Raptor 2 Build, second time around

[PhilosoRaptor]

Hello everyone,

Last time I built up my Raptor 2 I didn’t make any sort of thread or mention of it until it was long since complete and running, see the long overdue mention here http://www.oldminibikes.com/forum/more-than-two-wheels-/113893-homemade-kart-belated-intro.html#post954602

The time is upon me, I didn’t learn anything from Jurassic Park, and I will be bringing a dinosaur back to life! What’s the worst that could happen? Begin my second Briggs Raptor 2 rebuild.

I found this one of eBay for a good price and against my better judgment snapped it up. The first impression was very meh, the seller didn’t get very descriptive with the engine history and it shipped with a substantial amount of oil still in the engine which managed to soak every component. I knew it was going to be a tear down anyways. Otherwise everything looks really good internally, stock size steel bore, cylinder has cross-hatching and minimal wear, crank is clean. The only drawbacks were that the tank bracket was broken off, the sidecover crank bearing area is scuffed, and that it appears it has been stored for some time as the aluminum block is pitting and corroded in most areas.

So right now I am just contemplating what I want to do. I want to get the lifter bore area welded. The first welder I took it to tried but he said because of the pitting he couldn’t get any solid welds done. I am going to try and take it to some other people and see what they say. If it can’t be welded up I’ll just toss my 94-SS cam from my previous raptor into this one.

Link to full size here, click to zoom in and see the pitting I am talking about http://i.imgur.com/HZZpi6N.jpg

Other plans are the essential ARC billet rod and flywheel, billet lifters, and shaved eyebrows. Once I get a solid answer of the welding front I’ll make some more decisions.

I am looking for some advice on cam choice. Either for this engine or for the older raptor basically the cam will be used on a block with welded lifter bores. I have been considering and reading about the:

03-SS
- More lift .290 than my current 94-SS (.268), similar duration, higher target RPMs. Sounds like I wouldn’t have the chamfer the lifter bores. I would just have to source the proper 28lb valve springs. This at the moment seems to be what I am leaning towards.

233-SS
- Less lift .233, good duration, 20lb rated valve springs are readily available.

113-SS
- Less lift .242, but loads of duration, excellent top end, fast ramps and harder on the valvetrain. 20lb rated valve springs are readily available.

107-SS
- Big lift .315, but I would have to chamfer the lifter bores and I don’t have the tooling. Where are you guys getting 30-32lb springs? Would I have to go with a dual spring setup? More research is needed.

Thoughts, input, and comments are always welcome! Stay tuned for more updates! Happy riding.

 

[MB165]

i have with a 03ss, with a pz22 and 3hp flywheel once the clutch locks at 4000, ya hit the midrange then it pulls hard like a two stroke....big power hit, till i run out of timing advance (28deg. my fault) at around 6500. its in a db30, with 6:1 gearing and a noram cheetah. i just bought another block and plan on a 107ss for it. look at dynocams for springs and welding. they have a good machine shop

 

[David wulf]

I just put a 107ss in a raptor build and its killer . Along with a tilly and porting it screams , pulls to the upper 8's

 

[stephensimmons]

I just put a 107ss in a raptor build and its killer . Along with a tilly and porting it screams , pulls to the upper 8's

I'm also using a the 107ss and it's just what he said.

 

[joshua. c.]

1 have a 107ss in my engine as well. it is ported, with a shaved head, header with a muffler, billet flywheel and rod and a 22mm mikuni. it makes for one scary fast bike. before this cam I had a stock lift cam with aggressive duration I think it was a dyno cams 04-3 and there was a huge improvement in torque with the 107ss. and if you call arc they can give you spring recommendations. for the 107ss I was told to use the dual springs with the inner springs removed. just be warned though the stronger the springs the louder the engine. this thing is very loud, it sounds like a straight piped motorcycle. so don't forget to buy a muffler.

 

[massacre]

Any welder should be able to weld up that corrosion. Tough part is will you have to machine it flat afterwards?

 

[125ccCrazy]

the inside doesnt look bad but with the inside being impregnated with oil it might not weld so good...

you can run the 107ss without welding, welding is definitely a good idea if you can get it done but this isn't a block breaker cam.. You may have to knock a little off the counterbalances on the crank, basically smooth the rough casting down...I had to do that on a couple cranks with the 107ss, took around .020 off for a little clearancing.... the 03ss is a nice cam, you will need longer lifters for that one....

 

[MB165]

what is the 107ss idle like? does it sound choppy? what is acceleration up through idle to 6500rpm? can it handle a bigger carb maybe a 25 or 27mm?

 

[David wulf]

MB it's got a bad assss idle and were running a tilly 334 on it and it is evil fast off the line and why past 6500 . Doug's nanza that it's on has 6:1 gearing on it and it jumps off the line . I want to try a 22 mikuni on it cause the tilly is not a idling carb or it doesn't really act well trying to run half throttle , wide open or nothing . But wide open and you can't beat it .
I think it could handle a 24 flat slide but 27-28 mm IDK .

