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Engine run too lean for too long? Checking the free height of the valve springs I find the exhaust spring on the short side much more frequently than the intake spring. I have never seen one callapsed like that. Yikes!
Last edited by Glowgeek; 10-12-2021 at 09:05 AM.

If anyone wants a NIB Saito 90T let me know. I'm not asking much for it. The previous owner thought it had been run because it had been mounted. I pulled the plugs, obviously never run.
Last edited by Glowgeek; 10-12-2021 at 09:25 AM.

My Feedback: (6)


Dave
I use the Klotz Super Techniplate that is 20% castor. I know your feelings on using castor and I am thinking on switching when my supply is gone. I have had exhaust valves get carboned up on small 4C engines. I have also used a Go- Kart oil called Thor with good results but the price has gone up and it is now harder to find. My normal fuel is 18% oil and 3% nitro. This mix works good in all my engines for the type of flying I do. I am always on the look out for a lower cost oil that is good. The Klotz Techniplate is now about $70 and Super Techniplate is about $60 a gallon on Amazon.
I use the Klotz Super Techniplate that is 20% castor. I know your feelings on using castor and I am thinking on switching when my supply is gone. I have had exhaust valves get carboned up on small 4C engines. I have also used a Go- Kart oil called Thor with good results but the price has gone up and it is now harder to find. My normal fuel is 18% oil and 3% nitro. This mix works good in all my engines for the type of flying I do. I am always on the look out for a lower cost oil that is good. The Klotz Techniplate is now about $70 and Super Techniplate is about $60 a gallon on Amazon.
Pedro,
The Supertechniplate is running your castor content up to nearly 5%. By cutting it 50/50 with Original Techniplate you can get down to just over 2%, the difference between the two at that point is noticeable.
At the 14% oil mix I use, carbon is no longer close to a concern. While it was light at 5%, carbon is gone at 2% (14% total oil content).
Very happy with the long-term results.

My Feedback: (27)

Gary
That's a great idea. I do have two quarts of standard Techniplate here. My next mix will be with your suggestion. I need to find a good deal on a couple of gallons of Techniplate.
That's a great idea. I do have two quarts of standard Techniplate here. My next mix will be with your suggestion. I need to find a good deal on a couple of gallons of Techniplate.


Dave, Pedro,
A handy little tool, you may want to make a few. Made a few sets of these for the small machine screw sizes.
They got loads of use over the years.

Made from aluminum brass or steel. One setscrew, lightly snugged does the trick.

Drill on-size to match tap diameter.
A handy little tool, you may want to make a few. Made a few sets of these for the small machine screw sizes.
They got loads of use over the years.

Made from aluminum brass or steel. One setscrew, lightly snugged does the trick.

Drill on-size to match tap diameter.
Senior Member
My Feedback: (3)

As for the comments earlier on my rich LS, I will pull the barrel and needle out to have a boo, but have the carb swapped and will try and set up the new carb in the next day or two.
Nothing visible on the old one.
Nothing visible on the old one.

Then the house repairs start, so I will need to put up some shelving, store away my RC projects, clear the benches, organize my tools and get to work putting in new plumbing for the bathrooms, and have someone on tap to hire for some tile work.
Maybe in 6 months I can get back to RC, but for now, it is being put on hold. I have WAY too many projects and the days are getting shorter and colder, and I have 3 acres of fence to take down, a hydrant to move, and some gate repairs to do before winter. Then in spring can attack the pastures and get them seeded, fertilized, and weeds killed off for a first cutting. Going to start with hay fields, and once I have a burn pile cleared, plant some sweet corn and vegetables for a farm stand. Will see how that goes.
Until then, just have to give my Saitos a good oiling and put them away for now.
Senior Member
My Feedback: (3)

Based on thee pics and glow plug hole, (or lack of it) assuming this spring is on intake? I have seen most affected on exhaust with the increased heat and contamination.

Same here. On used engines if I find a short spring it's normally on the exhaust side. As a rule, if I find that one spring is shorter than the other by more than .010" I replace them both. Cheap insurance.


Yep,
The exhaust side is generally the hardest worked side. All the way back to the cam and lifter.
Aside from perhaps an even earlier failure ; A defective spring doesn't care which side it is on.
That spring is just dead, most likely a bad heat treat.
The exhaust side is generally the hardest worked side. All the way back to the cam and lifter.
Aside from perhaps an even earlier failure ; A defective spring doesn't care which side it is on.
That spring is just dead, most likely a bad heat treat.
Last edited by Jesse Open; 10-14-2021 at 04:26 AM.

Here's a thought. I wonder if the previous owner of that 120 overheated the top half of that intake spring during an attempt to remove the rocker pin, or even the keeper C-clip. One of those little butane torches would make quick work of taking the temper out of the top half of a valve spring. Just a few seconds of misdirected flame is all it would take. Always safer to use a heat gun.
And yes Dave, I'm wondering again,
And yes Dave, I'm wondering again,

Last edited by Glowgeek; 10-14-2021 at 04:59 AM.


Here's a thought. I wonder if the previous owner of that 120 overheated the top half of that intake spring during an attempt to remove the rocker pin, or even the keeper C-clip. One of those little butane torches would make quick work of taking the temper out of the top half of a valve spring. Just a few seconds of misdirected flame is all it would take. Always safer to use a heat gun.
And yes Dave, I'm wondering again,
And yes Dave, I'm wondering again,

Yep,
Very possible.
Any tech worth his salt would never bring a torch flame near that spring.
My favorite heat source in close quarters is a soldering iron or gun.
At the shop when rebuilding cylinder heads, we 100% checked seat pressure at installed height. Any springs not within mfg spec were replaced.
Last edited by Jesse Open; 10-14-2021 at 07:24 AM.



Ok Gentlemen. To "can't" or not to can't. Please opine, its a Saito 150 on a 89" 15 pound ish golden era of some unknown type. Gonna use the 1/3 chord general starting point for the cg. I don't have the factory spec.
Last edited by Hyjinx; 10-14-2021 at 08:11 AM.


Here you go Aaron.
https://rcplanes.online/cg_calc.htm
Hope it helps, has worked well around here anyhow.
Grandpa used to have some great advice on
"Wondering". When you don't know something and don't have a clue on how to find out, wondering is about all you can do.
On the plus side, at least you realize that you don't know
https://rcplanes.online/cg_calc.htm
Hope it helps, has worked well around here anyhow.
Grandpa used to have some great advice on
"Wondering". When you don't know something and don't have a clue on how to find out, wondering is about all you can do.
On the plus side, at least you realize that you don't know


My Feedback: (6)