more air. It also took me a while to determine why "use buell heads" is recommended. The Buell heads have a different valve angle, airflow & combustion properties. In theory you could machine the 883 heads to match but it is not cost effective.

883 front sprocket 27 tooth.
1200 front sprocket 29 tooth.

 

lol you can stick a potato in the exhaust and increase compression also but if the motor dont breath your not going anywhere very fast. 883 heads on a 1200 conversion area waste of time . for what it would cost to have them machined you could buy a set of 2004 or up 1200 headswhich are some of the best the moco has produced and still have money in your pocket. and yes asmaller sprocket gives greater gear reduction than a larger one.