Venturi Case

ZACATTACK Wed May 09, 2012 10:09 pm

Would it be dificult to remove the red venturi case on a Medallion .15? Thanx!

Jason_WI Wed May 09, 2012 10:35 pm

Do you have 15 wrenches?

Here is a Medallion 15 that I will replace the venturi and the drive plate on.

Remove the back cover with the 15 wrench.

Remove the cylinder and piston with the 15 wrench.

Insert a prop screw and either use an arbor press and press off the drive washer. You can also use light taps with a hammer on the prop screw with the back of the crankcase on a hardwood block.

Remove the crank

Remove the carb body collar with the 15 wrench.

Remove the carb body with a flat or round pry bar against the crankcase. Sometimes you need to heat the carb body with a hair dryer on high then try to pry or push off. Some are stuck on pretty hard.

Install the new carb body onto the crank case.

Sometimes the fit of the new venturi is tight. I use the collar threadded on backwards to turn the venturi onto the crank case. Once it is on most of the way I turn the collar around and turn it on all the way till it's tight against the back of the ventur to the crank case.

I then install the new drive washer with the arbor press.

All nice and pretty ready for the flying field or the display case.

**RknRusty** Wed May 09, 2012 10:49 pm

If it's like the .049, you can take off the drive plate and carb body without opening the engine. Just unscrew the carb retaining collar and it will push the drive plate off.

ZACATTACK Wed May 09, 2012 11:04 pm

Holy $h*% !!! I my wreck the motor doing that!! Alot of work for just a new venturi..Not doing it if problems are involved here Rusty..Looks like the job for Ron Valentine...He would do that!

**Cribbs74** Wed May 09, 2012 11:04 pm

RknRusty wrote:If it's like the .049, you can take off the drive plate and carb body without opening the engine. Just unscrew the carb retaining collar and it will push the drive plate off.

Rusty,

I use the method Jason describes above to remove the driveplate. I did try it the way you describe once and i found it enlarged the notches in the retaining collar because of the amount of force used to press the plate off. I have also had a wrench slip as well which caused the corner of the notch to chip off and gouged the collar. Have you experienced that or am I just doing something wrong.

Ron

**Cribbs74** Wed May 09, 2012 11:08 pm

ZACATTACK wrote:Holy $h*% !!! I my wreck the motor doing that!! Alot of work for just a new venturi..Not doing it if problems are involved here Rusty..Looks like the job for Ron Valentine...He would do that!

You won't wreck anything if you are careful. Work slow and always be sure you have a good bite with the tools. Heat is your friend here.......

No need to send it off. These engines were designed for the average guy to assemble/disassemble.

Jason_WI Wed May 09, 2012 11:21 pm

Adding pictures to my first post. It takes like 5 minutes or less. I just did a Medallion 15 tonight when I took the pics. New carb body and drive plate in 5 minutes.

Jason

**RknRusty** Wed May 09, 2012 11:32 pm

cribbs74 wrote:
RknRusty wrote:If it's like the .049, you can take off the drive plate and carb body without opening the engine. Just unscrew the carb retaining collar and it will push the drive plate off.

Rusty,

I use the method Jason describes above to remove the driveplate. I did try it the way you describe once and i found it enlarged the notches in the retaining collar because of the amount of force used to press the plate off. I have also had a wrench slip as well which caused the corner of the notch to chip off and gouged the collar. Have you experienced that or am I just doing something wrong.

Ron

I have only done it a few times with none of those problems, but I'm generally a lucky guy, so play it safe and do what you're comfortable with. Like Jason said, it's extremely easy to just tap the crank off of it. It's a good opportunity to inspect the innards too.

Jason_WI Wed May 09, 2012 11:48 pm

Pics added

ZACATTACK Thu May 10, 2012 12:02 am

Man not too bad at all after viewing those pictures. That Arbor Press is a nice thing that I dont have. How do you get the piston off the crank? Is there not a little set screw on the botton of the conrod? Thanx for the Pics!!

Jason_WI Thu May 10, 2012 12:06 am

No set screw. It just slides right off the crank pin when the cylinder and the backplate are removed.

The arbor press is from Harbor Freight and was on sale for $29.99 a while back.

Jason

ZACATTACK Thu May 10, 2012 12:14 am

How about the Mark 2 Special? The piston just slids off?? Could you not use a regular vice lined with hardwood to do this? Seems the same only your working on a horizontal plane as too a vertical one with the arbor press??

Jason_WI Thu May 10, 2012 12:25 am

Well it might work in a vice but it will be hard to keep the drive plate perpendicular to the crank shaft. Once the drive plate is pressed on crooked it will never be right.

**RknRusty** Thu May 10, 2012 2:41 am

I use an old prop screw and a hammer as per the Cox instruction sheet to remove the drive plate. One lick and the crank pops loose. A prop and a spacer and press it back on with the screw. That keeps the plate straight going back on.

John Goddard Thu May 10, 2012 5:16 am

As Rusty sez hammer and prop screw every time.

Silly question !!!!!Alert!!!!!

Why do you want to take it off?

FWIW The first time I tried it (it was an 010 though) I wrecked it
because I didn't know about Jasons hairdryer trick.
Very Happy

AT1984 Thu May 10, 2012 4:48 pm

I have two TD .09's, and have completely disassembled both for cleaning. If the Medallion is basically the same, disassemble it like Rusty said. You unscrew the collet with the Cox wrench, and it pushes the drive plate straight off. That way, you don't have to worry about it coming off crooked, and damaging the splines on the end of the crankshaft. I would take my time, to make sure the wrench doesn't slip. It does work!

I had mine apart, and couldn't figure out how to push the driveplate back on (doh)! I wrote to Barry Hobkirk, who wrote an article on servicing a TD .049. The TD .09 is exactly like it...just bigger, of course. Barry told me about pushing the plate back on with a prop. Silly me! Smile

Line up the splines, and push the driveplate back on, insuring its straight...then put a prop on it, and tighten it down (slowly). Pushes the drivplate right back on.

Just my 2 cents...

Allen

**Admin** Thu May 10, 2012 6:17 pm

Great carb body removal tutorial Jason! For all the Tee Dees and Medallions, I have always removed the driveplate by unscrewing the collet. If the driveplate is so tight that the collet wont remove it (you'll know the limit before it distorts the collet), then you tap or press the crank out.

jsesere Sat Dec 08, 2012 12:23 am

Good trick.

ahrma_581 Sat Dec 08, 2012 9:28 am

Jason_WI wrote:Well it might work in a vice but it will be hard to keep the drive plate perpendicular to the crank shaft. Once the drive plate is pressed on crooked it will never be right.

Vice is good for removing, prop to replace. Smacking things with a hammer should be last resort. Use an allen screw for removing, so there is a flat surface to press against. This works for both reedies and TD/Medallions. However for .15's you may need a larger vise than you happen to have.

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