[slashmaster]

My buddy asked me to bore out a moped engine block bigger. What do I get if I want to do that?

[SCzEngrgGroup]

My buddy asked me to bore out a moped engine block bigger. What do I get if I want to do that?

You'd use a boring head, but if you have to ask the question, perhaps this isn't a great idea. It's pretty easy to screw it up if you don't know what you're doing. And, your machine may not be up to the job, particularly in terms of stiffness....

Regards,
Ray L.

[escott76]

My buddy asked me to bore out a moped engine block bigger. What do I get if I want to do that?

You get one shot at doing it or you're buying a new engine block. It's not a trivial operation -or- setup. There's a bunch of finishing operations as well. Unless you can afford to scrap the original with no hard feelings these are the kind of jobs it's best not to accept until you've had a bit more experience with precision alignment and boring to tight tolerances.

[Kevin Taylor]

Small 2cycle stuff that only need's to go .010 or .020 can be honed Geting a good finish with a boring bar and still need's honing can be dificult also centering on a small bore and geting it to clean is tough . Don't know the marcket in your areia but I get $45.00 to bore and finish a small 2 stroke like a moped Kevin

[mc-motorsports]

I second what they said. It can be done on a manual mill, no problem, but usually only an engine shop it going to have the proper honing equiptment. And a power hone isn't cheap, I don't reccomend using the flimsy spring loaded tools that you use with a drill.

Around here, you can get a jug like that bored and honed for $50, usually drop it off and pick it up with the new piston for $80.

[CalG]

I have used a lathe. Mounting the cylinder on a faceplate, and spending the time to indicate the workpiece.

Sizing to "tenths" on a first over rebore for a Suzuki RM 80. Much like your moped cylinder.

Not a fast job by any means. A "Quick-Way" boring bar, or similar with all the fittings makes the task simple!

Cal

[poppanitrous]

Hello,
I am student learning programming on a HAAS C.N.C.'s.
However i would like to have a basic milling machine in my garage since i race MX and i go through engines after a season.

I know this will make some cringe, but i cannot afford an OLD BRIDGEPORT, but are the chinese knock offs and/or Harbor freight MINI MILLS capable of boring 80mm stroke jugs?

I have seen boring bars and kwikway products, i know the initial set up is expensive but what is the most cost effective route for me to go from boring/honing with a good cross hatch and keeping it from out of round.
Its funny you mention the spring hone, i have used them on 2 strokes with a ridge reamer to great success on small 2strokes as long as you only use assembly lube on wrist pin etc, but not on rings, dry assembly powder and the rings set fine and chamfering the piston skirts at the bottom helps with oiling.

I would like to bore my 200cc motor for my atvs for practice,i have a few and can afford to make a few mistakes.

What mini-mill(most cost effective used v.s./harbor freight mills new), boring bar, and honing equipment is the cheapest to get me started turning handles?

What budget is the least you would expect including dial bore indicators etc.
Im starting from square one and i need expert advice on a shoe string budget.


Thank you in advance
Poppanitrous
Vince-

[SCzEngrgGroup]

You will spend thousands on the machine and tooling necessary to do something that size. Even a Bridgeport would be pretty marginal, and a table-top machine, short of perhaps an RF-45, would really not be up to the job in terms of rigidity and precision. For sure you'd NEVER recoup the expense, even if you rebuilt your engine several times a year.

Regards,
Ray L.

[poppanitrous]

If someone asked you, i want to run an 11second elapsed time in the quarter mile, would you respond by saying the car you would need is way too expensive and not worth the money for you to do so dont bother?
What kind of response is that?

Decades ago BURT Munro set an under-1,000 cc world record, at Bonneville, 26 August 1967! Using cast parts in old tins, make his own cylinders, pistons, flywheels, etc. His micrometer was an old spoke! So dont tell me I CANT,I CANT AFFORD, this is a forum to share ideas for progression. This doesnt mean that newbies to this specific discipline need to be treated as though it cannot be done on the cheap.

