planenutzz

Lets see if we can get a sensible response to this question.

Those who have had Ray modify your FG90 did you end up with an additional nipple between number 1 & 3 cylinders? If so what was it's purpose and does it stay open or is it to be blocked off?

TIA

BarracudaHockey

My Feedback: (11)

Cleaned up the snarky posts, if your post is gone consider yourself warned.

Thanks and lets move along.

rcpollo

My Feedback: (6)

I don't see one betweenb 1 and 3. Are you sure you don't mean the one at the bottom between 2 & 3?

planenutzz

On my engine there is one between 1 & 3 as well as the one on the bottom of the crankcase. Hence my use of the word "additional"

rcpollo

My Feedback: (6)

I haven't noticed that one. Right now the plane is in Florida but I'm back north in Baltimore. Won't be able to eyeball it for a couple weeks. Will let you know then.

planenutzz

engine stand offs to be used on my test stand.

dunk

My Feedback: (153)

Do you guys that have the Morris mini motors intake and carb mod think it's worth it. I have the CH timing hub to install and I'm just on the fence on the mod. I was also thinking of sending to Ray but I'm liking the idea of using an actual walbro carb.

planenutzz

I have the MM parts but not going to use them, I sent my engine to Ray English for modifying, he confirmed that the saito rear intake plate incorporates his mods.

dunk

My Feedback: (153)

So if I do the hub swap I should be good to go. Just didn't want the cylinder temps issues. Are you going to use 15 to 1 or 20 to 1?

planenutzz

you need to get the master rod and slave rod bushing modified by Ray and you need to get timing corrected. Saito has 2 & 3 set at 40 degrees, 1 I am led to believe is at 30.

I'd send it to Ray to do the work.

dunk

My Feedback: (153)

Thanks for the clarification.

Jaketab

My Feedback: (2)

Sorry if I missed it previously in this thread, but regarding the prop drive flange upgrade from CH Ignitions. I'm not clear if Ray's modification is any different from the CH hub upgrade. It would appear from the information on the CH website that the hub corrects the timing issue. Below is a direct quote for the CH website regarding the $75 new prop drive hub upgrade.

"My friends the 3 sparks on the CDI’s are only up to 300 RPM for START ONLY. !!! Before starting the computer does not know what cylinder to fire. That is why ALL spark plugs fire at once. One of the cylinders will be on POWER stroke and will fire; once the engine fires and rotates and is above 300 RPM the Reset magnet will tell it to fire 1,3,2 and start the sequence firing order. Now…the issue you have is actually the TIMING of the engine. The factory timed the engine 47 BTDC and it is too advanced and uses a 30BTDC CDI…also there is a timing issue in between the #2 and #3 cylinder one is advanced more and one less. This New Prop Drive Flange sets the timing in accordance with the CDI (30BTDC) and corrects the timing between cylinders #2 &3. You can replace the prop drive and the engine will be running like a Swiss clock. We designed this in such a manner to minimize the set of skills necessary, no timing tools and other expenses involved. It is an easy DIY."

From speaking via phone to Mr. English, I believe he uses the uses the original Saito prop drive hub and makes the correction directly on it. The other mod he makes is to correct and enlarge the tolerance of the master rod bronze bushing. The factory Saito bushing tolerance is 0.001". His correction enlarges the tolerance to 0.003" which allows better lubrication to the rod bushing. Trying to recall this from memory, so please correct me if I have misrepresented his modifications.

Regards - J Tab

dunk

My Feedback: (153)

So what's the advantage of the bushing mod? More tolerance so you have less o a chance of seizure due to better lubrication and maybe a fewer more rpms?

I'd like to know if after Ray's mods if the cylinder temps are more inline or if a guy needs the MMM intake to achieve this.

Jaketab

My Feedback: (2)

Larger radials like the Moki, (I own two) use needle bearings as opposed to bronze bushings in a Saito. The Moki draws its fuel from the carb which goes directly into the crankcase. From the crankcase the oil is dispersed into the intake tubes to feed the cylinders. That's why the Moki can use a leaner gas/oil mix of 50/1. The needle bearings transfer oil better and have less friction resistance.

The fuel mix in the Saito is fed from the carb into a mixing chamber where it is picked up by the intake tubes and then to the cylinders. The Saito depends on blow-by oil from the combustion to lube the internal rod bushings. Hense the Saito must require a richer fuel/oil mix to adequately lubricate the rod bushings.

