Harley Davidson Forums banner

Wrist pin ream

7K views 28 replies 6 participants last post by  glust 
#1 ·
Replacing wrist pin bushings in my 02' twin cam 88. I've been able to find that the range for wrist pin to wrist pin bushing variance is .003" - .007" Is this correct? Thanks .
 
#3 ·
If you got that info from the H-D service manual it's correct for when that book was printed but doesn't cover any changes that would have been supplied in the service bulletins after that print date.
My take is those specs are way loose ! You should be able to slide the pin thru with some resistance, there's a technique to doing it, no measuring involved except to get close. I would go for .0015" to start and see what the feel is pushing the pin thru.
Just do not ream the bushing out to far or it's a gonner !
 
#4 ·
Thanks Schmidty. Like they say, you can always take more off but you can't add back on. I'll start light and work up. How critical is ball honing after reaming? Trying not to purchase another overpriced harley part #.
 
#11 ·
What is the measurement of your con rod wrist pin bushings right now ? In or out of spec ? How are you taking your measurements ? What instruments are you using ?
 
#12 ·
The pin that came out of the bike with 88" jugs (3.75" diameter) was .927" . The old bushings were sized well but the rear one had a burr across it that had translated onto the old pin. I am getting 98" jugs back from Scott at Hillside soon. I'm assuming the new pins are also diameter .927" . I'm going to wait until I have them in hand before I look at reaming the new wrist pin bushings.
 
#14 ·
I ran a scotchbrite Wrapped on a drill bit to try to take off as little as possible. I got about half of it out. Was worried about taking out too much and having the pin slop around. I'll work with it some more and see if I can save it. I measured the diameter of the old wrisst pin with a micrometer and it came out very close to .927" . (my micrometer doesn't go to thousandths) . Researching online it looked like stock wrist pins are .927"
 
#15 ·
Schmidty, I did not originally measure wrist pin bushing. I didn't remove them because they were out of spec. I removed them because the rear had nicks in it that had transferred to the wrist pin. It almost looked like a threaded rod got dropped on it. The nicks are evenly spaced like threads.
 
#17 ·
Schmidty, I did not originally measure wrist pin bushing. I didn't remove them because they were out of spec. I removed them because the rear had nicks in it that had transferred to the wrist pin. It almost looked like a threaded rod got dropped on it. The nicks are evenly spaced like threads.
We used to that on purpose ... knurling bushings ! Did both the bushings look like that or just one?
Knurling bushings is done to propagate oil infusion throughout the entire bushing. Also to shrink the bushing I.D. so it can be reamed to size.
 
#16 ·
Oh ! You already removed the bushings ... well that's that ! Now ya gotta install new ones so just try to not bore them out to much before final sizing. If ya goof up you can always try again cause they are replaceable !
I would wait for the jugs cause they'll come with new fitted pistons, rings and wristpins. Double check measurements on all parts prior to assy. too.
TIP: Put the new bushings in a baggie in the freezer for a couple hours before pressing them in, they'll shrink and slide right in no problem.
 
#18 ·
Just the rear one. The front was smooth as a baby's a$$. I wouldn't have given it a thought but the wrist pin looked to have been influenced by the rough spots. Very interesting about the knurling. Learn something new everyday. The marks were on the bottom of the bushing so I guess it makes sense that it was done to move oil up through the entire bushing? Thanks for all of your help and sharing your expertise.
 
#19 ·
I'm watching this thread, I'm interested now.
Wondering if your engine is gonna rattle like a bitch or be smooth as silk when ya put it back together? Smooth as silk, right ? Yea.
 
#20 ·
Schmidty, The crank seems absolutely fine. Scott is doing all of the piston and head work. All I have to do is re-assemble. I'm hoping for a smooth outcome and years of happy miles. If you see me heading down the wrong path with this, or have any advice to offer, I'm listening. My dad always told me, "When you are around people who know more than you, listen more than you talk." Thanks
 
#27 ·
I guess you knew, didn't you?
 
#25 ·
Great idea but Scott is only boring the cylinders and porting the heads. I didn't send him the whole motor. Just the jugs, heads, and intake manifold so he could port it to the other parts.
 
#23 ·
Wrist pin bushings usually have an oil hole in them where oil comes up through the rod to lube the wrist pin. Make sure you have these holes lined up of you will block the oil. Don' know if anyone pointed that out or not...just my 2 cents!

Poster is correct about some bushings are knurled to propagate oil flow. Also, it was a good suggestion re: putting them in the freezer. I've used this trick and it works well.

It's been a long time since my engine rebuilding days though! Good luck!
 
#24 ·
Thanks Bob and Jimmers. Made sure to get the oil holes lined up. As soon as I get the wrist pins back from Scott, I will mic. them and ream the bushings. More later . Scott should have my stuff back this week or next. Appreciate all of the advice.
 
#26 ·
First attempt at reaming bushings... FAIL. Got them too big, cut out too much, heard some piston slap at start up and a little skirt marking on the cylinder. Re-installed the old ones. Have not gotten re-assembled to the point to try it out yet. Hillsides work looks great. Excited to hear it run.
 
#28 ·
Yeah, I knew there was a pretty high probability for screwing this up. But that's how you learn. I listen to the folks who know, read up as much as you can, get the right tools, take your time and then dive in. My son asked me once how I know so much about wrenching, (compared to him I guess). I told him there is a pile some where of all of the things I have screwed up along that way that taught me the better way to do something. I told him once, "It didn't take a 5 lb. hand sledge to put it together in the factory, you shouldn't need one now." I appreciate SCHMIDTY and all of the other experts who have helped me along.
 
#29 ·
As a way of wrapping this up, I went ahead and put the old wrist pins back in. Got the bike all buttoned up and she runs amazing. Shout out to Scott and his crew at Hillside Cycle. They did a fabulous job punching my jugs out to 98". They also did a stage II port on the heads. Ill need to start working out the left hand to be able to work the clutch with the Barrett stiffer clutch spring he sent along. :) . Took her out for a putt yesterday and she runs like a dream. Completely new bike. Runs BETTER than new. Thanks for everyone's help and again, Thanks Scott
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top