I have been looking at a big bore kit for my 2005 88B. There appears to be 95,96,97,98 and now 100 CI kits available. That may not be a complete list for all I know.
Is this just the normal progression of technology or are there other considerations involved? Why would someone choose a 96 over a 97 for example?

I'd appreciate and thoughts on the matter.

 

The 100” is the newest by s&s, which I believe is shelved for now due to patent infringement on the newer HD lined cylinders. Apparently, they will have New 100” offering within a couple months.

Really no difference between the 95; 96, 97; and 98 kits. Just boring the jugs a tad more. Thousands of 98” kits out there. As reliable as the 95” I think. You would chose the bigger because you get a few more CI. You can expect anywhere between 1 to 1.2 hp and torque for each cubic inch. So you could gain a bit.

Personally, the 98” is the most cost effective to do. I would talk to anyone of the sponsors here. Plus, you’re near R&R cycles.

 

The 95" kit was the standard big bore kit; boring from 3.750" to 3.875". A 96" motor is the displacement of the later TC motor maintaining the 3.750" bore but increasing the stroke from 4.00" to 4.375". A few years back some started boring the 3.750" cylinders to 3.932"/3.938" which increases the 4.00" stroke motor displacement from 88" to 98"; there is truly no difference between a 97" and 98" top end. As a matter of fact, if one does the math, there is no 98" configuration; 97.39" is as big as it gets with a 4.00" stroke.

The 100" configuration is a 4.00" bore x 4.00" stroke. There are now aftermarket pistons available for the new HD 4.00" cylinders, so that will be the only way to get to 100" unless S&S hasn't sold out of their 100" kits. Personally, since the reliability of the 97"/98" configuration has been proven vis the unproven combination of the HD cylinders and aftermarket pistons, that is the path I have chosen for the current upgrade of my 95" motor; 98" with more compression, better heads and longer cams; shooting for 110/115 numbers. 1.2 TQ/HP per cubic inch is an admirable target but rare in most.

 

98" will provide a very good platform to work from even at 10.5: static it can be a very reliable motor depending on how much comp the cam bleeds off. My 96" er (Evo) is right at 1.2 and still has a little room for growth... I definitely wouldn't push the TC b motor more that that though. Cranks weren't the best and isn't that a balance shaft motor? That also absorbs a little of the power....

 

Yes it is the balanced TC motor... Thanks for your thoughts on the matter.

 

We bore to 98" here.
Scott

 

Ya don't say....ha ha ha

 

A 2005? I'd check run out because this conversation can turn into 103, 105, 107, 124.....

 

Yes an 05 with 3500 miles on it. I bought it off the original owners heirs. It was one of four bikes he owned. From the tie down strap scuff marks left on the handle bars , I'd say it got towed more than rode. parade bike?


I think I am still at a loss as to why a 95 inch big bore kit is still being sold along side the 98 inch kit.

I understand from the S&S website that their 97 incher has lower compression than the 98. Also why do they sell 95/98 big bore kits with cylinders? Why not just bore out the stock ones? (shrug)

 

Nice ride.

95" kit is standard BB kit from the MoCo; has been since the TC88 was introduced; typical MoCo strategy; sell an under powered TC88 but offer a 95" BB kit to bring the power up to where is should have been when it came off the assembly line. Some are of the opinion that boring to 98" does not leave a stable cylinder spigot (the part that fits in the case); however, there are enough of them running now without issues that the "sky is falling" mentality has been long forgot. I am not certain but would assume that there are piston options with the S&S kit that will set compression higher but maybe not.

Boring one's own cylinders is cheaper and having the pistons on hand allows the machinist to fit the piston to a true bore at the manufacturer's specified tolerance. Buying "kits", although I understand S&S is much better at quality control than the MoCo, can be hit/miss, i.e., cylinder bore not true and/or piston to cylinder fitment not to spec. OEM cylinder are cheap; my machinist has a pile of them on the floor in his shop. Many independents will work with customers on an exchange basis to reduce downtime as well. So boring OEM cylinders is usually the preferred DIYer option.

One thing to look for on the '05 models is excessive oil consumption; the valve guide seals were **** and many were replaced under warranty, so something to watch out for. One of my bikes in an '05 FXSTD and had that problem and the seals were replaced under warranty. As soon as the seals were replaced, I voided the factory warranty by building a 95" motor with gear drive cams; crank run out at the time was .0025". 25K miles later, I was checking things out and the crank run out had increased to .0045"; a little much for gear drive cams. So, I am now in the process of addressing the crank issue and rebuilding the motor in a 98" configuration. So, check the crank run out as part of your familiarization with the bike to establish a baseline for future reference.