I hope to soon acquire a Saito 90 cc radial and pair with a Top RC Focke Wulf. (Can't find one until the next shipment - darn covid delays) My personal thought is to purchase the Saito through my local hobby shop and install the prop drive flange upgrade myself to correct the timing issue. The key, IMO, is a careful break in period using a 15/1 mix and pre-lubing the crankcase before the start of each session.

Regards - J Tab

planenutzz

regarding the pre-lube that is a good point, Ray fitted an additional nipple between No.s 1 & 3 cylinders, I wonder if that is what it is for and if it is supposed to be open to breathe during operation or not. I have emailed Ray about this but no reply, might have to try a phone call which will be late at night for me.

darod07

This 2nd nipple must be blocked! My engine came repaired from Saito after master rod seizure and this nipple was fitted also. I received an instruction from Saito to keep this nipple blocked. Pre-lube of about 30ml of oil must be done after longer period on the shelf, not every time before flight.

planenutzz

yes well I'll see if Ray confirms that about blocking the 2nd nipple

dunk

My Feedback: (153)

Here is whatMM said.


"All of the engines now come with bronze Bush on the Big end


But all of the engine still need Prop hub and intake upgrade


If you upgrade the intake the vent nipples would have to be blocked off

because the crankcase would become the mixing chamber"

planenutzz

I spoke to Ray on the phone, what a lovely fellow to chat with.

The second nipple is on the new build FG90R3 as supplied by Saito. Ray advised you can block it is you want though said just connect the the nipples together via a Tee and run the line about half way up the crankcase on the firewall then down and out of the model.

As for the MMM I got same advice including running it at 30:1 !! I won't be fitting the MMM back plate and will sell that and the timing ring as I won't have a use for either now.

planenutzz

Ran the FG90 on the weekend! What a beast. Was mounted to my test stand, no baffles.
Biela 3 blade FW-190 style 20x12 prop. 15:1 Klotz KL-200 and 98 Octane petrol.

Idle 1290 RPM, peak 6400 RPM though it was getting hot so only did a few bursts at full throttle. I am hoping that when I fit the baffles that will bring those temps down to reasonable levels.
I richend up the top end, low needle was already quite rich.

Engine ran for 84 mins on a 9050mL / 32Oz tank. What a miser! Most of the running was around 3000 RPM with a few burst to 4500 - 6000.
then back to idle to allow it cool down. Lots of burble in the transition which I expect as the mixtures are very rich. Copious amount of black oil expelled from the exhaust.

I'm also getting oil leaking from the exhaust fitting to the head. Is that normal?

My only concern now are those temps. No.1 actually was the best performer and numbers 2 & 3 were getting hotter.
Could be the petrol I was using as it was 98 Octane and I would suspect was making it run hot as well as hit that 6400 peak RPM.
I'll ditch that batch of fuel and use it in the old mower, mix a new batch of 91 Octane, fit the baffle and re-run it.

I did find that the choke rod with the threaded part was useless, pulling the throttle body out as far as it would go would go would not suck fuel but putting finger over the trumpet drew fuel very quickly. I think I will make something that allow for that style of choking when in the plane.
Engine was very easy to hand start.

planenutzz

Gents,
for those with temperature probes on the cylinders how have you mounted them? Around spark plug base or wedged between the fins on top of the cylinders.

I have mine wrapped around the spark plug base but worried the base of the plug is much hotter than the head itself.

I have measured the head in a few spots with a temperature gun and it indicates fairly good temps however the telemetry shows high temps.

thanks
cheers
P

hpergm

I use the Jeti system's temp probes (MT-300), which will just about wedge themselves snuggly between the Saito cylinder fins and stay there without any further intervention. It's better if the probes' active parts face the back of the cylinders to avoid the cooling effect of the varying oncoming airflow messing with the measurements. The absolute measurement will vary from mounting point to mounting point. For me, wedging the probe between the top fins just below the spark plug works best. In a cowled and baffled install, the engine operates between 125 and 145 Celcius measured at those points.

planenutzz

thanks mate, 125 to 138 C are the temps I am seeing which seemed to be very hot to me. That is 257F to 280F or in your case up to 293C or 418 kelvin for the geeks amongst us!

Have fitted the MMM rear induction plate today and adjusted the tappets. I have new NGK CM6 plugs arriving Tuesday so will run it again and see how it performs.
The Telemetry system I am using is the IISI Cockpit V2 as it is standalone. My JR 12X does not have telemetry.

Carlo Vangompel

Can somebody tell me how to do Pre-lube the engine after a longer period of not using the engine?

Carlo

darod07

Simply take a syringe and inject 20 - 30 ml of oil through 2nd nipple fitted on top between cyl 1&3 while turning slowly prop anti-clockwise, then block nipple.