Author Topic: EX21 Temp  (Read 479 times)

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Offline Duff

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EX21 Temp
« on: May 13, 2023, 12:47:48 PM »
Had a Tom conversion Honda to EX21 some years ago. I get out about 15 times a season in PA. Runs great no issues. I just wanted to put this question out there. The motor starts out at 4140 RPM and drops to 4020 when it gets hot. On the runleader it reads 300-320 degrees. I suspect this temp is on the high side. But is this still OK?

Offline Painlesstom

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Re: EX21 Temp
« Reply #1 on: May 13, 2023, 06:46:50 PM »
That temp is a bit high, should be 270's or less. Water cooled muffler or dry? RPM's are about right though.
Tom

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Offline Duff

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Re: EX21 Temp
« Reply #2 on: May 15, 2023, 08:49:55 AM »
Yeah -  I'm on my 2nd dry. Water cooled is next. Need to Mod the blower intake some. And since I have foam behind the seat, I'm thinking about trimming some off the top edges to let air flow through.

Offline Painlesstom

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Re: EX21 Temp
« Reply #3 on: May 16, 2023, 06:53:09 AM »
Ahhh, ok. Temps are probably on par then with that dry muffler. Don't trim the foam for ventilation, it will just push air from the engine compartment into the cockpit and you'll smell oil and gas to some extent. The past couple years I've been making spacers for the hood scoop over the inlet, lets the flywheel fan breath easier and has improved cooling. Does your recoil starter have cutouts? That's something else I've been doing for quite a while to increase airflow on the Subaru engines. Current Tillotson conversions I don't even install the pull start, it blocks that much air.
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Offline Californiamokai

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Re: EX21 Temp
« Reply #4 on: May 16, 2023, 11:07:15 AM »
Caught your comment “ spacers for the hood scoop over the inlet.”  Curious, can you share s pic…

Offline Painlesstom

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Re: EX21 Temp
« Reply #5 on: May 16, 2023, 02:38:39 PM »
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Offline Hillbilly

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Re: EX21 Temp
« Reply #6 on: May 16, 2023, 04:47:46 PM »
Perfect display of the power of the Tillotson/Painless drivetrain.

Offline Painlesstom

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Re: EX21 Temp
« Reply #7 on: May 17, 2023, 02:24:27 PM »
Perfect display of the power of the Tillotson/Painless drivetrain.

Haha Thanks. It is a pretty happy picture.  >:D
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Offline Duff

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Re: EX21 Temp
« Reply #8 on: May 17, 2023, 07:09:56 PM »
Ahhh, ok. Temps are probably on par then with that dry muffler. The past couple years I've been making spacers for the hood scoop over the inlet, lets the flywheel fan breath easier and has improved cooling. Does your recoil starter have cutouts? That's something else I've been doing for quite a while to increase airflow on the Subaru engines. Current Tillotson conversions I don't even install the pull start, it blocks that much air.

I removed the scoop and covered the opening with wire cloth. My crate acts as a large scoop. I'm sure it helped get more air flowing. The blower shroud is from the Honda GC motor. Wonder if it was wider/thicker like the later model, would it help pulling air. I'm considering doing cutouts, but I'm concerned about a replacement if it cracks from pull starting. It is electric start though. Just want a good backup.

« Last Edit: May 17, 2023, 07:13:30 PM by Duff »

Offline Painlesstom

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Re: EX21 Temp
« Reply #9 on: May 17, 2023, 07:19:41 PM »
That hood setup is fine with the mesh and crate. No problem there. I've been cutting sections of the recoil starters for years, havent' had any problems that I've heard about. I personally run my engines without them installed, huge difference in cooling. It can still be used in an emergency, just not very convenient.
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Offline Duff

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Re: EX21 Temp
« Reply #10 on: July 29, 2023, 01:04:03 PM »
Update -

I removed the pull starter. I re-bolted by padding it with some pieces of pvc molding. Dropped a good 30->35 degrees. Tried attaching the air tunnel shroud using finger bolts but the threads didn't match so well. Need to try others.

During the winter I will install bolts from inside of the fan shroud pointing out. That way, if needed, I can just reattach the pull starter using wing nuts. Somebody posted this idea for the Tillotson motor - Good Idea !

Oh Forgot - RPM stayed above 4100 !
« Last Edit: July 29, 2023, 01:09:42 PM by Duff »

Offline Hillbilly

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Re: EX21 Temp
« Reply #11 on: July 29, 2023, 04:51:22 PM »
Congrats on your success, Duff.  The pull start sure blocks a lot of air.  Doubt you will need it again but you will be ready if you do.