Very true.... and as always... thanks for the details.... always informative and ' lookin out ' for us.... thanks Hulkss
120ST woes.... it's going in for teardown...
- Thread starter Spazz
- Start date
Very true.... and as always... thanks for the details.... always informative and ' lookin out ' for us.... thanks Hulkss
Wow.... that much of a change... why not wait until you need to? I mean... the only reason I am contemplating the upgrades is because I am in there with issues... if I had no issues I would just run it until I did.
I take it September your warranty is up? Mine is 8 Aug
When I start mine now it sounds like there is a guy inside with a hammer trying to get out. Dealer says it's normal. It does quiet down though when hot. Piston slap I guess. I don't like it.
My next big ride is to Alaska and back. I want to make it without any concerns. I would like a 100,000 mile capable motor.
I'm keeping the 4.060 120" bore and dropping from 4 5/8 to 4 3/8 stroke and increasing rod length to 7.667 from 7.575. "Standard" proportions for a 113 with all Harley parts.
I did order a custom blueprinted and balanced flywheel and connecting rod assembly from Darkhorse. Specifically balanced for the pistons I will use.
Working on other component details now.
My next big ride is to Alaska and back. I want to make it without any concerns. I would like a 100,000 mile capable motor.
I'm keeping the 4.060 120" bore and dropping from 4 5/8 to 4 3/8 stroke and increasing rod length to 7.667 from 7.575. "Standard" proportions for a 113 with all Harley parts.
I did order a custom blueprinted and balanced flywheel and connecting rod assembly from Darkhorse. Specifically balanced for the pistons I will use.
Working on other component details now.
That really sucks you guys are having these issues with the 120st. I was actually wanting that upgrade next year. I would have thought, considering what I thought was a successful 120r would have been a some what bug free 120st. They share similar specs except for the cams. It seems to me HD should find a way ease this discomfort for you guys who jumped first on the 120st. It quit disappointing to say the least, I hope they take care of you guys.
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Another update:
Bottom end was fine... jugs in spec.... so....
Not upgrading anything at this point...
Heads are getting reworked.... honing the jugs... new pistons and rings....
Should be a week and I'll have her back home
100% covered by MOCO....
Sent from Note4 via TapaTalk
Bottom end was fine... jugs in spec.... so....
Not upgrading anything at this point...
Heads are getting reworked.... honing the jugs... new pistons and rings....
Should be a week and I'll have her back home
100% covered by MOCO....
Sent from Note4 via TapaTalk
Ring gap was off a touch... getting upgraded parts, but not performance based... just reliability for now.
Sent from Note4 via TapaTalk
Since the warranty will be gone, I'll do it this time. I hope I have as much fun as you did with your engine build. Thanks for your posts on the subject.
New piston fit is .0026" - .0036" loose. Service limit is .0061.
It would be nice to get the +.010 pistons and rebore & hone to fit at the min end of the range.
My favorite kind been working with you guys for years. Now all the technical aspects you always have make more sense.
These big engines are pushing the limits on engine durability. With a proper hone finish and piston fit most will break-in and run a long time and some will not.
These engines require a top quality plateau honed cylinder finish.
plateau-honing
plateau.pdf
sunnen.pdf see page 13
Dave Mackie Engineering: "Our pro-cylinder/piston preparation utilizes several steps to simulate actual engine conditions. We use state-of-the-art equipment and the latest honing techniques used in NASCAR, Detroit, Formula, etc. Our plateau and soft brush honing techniques result in a shorter, cleaner break-in period, better ring seal, and longer engine life."
head-quarters cylinder_boring
