New Roper project rolling chassis

Daniel Coop

Well-Known Member
#1
Another nice find here locally through a club brother in Denver. I scooped up this nice Sears Roper rolling chassis. It's mostly there, the frame is clean, with no cracks bends or re-welds. Slightly takes the sting outta losing a near mint Cat 400 by an hour, but then I saw it on this very forum...:doah:


Now it's time to decide what motor...My new Raptor?


Any help finding an OG seat, grab bar and gas tank would be awesome, although I don't think this model originally had the gas tank cuz I don't see any way to mount it. I think they definitely look better with the tank.
 
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#2
Roper is the next best thing ! I did one for last year's build off and it really is a great riding bike . Have fun with it and join the build off , only 5 days out !
 

Daniel Coop

Well-Known Member
#3
Thanks Chipper, I will be more vigilant about watching my local Craigslist listings, to avoid losing more bikes to other parts of the country. Lol! And maybe I will join the build off this year. Plenty of bikes for me to choose from...

Much to my disappoinment, it looks like I will be stuck using one of my stock carb Predators or GX200 motors. Now I am definitely going to need a gas tank and to fabricate the mounts. Looks like it's going to be a Resto-mod.
 
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#5
Tec will be great as that was original , I used a 5hp Briggs with Tecumseh carb , worked great too ! Check my 2016 build off , may help with ideas ?
 

Daniel Coop

Well-Known Member
#6
A Tecumseh H40 is out considering I don't have one, but have 2 Raptors and a few clones and one genuine GX200. Not only that, but I need more power than 4HP. Thought about getting a Tillotson carburetor and manifold from Reiken's Racing for my Raptor. Only problem I see is that the one designed for the Raptor motor is made to run on alcohol, but all the Tillotson carbs look similar, so couldn't I just use the one designed for 4stroke gas engines?
 
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#8
Look into running a Mikuni VM22 on that Raptor, as long as you have fuel tank clearance for gravity feed. If not, you will need a fuel pump. They do require some jetting and tuning of the needle and circlips, but once you get them dialed in, the throttle response is amazing.

Also, if it's a stock Raptor or set up for class racing, it may contain the original cam. The Raptor cam as supplied is fairly mellow, and you can get a replacement cam a little hotter for not much money. Takes some research and a bit of a learning curve, but you get a lot more motor doing some very simple modifications.
 

Daniel Coop

Well-Known Member
#9
Dave, I would love to try to run a Mukini as I have 3 of them, but can't seem to find a manifold. I have seen it done and wondered why this part is not manufactured? Do you know where I can locate a manifold? I would really prefer to run a Raptor in this bike, but like a lot of us, we have to work with what we got due to budget. I'm still going to have the same fuel tank issue with a clone. And was just outbid on eBay for one last night. Can't seem to have any luck on eBay. Need a Tank... Anyone?
 
#10
A few of the guys were making them. David Wulf (member here) might be able to do so. He was building Honda clone carb manifolds for Flatheads I believe. Also, some of the guys were using Tecumseh carbs on them, (yes another manifold fabrication) with success.

You really need to search around using google, and you'll start to see options. Note that even a stock Raptor may not benefit from a VM22, without some cam to it. That carb also sticks out at an odd angle, requiring some exhaust work to clear.

In all honesty, if this is the Alcohol briggs you got off of ebay, you might be better served getting a standard pulsa jet (stock briggs) carb and tank. The difference between the stock carb and the Raptor carb is "mostly" the lack of a choke. Most of us cruiser types need a choke, instead of trying to start with a palm over the intake, or an external fuel pump like the kart guys use.

Once you get into Mikunis and manifolds and cams, forget a budget. Because then you need to start thinking of flywheel, advance keys, and some fine tuning. But boy do they run. I'm running a Raptor motor now on a Tote Gote, with later pulse jet and a hotter cam, even degree'd it, billet rod, a few other items I forgot.

Maybe do some research, then start a new thread on the specific way you want to go with the Raptor, and some of the more knowledgable Briggs guys will step in with good advice. I'm a hack at this stuff.
 

Daniel Coop

Well-Known Member
#11
One of my Raptors are basically stock, with just a speed nut starter and the other one I just got off eBay is an alcohol race engine. I'm really not trying to benefit from performance as much as I just need the clearance in this frame. The stock Briggs fuel tank hits the downtube and there's just no room on this bike, otherwise I would leave it alone.
 
#12
Here are a couple pics that may help ? David Wulf does make some very nice carb adapters , This is a tank I bought on ebay a couple years back for $20 , they don't come up often at that price though , I had to weld mounting brackets onto tank but for what people want $$$ for a Good condition Roper tank this was a no brainer for myself as I really liked the look it has on this bike , good luck !!
 

Daniel Coop

Well-Known Member
#15
Hell yeah, chipper. That bike is nice. I'm already thinking about copying the extended swingarm and jackshaft setup. One thing I hate about the Roper is the super narrow rear wheel. I was considering trying to stuff an extra DB30 rear wheel I had laying around in there, but if it does fit, it will be tight as hell. Maybe on top of extending the rear swingarm, I can widen it to fit. It'd be nice to use that wheel, the Doodlebug sprocket adapter and split sprockets along with a rear disc brake. If I am going resto-mod, why not?

I will probably just spend the money on a new chrome cylinder style gas tank to mount directly to my GX200. GokartUSA sells a nice, albeit expensive fuel tank kit.
 
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#17
I just got a Roper and am currently working it. It has a 5hp Briggs on it and the PO bolted some metal straps to extend the mounting plate just enough for the tank to fit. Not sure how it's going to work because it's not that stiff, but a similar mod might be something to consider.
 

Daniel Coop

Well-Known Member
#20
Going to work on grinding the slots forward on the engine mounting plate to give myself better clearance on the backside of the engine. I'll do it lightly and clean, hopefully nobody will know the difference as this frame is untouched/uncut and clean. (Although repainted not very well)
 
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