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984 vs. 1203

Buellxb Forum

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MJ Century

Member
Joined
Apr 17, 2010
Messages
13
I know the two engines share many parts but what about the throttle? Does the 1203 have a larger throttle than the 984? I can't find any specs for either engine.
 
up to 2004 throttle bodies and injectors were different. don't know about later models.
 
While were on the subject(sorry to Jack). What's The difference internal?? I mean is it the bore? Stroke? Or ????? Just wondering.
 
While were on the subject(sorry to Jack). What's The difference internal?? I mean is it the bore? Stroke? Or ????? Just wondering.
Click to expand...

On Buell.com I saw that the 984 bore is the same as on 1203 - it is 88,9 mm. However the stroke is different:
- 1.203 cm3 - stroke is 96,8 mm
- 984 cm3 - stroke is 79,4 mm

That suppose to mean that the Crankshafts are different
1203 Crankshaft should have a bigger Diameter.

The Compression ratio on both engines is the same. It is 10,0:1.
That means that the Combustion Cgamber is the same.
So the Connecting Rod should have been shortened on 1203. (Of course if the pistons are the same)
- 1.203 cm3 - Connrod should be shorter
- 984 cm3 - Connrod should be longer

That was only my logical assumptions.

As to the Crankcase and Cylinders... Sorry I do not have any Parts Catalogue so I do not know other parts differences.

It would be very interesting to find out the whole list of the same and different parts.
 
the cylinders are different, I think the 984 should have a higher compression but I could be wrong.

I know that 984 pistons in a 1203 give a slight boost in performance (or did in some gen) so I would think it bumps compression.
 
The best way to find that list is to have the latest Parts Catalogue and to compare both engines.
 
same cylinders, same heads, different crankshafts, different pushrods, different pistons.
 
ich is correct! The 12 has a raised dome on the top of the piston, which leads to higher compression.

Oh and t-body is bigger on a 12.
 
I thot the dome was on the 9's, to raise the comp in a 12 you would use 9 pistons, or am I wrong as usual
 
U might be right uly now that I think about it! I dont remember exactly. I know the pistons are different though. They have the same 10:1 compression ratio.
 
Dont ask me the math, but to get the same compression in the 984 the needed to ad the domed pistons. the 1203 has flat pistons. If you put the 984 piston in a 1203 you raise the compression. That I know is true.

Now a guess, I think the compression goes to around 11.something/1
 
not really pump gas friendly then, with that amount of compression, unless you are lucky enuff to have some of those stations that have 95 octane and no ethanol
 
Makes since now that I think about it Thunderstormgrowl. I know the stroke on the 984 is something like 3.125 and the 12 is 3.8something.
 
Dont ask me the math, but to get the same compression in the 984 the needed to ad the domed pistons.
Click to expand...
I feel kinda stupid for not thinking of/remembering that[confused]
 

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