 

[David wulf]

MB it's got a bad assss idle and were running a tilly 334 on it and it is evil fast off the line and why past 6500 . Doug's nanza that it's on has 6:1 gearing on it and it jumps off the line . I want to try a 22 mikuni on it cause the tilly is not a idling carb or it doesn't really act well trying to run half throttle , wide open or nothing . But wide open and you can't beat it .
I think it could handle a 24 flat slide but 27-28 mm IDK . We will have it at windber and you can try it out and see what you think .

 

[stephensimmons]

MB it's got a bad assss idle and were running a tilly 334 on it and it is evil fast off the line and why past 6500 . Doug's nanza that it's on has 6:1 gearing on it and it jumps off the line . I want to try a 22 mikuni on it cause the tilly is not a idling carb or it doesn't really act well trying to run half throttle , wide open or nothing . But wide open and you can't beat it .
I think it could handle a 24 flat slide but 27-28 mm IDK . We will have it at windber and you can try it out and see what you think .

28mm flat side would be too much, trust me I know. But the 24mm is the sweet spot with a #35 idle and a #105 main.

 

[PhilosoRaptor]

Small progress. I have shaved off the eyebrows. I also dropped off the block with a professional welder. He took a look at my friend's attempted welds and said that he didn't prep or clean the metal properly. So hopefully it'll all be welded up by mid week and then I can begin grinding down the excess material.

Also thanks a bunch for the input and suggestions folks! It is much appreciated. The 107-SS is sounding more and more like what I have to get. Really getting the impression that it is a good power-making cam and being easier on the block is a good thing. Looking at the Dyno profiles and website it recommends their dual spring setup with the inners removed 107-SS profile so that simplifies the part search. It should be noted that for the time being I will be using the stock Raptor carb. I don't have any provisions yet for a fuel tank mounted elsewhere so for the sake of simplicity I will forgo getting a better carb at the moment. I figure if the stock carb can take a 94-SS cam up to 7500rpm it should do.

For those of you who are running the 107-SS, are you still using the recoil pull starter? That is what I will be doing. I have gotten used to pull starting my old Briggs with the roll it over to the compression stroke and then give it a good pull. I haven't had my arm jerked off by a backfire in awhile. Although I always am thinking about it in the back of my mind!

 

[CarPlayLB]

I have the 94-SS cam in my Taco T100 engine. Roll it over to the compression stroke is strongly recommended. If not, your hand will be very sore! Mine was!

 

[David wulf]

The raptor I did with the 107ss and about 20 thou shaved off the head is pull started but you have to roll her over to the comp stroke and go , if not you wrist or the rope breaks .

 

[MB165]

oh man they will get ya. a larger starter handle and use a glove in case of kick back is recommended.. if ya add a little 3hp flywheel to the mix, makes it like a mower without a blade attached....

 

[Scumbag]

The raptor I did with the 107ss and about 20 thou shaved off the head is pull started but you have to roll her over to the comp stroke and go , if not you wrist or the rope breaks .

I'm reading along & try'n to learn. This may be a dumb question, but how would I 'roll it over to the compression stroke'?

Thanks for the step by step rebuild PhilosoRaptor ! (really helpful for me over here)

 

[stephensimmons]

I'm reading along & try'n to learn. This may be a dumb question, but how would I 'roll it over to the compression stroke'?

Thanks for the step by step rebuild PhilosoRaptor ! (really helpful for me over here)

Pull the string till it gets hard then get a good grip and pull!

 

[PhilosoRaptor]

Yup, I learned the good ole roll over to the compression stroke from here after I built my last flathead with the 94SS. Saved me a lot of grief! Another good thing to do is not to pull for a long stroke just a quick rip after you get to some resistance.

Well, the sun has set, literally and figuratively on this block. My welder couldn't get any good welds, he said it was a bad casting where the manufacturer may have used too much lead in the mix to get it to cast better. Actually burnt through a little to the outside near the intake lifter bore. That is why you can see a glob of JB weld setting in the photo. This block will now just be put back together as cheap as possible to be a stock Raptor 2 and nothing more. Or just kept for spare parts, either way I am becoming a hoarder.

With that being said, I really wanted to rebuild another Flathead this summer and I am not giving up on those ambitions. I am sourcing another block at the moment and it will get rebuilt with the same gameplan as I had originally intended for this one. I will still borrow some of the good parts such as the crank and the carb. After watching stephensimmons build with the 107-SS, I gotta get me some of that power! Stay tuned for more and thanks as always for the tips and tricks!

 

[David wulf]

I would find another welder . I've seen a lot of these blocks welded , old and new and if cleaned properly weld just fine . Have never heard that LEAD line spoken .

 

[joshua. c.]

iv found for easer starting, start the engine with the throttle closed, then quickly rev it up when it fires. it reduces the compression a bit and it wont be as likely to kick. I also retarded the billet flywheels timing back to stock to further reduce the problem. my engine hasn't kicked back on me in over 2 years.