Adapting Briggs Build to accept bigger engine

[MEASURE TWICE]

The best thing is that device you have been using that slips over the end of the shaft and I thought about it, but I did OK.

Thanks for mentioning about center drills.

I remember using the centering bits as suggested when I was at a monthly paid membership at a shop. I did start using them and may buy some for myself.

My center punch I could maybe sharpen it and if I do it may do better. In the future I could have something hold the center punch (like a pliers) so my hand does not get smacked if I miss the punch with the hammer in the other hand!

I was also thinking are there reasons for various angles or type of center punches? And I mean not just the ones with the springs in them. I had one that was not adjustable, but had a spring in it and someone I loaned it to took it apart.

He said it was better that way without the spring. I'm not sure if he lost some of the parts to it. I tried to put it back together, but it did not work again with the spring. You have to careful who you allow to use your tools, but anyway it was less than $10, so a lesson learned there.

For S&G's, I looked at the tip of the pilot bit I was using, that being a standard steel bit of smaller size under lighted magnifier lamp. I also did the same for the center punch pointed end and figured the dent in the metal by the center punch has to be as big or bigger than the pilot bit after using the punch on the metal surface.

Then I came to realize I would probably with that hardened steel shaft, I would not have gotten a larger enough dent to have it work unless I went with a smaller pilot bit. Then successively using larger pilot bits. This worked before for me, but I guess I forgot. The Centering Bits you mentioned is basically the same thing but faster and less chance of bit wobbling.

When I thought of the bits I had before, but could not find what they were called, I saw this, but they are not exactly what I had before used, that were a centering type bit.

Lip and Spur Bit I looked up on the internet and found those bits are usually made for wood or only thin sheet metal. I however did see a places selling them that said steel, an am not sure they are for real. I never much buy from overseas for time to wait is long, but see this place is not in China, it say Britain. The shipping is more than the set. Just though price seems too good to be true. You know what the Post Master say about that! Maybe it could be OK but there are reviews I found that are bad. Funny how mostly rated at 1 or 2 of 5 stars rating. Then all others are mostly all 5 of 5 of which there are few in chronological order.

Ebay has the same outfit selling these bits, but there they say they are for Wood.

https://www.buysend.com/en-US/Produ...power-tools/&gclid=CP6D3-vn7dACFZNffgodVicIZA

Then I found what I bought at Sears a long time ago and the set was worn out and were thrown out. But these are what I bought, DEWALT DW1263 14-Piece Cobalt Pilot Point Drill Bit Set.

So I forget if the points wear out quick or not, I know only that for a while the bit centered nice. Then if they wore out the tip, then the drill bit if still sharp on all the other more important surfaces really did not matter, it was like the usual steel drill bit.

https://www.amazon.com/DEWALT-DW126...1481516819&sr=1-13&keywords=hss+drill+bit+set

Well back to putting this bike together again. The chain breaker made in USA is really good so there is a new tool that will last and has replacement tip if I need to get another. It came with one extra and some kind of glue that you heat up to hold it in place after it cools. Maybe simple is better.

 

[curtisfox]

They are for wood called brad point, more of a tapper. They also have them for metal Irwin i think makes them, but better in the long run with center bits. Then with regular bits after, rather than buying a hole new when they get dull.............Curt

 

[MEASURE TWICE]

http://www.harborfreight.com/center-drill-countersink-set-5-pc-60381.html

I was thinking if I pickup these cheap at HF are they any good. I have had a few things that were not usable on hard steel, like the 15 dollars set for tap & die. Maybe for aluminum, but nothing like hardened steel.

I guess if I buy them, I'll be sure to keep the receipt! Just time to drive back is not worth the price unless I am go nearby or for something known to be OK, like angle grinding disks.

 

[curtisfox]

Cheap enough, give em a try. Should last a long time, if taken care of.

Sharpen your center punch on your angle grinder LOL..........Curt

 

[MEASURE TWICE]

http://www.homedepot.com/p/The-Hillman-Group-35-Offset-Link-881725/202242576

I have these offset links that I actually bought at OSH not Homedepot, but are the same Hillman part.

I see the small cotter pins and there already installed, just slightly at about 35 degree angle. I wish they would have just left them unbent loose in the bag. I looked to be able to find just replacement cotter pins that small for the offset link for #35 chain, but could not find them in OSH.

