I already think I know who will have the answer to this one, I'm planning on making the threaded pipe with a nipple for a saito but I don't know the thread, Does any one know what the thread sizes are on the saito mufflers. I am doing it for a 100 but the other sizes would be good too because when I have time I will make some for the other sizes too and hopefully help out a few of the guys here on RCU who want smoke.

Dauntae

D:

The small blocks are 10x1, mid blocks 12x1, and big block engines have a 14x1 thread.

Note this does not include the new FA-125 and FA-220. Jim and Hobbsy have posted the 125 as 1/2"-20 and the 220 as 15x1 mm.

The 1/2"-20 is very close to a 13x1.25 thread, the two would be easily confused, and since Saiito already uses a 16x1 thread on the intake of the 150 and 180 engines I'd suspect a meassurement error on the 220 also.

Bill.

Here are the 2.20 measurements again,

Dave:

Your caliper on the thread does indeed show 15 mm. The picture I rmember looked like the measurement was taken on an unthreaded area of the pipe.

Your first picture shows 13.76 mm. What is that a measurement of?

On the FA-125, there's only 0.02 mm difference in the pitch between the 1/2-20 and the 13x1.25 threads, a 1/2-20 will screw into the 13 mm thread, but it will be sloppy as the 13 mm is slightly larger in diameter.

Bill.

Bill, the first picture (in the above post) is the ID of the 2.20 exhaust port. Interestingly the Saito 1.50 exhaust pipe will slide right into the 2.20 port but is larger than the 1.25 port. The first picture is the measurement of my 1.50 exhaust threads, the middle picture is the 1.25, 1.50 and 2.20 exhaust pipes with their respective nuts, last, I measured a 1/4 inch bolt to make sure my caliper is right on. When did they change the 1.50 to 16mm, Thanks

Dave:

The FA-150 is 16 mm on the intake port only, the exhaust is still 14 mm.

If you have a 1/2-20 die, see if it will thread easily on the FA-125 pipe. If the pipe is 13 mm the 1/2 die should be 0.012" smaller than the pipe. and as I said, just 0.02 mm difference in pitch.

Bill.

That splains it, I looked at my ScrewChecker and it has no 1/2 inch hole, I may have a 1/2x20 tap but that might not show if its close. My largest die is a 1/4x20.

PS. playing with Saitos is too much fun and I'm neglecting remodeling my shop.

Dave:

Back in prehistoric times, when I first started messing with European cars, I wondered why they used so many 5/16-20 threaded fasteners, and why I couldn't get them at my local hardware store. Then I found out they were really 8 mm x 1.25 threads. Yep, that same 1.25 pitch, that measures so close to 20 tpi.

And that 5/16" is almost exactly 8 mm, just as you can use your 7/16" wrench on an 11 mm hex, and most 1/2" wrenches fit 13 mm, although usually a tight fit. And your 9/16" works on 14 mm, but loosely.

These similarities have led to much confusion over the years.

Then we throw in Whitworth, British Standard, the BA and CEI sizes...

Bill.

i have a Saito 40 with a muffler thats pressure tube has been broken, leaving only 3 mm behind. is there a place i can buy a muffler or how would i fix it? thanks! also, would normal krylon paint be adequate for painting the muffler black again? thanks (again!)

well it's not really a muffler, it's a header.

Fore:

Living in the North Tower, on the Tower of the Curve makes things a bit different from what they are here.

But if T'aiPei is any where near what it was when I lived there you'll find many small shops that could weld it for you. Alternately, have you tried ordering directly from Saito?

Anyway, Krylon wont stand the heat of the exhaust, but there are other paints intended for exhaust manifolds that might work.

Bill.

oops...

Thanks again Bill, You are the one I had a feeling would reply, Tommorrow if I have time I will make a few up and test fit it in the engine, However I really don't want to add all the extra oz. To my Hog bipe I've been building but I'll see what it comes out to after I finish and decide at that point, Thanks again Bill you are a true welth of knoledge.

Dauntae

All:

This was just posted in the "Club Saito" thread:

Quote:

Gentleman,

I just wrote a note to Brenton (who by the way runs an incredible web site) with the following information.

The muffler thread size on the production run 125a engines is 13 x 1mm. The original preproduction protoypes had the 1/2 - 20 threads but that size did not make it to production.

Pete (Bergstrom)
Radio & Engine Category Manager
Horizon Hobby Inc.

Thought it might be of interest.

Bill.