Briggs model13 stock rod and cast iron flywheel limits

S

scooter_trasher

Member
Hello just a quick question ,(because I haven't been able to find the answer) I've came across two 5hp briggs flatheads I'm going to use on a couple vintage mini bikes, does anyone know the safe rpm limits for a stock rod and cast iron flywheel? I'm not out to break any land speed records , but I'd like to run to around 5,000 without grenading
 
We used to race flatheads with stock rods up to around 6500 some probably ran them more. That being said, the reason for the rules change to aftermarket rods was because Briggs sourced some rods out of China and they could break at any RPM. If it were me, and especially if the motor is apart, I would buy an aftermarket rod. 5,000 rpm on the flywheel should not be a problem as long as it was never damaged........Also the earlier rods that had bolt on dippers were problematic because the dipper would break and the engine would starve for oil.......
 
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Chipg56 said:
We used to race flatheads with stock rods up to around 6500 some probably ran them more. That being said, the reason for the rules change was because Briggs sourced some rods out of China and they could break at any RPM. If it were me, and especially if the motor is apart, I would buy an aftermarket rod. 5,000 rpm on the flywheel should not be a problem as long as it was never damaged........Also the earlier rods that had bolt on dippers were problematic because the dipper would break and the engine would starve for oil.......
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I may do the billet rod & flywheel thing on one bike, especially if I can find a rod & billit wheel for the Big block Tecumseh H60 I I'm planning on putting in a vintage chopper frame I picked up with these Briggs motors, (that just happens to be 10" wide instead of 8") , I hear Tecumsehs have notoriously weak rods, but for the other bikes I'm basically just looking for some grunt, the Briggs motors will likely get pto cover changes to allow for mounting a torque converter without adding a jack shaft, go fast parts other than pipes, will likely take a back seat for now , I used to get 50mph out of my 69 Ruttman Judge (Pac Mule) with a copper briggs 5 flathead , with only a governor adjustment, that's fast enough and everything after that had HS50s, Briggs supposedly walked away from powersports in late 69.
 
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Chipg56 said:
Briggs never walked away from sanctioned racing.
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I don't know about sanctioned racing , but they certainly walked away from the mini bike and go cart manufactures after Manco talked to them about the product liability lawsuits over a couple of fires from kids turning their carts upside down, Briggs decided they would no longer waranty their motors for powersports use, effectively walking away from the industry, that came from the owner of manco, one of the owners of little indian also discussed needing to find another engine supplier go to about 4:00 minute mark and hear for yourself
 
I believe you are correct that, at some point Briggs walked away from yard carts and mini bikes but my point is finding performance parts for the 5HP flathead remains easy, new or used. Check throughout these pages concerning any such Tecumseh parts and you will find availability difficult to dismal, perhaps impossible.
 
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Thatas odd because i have a 5 Briggs flathead. The shoud says FUN POWER right on it. In fact most of these came from yard carts mainly the Manco Dingo. That Funpower shoud says its a 95 and a buddy has one from 96. Not to mention the Raptor, Animal, LO 206, and the World Formula. That sure seems like the opposite of walking away imho
 
FlatheadsForever87 said:
Thatas odd because i have a 5 Briggs flathead. The shoud says FUN POWER right on it. In fact most of these came from yard carts mainly the Manco Dingo. That Funpower shoud says its a 95 and a buddy has one from 96. Not to mention the Raptor, Animal, LO 206, and the World Formula. That sure seems like the opposite of walking away imho
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I had a 5 HP briggs in my 69 Ruttman, the smaller mini bikes had Tecumseh motors , the Tecumseh 5HP was a big block and wouldn't fit the bikes (too Wide), 1970 rolled around and all the bikes that had the 5HP Briggs were fitted with 4HP Tecumsehs, I think it was 71 when they started using the new small block Tecumseh HS50s virtually all mini bikes in the seventies ran Tecumsehs , because Briggs would not waranty their motors for powersport use, between the Honda invasion and us baby boomer moving up to dirt bikes the mini bike boom was over , what was once over 100 mfgs dropped down to almost nothing by the mid to late seventies. Fun Power came much latter
 
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1969 started out looking like it could be the biggest year ever, with literally thousands of orders for mini-bikes, and a few orders for a new fun kart on the books already. Unfortunately there was nothing but problems in the shop, due to the fact that Ken O’Nan, the plant superintendent, was so busy trying to set up the trailer manufacturing building so they could start building camping trailers. To make matters worse, Briggs & Stratton made a decision, not to sell engines to be used on mini-bikes anymore. In January and February the balance of the Briggs & Stratton engines were used up on the frames that were made to fit them. January ended with 660 mini-bikes built and February was only 402 mini-bikes built. Because the old frame that used the Briggs & Stratton engine would not work with the new Tecumseh engine, something had to be done to switch everything over to accommodate the new engine. Ken and Regis were good friends and kept in touch, when Ken found out that Regis was selling out his share of the snowmobile business, he wanted Regis to come and help get the mini-bikes switched over and production back on track. Raymond and Regis talked, but Regis would only come in to help if he would have full control of the shop, this did not set well with the current shop management people. Regis said that he would guarantee to get production up to 3000 units per month by the end of July, for an hourly rate plus a bonus when he met the goal, but Regis insisted on total control. Raymond, realizing that Regis could do the job, made the decision to agree, and things were on their way. The first month was the hardest, Regis worked up to 20 hours a day, changing fixtures, and building new welding systems that made it easier and faster to weld. Little by little Regis improved every aspect of the production. March production was up to 1304 units, April was up to 2005 units, May was up to 2130 units, June was up to 2780 units, and July production hit 3077 mini-bikes built. Raymond was happy, Regis got his bonus, was happy, and left to start a new business, and the workers were turning out more units, but not working as hard, so they were happy. “LiL” Indian successfully made the switch from Briggs & Stratton to Tecumseh, and made some improvements on the bikes as well. In 1969 “LiL” Indian had 16 models of mini-bikes, 4 models of Go-Karts. Total production for 1969 was 16,677 mini-bikes, 792 fun karts & 6 camping trailers. 1969 turned out to be the biggest production year that “LiL” Indian would ever have. A total of 17,475 units were built. It was a very good year.