Anyway I need to use one of the offset links on a regular 35 chain to shorten by 1/2 link. My engine platform will set the tension as long as I use the 1/2 link to get it in the range that the engine can slide forward to tighten just a hair more and be just right. Without the offset half link I would always have the chain too loose no mater how far forward I slide the engine forward.

I will still use a master link since when ever maintenance is done, I can replace with extra of the master link clips, but the cotter pins for the offset link is meaning buy another bag of all three offset links. They are harder to find then the master links.

I know that the master link needs to have the closed end of the clip forward toward the direction of travel.

As for the offset link, I've seen the wider end in a chain all of half links facing forward toward direction of travel. Will I want to install the single offset link to achieve adding a 1/2 link in a regular chain in the same direction?

I'd put the wider part of the offset link that has the pin that uses that tiny cotter pin on the end to hold it in place, toward the direction of travel? Looking at the crankshaft of my Briggs Engine, with the sprocket on it as it turns counter clockwise, the wider side of the offset link to the left?

 

[MEASURE TWICE]

I decided to use the offset (single half link) to get chain length into the range in which moving the engine forward or aft would be able to set the chain tension. This is for the engine to top jackshaft where the centrifugal clutch is mounted.

The short shaft on this 3.5 Briggs problem resolved sort of. Now a 1:1 ratio from the engine with a 13 tooth sprocket to the top jackshaft 13 tooth sprocket.

I'm making up the chain that will go then from clutch output sprocket a 12 tooth to a 28 tooth sprocket on the bottom jack shaft.

Since the bottom jack shaft can slide up or down a considerable amount, to adjust chain tension, I won't be using any offset link (half link), just a master link.

I will have from the about 2.5 inch pulley on bottom jackshaft to 15 inch rear wheel sheave pulley the connecting belt.

Over all ratio about 14:1 going to a 26 inch wheel.

I used to use 20:1 ratio, but since this engine is a 3.5hp in better shape than the older 3hp maybe it will be OK.

If not I will have to some how have the clutch on the engine with that stubby crankshaft, I am looking to get a crankshaft that is a bit longer.

The picture shows that I put the offset link so that the cotter pin closed end is forward in direction of rotation, just like the master link clip. The thin end of the offset link is forward, but I don't think either way matters any. I just wanted to be able to install or remove the master link clip and hot have anything in the way and this work out OK.

I checked the chain and it felt almost OK after tensioning. It tried to catch a bit on one sprocket once in a while and I was a bit perplexed. I had the same before happen, but now realize that without a load it does this, but when under load it goes away. It never really gets stuck or tries to jump, but I was concerned.

If the clutch was on the engine then there would never be any chain movement unless there was a load. This set up is different, but it is a work around when the engine has that stubby crankshaft. I also do not have the 20:1 ratio as before, but have to settle for 14:1 with less a pair of sprocket to help.

I used a few thing washers as spacers so the chain does not rub on anything it is adjacent to. The sprockets have one side with a cut away slot to allow the chain to not rub on the sprocket, but the other side I felt needed some spacers.

 

[MEASURE TWICE]

I've gotten to working on the bike again and found where in the past I marked up some of the sheet metal cover I was going to modify so my other changes could work with the bigger Briggs 3.5 in better condition. Just too late to do grinding, and I thought just to see it work and smooth nibbles of metal away later on would get more done right now. Now where the heck is that nibbler I had back in the 80's? Anyway I remember it was for thinner electronic chassis building and it would not handle the heavier sheet metal covering the chains, sprockets, and clutch anyway. Tomorrows another day!

 

[MEASURE TWICE]

I got the jackshafts set up now with newer used engine and cut chain and set tension.

Next I'll disconnect all from the engine crankshaft and just test the engine with the carb that I used with the older engine. This one from an edger was using a pulse jet type carb that did not use a gravity feed system. I expect it will run just fine as it did with its original carb. But I have to wait till tomorrow it is too late now.

Then When the throttle is set and idles OK, I go to the next step and hook up the chain from the engine sprocket to just the top jack shaft.

After that then put the clutch on the top jackshaft and connect the chain to the bottom jack shaft. I'll ether have the rear wheel up high to clear the ground and test the clutch with the belt and tire on, or just see the bottom jack shaft pulley turn.

