Hopped up Briggs twin build

[19richie66 17,508]

Following along as well. Been watching Mr. Studabaker’s mud run videos. Looks like a blast. Hope to make some mild trails here but nothing that wild. Carry on 

[ebinmaine 67,498]

7 minutes ago, Tuneup said:

Not that I need to be more impressed by your creativity on these machines BUT we have a horizontally opposed engine here. Doesn't anybody see the great opportunity? Did anyone ever hop-up a VW? I'm not saying dual Webers or Delortos but a nice dual carb setup with stacks would be the bomb.

 

K582 with a pair of tiny little carburetors sitting on top of custom-made cross ram manifolds.

Shave the heads.

Regrind the bump stick a bit to bring the lobe centerline closer together for a more interesting idle. 

 

Sounds like fun to me. 

[Tuneup 1,433]

Yeah, a little twin in a WH frame with duals... I had my Bug bored and stroked but ran out of cash so had the progressive central carb. Duals would have freed up some HP but she did get up and go, for a Beetle. Tough to keep those heads cool if she wasn't moving air over that oil cooler. I miss those days. Advice to the young uns. Girl friends cost money! If I wasn't paying for her and tech school, that '73 Sport Bug would have been a screamer! That girl's still around today so some investments ARE worth it.

[Gregor 4,846]

My C-175 came with the Briggs 18 Twin on it. Model # 422437 Type 1049 01. I have not seen a C-175 with the Kohler on it, so I cannot tell you the differences between the two. I can say that the shaker plate was completely removed, and the frame re-drilled for the Briggs. I replaced the belt. I am 99% sure it is an 85" belt, but it's been a while. (still waiting on parts) All of the safety switches had been by-passed. I am using the brake pedal safety switch, but not the PTO switch. I don't plan on having any implements on the tractor at this time. The Briggs has magneto ignition, and has the correct ignition switch. I don't know what the Kohler is.

It looks to me as though the PTO Housing Rod has been cut off at the top. I don't know why anyone would have done this, but it just seems short to me.

 

I ordered a new carb, and also bought a rebuild kit for the old one. The rebuild kit came with the parts necessary to rebuild the integrated fuel pump also. It cleaned up well, so I reused the old carb.

When I check the tracking number for my parts from Lincoln, it simply say, "In Transit  Arriving Late" It has said that for the last 6 days.

[Greentored 3,211]

Theres a few guys out there with twin carbs on these oppy's, and they say 'it helps'. Help? Id think it'd wake them up big time!

I decided to stick with 'simple' for this application- farting around with one carb can be enough of a hassle with what we're doing haha.

I gotta get a good vid uploaded so you guys can hear it- its pretty lopey even with the stock cam.

Edited July 9, 2021 by Greentored

[Horse Newbie 7,069]

On 3/18/2021 at 12:10 PM, Charbs152 said:

i love my 18hp briggs opposed twin in my C-175.  Things a beast.  Looking forward to following your project.

I have an opposed Briggs on my 1984 Workhorse GT-1600 that I can't wait to get acquainted with...

[Horse Newbie 7,069]

On 3/21/2021 at 5:40 PM, Charbs152 said:

The fuel pump is integrated into the carburetor and runs on vacuum 

Go on Youtube and to Taryl Fixes All, and look up Twin Cylinder Briggs Fuel Pump and Taryyl can give some good info on the fuel pumps on these carbs.

[Horse Newbie 7,069]

On 7/7/2021 at 4:13 AM, Greentored said:

Why is there not a place for others to "like" or put up a smiley face on my posts?

I know sometimes when I don't see the "reaction" emojis, I need to scroll down the page and log in...I guess because I usually come to Red Square through an email notification, and sometimes I guess I have lost my last log in.

 

Edited July 9, 2021 by Horse Newbie

[ebinmaine 67,498]

4 minutes ago, Horse Newbie said:

log in

I never log out!!!

[Horse Newbie 7,069]

14 minutes ago, ebinmaine said:

I never log out!!!

Me either...I usually just hit the email notification...hit "go to this post", and it goes to Red Square...but sometimes (don't know why), I have to log on...

Edited July 9, 2021 by Horse Newbie

[Lee1977 6,659]

On 7/7/2021 at 11:57 AM, Greentored said:

Marked the flywheel and just filed the trailing side of the key where it meets the wheel itself until I got another 2 degrees off my mark

We used off set keys on the 5 HP  flat head Briggs go kart engines. I had a 90 thousands off set key on mine and running a 3 HP fly wheel. Made an aluminum bracket to lower the coil. That thing would kick back like a mule almost pull you shoulder out of joint, but it ran great. Double vacuum pump and tollisen carb. also did some grinding on the intake and exhaust and a stainless steel oil dipper. The engine we started with was a IC 5 HP Briggs with ball bearings on each end of the crank. We never told the others what we had, they would say you can't use over a 40  or 50 thousands off set key.

Edited July 10, 2021 by Lee1977

[Bill D 1,921]

Any video?  I want to hear it running!

