Topic: Mowinmachine's "Stretch job" and mods for 2011 FX.

[mowinmachine]

Yes, and I had thought about doing that but I wasn't able to find a machine shop that would do it handily ( in my area). I also thought about finding one of the lder style cranks so I could attach brass counterweights. I decided instead to go with the new billet crank. I like the idea of the crank and counterweights being all in one piece.

[Rooster]

Ports are looking good, I would smoothe those valve guides.

[mowinmachine]

 Are you referring the the valve guide sleeves?

[Squidd]

Knock the leading edge of the valve guide off...

[Rooster]

See the red arrow.

That sharp thing is sticking up there in your flow.
Personally, I just all but get rid of it, grind it down to a smooth little pimple in the bottom of the bowl.

Those sharp edges are no different than all the ones you spent so much time blending out every where else.

[monkeyward71]

See the red arrow.

That sharp thing is sticking up there in your flow.
Personally, I just all but get rid of it, grind it down to a smooth little pimple in the bottom of the bowl.

Those sharp edges are no different than all the ones you spent so much time blending out every where else.

yes sir!

[mowinmachine]

So you basically cut that off? I'd thought about that but I wondered if that would cause an issue since I would basically be getting rid of some of the sleeve altogether. Then again it obviously sounds like you don't have any issues with yours after you did so.

[Rooster]

One thought though, I work on flatheads, lol..I don't know how much guide will be left in an ohv? At the very least you should relieve the corners of it.

[mowinmachine]

 I think I'll play it safe and just round over those edges a bit. I removed quite a bit of material already thus there should be a marked improvement.

[BoNewCo]

It going to be ready to try out at Dixon Mar 5, Seth?

[mowinmachine]

Probably not unfortunately. I am still waiting on parts, need to put the engine together, make a new exhaust system, and do some testing. Can't see that happening in less than 2 weeks.

[sr71mopar]

I would put a very small radius below the intake valve towords the outside.

[mowinmachine]

 I Spent some more time working on the mower today and last night. The plan was to first build the engine then prep and paint the chassis and sheetmetal.

 First of all, I filed the over .020 rings down to fit. The goal was to hit .006 but I accidentally wound up filing just a tad too much so they're both at around  .008. Oh well. Close enough. As others had mentioned, I just stuck a file in a vice and held the edge of the ring against it flat. This worked pretty well. Next I punched out the brass sleeve for the throttle shaft, tapped the hole, and stuck in a bolt. Pretty simple. I also replaced the old rod bearings in the ARC rod with new ones.

 The parts arrived from EC. By the way, I had really fast service from them. I got my parts in less than a week after ordering them. Thanks guys! Anyway, I ordered one of those new ARC cranks. I like the idea of having a one piece solution for the crank and weights. The piece is extremely well-made. Almost too "purty" to use. After spending a few hours cleaning the crap out of the crank case, giving the cylinder a home job, I was all ready to start assembling the engine. On the reccomendation of Kevin and others, I had also ordered the "new" style of valves with the automotive style shim keepers. The first valve snapped into place nicely. The second one slipped and the shims went flying into oblivion, never to be seen again. #@!%$#!! Spent an hour looking for them. They're gone. Thus I can't continue assembling until I have those. Lesson learned. I ordered a few more sets of shims. Next time I'm putting them in a room in the house where they can be found if they fly off again.

  Anyway... I have a month to get the mower back together again. Thus I moved on to getting other stuff ready. I sanded down and primed the hood and fenders.  Being a cheap person I bought spray paint that was on sale. The color was this cast iron color. Actually looked pretty good.  Also painted the chassis. This is about the 3rd time this chassis has been painted. I just use rattle cans for all of it.

  Next I worked on checking out the situation with the clutch. This one is going on 3 years old and I've never done any maintenance. Its a Titan. Anyway, despite being used hard for 3 seasons its still in nearly perfect condition. I just cleaned it up and gave the needle bearings a little grease. Also cleaned up the axle and added a new 32 tooth sprocket for size 40 chain. I had been using #35 but it tended to stretch and slip off after 3-4 races. Hopefully size 40 will solve some of this.more picsmore...