Cover on left side over the chains, sprockets, and clutch for sure anytime I run with engine connected.

The right side cover over the carb and throttle I can leave off till later.

Looking like I can have it going trail riding, but in fairly cool weather.

The funny looking bracket is left in place for if I ever use the belt connection with large pulley with back idler. I took the idler pulley off and made the inner side of the bracket clear the use of chain near by.

 

[MEASURE TWICE]

I got the cheap set for 7 bucks for 5 of these small centering counter sink drill in a set. They have two sides so it is 10 drills actually.

I used two of them after using a center punch on the end of the jack shaft I want to tap. I just wanted to be sure the center punch nick would hold the first drill steady.

Then the number 7 drill bit for the 1/4 by 20 thread tap and it was centered better than before. I cut off the other end as it was not as good and also needed to be shorter to fit and not hit the air filter.

Even though HF some of the stuff is bad, these are good and sharp. I looked at the parts before and after using them and they did not get noticeably worn.

A cheap tap and die kit for 10 bucks at HF was not worth anything but the plastic case it came in. Maybe I keep better track of receipts now. The Vermont American (made in China) from OSH in a set with the #7 drill bit and 1/4 by 20 tap I used a few times does a real good job.

I insured that the work was plumb on both X & Y axis with a bubble level.

The drill I have also has a bubble level. I kept my eye on the bubble and momentarily would look at the bit to see if shavings were happening.

For the centering drill kit I used the 25% off coupon so about 5 bucks, what a deal at HF yesterday!

Two more pictures on next reply.

 

[MEASURE TWICE]

Putting everything back together again now!

 

[MEASURE TWICE]

Put everything back together, but want to test out the engine with the carb it was never run with yet. I'll not have any of the tranny connected up when doing so. Also will yet see how it runs before threading the recoil starter pull cord through the hole in the cover on the right side of the engine / carb.

Along with the centering drill set I bought a HF that was a good deal, I tried out the allen wrench set that is both short and long handle for both Metric and Standard. The did not snap right away, I'm hoping they are also a good deal! Another of the free flash lights with hook and magnet attach point was nice. Three leds on or Twenty Five for real bright.

 

[MEASURE TWICE]

Another good thing happened. I wanted the tapped bolt on the end of the jack shaft to have a flat washer that made it so that it would compress just a small amount along with a split lock washer at the end of the shaft. The washers that I got that have an inner bore equal to the jack shaft diameter, shimmed it just right before. Now I needed a thinner washer or I would have to shave down possibly a spacer.

When I could not find what would work. I bought a few washers same package as before. When I got home I saw they were a bit thicker even though the same part number on the package.

I removed a few of the originals and add two of the newer thicker ones, mixed an matched for a perfect shim.

Without opening up stuff in the store, you don't realize there is not really a set standard on some of the hardware dimensions.

 

[MEASURE TWICE]

https://vimeo.com/198453385

I ran the newer used Briggs with the same carb/tank setup that was used before on the older used Briggs and it ran good. The engine had not yet warmed up in this video.

When it warmed up a little more I have another video, but it was not for long I ran the engine with the fuel line attached. The gas shut off valve started to leak. Four years old and I need a new one. I ran the fuel in the bowl till empty and noticed it idled a bit better. I do not have the governor hooked up due to the elbow intake manifold.

I realized I could adjust the minimum butterfly throttle position to go a bit slower and will try another time.

Not sure I ever saw that same fuel valve available on Amazon anymore, so I might need to use a different one and find possibly needing to figure how a different type could be mounted.

I also had just one chain hooked up and with the cover on for safety, I notice the top jack shaft run smooth and no chain noise. After the cover removed I saw the sprocket and chain looking the same so it seems good.

Would have done more but hot engine and a leaking shut off valve is no way to test, another day I get back to it!

 

[MEASURE TWICE]

http://www.ebay.com/itm/321903405337

Ebay has the part and is less than any place I checked, so soon I replace the gas valve.

 

[scratchbuilder]

Het MT, I swapped cranks..the 3hp 5/8 shaft with the 3.5 3/4 shaft. I put the 3hp 5/8 crank into the 3.5 engine. Used the micrometer on the cranks, the same. Rods, the same. So when I get a new head & side gasket I'll fire it up and hope for the best.

