I have and do understand the words of wisdom that you have written down. Thanks for the replies guys. Moving forward, somewhere in my lopsided brain, going to a 107 in.ł motor would be the last time I would be able to use my original, stock, cylinders. That being said, I purchased some new old stock 3.875 / +.010 diameter German made Harley Davidson pistons in the 📦 box. Between buying the pistons, a new upper gasket reseal kit, and having the cylinders board to the diameter of the new pistons, I don’t think I’m going to be into it but about $500. I talked with a very recognized engine builder about all of it, except the damn inside diameter of the 3.875 head gasket. Hence, my question. I will call him and verify that I will use the correct gasket. The main reason I don’t want to go to a full-blown 107, because I already have 104 hp and 119 lb/ft of tq. I want to keep the piston weight down to or as close to factory specs that I can. When or if I decide to ever go to 107 in.ł, I’m gonna have to pull the whole motor and have the bottom end done, hence, big bucks. I personally wouldn’t put together a 107 and worry about the bottom end stress on a 60 or 70,000 mile motorcycle With my wife on it unless I knew the bottom end was bulletproof. I really don’t give a crap about Dyno numbers. As long as it pulls and rides reliably, that’s what I’m after. Going to 107 in.ł, I’d change my now 4.5 injectors to 4.9 injectors, crank work, case work i.e. Timken bearing etc. The head work that I had done On my heads when I originally built the 103 was exceptional. That’s why I got such good numbers out of a stock 103 with an S&S 570 cam. I like my S&S 570 for the riding style I have. Therefore, 3.885 bore is where I’m going. And if I wear the .885 bore out, 107 in.ł it will be. Oh yeah I forgot, plus, I don’t want the added heat of a few more cubic inches. What I have now is plenty lol. And at the end of the day only going .010 oversized, I don’t have to have the engine re-tuned. The TTS will accommodate up to a 20% increase with no worries.

 

3 posts and done

 

Just call fuelmoto...order up their 107 kit with woods 777 cams add a power vision tune and you'll be very happy for a long time. I don't have weights in front of me but I doubt the difference between a 103 piston and a 107 can be felt on a harley. I just did a 117 drop on ,so I went from a 110 to 117...the pistons were heavier but the wrist pins were lighter than the old ones...see what they did there? I'll be honest and say that I can feel a difference...it vibrates even less than it did before. I do have a darkhorse crank and it feels like it was setup for the new weight...very smooth. I wouldn't worry about going 107 and being done with your stock cylinders...I might be wrong but you could probably still get a .010 over pistons that'll allow you Clean up the cylinders for another rebuild. Even if you can't do that there's plenty of cheap take offs available or go all out and get a new set from fuelmoto or s&s, still a cheap option and I don't recall reading about any issues with anyone using those parts. Did a fuelmoto 107 kit for a friend of a friend last year and he sent me a text a few days ago saying how much fun his bike is again. Go all in...otherwise it's like only putting your pecker halfway in because you don't want to wear it out for the next guy...f the next guy lol.

 

Pretty much right on on all counts. As you can see in the piston weight thread, doing the bottom end for balance reasons isn't necessary. Piston weights aren't an issue. They're compensated for with pin weight.
Any heat issues would be tune related and 107s can be bored .10 over as well. That said when the first guy that bored mine did them out of round, I picked up another set of cylinders for $50.
Another 10 to 15 hp/torque, or more in my case with different cams etc. is a nice little bump that can definitely be felt on the butt dyno. I'm seeing mid to upper 120s with the right supporting hardware, good flowing heads, and a good tune.
Nothing wrong with 104hp and no reason not to keep the 570s. They're a good cam.
But even another 10hp/torque would be beneficial, especially riding 2up, and would quite likely even run cooler by the motor not having to work so hard to pull the weight of 2up riding. It can also improve fuel mileage for the same reason. I've seen more power do just that unless you can't control the right wrist of course.
As for crank work, if you're willing to risk it as is with a 103, no reason not to with a 107. And the timken bearing is an unnecessary waste of $$$ if/when you do address it that can actually hinder self alignment. Some builders even refuse to do it.
I see it as nothing but a feel good thing. Makes the customer feel good by having it and makes the builder feel good about his bottom dollar.
Throw an S&S crank in and be done. No welds to come loose either.

 

I just pulled off my 98" rev perf cylinders of my 88. Going back to 95" and boring my old jugs. Cheaper. I won't do nikalsil again, to expensive to replate. For the cost of replating I could get S&S for another $100, which is iron and should be able to be bored next time.

The shop said he will not bore cyliners on 96", crap bottom ends

Will need to decide what to do with my 96" soon has 70k. You could argue building anything after 02, is questionable.

 

Shop won't bore to 98"? Find another shop; 3.938" bore has been common practice for over 8 years. Everyone thought the sky was falling when shops started boring to 3.938"; spigots would be too thin and would not hold a true bore; however, that has been proven not to be the case. I run a high compression 98" motor making 115/115 numbers with no issues. Nikasi was a "thing" back in the day but soon faded; too many issues.

 

You missed the point.

He won't bore for 96" bikes cause bottom ends are junk. As in 2007+ bikes. A stroked 88". I am going to 95 from 98" on a 88". He will not bore any size for 96", a post 2007. I am not sure you should bore for any bike after 2002, myself. But he will do that

 

​​​​​​And never mind the countless bikes out there that have done just what you claim shouldn't be done, right? Well you enjoy that "upgrade" from 98" to 95".

 

It is not an upgrade it is maintenace. The cylinders were scared. I didn't feel like spending the money to have the nikalsil re done, so I just bored out my old stock ones.

 

You really need to think through your replies ... Just a thought :>)