96 heritage engine issue
Seasoned HDF Member
Joined: Dec 2005
Posts: 20,030
Likes: 8,086
From: poway
I will get a picture of the plugs for ya.
I am still trying to understand how tuning would cause a worsening vibration as rpm increases i get poor preformance and detonation causing issues. I will say I am not a stranger to tuning carbs, unfortunately i do not remember the jet sizes. Ever try and sync 4 carbs? Pain in the butt! With that said the bike does not hesitate there is no signs of over or under fueling it is a solid vibration coming out of the engine it would probably push past 4k rpm it is just currently rpm limited to this and with the vibration as bad as it is i know it would probably be a bad idea to push past.
Wiesco stated that the pistons weigh 350g and that wrist pin is 80.5g this is lighter by 47 grams per piston from the stock setup. I do plan on verifying this info my weighing them myself but with the information provided if that is put into a calculation for force at 4000rpm a difference of 94 grams is able to apply 371 lbs of force, don't know about you but that is a hell of a lot of imbalance in the bottom end. As that is the heavy end of the crank that is producing that force I really believe that is the culprit here unless someone can explain how I am either over thinking that or am missing something.
FYI i am not saying i know it all and i am arm chairing it at this point, as i am still tied up on another project in the garage before i start on this. I do appreciate you guys input i am just trying to understand the recommendations that you are giving and filling in any of the info i have forgot to include.
Have not been able to find a heavier pin yet, anyone know who to ask?
Thanks yall
I am still trying to understand how tuning would cause a worsening vibration as rpm increases i get poor preformance and detonation causing issues. I will say I am not a stranger to tuning carbs, unfortunately i do not remember the jet sizes. Ever try and sync 4 carbs? Pain in the butt! With that said the bike does not hesitate there is no signs of over or under fueling it is a solid vibration coming out of the engine it would probably push past 4k rpm it is just currently rpm limited to this and with the vibration as bad as it is i know it would probably be a bad idea to push past.
Wiesco stated that the pistons weigh 350g and that wrist pin is 80.5g this is lighter by 47 grams per piston from the stock setup. I do plan on verifying this info my weighing them myself but with the information provided if that is put into a calculation for force at 4000rpm a difference of 94 grams is able to apply 371 lbs of force, don't know about you but that is a hell of a lot of imbalance in the bottom end. As that is the heavy end of the crank that is producing that force I really believe that is the culprit here unless someone can explain how I am either over thinking that or am missing something.
FYI i am not saying i know it all and i am arm chairing it at this point, as i am still tied up on another project in the garage before i start on this. I do appreciate you guys input i am just trying to understand the recommendations that you are giving and filling in any of the info i have forgot to include.
Have not been able to find a heavier pin yet, anyone know who to ask?
Thanks yall
This guy talks about too much advance.
FWIW I've not had issues syncing 4 cylinder carb tho all of the stuff I do is inline 4.. The trick is to sync at about 3000 then blip the throttle a couple time to make sure the mech is settled. The V4s and leadwings can have issues with cross over linkage tho V4s were beyond my time as a Hinda Mech.. Did service a few.
BTW. IIRC HD balanced an EVO at 52%. Wouldn't going to lighter pistons make is closer to 60?
Thread Starter
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Intermediate
Joined: Sep 2022
Posts: 31
Likes: 9
From: Washington
Not sure what you are saying about detonation.. Are you saying you get detonation before vibes? Or that you can't have vibes before detonation?
This guy talks about too much advance.
https://www.youtube.com/watch?v=TjdZBZoYw2U
FWIW I've not had issues syncing 4 cylinder carb tho all of the stuff I do is inline 4.. The trick is to sync at about 3000 then blip the throttle a couple time to make sure the mech is settled. The V4s and leadwings can have issues with cross over linkage tho V4s were beyond my time as a Hinda Mech.. Did service a few.
BTW. IIRC HD balanced an EVO at 52%. Wouldn't going to lighter pistons make is closer to 60?