 

[MEASURE TWICE]

I have some cranks now I will get a chance and see about swapping them in also. For the pillow bearing holders, what I got from the AGK kit for jackshaft, I never realized that it would have been best to make my own holders or get a kit that has holder for the bearing that have more surface contact with the outer bearing sealed race. Also they brake press cut the hole in the bearing holder for the outer bearing and it leaves a rough edge. Most of the cut hole is too wide a diameter and the bearing is loose in the holder.

I already have used them like this, but am going to try and shim the bearing in the holder with aluminum or copper thin sheet material. Also the spring clip that is on the holder I have made a corresponding weld dot (and shape with Dremel). This is to keep the outer bearing surface from moving and wearing out the holder and the outer bearing surface.

I know the spring clip only has some much grabbing force. But it is OK, I just want to be sure the bearings are turning not the outside of the bearing in the holder. The shaft on the inside of the bearing surface is tight enough and a special Locktite kinda stuff made special for bearings I may use some there.

I will inspect and just replace the bearings after a while, but when I hear the tell tale noise of the bearings grinding, I would like it to be just the bearings that take the wear and nothing else to replace.

I got the new fuel valve and am ready to reassemble the bike and test out 13 or 14:1 ratio. If it is not good enough I have the two engines and 4 crankshafts I can all mix and match. Maybe back to belt clutch with the 5/8 long shaft or 3/4 long shaft from the ones I can clean up I got from Tony01. I have the 3/4 clutch that uses 35 chain. With that I can be back at 20:1 or even higher which I don't think I do, but nice to know I can if it comes up.

The regular aluminum foil is so thin it rips. Still enough stays in place I could go with that, but I have some copper foil that is thicker by a small margin and I fill give it a try.

 

[curtisfox]

Do you have a picture of the bearing you got from them, sounds like you are talking about self aligning bearings?................Curt

 

[MEASURE TWICE]

These are standard roller bearings with snap ring. They are fixed not self aligning. They are not set in a big pillow block, like some with oiling port.

Shown in picture the height of the bearing is such that it sticks out the back of the holder a small amount. You can see the break edge from the stamping cut.

I made sure where I bolted the holder that the bearing sticking out the back did not contact anything. A bracket that the holder bolts to was shaped so that it does not contact.

Special bearing I know are made that are self aligning and they are not these.

Even if they were self aligning bearings, you would not want to mount them loosely.

The bearings were OK to a degree, but the mounts were really not ideal. The replacement bearings I bought recently do not spin as easy. I thought that was not good. I now realize that is the grease inside. This is normal and is better in the life span of the bearings. When you feel a grinding that is when they are tossed in the trash.

They are called Bearing Hangers the flat stamp cut parts:

https://www.affordablegokarts.com/m...e_Code=A&Product_Code=10140&Category_Code=PCJ

The snap ring bearings:

https://www.affordablegokarts.com/m...e_Code=A&Product_Code=10130&Category_Code=PCJ

The kit I bought local, same as on Ebay:

http://www.ebay.com/itm/VINTAGE-MIN...22597b0&pid=100005&rk=1&rkt=6&sd=121661858488

 

[MEASURE TWICE]

Got the bearing hangers modified and seeing how they will work on the brackets.

The use of copper foil to shim them more firmly in the hanger yet to decide if it can work to make it any better to fix the loose fit.

I looked at some bearings that come in nice hangers that have oiling ports, but it is a large pipe thread that is used to mount the bearings. Totally different than how I have it now. Least expensive I've seen some around $25 for each on Amazon. I'd need 4.

Self aligning bearings are still probably more. Also there seems to be a lot of different shaft sizes that are metric, but I am using 5/8 inch standard. I don't want to sink more money into just replacing what is only around $10 for 4 bearings the way I have it set up now. Just like to make it as best I can with simple means.

I think maybe I will get some kind of hour meter for running time to decide when to just change the bearings, not waiting for that screeching sound.

Will try to have it done before next rain to see about the ratio at 13 or 14:1 and the newer used Briggs 3.5!

 

[curtisfox]

Just take a chisel or punch and hit the retainers in one or two spots and they will fit tighter......Curt

Also they make a small pointed needle for grease gun, take a small point pick lift the seal to get the needle in and grease the bearings later down the road.