Jesse Open

Real valve seat grinders are lifted during the cut repeatedly to interrupt the cut and avoid plowing the ditches. Likewise, proper lapping involves short, alternating back and forth strokes, also with frequent lifting.


Angular, fluted reamer-like cutters may be used instead of grinders. Whe major cuts are made, the top and throat area are re-cut to un- mask the pocketed top and provide a seat of constant, concentric width.

These toy engine seats are already pretty crude right out of the box !

the Wasp

My Feedback: (1)

any one know what this home made tool is ? LOL guess LOL
it is 5 inches long and made with 10 magnets I had just setting around. each magnet is 3/8x1/2 inch. these are very strong magnets, they even work threw my finger LOL. I guess you could make this tool with only one magnet if you had a metal handle for it. but for some small valves you will need to turn down the magnet's OD on a lathe. or find magnets with a smaller OD.
if you LOL figure out what it is for don't tell the OS guys LOL

Jim

the Wasp

My Feedback: (1)

did that!
Jim

Jesse Open

This too?


"Angular, fluted reamer-like cutters may be used instead of grinders. Whe major cuts are made, the top and throat area are re-cut to un- mask the pocketed top and provide a seat of constant, concentric width."

1200SportsterRider

The black Saito 150 rebuild is this far along, new Boca's installed, new RMJ ring coming, good used cam and followers installed. The cam box is in the picture in case someone needs one that takes the followers without the mushroom heads, the cam box is for an early 120?, designation unknown to me.
I hope the scribe or otherwise write 150-S on the red patch. I'm still thinkin on it.

Jesse Open

Dave, I believe that cam box is from a FatHead Saito
The red tag, if you like, can be lifted after heating with a soldering gun. You could make a custom, brass tag (?)


Jim , Forgot to add those micro pics were outstanding. Good effort on saving the cylinder too. The comments were hopefully a bit helpful.

1200SportsterRider

Thanks Gary, I found the tappets for that housing at MacGregor's, more later on the tag.

Jesse Open

Looking forward to a pic of the completed engine!

FlyerInOKC

My Feedback: (6)

Same here!

the Wasp

My Feedback: (1)

yes I read that
Jim

1200SportsterRider

I was about to order an RMJ ring for the 150, there is a choice of ring thicknesses, so I have to measure the ring. https://rmjmachineworx.com/online-st...s/saito-fa-150

The choices, .039" and .0585", I checked and the 300 offers the same choice.

Glowgeek

Your right Dave, RJM does offer two different ring thicknesses. Weird.

The 150 is a strange animal, some lower compression and some higher but with no readily visual differences in the cylinder, piston or rod. At one point we were going to figure that out with measurements but never really nailed it down. As I recall you had one marked "A" and I had one marked "K" but both were high compression units.

I sold my 150 and replaced it with the same sized case, only slightly heavier, but way more powerful 180. That 180 has recently been converted to gas. Final bench testing commencing sometime over the next week.

For those interested in the DIY glow to gas fuel control system I'm implementing details can be found here: https://www.rcgroups.com/forums/show...ecommendations

Jesse Open

Were you able to trim the seat to a consistent width?

Glowgeek

Looks to measure .0575", even with the crusty carbon. It's seen some run time.

the Wasp

My Feedback: (1)

Gary, go back and look at the Pics, it is imposable to get that seat width consistent with only a valve to work with. even Saito with all their tooling didn't get it correct. and to add, as I said nothing is at a 90 degree so the valve face is not level to the celling. not my fault. it all shows it in the pics.

Jim

the Wasp

My Feedback: (1)

good luck, just know if it fails the cylinder will most likely be worthless. and if it works you should do both sides on a twin

Jim

Glowgeek

Likewise, I had an exhaust valve that wouldn't seat on a 60T. In my case the valve guide was worn beyond serviceability. All the lapping, grinding or cutting in the world wasn't going to help. The only fix would have been to replace the valve guide, not something I have tooling for.

Typically I find valve guides in good shape on used Saitos, even high runtime ones, but that was not the case with my 60T sample. I believe that the previous owner may have used lapping compound at some point and failed to clean it out thoroughly before running the engine. Just a guess but I can't see any other way where only one of four guides was worn out on such a low run time engine.

1200SportsterRider

I just checked and neither the 180 nor the 2.20 offer a choice in ring widths. To satisfy my own curiosity Ill measure both today.

Jesse Open

I have seen several Saito guides that were made sloppy at disassembly. During operation with sloppy rocker clearances, the valve tips become peened into a slighy mushroom shape. Forcing those valves out broaches the soft guide resulting in a sloppy fit.

If I encounter any resistance at all it is time to use a stone on the side of the stem tip to relieve the mushroomed area.

Even seen stem tips that were deformed to the point where the keeper groove had collapsed and pinched the keeper clip. One clip had cracked in two.

Glowgeek

Great tips for disassembly Gary. Words to live by.

706jim

Since Saito cylinders don't have a removable head are the valve guides parallel to the cylinder bore? I own two Saitos but have not disassembled them to check.
Otherwise, I have no idea how they would machine the valve seats.

Glowgeek

The valves are canted and the combustion chamber is hemispherical. Valve location leaves just enough room for tooling in the cylinder for cutting the seats.

Jesse Open

Often the spring retainers are just a bit sticky going over the valve tip. Good clue that you should de-burr the sides.

The HC FA-65 I took in last week was the worst I had seen so far. The owner had heated the rocker pivots with a torch to remove the pins. In so doing, he had destroyed the springs. The C Clip keeper on one was cracked in two, both were very tight in the grooves. The new clips would not fit the keeper groove at all.

New valves, springs, retainers, keepers and re-finished tappets. Along with a ring and bearings. The spare parts box took quite a hit on this engine!

Ready for it's next plane.

Jesse Open

Sorry Jim, I just now saw this.
I was hoping you would be able to make a tool similar to what we discussed. Actually it would take two , one for the throat and one for the topside.

Hope I didn't sound negative!
What you have done looks great, getting that seat narrowed and constant would be a big improvement. Maybe Dave could turn a couple of cutters (?) I would be glad to give tips on making them should be very basic.

Yes, the makers do get pretty sloppy in this area!

Jesse Open

Dave,

Just happened to recall that Sr, Telemaster had some cylinders and pistons that were pulls from brand new engines. I think they were for the 150. He was willing to sell them. Maybe still has them (?)


FYI

RE ring thicknesses:

The .039" ring is 1 millimeter thick.
The .0585" ring is a 1.5 millimeter
thickness.