93a super rat

[budpat105]

So I picked up a fairly complete 93A super rat. Hadn't been started for a couple of years (maybe because it wouldn't start). I redid some electrical connections and got spark, cleaned carb (twice). Still not even a pop when kicking. Screwed in my old hose style compression tester. Looks like 105 on compression. Guess I'll pull motor and do my first leak down test before I pull top end. Is there any improvements that I should do? Different carb? etc? I am not doing a total restore, just a preservation that is reliable runner.

[thrownchain]

It should at least start at 105 lbs. Check the timing is spot on. Make sure nothings living in the exhaust pipe. Make sure you have fuel flow. A leak down test won't hurt. Don't be surprised if you have to replace the seals.

[Bullfrog]

I'll take a different tack than "thrownchain" - doing a pressure test is an EXCELLENT idea. Wayeeee more folks ought to be set up to do pressure tests if they do their own engine work. Way to go!
Ed

[TheBevman]

To add to the above, you might want to vacuum check the seals too while you have it set up for the pressure test. its the same procedure, values and set-up (for the most part); 6 in/hg and no more that 1 in/hg loss in a min. I personally aim for less than that over a 5 min period, but that's me.

A vacuum brake bleeder works great, Harbor Freight has them for less than $25 (bring in a 20% coupon and save a bit more)

Here's a link to the bleeder I have:
https://www.harborfreight.com/brake-ble ... 63391.html

Bev

[thrownchain]

If you have the equipment, compression test, leak down test and check the timing. All good to do. A leak down is the most comprehensive as it checks seals, gaskets and mating surfaces for leaks. And may even show you pourous cases. When I tear down a motor I check timing to see how far it's off. Surprising at times.

[budpat105]

OK school me. To check the timing on a non running bike would just be checking point gap at the second (left) mark?

[thrownchain]

There are 2 marks on the case above the flywheel. Also a mark ( line) on the wheel. I use a buzz box to do my test. It changes tone when the point open. Spin the flywheel counter clockwise, the points should just start to open at the first line. So when the line on the flywheel and the 1st mark on the case line up is when the points open. If using a buzz box the tone will change, with a little practice you set timing spot on every time. An old option is to put something extremely thin in the points and put a gentle pressure on it like you're pulling it out, just as the marks align the pressure should ease and let go of whatever you use.

[thrownchain]

The second line is for top dead center.

[viclioce]

What do you use to make the buzz box and to which points do you connect it? Victor

[thrownchain]

The one I use currently is part of an old Volt/ Ohm meter. Basically you need power, usually a small battery, ( my original used 2 AA batteries) some type of buzzer or beeper. Wire and alligator clips. Make a circuit from clip to battery to buzzer to clip. When you complete the circuit the buzzer should sound. Hook up one clip to the wire from the points, the other to a ground point on the motor or to the ground wire from the stator. Again the buzzer should sound. When you open the points the sound should change, so when you turn the flywheel and the points open the sound changes indicating that. I like using the buzz box because you go by sound, so if you're timing against a dial indicator, you can focus on the sound and see the gauge. Will work on any points system for static timing.

[thrownchain]

I long for the Radio Shack. Only need about $4 worth of parts.

[viclioce]

Me too. Alas Radio Shack has gone the way of the Dodo.

[taber hodaka]

I probably am the only one that set my timing by point gap?? never had a problem.------Clarence

[thrownchain]

Whatever works. I like the visual that the points open at the timing mark.

[taber hodaka]

agreed I also did use the light in the early years. Clarence

[viclioce]

I still do my points visually. Danny gave me the idea of using popcicle sticks to wedge in between the fly wheel & the case to keep it from moving. Works really well too. I line up the marks and use a .013 gauge and adjust until it just rubs. Victor

[ossa95d]

Victor I'm confused by your comment. Maybe I'm just reading it wrong. If you set the point gap at .013 when the marks are lined up your timing would be way off (advanced) and it might not spark at all due to a too short duration when the points are closed. The gap should be zero when the timing marks are aligned.

[viclioce]

The Left mark. Not the Right one. Works every time for me! Victor

[taber hodaka]

I think your concept is missing something. The points should just start to open at the first mark. The max point gap should be 13 to 15 thousands at the top of the lobe that could be at the second mark or top dead center I don't know I have never heard of that. Clarence

[thrownchain]

I'd like to check the timing after doing the gap method to see how it stacks up... would be interested to see how close it actually is.

[Bullfrog]

I think maximum point gap is achieved by the time the flywheel mark lines up with the "second mark" on the cases (which is top dead center). The popsicle sticks help hold the flywheel still against the magnetic forces while the gap is adjusted. I like to confirm the firing point with a timing light after setting the timing by the gap method OR the "points just open at the first mark" method. My generalized experience is that if I take care with setting points by either of those methods, the timing checks out to be within about +/- one line width most of the time. (I'm partial to setting timing by checking when the points release a strip of cellophane . . . though cellophane is getting harder and harder to find. I do have to keep in mind that the thin strip of cellophane should not be released till just a hair AFTER the flywheel mark passes the first mark on the case - to allow for the movement needed to release the cellophane.)
Ed

[budpat105]

so after all this time I finally got my leak down system? made, lost pressure about as fast as pumped in. Leaking on seal on clutch side of crank. I'm so glad I did that! So I took cylinder off after that. Does anyone have a port drawing of a 93Acylinder or is there another way to tell if its the correct cylinder?

[olddogs]

If it has a motor number that starts with M, has 100cc on the lower left side of the cylinder, has no oil pump or reed valve and 4 intake to cylinder studs, its a Super Rat engine. Good question as many Hodaka engines are interchangeable between models.

[taber hodaka]

The motor number will indicate if it is a super rat model 93, 93A, or a 93B, and each of those corresponds to the 100B 92's. Clarence

[Al Harpster]

This is from the Super Rat Workshop Manual Supplement.

I expect the port dimensions are all taken from the top of the cylinder.

The Dimensions Marked STANDARD are most likely the 'factory' target dimensions.

I have ZERO idea what the tolerances might be. For a casting there can be some considerable variations.

Hope this helps.