spark plug hole dial indicator ?

cleopatrisha · Sep 27, 2007

I see there are a few choices out there when it comes to purchasing a dial indicator my question is what type, size, ect. do I buy, to check my timing on my 2 stroke dirt bikes. I am not looking for anything real expensive because this is just a recreational sport for me.

Big Bore Stroker · Sep 27, 2007

Type would be one that reads millimeters. The jap bikes give you mm specs for checking timing. Analog would be the cheapest.

76GMC1500 · Sep 27, 2007

All of your bikes have steel frames, so buy whatever standard magnetic base indicator you can find and just stick it to the frame and drop the rod through the hole.

Big Bore Stroker · Sep 28, 2007

They make units that will thread down into the spark plug hole.

76GMC1500 · Sep 28, 2007

Yeah but you can use them only for that one purpose. A magnetic base indicator has a thousand uses. When he upgrades to 4-stroke, he can use it to set his valve lash or something.

Ol'89r · Sep 28, 2007

76GMC1500 said:
Yeah but you can use them only for that one purpose. .

And that is what makes them so accurate. Best to use the tool made for the job.

Jaybird · Sep 28, 2007

The job is only as accurate as the measuring device, and the clown at the other end of it.

I am not aware of any company making thread hole specific dial indicators. Aren't these simply threaded adapters that allow an easy mount for your instrument?

I can see them being very handy, but I cannot see where they would add, or subtract, from the accuracy of the job.
Mag base is all I have ever used for that task.

Cleo,
Tools are an investment. Cheap tools will net you cheap results. Proper tools cost a bit of money, but they provide you with not only the best accuracy, but longevity as well.

That being said...if all you can afford to get is a Chinese indicator and base from the American Legion tool bazaar, then by all means purchase it and do the best you can with it.
I buy ching li stuff to carry in the field with me. Hard to get too mad losing one, or letting a pal hold on to it for awhile. And, much better than carrying high-dollar instruments around, to get lost or stolen.
I'm talking instruments that are going to cost you mucho coin if you get quality stuff...micrometers, dial indicators, calipers, etc...
Farm supply houses will often times have cheapo Chinese tools of all sorts to choose from. These will get you by in a pinch.

Ol'89r · Sep 28, 2007

Jaybird said:
The job is only as accurate as the measuring device, and the clown at the other end of it.

I am not aware of any company making thread hole specific dial indicators. Aren't these simply threaded adapters that allow an easy mount for your instrument?

I can see them being very handy, but I cannot see where they would add, or subtract, from the accuracy of the job.
Mag base is all I have ever used for that task.
QUOTE]

Jay.

Mine is made by a company named Yamaha. Part # 90890-03002. I also have one made by a company named Peacock. They are pretty old and I'm not sure if they are still available. I believe Motion Pro sells the spark plug hole type.

Having used both, I find the spark plug type much more accurate. The magnetic base type are hard to use because there are usually not any flat surfaces on the frame to mount them to and they can move or slide down unless you c-clamp the base to the frame. Also you have a conglomeration of clamps and rods attaching the dial indicator to the base and that produces movement in the reading.

The spark plug type screws directly into the plug hole and the reading is the same every revolution. No movement between the base and the dial indicator. Most of the time you don't even have to remove the gas tank.

But maybe I just need more practise. :whoa:

Jaybird · Sep 29, 2007

If a Starret indicator mounted on a mag base is inaccurate, then we are all in trouble!

Do I trust a dial indicator sold by Yamaha? No...sorry, I am just not into buying second tier equipment that has been private labeled (unless it is part of my ching li collection). Although for that operation, it is probably as accurate as needed. I do however trust the accuracy of Starret, Mititoyo, or B&S, and I also trust that I can accurately, and repeatedly, do the job without the aid of a specialized tool.

That being said, I think that a threaded adapter to use with a quality instrument would be the way to go.

Bunya · Sep 29, 2007

Folks, you're not splittin' tenths here. The chicom stuff's accuracy is perfectly adequate for working on bikes.

The choice of screw in or magnetic base is really up to the individual. The screw in base offers quick, easy, foolproof readings but is limited by it's single purpose use. Using a DI on a magnetic base is a little more cumbersome and takes more time to get set up. I agree that they can be a PIA to get them stablized on a bike, but it's certainly not less accurate or repeatable when set up properly. It has the huge benefit of being able to do a large variety of measurements routinely required on both 2 and 4 stroke bikes. If you plan on doing much of any work on bikes, you pretty much have to have one on a mag. base no matter what. If a DI with a standard point (tip) won't reach deep enough, you can purchase point kits with a variety of styles and lengths the extend the reach.

If you have more money than time, you could pick one up that screws in. But if you can only afford one of them, get the mag. base and learn how to use it. Mitutoyo and Starrett are silky smooth and just about bullet proof, but unless you're doing this day in and day out, they are overkill.

