Cam timing
 

So I've run into a cam timing snag I've never encountered before.

My SOP is to line cams up with timing marks during assembly and then check to see if rockers are the same height at TDC of the exhaust stroke. This is not working with the Saito 200ti. With rockers level I have two choices, crank retarded 1/2 tooth or crank advanced 1/2 tooth.
So far, after much assembly, disassembly, reassembly etc due to not trusting myself I have set the front cam advanced 1/2 tooth. Hope that's right. I haven't tried the rear cam yet.

Prototype print in PLA with 1.6mm walls, top, bottom and 60% infill. This thing is insanely strong. Took less than an hour to print and cost about 4 cents.

https://cimg7.ibsrv.net/gimg/www.rcu...22aee5e09f.jpg
https://cimg6.ibsrv.net/gimg/www.rcu...c911762e96.jpg

a good way to load a boat engine?
 

Got the head bolts in and mounted so the engine is ready to be test run.
The current complication is that i could not find a prop driver that fits this engine so that complicates things.
I could mount it back in the boat and fill up my bath tub to run the engine there but i really want to avoid that if possible.

Running without a load sounds like asking for the engine to explode.

Suggstions?

about damp filament
 

Pla will get brittle with it gets damp; this can become so extreme that is breaks just by unspooling it.
Also the boiling off of that water when the filament is in the heat blok part of your extruder can cause it to get blocked.
Or you get uneven flow making prints ugly.

So when you are not using it then keep it in a ziplock bag.

When you are trying abs make sure the slicer includes a skirt/fence around the print.
This will reduce drafts and that will reduce uneven clooling and the warping that is a result of that.

Yes, I remember. But I am pretty sure, that his tightening of the bolts was not the issue there. Via PM I had warned him about keeping the RPM below 9K on advise of JustEngines, and I warned him for the 18 x 6 prop he used being too light for that engine on methanol. He replied that his OS Gemini manual stated 10K (or something along those lines) and that he thought it would not be a problem.

So he went ahead and one of the conrods failed at around 9500 RPM.

I have never had mine above 8200 and I am extremely careful not to ever exeed that RPM.

FWIW, for the ASP/Magnum, my recommendation when running gas is an ASP 18 x 6Wideblade, or a good 17 x 8 or maybe 16 x 10, but no lighter than that. prop for 7500 on the ground and you should be OK. That still is (after full break in) a good 2+ hp on the ground and more in the air.

Find a small pond or lake with a platform close to the water. That is how I did it.
Or place the engine in a stand, and sacrifice a deep bucket by drilling a hole in it in which a propshaft fits.

Like can be seen in this thread: https://www.modelbouwforum.nl/threads/pokkeboot.254062/ A few pages from the beginning...

I've run a 18-6 classic series master airscrew on the OS boxer, but settled on a Xoar 18-8 laminated series...you still have to watch the overrun rpm, and manage the throttle.

The quality of those rod caps screws, who knows what grade they are... OS even uses all thread rod cap screws... they really need to be shouldered screws, and a short portion of that shoulder should act as the bearing cap aliment... its the weakest link in those engines... could even go up one screw size... I haven't taken mine down that far to have a closer look, just pulled back the cylinders to verify it came with the late style bronze rods.

Oh definitely, those boxer engine's performance on CDi is quite impressive, much improved over glow ignition.

no spare screw
 

The only axle and screw i have is the one that is glued into the hull.
Think best is just to "bite the bullet" and open the windows of the bathroom and run the setup as designed.

Good thing the guys next doors know me well enough to not be wondering why i run a engine in the bathroom.......
https://cimg8.ibsrv.net/gimg/www.rcu...fc5cccb2da.jpg
test fit

and another small delay
 

Rotating the screw shaft by hand showed its "dry" inside.
There is one of those "grease gun" couplings on the axle at the engine side.
At the workshop at work there is a suitable grease gun so il take the boat with me and fill the shaft with grease tomorrow.

^this seems like a phenomenally bad idea. Can you make sure to record video with sound, please.

of the grease gun?
 

Il see if i can find and charge my old gopro.

