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Thread: 1940 Indian Scout 45 ci 640 motor

  1. #1
    1914THOR Guest

    Default 1940 Indian Scout 45 ci 640 motor

    I was hoping some people could assist me with some aspects of the scout 45's. I picked up a fairly complete scout 45 ci motor from 1940. It has a M344 chief carb on it. I would like to rebuild the carb, as well as the engine. Where can I pick up rebuild kits for the upper and lower end. as well as a carb rebuild kit?Also, does anyone have any spare scout chassis?or parts for one that I could purchase. I figure I'll build a flat tracker or bobber until I can get most of the correct 40' parts, if anyone has any parts drop me a line at (920)627-2163. Also if anyone could provide different areas of caution as well as new innovations that fix old problems on the indian 45ci motors, that would be great. I would love to hear insight from experts in the field of indian old iron. Thanks again to all who can help in this labor of love pursuit.
    Dave Koenig

  2. #2
    AdminGuy Guest


    Hi Dave - the military manual may be a good start for you.

    The male/female rods have 10 thou clearance. Couple other unique Indian type things when fitting the lower end. It's pretty straight forward. A dealer like Rocky in Ohio could help you alot. i SAY ROCKY BECAUSE HE'S closest to you.

    Check the secondary to rear wheel chain drive alignment - I found that interesting.

    I'd strongly recommend lip seals where ever possible.

    post your questions as they arise.

  3. #3
    1914THOR Guest

    Default 45 ci engine in 741 frame

    Thanks for the reply. I also could use some insight into how much one has to modify a 741 frame to get a 45 cu in motor, with standard heads, in that frame. Any ideas would be great, I would like to avoid grinding down the back cylinder. So a frame modification might be aq better idea. Also, how much off is a 741 fork from a sport scout fork, and can one still mount a skirted fender in that type of fork? or use Sport scout wheels with that fork? thanks for the help.

  4. #4
    1914THOR Guest

    Default 1940 640 Indian Scout parts

    I'm Looking for anyone who might have some extra 1940 640 scout parts.

    Q's: I have standard heads on my 640 motor, if I would find some bonneville heads would I then also have to get bonneville pistons?Will one have increased power or performance with the bonneville heads? Also, can I get some more details on the best places you found to use Lip Seals.

    The parts I need are below:
    1940 Indian 640 Sport Scout Parts:
    Solo seat with springs/front bracket
    complete Tail light
    Front headlamp Mount
    Top,Front, and rear motor mounts
    extra handwheel breaknut for fork(there is a busted
    one on my fork)
    kicker pedal
    side kickstand & spring
    battery tray
    footboards and L brackets
    1940 scout front and rear skirted fender
    side trim for skirted fenders
    amp guage
    dash cover
    complete speedo cable
    air cleaner(for the chief carb I plan on using)
    right front break lever
    fuel lines and oil lines
    tank emblems
    complete exhaust(or whatever you have)
    generator drive sprocket and chain
    generator chain cover

  5. #5
    Perry Ruiter Guest


    I'm not an Indian guy (never owned a Chief or a Scout and have no plans to), so I may be all wet (wouldn't be the first time) - but, my understanding of the Bonneville heads is that they are recessed for the Bonneville pistons which pop up above the top of the cylinder surface. So if you put Bonneville heads on a motor with regular pistons you'd actually be decreasing compression ... Perry

  6. #6
    AdminGuy Guest


    lip seals on shafts. Pretty much all of them.... the main case leaks into the primary via the shaft, trans -both sides, where the primary drive enters the primary case- the big hole. THe mag drive.

    Any of the big five IND supp will have your stuff. alot depends on if you want a pretty bike, or a functioning rider. In a word - Ziggy.

    HEYYYY!!!! I need heads also - any condition.

    The increase that a bonn engine gives is hardly noticeable. A stroked engine with high lift cams may give you what you desire.
    My stock engine pulls pretty darn good. You have to weigh the pro and cons of pushing a 70 year old tractor to it's max. A stock 45 ind runs pretty darn good as is. I enjoy it for what it is. Straight pipes impress the onlookers. Sounds fast - but it ain't. Hee-hee-hee....

    THe magic with a bonn engine is the cams and the slight reconfiguration of the lifters. not a whole lot of gain. BUT! Filling in the combustion chamber in the heads- thus changing the compression ratio, high lift cams, your own home spun design, straightening out the intake ports. Fill 'em in. larger exhaust valves. lighten it all up. titanium con-rods. to avoid flex at high rev. breath it all out for easy flow. Well you get the picture..... time and money. For what gain? Now you have a really fast (expensive) tractor that will eat parts.

    A CV carb on a stock 640 would give you the same effect of a bonn engine.

    I've ridden some really fast scouts and well.... a stock 500cc brit bike with four gears will out run and out perform most chiefs.
    You can lighten and modify a british OHV para twin for a fraction of the cost and twice the performance. That's a fact.

    You really have to love riding around on a tractor. Takes a certain mind set. It's not at all about speed. Far from it.

    A 45 in a Jr scout frame- now that's cool. Howard rules!

    Matt Blake - Iron Horse corral -for fenders.

    Your wee generator chain may fail at the best of times. Routing the breather into top of chain guard a good idea. nice oily mess...