copy and pasted from https://www.alliedleisurecorp.com/littleindianhistory
 
Chipg56 said:
I believe you are correct that, at some point Briggs walked away from yard carts and mini bikes but my point is finding performance parts for the 5HP flathead remains easy, new or used. Check throughout these pages concerning any such Tecumseh parts and you will find availability difficult to dismal, perhaps impossible.
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I agree on the Tecumseh parts problem,you would think that in a time of programed cnc machining someone would be able to order a billet rod like a regrind cam, how hard could it be to download the program ? it's getting a bit difficult finding flathead briggs stuff also, when you compare it to what used to be out there for the small block Chevy of small engines and what's out there for the china stuff, the harbor freight predator 212 rules the world now, maybe not so much in the racing cart scene, but mini bikes and what you call yard carts anyway, but they just don't look right on a vintage sixties or seventies mini bike, missing the nostalgia, even if they are getting 23HP out of them.
 
Briggs made a big move back into the yard kart scene shortly after they started their Motorsports Division. It was fairly short-lived however, somewhat in part with Manco filing bankruptcy in the early 2000s and subsequently going out of business. Those are the '90s FunPower engines that Donald is talking about.
 
scooter_trasher said:
I agree on the Tecumseh parts problem,you would think that in a time of programed cnc machining someone would be able to order a billet rod like a regrind cam, how hard could it be to download the program ? it's getting a bit difficult finding flathead briggs stuff also, when you compare it to what used to be out there for the small block Chevy of small engines and what's out there for the china stuff, the harbor freight predator 212 rules the world now, maybe not so much in the racing cart scene, but mini bikes and what you call yard carts anyway, but they just don't look right on a vintage sixties or seventies mini bike, missing the nostalgia, even if they are getting 23HP out of them.
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No problem getting hop-up parts for the 5HP Briggs flathead. (We've got plenty of good used billet rods too if you would rather.)
I have most anything you can dream of in stock -- and will for as long as I'm still on this earth. :)


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🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
34 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
CarlsonMotorsports said:
No problem getting hop-up parts for the 5HP Briggs flathead. (We've got plenty of good used billet rods too if you would rather.)
I have most anything you can dream of in stock -- and will for as long as I'm still on this earth. :)


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
34 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
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That's nice to know , THANKS , I'm probobably take you up on some of those, the whole world runs on used parts. When I was a kid it was govonor delete,compression bump, carb boring and gearing for me, never saw the need for jackshafts and torque converters weren't a thing yet, at my age with two and three year old grandchildren,after spending over fifty years building and riding dirt bikes and Harleys ,for some reason the mini bike bug has hit me, with four frames and six motors in my over filled garage, I won't be able to start working on stuff until after spring cleaning,( I WANT TO GET MY GARAGE BACK) so I'm on a learning curve and parts finding stage right now. I'm thinking side cover changes to later model four bolt for the torque converter backing plate and if I'm doing that I may as well go with the roller bearing, (IF THEY WILL FIT), hopefully I can score an I/C motor or two on the cheap.
 
scooter_trasher said:
I had a 5 HP briggs in my 69 Ruttman, the smaller mini bikes had Tecumseh motors , the Tecumseh 5HP was a big block and wouldn't the bikes (too Wide), 1970 rolled around and all the bikes that had the 5HP Briggs were fitted with 4HP Tecumsehs, I think it was 71 when they started using the new small block Tecumseh HS50s virtually all mini bikes in the seventies ran Tecumsehs , because Briggs would not waranty their motors for powersport use, between the Honda invasion and us baby boomer moving up to dirt bikes the mini bike boom was over , what was once over 100 mfgs dropped down to almost nothing by the mid to late seventies. Fun Power came much latter
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That is my point. Briggs didnt completely stop in the 60s if the funpower was in 90s
 
CarlsonMotorsports said:
Briggs made a big move back into the yard kart scene shortly after they started their Motorsports Division. It was fairly short-lived however, somewhat in part with Manco filing bankruptcy in the early 2000s and subsequently going out of business. Those are the '90s FunPower engines that Donald is talking about.
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Actually Briggs got burned by the consumer safety commission toward the end of the 90s and had to recall 160,000 fun power units over fires on roll over accidents and quit suppling the fun cart industry a second time, watch the owner of max torque talk about it starting at the 5:00 min mark
 
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