Are boring bar witness marks in cylinder cosmetic?

**powerabout** · 06-25-2015, 08:11 AM

except I would never send a 2 stroke outboard piston to a boring shop
I would just tell them what size finish I want, its all right there in the worksop manual

**[email protected]** · 06-25-2015, 03:51 PM

Sounds good assuming you have the measuring equipment to blueprint it yourself.... I'm guessing what there calling witness marks are made by manually locating the boring bar instead puting the feed on auto. Seems time consuming to me on top of getting a crappy job.

**TEXAS20225** · 06-25-2015, 04:50 PM

This not blue print material by any stretch its just a good practice to develop by any one who assembles motors for sale and guarantees them

He must know what he is selling, buy yourself a bore gauge learn how to read it ,check your ring gaps on all holes "everytime" in my opinion only a ball hone is a lazy mans way to try and champher the ports, i have mine ALL done by hand they are very nice and in 7 years using the guy im using now i have not had a single motor snag a ring or drop a hole because the sleeve did not touch the sleeve holder all the way around and stick the piston. Actually Ive only had one motor blowup and it was because the owner forgot he did not have the auto oiler still on ( yes i remove all of them) and i clean my own injectors and add two new switch boxs and regulators along with new reeds (lapped) its about reputation for me and please believe me i take this position AFTER using every machine shop in this area of Texas they are all Hackers they will get no more of my money. and about the finish size i have never bought a set of pistons that did not give you the bore size its my job to ask for it and check it when it returns to me JUST MY .02

**flabum1017** · 06-25-2015, 04:50 PM

Talk to Brucato again.... he will tell you all new injectors are scaled back a small amount from the factory to stay with epa regs.... the older injectors are a little more rich, about 2%. I had two sets done last month by them and I had to replace 6 air injectors. Brucato told me to just put the lowest flowing fuel injectors with the new air injectors.............

BTW, you won't notice 2% and it certainly won't do what happened to you motor...............

**TEXAS20225** · 06-25-2015, 04:53 PM

X2 i see injectors get blamed for a whole lota stuff that they did not do

**SunDaze** · 06-25-2015, 09:43 PM

Yes. I talked to Rich at Brucato FIS and he told me virtually the same thing about 2 weeks ago when I related my tale of woe to him. He said other fuel injector cleaning shops have noticed it, too.

**flabum1017** · 06-25-2015, 10:25 PM

Originally Posted by powerabout

except I would never send a 2 stroke outboard piston to a boring shop
I would just tell them what size finish I want, its all right there in the worksop manual

I always send all the pistons with the block on performance stuff..... mark them for each cylinder..... fish motors don't and get put together as long as they are within range........

**Dave Strong** · 06-25-2015, 10:36 PM

Originally Posted by flabum1017

I always send all the pistons with the block on performance stuff..... mark them for each cylinder..... fish motors don't and get put together as long as they are within range........

Let the Dude doing the machine work tell ya where they go. Then go from there.

There is a reason you sent that stuff to him in the first place. Cuz he knows what going on.

Dave

**baja200merk** · 06-25-2015, 11:04 PM

Originally Posted by Da Bull

Winner Winner chicken dinner. You hit the nail on the head. How can a machine shop size a cylinder to a piston if they do not have said piston in hand??? Can`t be done! New pistons are not that perfect. Each and every one must be measured.

DB

New wisecos work great and the pins don't come out.

Originally Posted by powerabout

except I would never send a 2 stroke outboard piston to a boring shop
I would just tell them what size finish I want, its all right there in the worksop manual

this....... It's 2015 they r closer in size from the factory then you could measure in your shop 20 years ago.

**Dave Strong** · 06-25-2015, 11:26 PM

Originally Posted by baja200merk

New wisecos work great and the pins don't come out.

this....... It's 2015 they r closer in size from the factory then you could measure in your shop 20 years ago.

So now that its 2015 you just send the block to the machine shop and tell them ya want it 30 over and just put her together and good to go.

All the new pistons are so close in size just make them what I say. ??? What rings you going to run ? Some rings need a different finish than others.

Dave

**baja200merk** · 06-25-2015, 11:33 PM

Even the worst bore gauge in the world is less then $100.

My machine shop is the bench next to me with the boring bar on it. But yea it's written on the wiseco box if you can't check the bore hone it to size and check ring gap. I Would say you need to bring the motor somewhere to have it assembled nevermind bored. It's all in that text book looking thing oh wait they have them on computers now too kinda like the fancy typewriters that build the Pistons while the machineist is on a smoke break.

**Dave Strong** · 06-26-2015, 12:16 AM

Funny thing is all those dimensions that are given are at 68 deg F. Change the temp and it all goes sideways. Thus the assembly room, no dirt all parts at the same temp. Not all about no dirt..

Dave

**powerabout** · 06-26-2015, 12:34 AM

I wonder how round the bore ends up when you run 145f thermostats and you light a fire over the piston at 1100f?

**[email protected]** · 06-26-2015, 01:40 AM

Like I've taugh literally hundreds of automotive techs, even good machine shops have bad days. If you don't know it's perfect than its your time or money making it right in the end! Go to your machine shop and if he didn't mark which piston fit which hole than he guessed just like you and he should be reboring all 6 and supplying 6 new Pistons unless you are one of those guys that will mix bore sizes in the same engine but that's another subject for argument for another day.

**powerabout** · 06-26-2015, 02:52 AM

Originally Posted by [email protected]

Like I've taugh literally hundreds of automotive techs, even good machine shops have bad days. If you don't know it's perfect than its your time or money making it right in the end! Go to your machine shop and if he didn't mark which piston fit which hole than he guessed just like you and he should be reboring all 6 and supplying 6 new Pistons unless you are one of those guys that will mix bore sizes in the same engine but that's another subject for argument for another day.

read from above, giving the machinist the piston ( for an outboard) is the beginning of the problem.
Ask any OMC/Merc factory tech, how many calls they get about boring an engine and also how many after from customers who have a noise or a seizure all because the machinist thinks he knows the piston to bore clearance of an outboard not to mention even where to measure the piston to do that.
Millions of production outboards had the holes bored,honed, slugs dropped in and away they went forever.
Not to mention how many factory race engine were done the same.
A 2 stroke outboard is not a car engine, which machinist and rebuilders keep proving all over the world and have for many many years.