741 frame dimensions?

I recently acquired a 741 front frame that has neck issues; I am guessing this frame was a donor & gave up its neck for another project. Someone half-fast welded on a different neck (with slight 'rake') with bubble gum/seagull sh*t welds. I am going to remove the neck and evalaute what is salvageable.

My questions are, what is the measurement of the tope tube, from neck casting to seat casting?

Stated another way, how much tube is exposed between those two castings?

What is the length between castings on the tube that runs from lower neck to front of motor?

Thanks in advance. Also, which rears will bolt up to 741? does 640?

Any sport scout rear section will bolt on. One of the best riding 741s I ever rode had a 640 rear section and wheels.The 640 rear section has much more bracing and is very rigid. The racers liked the 741 rear section because it was lite but it doesn't handle as well as the heavier rear sections. I will walk down and get a top tube measurement in a little bit.
Dusty

tprjj
Most of the frame measurments are in the 741 manual that you see for sale as a reprint but good information nontheless and very useful to build
your frame jig with or streighten or check your frame parts.
another reason that dirt track racers use the 741 rear frame is that it puts the axle lower so raises the primary cover for more ground clearance.
Also the use of the 741 fork is common as it is slightly longer than the 640.
good luck with your project.
zooma

tprjj49707,
No top tube measurement tonight the rubber between the tanks is so old and hard I can't get it out to see where the castings end. If no body has a bare frame I can pull the tanks this weekend. There is a print of a 640 front section in the archives at the Virtual Indian site. I have a bare 640 frame but I am not sure that the top tube is the same length.
Dusty

Thanks Dusty Dave. Don't pull the tanks just for a measurement...I saw 640 rear plans on VI, I am not a fabricator so I have to estimate time to build times hours labor plus materials.

I saw where you had 741 rear plans in the works on the LAST page of this forum from 1999...did
you ever get that project off the ground?

tprjj49707,
Never did get the 741 rear drawn, just couldn't get a fame and a draftsman together. Lyle Landstrom runs the Blueprint Project now.
Dusty

tprjj49707,
Where are you located? I have a scout frame fixture table and can repair your front section reasonable for you if you would like to discuss it, feel free to contact me at rocky@ironwigwam.com .
Rocky
1957S/VG

what is the measurement of the tope tube, from neck casting to seat casting? - 390mm


What is the length between castings on the tube that runs from lower neck to front of motor? - 300mm

taken from my spare 741 frame by trusty tape measure

are spare castings available ? ESPECIALLY THE HEADSTOCK CASTING

Thanks Blackbob....my only question is your last item...are you stating necks are available, or are you in a similar quandry
seeking one? I struck out finding one on my own. Anyone with leads on that OR a 741 right case half let me know.

no, i was asking if the castings are available, my spare 741 frame has suffered at the hands of a chopper god when I got it it was raked to take a 10" over set of HD springers, it had heavy gussets welded either side of the neck casting, once removed - this is what I am left with

I will be glad when this 'old school chopper' fad has run its course.