[mowinmachine]

 Just got spending literally all weekend as well as every night after work working on the mower. I focused on the engine first. I have not worked on a Briggs OHV engine before so this was one of those instances where I got to learn something new which meant it took a lot longer to do.

 You don't want to use the older stock keepers for the valves. Apparently those tend to pop off and thus destroy the head. So I ordered the newer style valves and keepers, which are like those you'd find in a car. Little shims. I just about sweat bullets getting the keepers on because I was trying to use dual springs. The newer more robust springs have an inner and outer spring. You're not supposed to use the inner. The inner will come out. Just use the outer. That made it a lot easier to install.

 I next installed the ARC rod and crank. These are both highly precise components. Much better than the stock crank. I used a smaller torque wrench and applied 30 weight oil to the rod bolts. These were torqued to 28 foot pounds. The rest of the engine was assembled. A second breather hole had been previously drilled through the crank case right behind the raised area where the pushrods come down. This will allow the engine to "breathe" more easily. The drain hole at the bottom of the original breather was also enlarged. I took the custom steel plate I'd last used on the old engine and used it on the new one.

 Next I installed the ARC flywheel. If any of you get one of these you'll see that the blower housing will be raised too high above the flywheel fins- by about an inch or so. So I measured the distance from the top of the fins to the top of the blower housing. I left a small gap of course for the flywheel to spin. I cut about an inch off of the entire bottom of the housing. I had to drill new bolt holes to re-attach.  As a finishing touch I painted the tins and blower housing the same color as the hood. End of Saturday.

 Today the plan was to install the RAGB and "upgrade" the chain from a #35 to a #40. I had previously ordered new sprockets. The RAGB side is a 12 tooth and the rear axle is a 28 tooth. The RAGB I have is a 2:1 box thus I have to compensate by running unusually small sprockets.  What I've learned over the years of doing this is that the alignment of the sprockets needs to be absolutely perfect. Seems like a big DUH, but even the tiniest amount of friction can cause the chain to prematurely wear out or come off during races. I had never really gotten the previous setup to work perfectly right. So this time around I spent the better part of a day tweaking the new setup. I took the spring loaded tensioner I'd made last year and made some changes. The way this works is that I have a vertical piece of square tubing with a slot come up and down in the middle. The sprocket itself is mounted to a steel plate with a spring on the top that pulls upward and attaches to a bolt welded above. big washers are on either side of the slot. A nut is screwed on until its almost snug but still allows the whole tensioner to ride up and down.  

  I repositioned the spring so that it pulls exactly straight up. Before it was sort of at an angle. I took a steel ruler and checked the plane of all three sprockets. The RAGB and rear sprocket were fine. The tensioner was off. I poked around and found some loose spacers and after doing some filing and fine-tuning got the sprocket to ride exactly in the center of the chain. The chain now rides very smoothly with no drag or sticking. Hopefully this will prove to be reliable.

 Unfortunately with the larger RAGB sprocket the chain and tensioner were hitting the RAGB mount. In order to solve the problem I cut the part of the mount it was running into and welded a new piece behind where the piece had previously been. That worked fine.  

 Lastly, I used a piece of brass pipe to cut a couple of 2 inch lengths to be used as spacers for the spindles.

 Anyway, what's left now is to install the engine, modify the exhaust to work on the opposite side, install the sheetmetal, make some adjustments, and see if it will run. GREAT BIG thanks to all of those who helped me out on here so far.

Oh- almost forgot. I installed the reccomended high torque starter for the ARC flywheel as well. You have to make sure that there is a gap between the top of the starter gear tooth and the Valley of the ring gear on the flywheel. The gap is the width of a paper clip. I assume that this is to prevent the teeth from getting stuck and to mesh correctly. This was a little confusing. The starter gear is recessed below a protective housing. Unlike the stock starters you can't spring the gear backwards and get it to come up. My solution was to take a small hex key and grab the underside of the gear, pull up, and stick another hex key under the gear so it won't go back down. Thus I could then hold it to the side of the engine and determine the gap. The starter came with a little bag of shims. Mine took about 3 shims per bolt to get the correct gap. This is a pain to do because the shims will want to fall off the ends of the bolts as you hold it against the engine. Anyway- worked pretty well.

more...more.

[TeamScoot]

whats with the hose clamp on the axle?