This guy talks about too much advance.
https://www.youtube.com/watch?v=TjdZBZoYw2U
FWIW I've not had issues syncing 4 cylinder carb tho all of the stuff I do is inline 4.. The trick is to sync at about 3000 then blip the throttle a couple time to make sure the mech is settled. The V4s and leadwings can have issues with cross over linkage tho V4s were beyond my time as a Hinda Mech.. Did service a few.
BTW. IIRC HD balanced an EVO at 52%. Wouldn't going to lighter pistons make is closer to 60?
I just found 4 carbs to be a pain in the butt because if you tweak one then you have to rebalance all of them and at 13k rpm can be a bit tricky trying to get everything to hit just right, wasn't horrible just a pain if you know what i mean. My experience was from r6 where they used two different sets of jet do to engine heat differences and trying to widen the torque band IIRC, i ended up using the same jet for all carbs and dear lord she would hit around 6k and not let off until 13.5-14k and it was like a damn rocket for sure, to be young and dumb lol.
So maybe I am thinking about it backwards, I guess I will have to go read more but I thought lighter pistons would push it to a lower balance weight. If they do balance to 52 then that would push me to like 46ish which is way off.
Thread Starter
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Intermediate
Joined: Sep 2022
Posts: 31
Likes: 9
From: Washington
Ok you are correct the lighter piston would make it go in this direction, i was wrong and had it backwards in my head. So i guess pulling the engine and measuring all of this is going to be my next step. As I am working with a bunch of unknowns I need to solve for them first. This will also allow me to fully inspect everything and make sure all is as it should be.
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,197
Likes: 7,698
From: Poolville
Not offended in any way man, just trying to look at all the variables. And as compression increases believe it or not your AFR changes and the requirement for fuel changes as well. This is why I asked what jets are you running with the combination you currently have..
Thread Starter
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Intermediate
Joined: Sep 2022
Posts: 31
Likes: 9
From: Washington
Well i got some more information, as 98hotrodfatboy pointed out the pistons that came in the kit that i purchased were not off the shelf pistons. I reached out to wiesco and low and behold they are even closer in weight to stock pistons still a little light but they are closer 376 for a bare piston, the pin is still the same weight at 80.5. So It really looks like a full tear down is in my future, i must have screwed something up... ugh lol
Seasoned HDF Member
Joined: Oct 2015
Posts: 13,596
Likes: 35,077
From: Pine Flat Dam/South Bay Area, CA
Well i got some more information, as 98hotrodfatboy pointed out the pistons that came in the kit that i purchased were not off the shelf pistons. I reached out to wiesco and low and behold they are even closer in weight to stock pistons still a little light but they are closer 376 for a bare piston, the pin is still the same weight at 80.5. So It really looks like a full tear down is in my future, i must have screwed something up... ugh lol
Thread Starter
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Intermediate
Joined: Sep 2022
Posts: 31
Likes: 9
From: Washington
Thanks!
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,197
Likes: 7,698
From: Poolville
Also need to check your piston to cylinder clearance, forge Pistons should be at least 0.0035" to 0040" for your bore..
I did not like what I read when I located the information on your piston cylinder kit It appears they were only honed for a 0.0022" clearance.. ok for cast but not forged..
I did not like what I read when I located the information on your piston cylinder kit It appears they were only honed for a 0.0022" clearance.. ok for cast but not forged..
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Seasoned HDF Member
Joined: Oct 2015
Posts: 13,596
Likes: 35,077
From: Pine Flat Dam/South Bay Area, CA
Also need to check your piston to cylinder clearance, forge Pistons should be at least 0.0035" to 0040" for your bore..
I did not like what I read when I located the information on your piston cylinder kit It appears they were only honed for a 0.0022" clearance.. ok for cast but not forged..
I did not like what I read when I located the information on your piston cylinder kit It appears they were only honed for a 0.0022" clearance.. ok for cast but not forged..
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,197
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From: Poolville
Clearances also need to be calculated with the silicon content in the pistons taken into account. A forged piston with a high silicon content will have low expansion and can be set up with surprisingly tight clearances. There's no rule of thumb, you go by what the manufacturer recommends. If you set the clearance on the tight side of specifications, the break-in process will be slow and tedious, but will be rewarded with a quiet running top end and long piston life.
hypereutectic Pistons are a different breed .