Edited July 12, 2021 by Bill D

[Greentored 3,211]

On 7/9/2021 at 11:48 PM, Lee1977 said:

We used off set keys on the 5 HP  flat head Briggs go kart engines. I had a 90 thousands off set key on mine and running a 3 HP fly wheel. Made an aluminum bracket to lower the coil. That thing would kick back like a mule almost pull you shoulder out of joint, but it ran great. Double vacuum pump and tollisen carb. also did some grinding on the intake and exhaust and a stainless steel oil dipper. The engine we started with was a IC 5 HP Briggs with ball bearings on each end of the crank. We never told the others what we had, they would say you can't use over a 40  or 50 thousands off set key.

I remember those days ha. Ran quarter midget style karts in my teens, we had to run 5hp Briggs on gasoline (race gas) and limited mods allowed, but ran a #5 key. I remember my father bouncing his head off the roll cage more than once and letting out a nice string of words I cant repeat here

Thats also why I stuck with a couple extra degrees on this one- dont think that plastic starter drive is gonna take much of a kick back.

Edited July 13, 2021 by Greentored

[Greentored 3,211]

Here ya go! Disregard the strange knock- I'm battling some weird issues with the shroud whacking the flywheel and cant figure out where. Its dead silent with the shroud off....  strange.

https://youtube.com/shorts/oVn7qlJYFr8?feature=share

Edited July 13, 2021 by Greentored

[Tuneup 1,433]

Sweet! thanks for that. Kinda reminds me of an old cammed Goat lightly rocking its suspension in a parking lot.

[Bill D 1,921]

Beautiful!  Love the way that sounds.

[19richie66 17,508]

Sounds great!  Love the header. 

[Gregor 4,846]

I need a header like that for my 175. But it brings back the age old question of, Does it hurt a small engine to run without a muffler?

[ebinmaine 67,498]

45 minutes ago, Gregor said:

Does it hurt a small engine to run without a muffler?

 

I've never seen any proof that it does. I am most certainly open to appropriately researched correction on this.

 

[Gregor 4,846]

In the end I opted for 2 mufflers. I think it sounds nice, and I don't have to lay awake nights wondering if one of my grand kids is gonna start stuffing rocks down those pipes, cause it looks like fun.

[Greentored 3,211]

Perhaps someone else will chime in here with a different experience, but in my 46 years on this planet, I truly do not think Ive EVER left a factory stock exhaust on anything for long. Ok, maybe a couple push mowers. 

Much of the 'off road' and racing stuff was running some form of pipe with no muffler, and I have never, EVER had an issue or even heard of it hurting anything except maybe eardrums. In most cases, a less restrictive exhaust (in other words higher flowing/no muffler) is actually better for the engine, as the gases can get out easier and the engine will run cooler.

As for back pressure or some mild form of restriction, that is much more critical on a 2 stroke than a 4 stroke, but still, as a general blanket statement, many 4 strokes do seem to run a little better with a little bit of back pressure, for whatever reason......

[Greentored 3,211]

Wanted to add: any significant change will likely require richening the mixture a bit!!!!

[ebinmaine 67,498]

27 minutes ago, Greentored said:

many 4 strokes do seem to run a little better with a little bit of back pressure, for whatever reason

From what I was reading the other day there are indications that a four-stroke liking what we think is back pressure is most likely due to a more appropriate scavenging event given a correctly sized exhaust.

[Greentored 3,211]

20 hours ago, ebinmaine said:

From what I was reading the other day there are indications that a four-stroke liking what we think is back pressure is most likely due to a more appropriate scavenging event given a correctly sized exhaust.

That makes sense. Exhaust (and intake manifold) design can play a huge role in 'making' more power, but I've never been able to wrap my head around it well enough to attempt perfection. In our cases with these low RPM tractors where torque is key, both intake and exhaust would have to be 5-6 FEET long to be effective haha. The whole purpose of a properly tuned exhaust is to have enough pipe length that when the exhaust 'pulse' heads down the pipe, it produces negative pressure 'wave' behind it as the exhaust valve closes. During that time, the intake valve is also opening (overlap period) and that negative pressure wave in the pipe will scavenge all the gases out of the cylinder, as well as 'pull' some of the incoming mixture in past the intake valve, basically 'packing' more mixture in the cylinder than could be pulled in with the piston during the intake stroke.

@19richie66 mentioned Studabaker and his mud run vids with his Cub- he is extremely active in the offroad community and 'Mad Scientist' would be putting it lightly.....super good guy to boot. He runs a very strong K341 with all the bells and whistles, making 30+hp and mountains of torque that often pushes his 850 POUND machine past many of us that average 200lbs less! He DID build a correctly sized, 5 foot long tuned pipe that exited behind the machine. The exhaust pulses 'pulled' so much mixture through during the cam overlap phase that it smelled like raw fuel and used an ungodly amount of it as well. He was actually OVERscavenging during the overlap phase and pulling so much incoming mixture through, it was going right out the pipe and wasting it. He went to more of a 'standard' pipe and muffler, the fuel smell stopped and cut his fuel consumption in half!

Kinda crazy how 'correct' can be too correct, aint it?  Thought you guys might enjoy that story.

[ebinmaine 67,498]

3 minutes ago, Greentored said:

Kinda crazy how 'correct' can be too correct, aint it?  Thought you guys might enjoy that story

That is pretty cool and adds even more thought now...

Makes me wonder if a slightly different cam design would be able to utilize even more of the available fuel.