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Discussion Starter · #1 ·
I finally got an honest summers work out of my good ole” JD 100. Once a week mowing for about 45 minutes was not too much for her but on occasion she will quit after fouling out plug. I pull the plug and clean off the oily deposit. She is burning some oil (about 3-4 oz. per 45 minutes) and as stated passing some to the plug too.
I’m willing to spend some $$ to address the problem and have already spoke with someone at a very good shop in the next town who would be glad to do the job in Feb. Now I was wondering if I should take a crack at this myself. I’m pretty handy and do lots of car stuff not to mention bringing this 100 to life again. But I have never done an engine rebuild. I have read most all WFM posts about the 100 and have the maintenance manual and have read that. I of course know there is no direct replacement for the Briggs 190707. The valve guides likely have to be redone and I can only guess the condition of the cylinder and piston. I do not know the maintenance history of the unit as it was given to me by someone long gone. This Briggs I understand is not cast iron and have also heard that rebuild outcomes on them can be marginal. Rebuild kits are available. Might I just put in new rings and new valves only? I could pull the piston and at least see its condition. Of course, I could just keep her going as is watching the oil and cleaning the plug. Any general guidance, tips or experiences would be greatly appreciated.
 

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It is possible by doing machining to make the engine better than when it was new. Do not buy a kit but take the engine completely apart and see what needs to be done. Assuming you do not have specialty tools take it to a machinist/engine rebuilder and have him/her tell you what needs to be done. Tell them you want it done right not necessarily cheaply or quickly. They may even be able to get all the parts you need for a rebuild at a good price. Briggs sells lots of repair parts for these motors including kits to put in bronze valve guides. Putting new valves in will not solve problems it the guides are worn. Whatever you do if it is at all possible use chrome rings in it when you put it back together. Roger
 

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I'm veeeeeeeerry slowly working on re-powering my 100. My engine was too tired to be worth messing with and the machine's a bit rough anyway so I thought I'd give it a hack.
I got a free B/S 14.5 HP 'Quiet' engine I'm working on adapting. While this may not have been the ideal size engine to try and fit in, it was the ideal price
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As you may know one of the big problems with the 190707 is the unique shaft size it uses (7/8"). The 'new' engine (and most newer engines) has a 1" shaft and a different size bolt on the end (7/16th, not sure what the old one was but it was smaller).
Using a 7/16th cobalt bit on the drill press I was able to enlarge the bolt hole through the shaft that the PTO rides on (this is some very hardened steel), and using a 1" cobalt (plated, I cheaped out a little here- this metal is much softer cast steel or something) bit bored out the main pulley to 1" up to about 1/4" from the bottom where the PTO shaft fits in. This metal is pretty soft and I used a dremel and square file to enlarge the keyway.
I haven't had a chance to test fit it but it should bolt on to the engine just fine now and function like it originally did.
Doing the same steps should allow you to use any 1" shafted engine, perhaps even one that fits the 100 more appropriately.
Just a thought as these steps may be easier/cheaper that having you older, outdated engine rebuilt, plus I now have the flexibility to put a variety of different engine in in the future.
As an aside, I did have to modify the engine tray to suit this new engine, and many other aspects of the tractor, but like I mentioned, it's probably not the ideal engine for this machine. I think you could find an engine that fits everywhere else properly and only have to modify the pulley to make it work.
If you're interested in any of this and need clarification to any of what I'm saying just email me and I'll try and help.
Good luck!
 

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Discussion Starter · #7 ·
Ben: Many thanks for the detailed info about your 100 repower project. Being able to use other B & S 8HP 1" shafted engine(s) would be nice. I would really like to keep the old girl in as close to as built condition as possible. Please post your progress report if and when you can. If you can show pics, that would be great.
Regards, John Lewis.
 

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Hi all, well things have been delayed again. After enlarging the pulley to 1" it didn't fit. So I checked the drill bit (which I purchased just for this) only to find it's 1/64th under 1". So I'm on the hunt for another 1" bit to finish that step.
I'll get pictures when it fits right
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--ben
 

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Okay, after this long I finally got the right drill bit (took four tries, cheap Chinese bits!).
I hope this shows what I was talking about.
I bored out the main pulley to 1" leaving about 1/4" collar at the bottom of the original 7/8th" diameter so the shaft that the PTO pulley rides on still fits (if you've taken these apart you'll know what I mean).
I also drilled out the same shaft (that the PTO rides on) to 7/16th (the size bolt the new engine takes- yes, I snapped the tip off the bit).
You should be able to see the collar in both pictures and the difference in diameter.
I don't have a good way for making the key-way deeper so I'm just doing it by hand with a small square file. The remaining key-way isn't bad so I may also just reduce the size of the key to fit.

 

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Hi, well it stalled out for a bit. I was looking for a new gas tank that would fit with the bigger engine.
I couldn't find anything right at a reasonable price in Canada but had seen one on Surplus Supplies website that Roger had mentioned. I was recently in the states so I had one shipped to family there and now have it, and it looks perfect. I need to trim the hood to fit around the airfilter housing and perhaps modify it in the front (it just hits the OHV cover), once I have the hood fitting right I'll make some brackets for the tank. After that all I should need is a muffler.
I'm doing this as cheaply as possible really, it could be done faster and maybe easier if you were to buy slightly more compatible parts.
It was really easy to make the pulley and PTO work with the 1" shaft, if the engine was a bit smaller I might have been able to more or less drop it in without changing much else.
I have driven it around with the new engine and the original tank bungeed on so I know it basically works.
I'll get pics when I get it done or so.
 

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Okay, I know it's been a long time but I'm about done with this now.
This was a super on the cheap project that I just worked on whenever, so it may not be the best looking, but it's functional. Did a little mowing with it today.

I had to mount the hood up a bit higher so there's about a 1" gap at the top of the 'instrument' panel. I cut it out around the air filter housing, hoping to fit it down like the original position, but it wouldn't clear the OHV cover in front, so the cutting was unnecessary, but oh well.
I made a muffler (no picture of it), it's kind of ugly and loud, but not much louder than the original setup.
I made a frame for the fuel tank out of old bed rail, which worked well.
The whole thing could use a paint job, but I don't know if I'll be doing that before selling it.
With a smaller engine, something similar to the original 8 HP, this could have been way easier, but I got the 14.5 for free so that's what I used. Really, modifying the pulley for a 1" shaft was the easiest part, so to anyone thinking of repowering a 100 don't let that aspect scare you from doing it.

 

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Thanks. Yeah, I didn't need to cut the hood in the end, but it's not a big deal since the whole thing's a bit physically rough.
Like I said, a smaller engine similar in physical size to the original would have been a drop in fit with just modifying the pulley/PTO, but it was fun figuring it out.
 
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