Hard starting Yamato 102

[ZUL8TR]

adapters

I installed a new pair of B10EGV plugs and gaped them then at .025" I noticed that they are VERY loose when screwing them in all the way to the plug gasket before I tighten it a 1/2 turn with a plug wrench.

Could the soot on the threads be going between the plugs and the inserts because there is to big of a gap between the two? Maybe I have some cheap low quality inserts?

From the pics of the other plugs you replaced the fit was loose with thosa as well.

The plug should fit in the adapters without the excessive looseness you describe. I run them with that plug and no carbon is on the plug threads like in your pictures. You have a poor fit and that will reduce the plug heat transfer to the block, not good. Get some proper ones from Ric Montoya or Tom Johnson tjohnston@localdialup.com or Tom Cronk tcronk@tampabay.rr.com.

[BillCNC]

From the pics of the other plugs you replaced the fit was loose with thosa as well.

The plug should fit in the adapters without the excessive looseness you describe. I run them with that plug and no carbon is on the plug threads like in your pictures. You have a poor fit and that will reduce the plug heat transfer to the block, not good. Get some proper ones from Ric Montoya or Tom Johnson tjohnston@localdialup.com or Tom Cronk tcronk@tampabay.rr.com.

ZUL8TR,

Ya, ... these are really loose, ... like a $2.00 hooker.

I got these from Tom Johnson, ... along with the BR10EIX plugs he recommended. I also got a flush plug water fitting from him, ... that works great BTW.

[johnsonm50]

I wouldn't jump to conclusions on suppliers [TJ has been good to me]. Keep in mind you're asking for easier starting -not having that much to do with all out performance. Maybe those plugs are what the doctor ordered?

[bill boyes]

Gezz you sure are getting lots of advice here. The reason your plugs have carbon on the end of the threads is because the threads protrude into the combustion chamber. They are long reach plugs. Which is ok. With 18mm to 14mm inserts make sure the insert does NOT protrude into the combustion Chamber. Why, well I have seen motors with burned pistons with long inserts.
Hard starting Yes while the motor is deep in the water they can start hard. See B and H remark. Look just retard the timing to start then advance it after the motor is running as they do in Japan.

[mercguy]

ZUL8TR,

Ya, ... these are really loose, ... like a $2.00 hooker.

I got these from Tom Johnson, ... along with the BR10EIX plugs he recommended. I also got a flush plug water fitting from him, ... that works great BTW.

So from the resistor plugs, which he recommended and that everyone else says, ... throw them in the lake, ... and the loose fitting plug inserts, ... $53.00 down the crapper, ... Agrrrr.

Appears I need to switch sources.

THE BR10EIX plugs are just fine........I have ran them successfully for over 10yrs with no issues.......TJ is right....

PS: **** can the inserts and buy a 14mm head!!

[BillCNC]

Bill,

The threads DO NOT go past the insert length, in fact, the threads are slightly recessed. The soot on the ends of the threads is from gases going down into the thread gap on the 14mm side. Also, the soot and fuel residue is climbing into the 18mm threads as well. I also measured the depth of the inset and those threads are not in the combustion area either.

Conclusion, ... the plug inserts need to go.

I don't see any other conclusion from the photos.

[BillCNC]

Ok, ... looks like the plugs are a racers choice, ... some like them, some don't. But the inserts are junk.

[johnsonm50]

Ok, ... looks like the plugs are a racers choice, ... some like them, some don't. But the inserts are junk.

Thought I read somewhere that 18mm plugs are available? 14mm plug heads too.

[BillCNC]

Thought I read somewhere that 18mm plugs are available? 14mm plug heads too.

Maybe buying a 14MM head will eliminate all this issue with plugs fitting correctly. Who has them and how much are they?

[BillCNC]

Here is a short video illustrating the poor fit of the inserts. You can see how little of a turn it takes from the plug seating to it wobbling.

http://youtu.be/QvnMhfY-Qa4

[Jack Stotts]

Bill, since you will not be racing, someone may have a 14 mm head that is not legal in racing that they would be willing to donate to a good cause. If someone has one that is available, give Bill a post. Jack

[ZUL8TR]

inserts

Since the inserts are mass produced a perfect fit on threads will be difficult to get. All inserts have some looseness some more than others. However your video does appear to show more on the loose side of the fit. Do the BR10EIX plugs have the same looseness? As long as there is no sign of telltale carbon trail that passes the insert or plug to the outside of the engine I would just use them.

[BillCNC]

I have found what appears to be another issue but with my kill switch wiring. The starter pulley is rubbing away the wires. The wire IS exposed and I get a positive continuity on both wires when grounded to the engine.

The top of the starter pulley is .065" above the crank bolt hole. Could I shim the starter pulley with a washer to raise it up slightly to make clearance for the wires? Clearly I need to redo the wiring. It currently has a 4 pole trailer plug. I think I will opt for something smaller and maybe a twist lock connection getting rid of some bulk. I'm sure the wires will be less fatigued if the plug doesn't weigh as much.

Sorry for this dragging on guy's, ... But I do want it functioning in top order.

[BillCNC]

Since the inserts are mass produced a perfect fit on threads will be difficult to get. All inserts have some looseness some more than others. However your video does appear to show more on the loose side of the fit. Do the BR10EIX plugs have the same looseness? As long as there is no sign of telltale carbon trail that passes the insert or plug to the outside of the engine I would just use them.

Wouldn't the loose threads affect the heat transfer making it a bad scenario?

Bill, since you will not be racing, someone may have a 14 mm head that is not legal in racing that they would be willing to donate to a good cause. If someone has one that is available, give Bill a post. Jack

Thanks Jack, ... It doesn't need to be donated, ... I would gladly pay for it. No free rides here.

[Jack Stotts]

I did not intend to infer that you needed a free ride but someone may have one that is just using up shelf space. I looked through my stuff and have only Y-80 heads and they are 18 mm. Don't shim the pully just reroute the wire. Jack