Yamato 80 or 102 point ignition issues

[ZUL8TR]

On these point ignitions with locked mags and timing properly set with a dial indicator and buzz box to be dead on for both cylinderes where desired I have issues with timing changing somewhat after running. The points are securly tightened, cam lubed, mag lock plates tight. What gives? Could the points be worn at their pivot shaft thus causing the change of the timing setting after running with all else tight? The point cam lobe piece is new and the key and keyway are a good tight fit. Thoughts?

[Mark Monkres]

Tight spring tension could cause this. On the old Mercs. the manual indicates setting spring tension, I think it was in inch ounces

[Bill Huson]

True. At one time I had a Mercury spring tension tool.

[JBM]

I took the points out and ran a 102 with Atom modules. It ran great!

[bill boyes]

Never had a Y 80 that the timing would stay as set. Many others have the same problem.

[ZUL8TR]

timing change

Never had a Y 80 that the timing would stay as set. Many others have the same problem.

At least my situation is not unique, but it is strange? All I can figure is something is moving that is not obvious and it happens after top rpm runs. I will keep searching. Hope somebody out there knows what it is.

Thanks for all the comments.

[bill van steenwyk]

The cause, and solution to the problem

To find out why your timing will not stay where put on the bank, try this simple experiment:

While you have the cranking pulley and flywheel off, grasp the top of the crankshaft and try to move it back and forth. NOT UP AND DOWN, but back and forth.

You will quickly see why your points will not stay where put when going thru the timing procedure. There is play in the needle bearing in the top of the crankcase that needs to be there for clearance and oiling purposes. When that clearance is there, the points will not stay in the same place where they were when the engine was timed, as timing was done with the motor not running.

First thing that happens when you crank it up is the crank moves just slightly sideways, one way or the other, and your timing is no longer where you set it.

We had this problem in the early 80's with the first Model 80's converted to alky burning RB's. The way it was solved was to go to a Konig or other type CD ignition and replace the one top needle bearing with two roller ball bearings so the crank could not move sideways when running.

I still have two ignitions like this available for sale. One problem, you would have to make the modification with the ball bearings and then the motor would not be legal for stock use. If you have only a "lake racer" it is a relatively easy mod to make and solves all the ignition timing problems, plus motor starts and runs better.

[STEVE FRENCH]

I took the points out and ran a 102 with Atom modules. It ran great!

Are these the red ones they sell for lawn mowers?....How da heck do you time them?.....I've had folks tell me they drop in and run fine....OK, In a lawn mower maybe. http://hackaday.com/2011/09/04/engin...nition-module/
http://gardentractorpullingtips.com/ignition.htm
http://www.ebay.com/itm/Solid-State-...item2a2b54cc14

I bought a set......Their still on shelf in package.

[ZUL8TR]

crank slack

To find out why your timing will not stay where put on the bank, try this simple experiment:

While you have the cranking pulley and flywheel off, grasp the top of the crankshaft and try to move it back and forth. NOT UP AND DOWN, but back and forth.

You will quickly see why your points will not stay where put when going thru the timing procedure. There is play in the needle bearing in the top of the crankcase that needs to be there for clearance and oiling purposes. When that clearance is there, the points will not stay in the same place where they were when the engine was timed, as timing was done with the motor not running.

First thing that happens when you crank it up is the crank moves just slightly sideways, one way or the other, and your timing is no longer where you set it.

We had this problem in the early 80's with the first Model 80's converted to alky burning RB's. The way it was solved was to go to a Konig or other type CD ignition and replace the one top needle bearing with two roller ball bearings so the crank could not move sideways when running.

I still have two ignitions like this available for sale. One problem, you would have to make the modification with the ball bearings and then the motor would not be legal for stock use. If you have only a "lake racer" it is a relatively easy mod to make and solves all the ignition timing problems, plus motor starts and runs better.

So if the clearance needs to be there was the factory design for not having dependable timing? That is strange since on old mag point mercs that I have worked with I never had that issue with good condition rollers and ball bearings in place.

I will try that side to side test with a dial indicator on the crank and report back. By the way with cold #10 plugs this engine starts like a trolling engine with out lifting the prop out of the water, and idles great.

Thanks for the tip to try.

[bill van steenwyk]

So if the clearance needs to be there was the factory design for not having dependable timing? That is strange since on old mag point mercs that I have worked with I never had that issue with good condition rollers and ball bearings in place.

I will try that side to side test with a dial indicator on the crank and report back. By the way with cold #10 plugs this engine starts like a trolling engine with out lifting the prop out of the water, and idles great.

Thanks for the tip to try.

Regards "if the clearance needs to be there":

I have no idea what was in the minds of the Japanese engineers that designed the engine.
You can surmise from the very limited induction system, (very small reeds and only one 25MM carb) that ultimate performance was NOT what they had in mind, but longevity was by limiting the RPM of the engine. If you examine the rules under which the Japan Motor Boat Association ran the parimutuel betting for which these engines were designed , they had to REFUND any and all money which was bet during the course of a race meeting if any race was not completed due to a failure an engine. My wife and I saw the results of such an occurrence at one of the Marine Stadiiums during the mid-70's, and the result was a fire bombed out pay off area.

