Found a piston crack
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Road Warrior
Joined: Mar 2013
Posts: 1,897
Likes: 1,413
From: Lost
Would do two search,
The first is cylinder detonation problems from running too lean to first understand that and why it can crack the piston,
Then the second search is Harley tuning too lean to meet EPA standards that cause the detonation problems to begin with.
Granted that problem could have been induced by clogged fuel filter, not enough pressure on the rail, or clogged fuel injections to cause the lean problem, but with Harley tuning AFR well above 14.7 to start with, main reason for most detonation problems in the first place.
And going to guess, motor is still on Harley stock tune, way too lean to start with (fuel is cooling).
The first is cylinder detonation problems from running too lean to first understand that and why it can crack the piston,
Then the second search is Harley tuning too lean to meet EPA standards that cause the detonation problems to begin with.
Granted that problem could have been induced by clogged fuel filter, not enough pressure on the rail, or clogged fuel injections to cause the lean problem, but with Harley tuning AFR well above 14.7 to start with, main reason for most detonation problems in the first place.
And going to guess, motor is still on Harley stock tune, way too lean to start with (fuel is cooling).
I guess going stage I would have been helpful. On the other hand I like how stock bike is quiet, I barely hear my bike or exhaust when riding.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,830
Likes: 7,968
From: poway
Would do two search,
The first is cylinder detonation problems from running too lean to first understand that and why it can crack the piston,
Then the second search is Harley tuning too lean to meet EPA standards that cause the detonation problems to begin with.
Granted that problem could have been induced by clogged fuel filter, not enough pressure on the rail, or clogged fuel injections to cause the lean problem, but with Harley tuning AFR well above 14.7 to start with, main reason for most detonation problems in the first place.
And going to guess, motor is still on Harley stock tune, way too lean to start with (fuel is cooling).
The first is cylinder detonation problems from running too lean to first understand that and why it can crack the piston,
Then the second search is Harley tuning too lean to meet EPA standards that cause the detonation problems to begin with.
Granted that problem could have been induced by clogged fuel filter, not enough pressure on the rail, or clogged fuel injections to cause the lean problem, but with Harley tuning AFR well above 14.7 to start with, main reason for most detonation problems in the first place.
And going to guess, motor is still on Harley stock tune, way too lean to start with (fuel is cooling).
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,830
Likes: 7,968
From: poway
It does seem to help but it's only a few degrees.. I recently leaned out the whole map on a my tmaxed 107 EGC 1/2 point AFR. Picked up about 3-5 MPG but the oil temps went up a few degrees..
Seasoned HDF Member
Joined: Mar 2021
Posts: 17,894
Likes: 3,551
From: backwoods
First thing I would do is check pinion runout to make sure the crank is still healthy. If crank is good, check out the 107" kit from Fuel Moto. It runs about $1400 and comes with everything you see in the picture and would really wake up that engine of yours. Cheaper than oem in the long run and probably better quality components. Of course you also have to budget for a dyno tune following install but as already mentioned, you might as well make some lemonade while you have it apart!
You starting chasing every hp, plan for darkhorse next year and tranny too, expecially on an older bike.
Road Captain
Joined: Jun 2008
Posts: 714
Likes: 53
107 or 110 big bore fuel moto
May as well
Same cost
You will have to buy a Power Vision which you will not regret
May as well
Same cost
You will have to buy a Power Vision which you will not regret
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Seasoned HDF Member
Joined: Dec 2005
Posts: 19,830
Likes: 7,968
From: poway
Haven't looked at the price but it seems to me that you can save money on a 107 because you can reuse your old cylinders..
