I will soon be restoring my Rupp Roadster 2 and one of my rear shocks has a slight bow or bend in it plus they are really just springs on a tube and they do not have any hydraulic fluid damping like modern shocks. I seen that they are 13 inches from eyelet to eyelet. Has anyone put on hydraulic motorcycles shocks on their Rupp and how did it work? I seen some hydralic shocks on Ebay and other sites for pretty reasonable prices.
Good aftermarket Rupp Roadster 2 rear shocks
- Thread starter GustoGuy
- Start date
Which brand of hydraulic shock have you used? Does it ride better with the hydraulic spring on a shock then the original spring on a tube mechanical shock?. Purists also like an original 4hp HS40 too. I will be putting a Predator 212cc on it for better performance. I weigh 190lbs and 5, 11 so I not a little kid and I heard with the 4hp engine they are pretty gutless in stock form.
Well, I am rebuilding my original Betor Shocks. Hopefully I won't bottom them out when riding the Rupp. I may have to go for the aftermarket one then sold on Blackwidowmotorsports since I weigh more than a ten-year-old kid who they originally designed the Rupps for. The inserts were quite egged out and I bought new inserts from Blackwidowmotorsports. I didn't realize he was in Minnesota and I got my package in just 2 days. One of the shocks was full of rust on the inside so I filled it with rust remover and I am let it soak really well. I will then clean it out and paint the inside of the tube with Rustoleum anti-rust spray paint and I will paint the shock bodies with semi-gloss Rustoleum. Here is a picture of what I am doing. I have a 1995 Tecumseh HS40 and I will see if it runs. I would like to get an old blower shroud off an original HS40 from the 1970s and paint it and decal it to look new as long as it runs I will use it as a backup engine and the Predator 212cc for my daily rider.
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those 1970 and 1995 shrouds are different sizes. the 1995 shroud sticks out further than the 1970. and they are set up for a different flywheel and starter cup combos. and unless your newer engine has a points set up the new shroud probably wont fit over the later model external coil. just a heads up that shroud swap is possible but isn't just a bolt on mod. the later 80s model shroud isnt a perfect match to the original but it woold be a bolt on mod and woold look closer to original than the 95 model shroud woold.
if you want the old rounded style H30-HS40 tecumseh motor starter housing, you usually have to change the flywheel and starter cup too. As Josh said, when they went to the more square motor housing (about 1973 on the HS40), they did it because they changed the flywheel too. And if your crank is the newer style 1/2-20 nut for the flywheel (a change made around 1983-ish), there's no way you can put an old style flywheel on that crank.
So I would need a shroud from the 1980's which will look more like the original engine than the 1995 model. I am not even sure how well the engine runs since it came with the bike. So the Tecumseh engine is an unknown. I am sure a purist would not want a bike with a newer version of the HS40 and they would hate the idea of a Predator 212cc on Rupp roadster 2 even more. I heard old HS50 snowblower engines built in the 1970's will accept the shroud from an HS40 and you would end up with an extra 20% more power. But I doubt it will hold a candle to a mildly modified Predator 212cc with a low restriction exhaust and intake with a bored clone carburetor for NR racing. I put a bored carb on my DB30 Predator 212cc and OMG it made a big difference the box says that the carburetor will add 3/4th to 1 additional hp. Here is the box for the bored carburetor. Looks stock but I seen a nice increase in performance. I have a shoehorned H50 on my Arctic Cat Prowler and compared to the Predator 212cc on Doodle beast it is underpowered yet still a fun bike to ride.
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I like power. I am 5 11 and weigh about 185 to 190lbs depending on dinner time. When my kids got older I replaced the gutless stock 2.8HP engine on the DoodleBug with a Predator 212cc. It turned it into a wheelie machine so I kept telling everyone to lean forward but they would not listen and several people wiped out like my stepdaughter who whisky throttled it and wheelied and flipped it and bruised her hip when she landed on the paved road. I fixed it by going to Midway Iron and buying 3 thick squares of steel total weight 12lbs. I put 2 of them (8lbs) right over the front fork and 1 down low on the frame so now nobody wipes out. It no longer has a tendency to want to pick up the front wheel it goes forward instead of over. Here is the link to how I fixed unintended wheelie.
https://www.oldminibikes.com/forum/...-for-wheeling-of-predator-powered-db30.78974/
https://www.oldminibikes.com/forum/...-for-wheeling-of-predator-powered-db30.78974/
How much power can you realistically get out of an old obsolete 4hp flat head engine which has no great upgrade paths. Maybe 6hp max? I heard Predator 212cc engines with a low restriction exhaust and air intake with a richer main jet were dyno at 9hp without touching any of the internal parts of the engine by NR Racing and the stage 1 kit with bored carburetor and low restriction intake and exhaust plus timing advance puts out a solid 10hp. I have that in my Doodle Bug and it absolutely runs away from my Arctic Cat Prowler with a shoehorned Tecumseh H50 engine and a 10T clutch. The H50 big block engine has quite a bit more torque than the HS50 and HS40 engines and the Predator 212cc mildly modified has way more Horsepower and torque than H50 does.
the hs40 s never going to beat the potential of an over head valve motor. but ridden an un governed hs50 with a big carb and header and no other mods on a doodlebug and it took off like a rocet. i can only imagine with further mods it could be much faster. im not saying it will ever beat a modified preditor but the hs50 can produce enough power for most riders to be happy with it. the reason i mentioned it was you stated you may use the hs40 as a backup engine. these days there are plenty of people with preditor engines in rupps foxes and speedways so if thats your choice go for it.
I thought use of the P-word in the Strictly US Vintage section was strictly prohibited!Lol. I have a mildly modified "P" engine in my Doodle Beast and I needed 12lbs of steel just to keep the front wheel on the ground. I put 2 pieces of steel (8lbs) over the front wheel on the name plate bracket on the Serengeti fork and 1 piece of steel down low on the frame in front of the engine. After that it no longer wanted to pop an unintended wheelie. Plus my HS40 is from 1995 so it is not an original engine anyway. I will document my build here on the forum. Did Rupp ever make a Yellow Roadster 2? I could not find that color among the color scheme for Rupp. I pulled the foot peg and it looks like the original color was Yellow. Here is a picture of the frame