I mentioned cost effective because who in their right minds in this exponentially falling economy would not want to find the best deal available for whatever the application is?

Im not looking for an R.O.I. (return on investment) im not starting a business. I have a collection of A.T.C.'s and i race MX.

So let me ask again in a different context.

What is the most basic/cost effective (yet stabile for structural integrity and the ability for not much repeatability since i wont use it but as a learing tool and only a few cylinders here and there (5 times a year) without re-tramming alot etc.

QUESTONS:
So given those criteria what: make, model, approx year, machine and which accessories (smallest yet most effective) formy dirtbike cylinders?
1) What machine and why? (cost effective,repeatability not a major concern since there are no deadlines it is for my personal collection)

2)what boring bar/honing equipment (most cost effective, approximate stroke and bore size 90/80mm

3)Are there upgrades available to this machine (lead screw/servos/motors/belt conversion etc that i can invest in the future to enhance it and make it more precise for repeatability if i was to change my options prior)?





Consider this i am going to do it depending on who is the person who has the most experience in the specific field where they will be able to answer this question without semantics.

So PLEASE ONLY ANSWER THE QUESTIONS 1-3, I dont need a background a tale of why this isn't goingto work for me and its too expensive and bring it to someone else.. Change your mind to assume this is hundreds of miles from the nearest machine shopand you get one trip to buy all the correct components either Online or in person so you have toget it right. WHAT WOULD YOU BUY IF YOU HAD TO BORE CYLINDERS? Now please try to answer just 1-3

Thank you in advance,
Poppanitrous

[mfgbydesign]

slashmaster: first thing you need is the new piston & specs for the clearance.
Then you can either take it to a small engine (up here a snowmobile shop) and pay $60 per hole, or preferably use a lathe and 4 jaw chuck. Bore it for a line-to-line fit and about a 32 microinch finish, and hone the rest of the way. You also need to chamfer the edges of the ports so you will need a die grinder also.

poppanitrous: my prefered method for M/C cylinders is as stated above: a manual lathe with suitable swing and a 4-jaw chuck. You can use one large boring bar for whatever size bore, and a decent cylinder hone that makes a STRAIGHT bore. I use kerosene for honing fluid. When looking at a used lathe, pay close attention to the taper and tightness of the gibs close to the chuck. That is where most of the work is done and will have a direct effect on the straightness of your bores. There are a lot of good, old lathes out there.
When you have your lathe you will be able to do oodles of other stuff for your bikes (screws, bolts, axles, brake disks, etc.) then add a MILLING ATTACHMENT so you can do a bunch of other stuff as well.

[MichaelHenry]

How do you use an old spoke as a micrometer?

[BoxRec]

How do you use an old spoke as a micrometer?

Well the only thing of use that an old spoke has is a fixed length

[Starleper1]

I used to machine/build all types of engines for a living. From BB Chevy to Kohler motors used in lawn tractor pulls.

Anyway my point is, it's not a matter of boring out the cylinder throwing in a piston and off you go.

The first step of the machining process was to deck the block but if the mating surface was flat enough you could let it be. It then went to a boring machine similar to this one to be bored out to .005-.010 under the finished size.



It then moved over to the honing machine. We went through 6 grits of stone to get the aquired finish on the cylinder. It's a bit of an art but once you figure out the tricks it's pretty simple. It can be very easy to get a tapered bore which will reak havoc on a motor depending on how tapered it is.

The machine was similar to this one.


Not to mention you need some type of bore gage to measure the bore. A simple caliper won't do here. If you want it done right and accurate take it to an engine machine shop. Don't waste your time trying to use conventional machines. There is a reason they build machines specifically to do these operations. Stay away from the hones you put in a drill. They have a time and place and in an engine block is not one.

I'm not saying you can't do it in that matter but be prepared to scrap some blocks/jugs or what have you until you figure it out.