But yea don't think sustained full throttle is a good idea if i want to keep any water in the tub.
Goal is to find out if the engine runs at all or is a write-off.

And the "snag-list" keeps growing the engine mounting holes are for m4 but the mounting plate holes are to small for m4.
Looks like the engine was mounted with m3 and not too secure either since the mounting hole are not perfectly round anymore.
Going to tap m4 in the mounting plate and then back it with locknuts so it will not vibrate loose.

If the mounting plate is metal, blue loctite will work

3mm
 

The mounting plate is 3mm aluminium so assuming the tapping goes well then your probbaly right.

I don't know. M4 screws in a 3mm aluminum sheet doesn't sound like much. IIRC, 2 times screw dia is the minimum thread engagement for aluminum.

PEM nuts or Rivet Nuts work well for thin sheet threading. Rivet Nuts also don't require access to the blind side of the sheet.

On that 200Ti, you set the valve timing in the same way you set any of the saito even fire twins... the intake exhaust opening / closing profile is different for each cylinder... it results in an offset in cylinder exhaust blow down from #1 & #2 cylinder... you set the crank to TDC, time the right hand cylinder ( planes starboard side ), and then rotate the crank counter clockwise ( direction of prop rotation ) 360 to TDC again, and then time the left cylinder. ( planes port side )


http://sceptreflight.com/Model%20Eng...0FA-200Ti.html

When I received the used engine the front/left cylinder huffed compression out of the intake just before reaching tdc, so I knew that cam timing was way off. No way to check the rear/right cylinder for compression due to the stripped glow plug. I was careful to keep parts identified as I disassembled and cleaned things up. Point being, someone reassembled it incorrectly. I think the front and rear cams had been swapped.

Bottom line, with THAT cam in the front/left cylinder I cannot time it so the center of the valve overlap period is aligned with crank tdc. It is 1/2 tooth out (7.5°) one way or the other. I'll try swapping the cams.

I had read Clarence Lee's review several times. He claims that both cams are identical and that they are from a 91S. He was probably reviewing a pre release engine. The cams available for the 200ti online are most certainly different part numbers. One fits a Saito 182 and the other is specific to the 100ti and 200ti engines.

You are too late for the claim of "to boldly go where no man has gone before":


:D

been there, done that...

Admittedly, that was before my wife joined me in the Netherlands...

He degrees the cam valve opening / closing on most of his reviews, he maybe seeing it has the same cam profile as the 91S... the 200Ti front cam part# is definitely from the 182TD ( left cam )... the rear cam has a unique part # for the 200Ti ... you can't mix them up.... has the swagged lobe moved, I never thought much of how they assembles those sintered metal cams.

progress
 

https://cimg7.ibsrv.net/gimg/www.rcu...107c3a9d9a.jpg
test fit
Next is to get replacemnts nuts and washers to secure the engine plate to the hull (m5 i hope..) , then do some plumbing for the coolant lines and hook up a fuel tank.

Am not in the Netherlands
 

i'll be grand....

RC outboards have got to be one of the neatest things on the planet!

He degrees them yes. I degreed mine yesterday. They way I have it installed both his and my cam's closing angles are the same but not the opening angle. So, not the same cam Clarence reviewed.

Well I you''ll have to verify the cams then... the large displacement saito's 1.25ci and above went to 40 tooth cam gears, so a 48 tooth gear wouldn't even mesh... maybe the previous owner knows something.

Front cam part# 182TD34
Rear cam part# 200Ti35

Not the 125, it uses the same cam as the 50 thru 115. The 120, 150 & 180 big block Saitos use a different cam,

The 200ti has the 24/48 spur gear configuration.

A wouldn't ask the time of day from the previous owner. Lots of things he did to this engine shows his carelessness.

Clarence Lee cam specs (claims front and rear are identical)

Intake opens at 40 btdc, closes at 60 abdc
Exhaust opens at 75 bbdc, closes at 25 atdc

The front cam I installed (May not be right correct one)

Intake opens at 24 btdc, closes at 58 abdc
Exhaust opens at 68 bbdc, closes 24 atdc

As you can see, My cam does have a significantly wider LSA.
The cam that was in the rear has an even wider LSA.