You might also take into consideration that roller and ball bearings require a better source of lubrication than what is in the Model 80. Perhaps sealed bearings were not readily available in the time frame the 80 and its forerunners were designed and built, which is pushing some 50 years now. We went to this type bearing because of the much higher RPM the RB's were turning on alky and with the other mods able to be done to them, and made a way to lubricate the bearings by forcing air/fuel mix to the bearing from tapping into the case and running a hose w/check valve to it.

The most important thing to remember is the motors were not originally designed to run at the speed and RPM that they have eventually gotten to here with 40 years of development and on 3 point Hydros when they were originally run on single step type boats and down in the water. (not jacked up as we do here in the states)

Perhaps they just ran good enough for the Japanese purposes and the longevity was what was desired?? Unfortunately we can't ask them, or Mr. K., for some of those decisions made many years ago. Just be glad the Model 80 was imported into the US by some forward thinking people, both here and in Japan. I have an idea Stock boat racing would be in worse shape than it is without the Yamato's.

[JBM]

Atom Modules

Are these the red ones they sell for lawn mowers?....How da heck do you time them?.....I've had folks tell me they drop in and run fine....OK, In a lawn mower maybe. http://hackaday.com/2011/09/04/engin...nition-module/
http://gardentractorpullingtips.com/ignition.htm
http://www.ebay.com/itm/Solid-State-...item2a2b54cc14

I bought a set......Their still on shelf in package.

I timed them by spinning the engine with a drill motor and using a timing light. The only problem I had was if you didnt pull the rope hard, it would start backwards.

[bill boyes]

Never had the problem with the 102. It stayed very close to where you set it. The Y80 was all over the place. Bill's thoughts are right on. Now I know why.
One thing about the Y 80. It did not care if the timing was off.

[bill van steenwyk]

Never had the problem with the 102. It stayed very close to where you set it. The Y80 was all over the place. Bill's thoughts are right on. Now I know why.
One thing about the Y 80. It did not care if the timing was off.

Bill:

Thanks for the plug about my "thoughts", but like most things I know about the Model 80 I can't take the credit. That belongs to Harry ZAK. He did not miss much if anything regards engines, and it make little difference what kind or who the manufacturer was. The ball bearings/lube path/CD ignition was all his idea.

To the comment by ZUL8TR regards setting up a dial indicator to measure what is happening. If your 80 is like most, you will not need an dial indicator to prove what is happening. Most move enough that you can both feel and visually see what is happening. If yours does that, that should be proof enough.

I am glad you have one of those motors that starts in the water easily. Everyone does not enjoy that condition, although that can be a mixed blessing at times as it encourages testing alone, which should never be done.

As I am sure you are aware there are many factors that can enter into the ease with which a motor starts such as the subject of this discussion, namely timing, and also other factors such as condition of the reeds and piston rings/cylinder bore, carbon in the exhaust ports/megaphone, carb adjustment, and the list goes on and on. Based on previous posts you are evidently accomplished in keeping you motor in good condition, and also your ability to share information.

A story that might be of interest (names are not important) was when the 80 was first approved for the F350 class in the PRO category, a person was running better than should usually be expected and every one wondered why.
Finally found out it could be attributed to the ability of that engine to keep the timing set where it was supposed to be. This was accomplished by going thru many upper crankcase bearings to find one that was on the "high" side tolerance wise, and then plasma spraying the place on the crank where the crank contacted the bearing, regrinding it to where very little clearance existed after starting and running. I seem to remember that the bearing was also packed with an Nuclear grade of Never Sieze or something similar that would withstand high heat.

The timing stayed where it was put and the motor was just that little much better than most of the rest. This and some other tricks of the trade such as coolant on the megaphone, shorting it just a little that could not be seen without removal, and a few other tricks managed to make him a winner for awhile, until caught during inspection at a race. A lot of work to go to and also required a tear down every race or so to replace the top bearing as wear was rapid on it.

But, as they say, where there is a will, there is a way. Never thought it was worth being labeled a cheater though. That is why I have always enjoyed the PRO category.

[ZUL8TR]

Y80 tips

Thanks for all the info, really appreciate it. I never realized this ignition was an issue with the Y80. Since just an AOMCI meet guy these days I will leave it as it is and adjust often as it is very easy to adjust timing with dial gage and buzz box. I will put in new points (Kawasaki 21008-028) since the present ones have been in there since I bought the Y80 back in 1978 from Dick O'Dea.

I will nixt the dial gage to check the lateral crank movement and just set the piston at the desired advance and hook up the buzz box and see if it goes on and off as I push on the crank.

As far as easy start in water that is a pleasure but I never test alone there are always other boats at the AOMCI meets to assist.

[matt mutz]

Check that point cam isn't cracked, Seen that enough to mention it.