Just my .02

[mike2768]

I read all the replies quick, i never seen anyone mention or ask if the cylinder is coated (most small engine like those are) if so then it will cost big $$$$ to bore and to re coat. I'm not saying it can't be done but you have to figure out if it's worth it to you for such a mod. If it where me i would find a larger motor (there lots out there) then mod the insides for more power, but thats just me :-)

[philbur]

Not the best of attitudes when seeking help. My first thought when reading it was "well F U too."

It's best to just ignore advice you consider as unhelpful.

Phil

If someone asked you, i want to run an 11second elapsed time in the quarter mile, would you respond by saying the car you would need is way too expensive and not worth the money for you to do so dont bother?
What kind of response is that?

Decades ago BURT Munro set an under-1,000 cc world record, at Bonneville, 26 August 1967! Using cast parts in old tins, make his own cylinders, pistons, flywheels, etc. His micrometer was an old spoke! So dont tell me I CANT,I CANT AFFORD, this is a forum to share ideas for progression. This doesnt mean that newbies to this specific discipline need to be treated as though it cannot be done on the cheap.

I mentioned cost effective because who in their right minds in this exponentially falling economy would not want to find the best deal available for whatever the application is?

Im not looking for an R.O.I. (return on investment) im not starting a business. I have a collection of A.T.C.'s and i race MX.

So let me ask again in a different context.

What is the most basic/cost effective (yet stabile for structural integrity and the ability for not much repeatability since i wont use it but as a learing tool and only a few cylinders here and there (5 times a year) without re-tramming alot etc.

QUESTONS:
So given those criteria what: make, model, approx year, machine and which accessories (smallest yet most effective) formy dirtbike cylinders?
1) What machine and why? (cost effective,repeatability not a major concern since there are no deadlines it is for my personal collection)

2)what boring bar/honing equipment (most cost effective, approximate stroke and bore size 90/80mm

3)Are there upgrades available to this machine (lead screw/servos/motors/belt conversion etc that i can invest in the future to enhance it and make it more precise for repeatability if i was to change my options prior)?





Consider this i am going to do it depending on who is the person who has the most experience in the specific field where they will be able to answer this question without semantics.

So PLEASE ONLY ANSWER THE QUESTIONS 1-3, I dont need a background a tale of why this isn't goingto work for me and its too expensive and bring it to someone else.. Change your mind to assume this is hundreds of miles from the nearest machine shopand you get one trip to buy all the correct components either Online or in person so you have toget it right. WHAT WOULD YOU BUY IF YOU HAD TO BORE CYLINDERS? Now please try to answer just 1-3

Thank you in advance,
Poppanitrous

[philbur]

A not uncommon student attitude. I'm here to learn and it's the world's responsibility to teach me. Isn't it?

Phil

[HawkJET]

Not the best of attitudes when seeking help. My first thought when reading it was "well F U too."

Thank you Phil for posting this. What adds to the "F U" is the fact that Poppanitrous isn't the OP and essentially hijacked this thread!

[Geof]

Thank you Phil for posting this. What adds to the "F U" is the fact that Poppanitrous isn't the OP and essentially hijacked this thread!

Technically correct but considering that the OP had long dissappeared it is more a case of picking up an abandoned thread that had been inactive for almost two months..

And where do you get the FU attitude from? Poppanitrous' first post had this comment:

I would like to bore my 200cc motor for my atvs for practice,i have a few and can afford to make a few mistakes...

And did explain he was a novice.

I am not surprised he was a bit PO'd at the replies because they are essentially useless in pointing him in a practical direction except for one which does give a little advice pertinent to doing cylinder boring yourself on a made-up setup.

[HawkJET]

It's best to just ignore advice you consider as unhelpful.

I am not surprised he was a bit PO'd at the replies because they are essentially useless

They are replies to SOMEONE ELSE'S thread! If he posted his own thread, it may be a different story.:stickpoke And the usefulness of a reply is not yours to judge, it is the OP's!
Besides, it makes more sense to heed Phil's advice.:cheers:

[waltpermenter]

Hi Poppanitrous, you would be wise to ignore anything from Himykabibble, Philbur and especially Hawkjet. Rudeness comes naturally for some but you can't call them on it.