TC top end interchange

[cowboy]

Does anyone here know if the complete top end from a 07 96in will fit on to a 03 88in both bikes are FLHT's head jugs pistons ect  I have posted on another fourm & made a few PH calls & came up about where I started not knowing 
thanks

[Sonny S.]

Pistons will not.
Will also need intake flanges for 06 & up

[TXChop]

Yup, sonny is right....pistons will technically fit, but may not be the best compression ratio for you....

Make sure you get the flanges to match the year of the heads.

[PoorUB]

T o clear it up for you the bore on the 88" and 96" are the same. The jugs are the same. The heads are the same untill 2008. The 96" come with a longer stroke to make up the extra inches. The crankshaft and rods are differant, the pistons are differant. Technically it will all bolt togather, but I doubt it would run!

[cowboy]

poorub why wont it run ? is it becaues of the pistons ? If all is the same except the pistons , then with a another set of pistons it should run , em I right or wrong in this thinking , I have called a few good shops & some same it won't even bolt up others say along the lines above here , I don't have the newer books & can't seem to find anything doing a search on the puter Thank's

[sean fxd]

<<poorub why wont it run ? is it becaues of the pistons ? If all is the same except the pistons , then with a another set of pistons it should run>>

yes with 95" pistons it will work fine.  like someone said you will need new intake flanges for the new style heads.

sean

[Sonny S.]

The 88" & 95" bikes use a different flywheel assembly than the 96" ers. The cylinder bore of the 88" is the same as the 96"... 3.750. That's why 96" cylinders will work on an 88, and 88 " cylinders will work on a 96, but the pistons will not. (because the stroke of the flywheels are different, 88" = 4.00 stroke, 96" = 4.375 stroke)
If you go to a 3.875  bore on an 88 you end up with 95".
If you go to a 3.875  bore on a  96" you end up with a 103"

Heads will work on either as long as you use the intake manifold flages to match the era of the heads.
So with all that said, if you buy heads and cylinders from a 96"er, use pistons that are designed for the 4" stroke of the 88"er.....and get a pair of 06 & up intake flanges 

[PC_Hater]

Now we know the heads and barrels from the 96" motors fit  - as long as you use the 06 up intake flanges, the question becomes:-
Why won't the pistons fit?
The compression height = how much piston there is above the centre line of the gudgeon pin
and the length of the piston are needed.
I assume the gudgeon pin diameter didn't change between the 88s and the 96s.

With that info you can work out if the compression ratio will be very low, or if the bottom of the skirt risks slamming into the flywheels at bottom dead centre. A piston that would give a very high compression ratio in a standard 88" motor might come just right in the hybrid 88/96.

But I think the above posts mean just use the 88" piston of your choice.

(gudgeon pin is such a nice name. whoever heard of a limp gudgeon?)

[Admiral Akbar]

"if the bottom of the skirt risks slamming into the flywheels at bottom dead centre. "

The good thing about running the same rod length and shorter stroke is that you got more clearance at the bottom than a stroker piston needs. Max

[sean fxd]

<<The good thing about running the same rod length and shorter stroke is that you got more clearance at the bottom than a stroker piston needs. Max>>

Bruce...er Max,

Isn't the compression height on the 103 piston (4.375stroke) way less than the 95 piston (4.000 stroke) so that the 103 piston would be way "down the hole" if you used it with a stock stroke crank?

Sean

[PoorUB]

Anyone know what the pin to deck height is on a stock TC88 versus a TC96 pistons? Seems to me the pin to deck on the 96" would be less, so if you tried to put 96" pistons on a 88" crank the piston would be down the hole quite a bit a TDC.

[Admiral Akbar]

<<The good thing about running the same rod length and shorter stroke is that you got more clearance at the bottom than a stroker piston needs. Max>>

Bruce...er Max,

Isn't the compression height on the 103 piston (4.375stroke) way less than the 95 piston (4.000 stroke) so that the 103 piston would be way "down the hole" if you used it with a stock stroke crank?

Sean

Aaaah, Yep. Piston CH is something like 1.090 for a 96 and 1.270 for an 88 so the is about 3/16 difference on the top.. If the bottom on an 88 just cleared the wheels then the piston on the bottom would have to be 3/16 of an inch shorter also.. Same rod length, flywheel diameter.. Max er Bruce

[PoorUB]

So what compression ratio do you get with the piston 3/16" down the hole? 6 to 1??

[ejk_dyna]

close ... 9.6 with zero deck goes to 7.1 with pistons .187 down the hole.  no compression releases needed...LOL

[PoorUB]

close ... 9.6 with zero deck goes to 7.1 with pistons .187 down the hole.  no compression releases needed...LOL

No premium fuel either!
Once you get it runng on gas, you can switch over to "distillate" like the old farm tractors ran!

[motrhd]

 Cowboy, all you need to make that setup work is a set of stock 88 CI pistons or 95 CI pistons if you are going for the big bore. Also the proper intake flanges as the ports and flanges were changed in '06. If you are looking for a pair of stock STD bore pistons, I have a pair around here somewhere with less than 10 miles on em. For those not really understanding stroker pistons; piston deck height or compression height is changed by raising the wrist pin(gudgeon pin) up towards the top of the piston as is needed. This maintains proper deck height and also the bottom of the piston skirt is cut off or trimmed to clear the crank. I have had pistons with pins so high up the the oil ring went over the wrist pin buttons. Hope this might help clear some questions up

                               
                                                                             


        What the heck is a gudgeon ?

[PoorUB]

What the heck is a gudgeon ?

Here ya go!

Gudgeon
From Wikipedia, the free encyclopedia
In general, a gudgeon is a circular fitting, often made of metal, which is fixed onto some surface. It allows for the pivoting of another fixture. It is generally used with a pintle, which is a male type of hinge pin which pivots in the hole in the gudgeon. As such, a gudgeon is a simple bearing.

In engines, a gudgeon pin (UK, wrist pin US) joins the small end of a connecting rod to a piston or crosshead

[Scurvy]

I am a visual sort of guy, so pictures always help me...

These are stock pistons, 88cu.in. on the left, 96cu.in. on the right.

Same diameter...


Shorter crown, shorter skirt, wrist pin higher


Looks to be considerably ligher! I like that...

[motrhd]

PoorUB thanks for clearing that up...LOL
I was being kinda rhetorical but thank you anyway

Scurvy, excellent show and tell, should set it straight. The 96 does look lighter.

[PoorUB]

PoorUB thanks for clearing that up...LOL
I was being kinda rhetorical but thank you anyway

Anything for the group!!