So I have a 05 twin cam 88 That's getting bored to 98",Stage 2 TMan heads,580 cam,S&S TC3 Cam Plate and pump.So I was checking my wrist pins and bushings and have a slight wiggle. Pins are .9260" and best measurement I can get with calipers is .9300"-.9315".So that is roughly .004"- . 0055" difference. Book calls for.002" clearence.So I'm getting all my tools bought to replace bushings(Not Cheap).I will be using Jims reamer # 1726-3 (Again,not cheap).Question is will I need to hone the bushing also?The way Jims make it sound is that his reamer cuts to exact size.I also believe I heard Scott from Hillside also say it reams to size,not sure.

 

I do mine with an old fashioned adjustable reamer bought used for next to nothing. But it takes a real fine touch and is not easy.
No, if you ream the bushing you don't need to hone to size. Reamer should be finish size. When all else fails, follow Jim's instructions.

And don't rely on digital calipers for accurate measurements, specially inside diameters. They are not a particularly accurate piece of kit due to a combination of movements and "feel" and the thickness of the jaws when measuring inside small holes like that. A proper bore gauge, inside mike or telescopic gauge and micrometer will be more accurate.

But you can usually feel if the fit is right. If you can push the pin through with no drag, or just the very very slightest drag, but no wiggle, it's good to go. If in doubt, err on the side of loose. A little extra clearance never got in the way, as Mr Harley said to Mr Davidson back in 1066 or so. But a tight wrist pin can seize up and cause mayhem.

 

Especially a new reamer will cut to size but you absolutely must hone them. The reamer will leave a slick finish and it will not have any oil retention unless you give it at least a few strokes with a ball hone. Be sure to use oil and clean it as you would a freshly honed cylinder. The one time I didn't use a hone, 10k later the front pin stuck in the rod and cost be a tear down. I've probably done 3 dozen over the years and that (next to last time) I got cocky, didn't hone, cost me.

I agree, when measuring engine parts, forget a caliper regardless of the quality. You need to read in tenths of thousands for most things and a caliper, digital or otherwise, simply cannot accurately and consistently do that. Even with expensive micrometers, it comes down to feel in the end.

Dry, if the pin will wiggle with only one end in the rod but no wiggle with it centered, it's good. If you feel a tiny bit of wiggle, oil the bushing and try again. Also, it does take some finesse and luck to get them reamed straight so the pin is precisely perpendicular with the engine case. If it's off even a little, the piston will go up/down leaning to one side or the other and that's not good. Not trying to talk you out of it, but it is an expensive job to tool up for so be sure you're it's necessary. If you do go thru with it, be sure you have at least 4 bushings on hand so you have spares in case you don't like the first ones you install and ream crooked.

 

im not a big fan of w pin bushing reeming,i prefer sunnen honing with the FW apart,i understand sometimes this just is not a option so the only reemer i would even consider is a JIMS unit as their tools are top notch,tha said use a quality bronze reeming fluid (goodson has the very good one) and take your time & dont force anything.i do use a JIMS reemer to do rocker arm bushings so i have the goodson fluid,PM me if you want me to send a bit of it,its pretty expensive to buy a big can for just one job

 

Yes its not easy getting a true measurement with calipers. I have some wiggle with pin centered on bushing(dry fit).But I put some oil on bushing and pin as you suggested and now the wiggle is pretty much gone.Maybe a very very slight wiggle if I work it for a minute. I should probably just leave bushings alone and run it.Whats your thoughts? Thanks for the reply 👍

 

That sounds exactly like my rear one last time I had the jugs off and I didn't think twice about running as-is and I already have all the tools.

It's your engine and you're there touching it - I'm not, so I won't sit here and pretend to know the answer. But sincerely, the rod bearings are "usually" about worn out by the time wrist pin bushings actually need attention. 90% the ones I changed over the years really didn't need it. Guys do top ends all the time and never even consider those bushings and you basically never hear about problems with them.

So it's your call. Tooling for that job is expensive and doubtful you'd ever use them more than one time. Always do what you feel best about

 

Thanks again.I think I'm going to run it as is.Once I oiled the pin and bushing there is very slight movement with some resistance(obviously because of the oil). If I were to hold crank rod horizontal (cant with it in bike) I would say there is enough resistance that it would slowly drop out with it oiled,and not just fall out.Yea it's not easy diagnosing over the internet, but from what I have explained would you install bushings or run it?

 

Let me say, I've never made my living rebuilding these engines but have done quite a few, mostly Evo flywheel rebuilding. I put things together with my main goal being longevity - not how fast will it go, but how long will it go fast. And I ride about 12-15k a year if I don't do any road trips.

If it were mine, and based solely on your description of the fit, I'd say run it.