    Your speedo will break. Don't bother spending money on it. Just ride with traffic -round 50mph. Spend the money on rebuilding the generator.

    Oh YA! Have you checked the alignment of your secondary sprocket to the rear wheel sprocket? A straight edge on the face of the front drive sprocket pointing to the rear sprocket will tell you alot. I'll bet the alignment is out 3/4 to 1.5". THis alignment is important. the spacers mean nothing and do not relate to this alignment. THat's just a smoke screen. Have fun!

    741 fork is narrower than 640SS. 640 fr fender will not fit. 741 fork handles better on the track.

  7. #7
    Tom Lovejoy Guest


    I would agree - a stock 45 Indian runs mighty well. From 0 to 85 or so they well really go, mine has always impressed me. If you remember how old a machine your on, I think you well be impressed. My bits of Scout as made me a real Sport Scout fan, 21 years and 50,000 miles. More than I ever expected from an antique. You get on the throtle and the Indian 45 well get up and go!
    I can run freeway at 55mph no problems at all, it will run 70 just has well - I just dont want to burn it up. They are a great machine, I have had almost no problems with the generator chain, just check it regular. Main problem I have had is valve guides not lasting very long - 10,000 miles or so. Finally seem to have that corrected - I think. Look into that, take measures to get more oil to the guides. It appears to be important to use a good material that will hold up. They may not really be fast, but they feel fast and as Admin guy said they sound fast :-) In their day they were indeed fast. I have ridden a couple times with modern stock Sporsters and they have always said man that thing can really go and I have always stayed with em no problems. In my opinion, except for the modern brakes and transmission the Sport Scouts a better machine! They could out run me if they tried - but they would have to try and in the curves the Scouts right with em.
    You can do all kinds of things to make it faster, but how fast do you want to go? also the cost will go way up. You get that Scout out on the road and in some nice curves and I bet you will be pleased with just how well an Indian Sport Scout well go. Talk to Butch Baer or Lee Standley or Max Bubeck and or some of the other greats and you will know lots about making a real fast Scout.

  8. #8
    AdminGuy Guest


    Where or what are u using 4 valve guides Tom?

    I see Stark has some more scout stuff up on site. cool!

  9. #9
    Tom Lovejoy Guest


    I have been told their cast iron and that is what they had stock - I've been told. Dont know if they have different grades maybe? But my vavle guides have lasted about 10,000miles. I talked to Bivens about it once and he said that was about the norm, that they did not last very long. But I have had old timers tell me they ran much farther between valve jobs, so I dont know?
    I have tried several fixes and I now have oil grooves in my tappets + tappet guides, put a hole in my little fluter valve. In 50,000 miles I have had 4 valve jobs, each time my guides were shot to hell. I would check my valve clearances and always find black powder in there, thought it was just from combustion - but it was my valve guides getting chewed up. I have sceen lots of Indians with the same thing. the guys adjusting his valves and I see all this black powder :-( Anyways after the last set, all of a sudden when I check my valves all I have is clean oil, no black stuff, so hopefully its fixed, but I dont know what fixed it. Maybe just better material?
    Johnny Eagles says Aluminum Bronze is the best to use and last super good. Thats what I was going to try next I have about 5,000 miles on the last valve job and all looks good so we well see.

  10. #10
    AdminGuy Guest


    hummm... I 'll try to be brief.
    so the oil and mist gets splashed around in cam case and is forced up via internal case pressure. Is that right? THis lubes the tappet guides. Some oil may make it up to the valve guides. I hope. THe carbon content of the cast iron acts as a lube on steel valve.

    If so (first) I'd check to ensure that the oil feed hole located bottom left of rear cam is not blocked. Is not block upon gasket install, by sealant or anything. Do some dry fit gasket matching. Not sure? make the gasket hole a wee bit bigger to allow for float. It's a small hole but important. Should have a clear line from oil pump right straight through. THis may have been the problem. use a drill bit and by hand spin it in the oil pump hole. make sure it's clear. Spray some WD/40 through it to ensure it's clear. It's approx. 1/8th inch hole.
    OHH!!!! THis is in regards to a Cast iron oil pump.

    oil grooves in tappet guides good. I don't think nessessary for both. I don't have either. Have not had a problem.

    Hole drilled in flutter valve. Copper diaphram used to control the case pressure of air/oil mist. Positive crank valve/vent. PCV. I believe the wee hole should be drilled if your doing alot of low speed work. So I'd get a new one in there Tom. Use a bit of grease on the four tabs to hold it in place on install. This is a scout only thing.

    What distance is the breather tube (that leads to this valve) in the cam case, from the case wall. Does it matter?

    Are the valve guides installed straight? Are the holes straight? Have they shifted? I've seen tack welds to hold the guide in place. A hack solution but it works.

    As the exhaust guides pass through the exhaust ports. Theys gits wicked hot...I can see the premature wearing. Cracking off the throttle for some crank case pressure every 10 or 15 min a good thing. S uck some oil up in there. If you run lean - you'll run hotter.

    Do you run a 1947 scraper? What kinda oil pressure is the pump putting out? Does it matter?

    Now how are we going to resolve the massive amounts of oil that these SS eat up? Better oil control rings?

    I'm not an expert -and have little knowledge of what I type.

    Kenny will be greatly missed. sighhhhhh....

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