Ol'89r · Sep 29, 2007

Jaybird said:
If a Starret indicator mounted on a mag base is inaccurate, then we are all in trouble!
I also trust that I can accurately, and repeatedly, do the job without the aid of a specialized tool.
.

Comm'on Jaybird, pay attention. ;) I didn't say they were inaccurate, I said that 'having experienced using both', I found the spark plug type to be more accurate and much easier to use.

I also trust that even though you have never used the tool in question, you still have a opinion on its use. :coocoo: :rotfl:

BTW. The Motion Pro screw-in dial indicator sells for $125.20 complete with screw-in adapter, indicator, pointers and a spiffy lil' wooden box to keep everything in. Part # 80-0250.

The Starret magnetic base sells for $ 108.80 less the indicator. With the indicator it sells for $ 327.60. I'm sure you could find one on e-gay for less.

Bunya · Sep 29, 2007

On sale now at Enco: 1" travel .001" dial indicator, magnetic base w/ fine adjust knob, 22 pc. point set - all the basics you need for the low, low price of only $18.95, black or white face - your choice. Chicom, but certainly good enough for wrenching on bikes. Just a guess but more than likely the Motion Pro model was born in China as well.

steve.emma · Sep 30, 2007

i have used a dial gauge to check and set timming on all my 2stroke bikes and in my opinion the threaded plug hole type is a lot easier. i aggree its no more accurate but its easier for someone who is less skilled in using this type of measuring equipment. the mag base type are fiddly to set up and on alloy framed bikes they can be near impossible to stick to any flat surface near the head. however i also agree its expensive to buy the adapter if you are not going to use it very often.... so do what i did and make your own! i basically modified a old spark plug metal body to fit my dial gauge then drill and tapped a hole on the side of the plug body for a lock screw to secure the dti. cheap to make and as long as it securely locks the dti and does not allow it move then it will work as good as a bought one for a lot less cash!

Jaybird · Sep 30, 2007

Terry, it's the "more accurate" part I have trouble with.
And I think I can visualize the form and function of a simple mounting adapter collet, without one bit of misunderstanding or misconception.

Since we are paying attention...:nener:

I think that a threaded adapter to use with a quality instrument would be the way to go.

Steve, great idea!

Ol'89r · Oct 1, 2007

Jaybird said:
Terry, it's the "more accurate" part I have trouble with.
And I think I can visualize the form and function of a simple mounting adapter collet, without one bit of misunderstanding or misconception.
QUOTE]

Then visualize this Jay. ;)

You have a magnetic base adapter sticking to an uneven surface or c-clamped to an uneven surface. Then you have a clamp holding a rod and possibly even another clamp holding another rod that eventually attaches to a dial indicator that is located 8 to 10 to 12 inches away from the magnetic base.

With the screw-in type of adapter, you have an adapter that screws directly and solidly into the spark plug hole. Then, you have a miniature dial indicator that slips into the adapter and solidly set-screwed in place. From there the dial indicator pointer sets directly on top of the piston. No movement or monkey motion. The dial comes up to 'O' every revolution unlike the magnetic base adapter that has room to move and flex and has to be reset to 'O' every few revolutions. If someone accidently bumps the frame, the gauge doesn't move or have to be reset. Common sense tells us that the one mounted closest to the point of measurement will be the most accurate.

It is for this reason and the fact that I have used BOTH methods that I contend the screw-in type is more accurate. This is merely my opinion based on my experience with using both tools. You are more than welcome to your opinion.

Granted, like Bunya said, either tool will do the job. Were not talkin' rocket surgery here or nuthin'.

Another reason for purchasing the screw-in type is many times the timing is set while the engine is still on the bench. The screw-in adapter is quick, easy and accurate to use and is actually less money than the magnetic base and dial indicator when buying new. Also, the magnetic base adapter won't stick to an aluminum engine. This would require buying or making another adapter to mount the dial indicator to a head bolt. The Peacock screw-in kit comes with the head bolt adapter.

You can stick a fork in this one, I'm done.

RM_guy · Oct 1, 2007

To be honest I have resorted to using a popsicle stick at times. Stick it in the hole and watch it move up and down as you turn the flywheel. When it is at it's highest point--you're at TDC! :) Like someone said, it's not rocket science.

76GMC1500 · Oct 1, 2007

That method doesn't exatly work. The piston "dwells" at TDC for quite a few degrees of crankshaft rotation. So, even with the popsicle stick at its highest point, the crank may be 5-10 degrees + or - of TDC. The proper method is to bring the crank to just before TDC, zero out the indicator mark the position of the timing indicator, then continue rotating the crank in the same direction until the indicator reads 0 again. Mark this 2nd position. TDC is exactly half way between the 2 marks.

spark plug hole dial indicator ?

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