Briggs 5HP I/C build ...I need some guidance!

CarPlayLB

CarPlayLB

Well-Known Member
#1
#1
Hello OldMiniBikes members!
I need some help. I just bought a very clean Briggs 5HP I/C engine off eBay. It is very clean bushing block with large roller bearing side cover. It is nearly complete, but I will need the tins and valvetrain. I will be building this with the billet parts, flywheel and rod, 'cause we need no stinkin' governors! I have built a few car engines, so I know the basics and have the right tools. This will just be for chasing the cats in the neighborhood (j/k) so I am not going racing or anything like that. Here is my long list of questions.

1) How exactly do I know what parts to buy? This engine is not coming with the recoil cover...is there part numbers on the block?

2) How are the valves adjusted? If they are too loose, do I buy different valves, or lifters? If they are too tight, do I grind the valve, or the lifter?

3) Do Raptor parts interchange?

4) I am planning on shaving my eyebrows, and the eyebrows in the block. Stock compression for Raptor was listed at 6.5:1...is that enough? By automotive standards that is incredibly low. Should I look for a thinner head gasket?

5) I am getting a more aggressive camshaft. Is it necessary to weld the lifter housing if I am not racing?

6) I am planning on using a motorcycle style carb...probably one off an "Animal"...is there another option I should look at?

Sorry for the long post...I just want to make sure I spend my money on the right parts at OldMiniBikes! Hent don't want no stinkin' returns!

Thanks in advance
Eric
 
J

Jay727

Banned
#2
#2
A little id of the block and carb can help you pick a model number.
If the block has two holes to mount the carb it's older and you can use 130292 0141-05 75061610 as the numbers.

If the block has dual carb mounting holes (three) you can still use the number above.
If it came with a carb that mounts to the tank with four torx screws, and uses a cup and pawl style recoil use well I don't know. I have these save as pdf files and don't have a number for that. I googled briggs website I think and found two (old and new) numbers to use.

If anyone tells you the local parts supply doesn't need a part number because these engines are common they're full of shit, these engine are old. My local parts counter guy acts like a retard if I don't have the numbers.
(my uncle had the biggest repair shop in my area in the 70's and 80's and back then you didn't always need numbers)

If you have too much valve clearance you can cut the seat, but you need a $125 tool and that eventually hurts flow so you're better off getting new valves.
If you have too little valve clearance you grind the valve stem. We used to do it on a 1" stantionary belt sander with a V to place the valve in for a square cut. Now I use a grinder and go very slow. Turn it as you grind.

Pretty sure most raptor parts interchange.

Welding lifter bores...I've never done it. When I was a kid I use to make cams by welding and grinding the lobes bigger. Now I have a Comp cam with double valve springs, had to remove material from the block to allow the lifter to go up higher. Never had a block break right there.

I used to shave only one eyebrow, the intake. I've shaved both before and cut the head down until the ridge is gone.
I've also ported blocks so the valves fit into the port and almost touch the underside of the seat.

Most people (used to?) use Tillotson carbs, thats what I've always used. They can be found on ebay but prices are going up.

But thats just my opinion...again my uncle used to own a huge shop with a junkyard in the back, when I screwed something up it was just a matter of digging up another 5hp and not repeating whatever it was I did that didn't work so well.

Heres my current neighborhood race kart.
The one pic I have. (any good briggs builder might notice the forced oil hole added to the experimental Horstman rod).

2005 Prowler Kart, 808 Key Chain Video Camera DVR 2 - YouTube
Some engine specs in the description of this video.
Briggs 5hp 9200+ rpm - YouTube
 
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CarPlayLB

CarPlayLB

Well-Known Member
#3
#3
That camshaft is too pretty to hide!

I have the block with the 3 hole intake flange. I do not have a carb or tank to match up.
I may go with a Tillotson, but they seem kind of hard to tune for me.

I have an old Horstman rod similar to the one in your pic. It sure looks like that dipper is too close to the case!
 
J

Jay727

Banned
#4
#4
Yea thats a three bolt intake case with the oil sensor cast into that side. I've seen stock blocks that have this area machined out for rod clearance, but not this one.

I'm changing it soon anyway, I bought a 5hp off ebay with an iron bore and flywheel side bearing. So I'm going to mod that block and end up with two bearings and an iron bore....should gain .00002 hp :laugh:
 
The_Ruppster_86

The_Ruppster_86

New Member
#5
#5
CarPlayLB,

I know you stated you don't intend on racing but what is your goal? What are you trying to accomplish RPM and HP wise? Are you looking for a low end torque monster, a high speed demon, or combination of the two? Then we can suggest and advise you more accurately to your specific build.

-Jeff
 
CarPlayLB

CarPlayLB

Well-Known Member
#6
#6
Jeff,
I just have a liking for things that run good!

I have always not liked the governed engines. I want to be able rev it up when needed. I am not about all upper RPM power...would rather have the torque down low and decent mid range. Reliable and consistant. Is 10HP too high of a goal for a mid-range power engine?

I also want to be able pull start it easily
 
B

bowtiebutler

Member
#7
#7
Sounds like a fun project! Yes, Raptor parts will interchange. From what I understand, shaving the eyebrows doesn't really help unless your really planning on turning some serious rpms, but I could be wrong. I too just picked up a couple Briggs I/C engines. One I am going back to stock with, the other I will be having some fun with. I just bought a 22mm Mikuni carb for it, but that's as far as I've gotten so far. Here are a few of my Briggs 5hp's. The black one is a factory original Raptor 3, the yellow one is a Raptor 3 clone, with a dyno 98-3 roadcourse cam. It also has a shaved head, and the short turn radius of the intake ported, as well as both ports have been cleaned up. The engine in pieces is one of the I/C engines, that is just going to be stock. I look forward to seeing your progress!:thumbsup:

Matt

http://www.youtube.com/watch?v=2hXZswG6N7M
 
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J

Jay727

Banned
#9
#9
STARPUSS said:
Picked this up from the Dump ]
Click to expand...
Yea, we have a junkyard here with a recycling pile, all day long people come in and dump whatever they found. I can't beleive what some people throw away. I picked up a flathead there for $20, and a 3hp flathead for $10. Sometimes I just want to sit there all day and save them all :sadcrying4::doah:
 
T

tim mclaughlin

Member
#10
#10
CarPlaylb, You will need the new style recoil with that crank.The kind that uses a cup rather than a starter clutch. The lifter area may or may not need welded. That depends on the camshaft used. A stock (gas) animal carb works well on a mild build. E.C. carburetors makes a nice intake for this purpose. The dyno 107ss cam is a nice cam for this application. No need for welding lifter bores with this cam and at .315 in. lift the head will need no modifications. ARC stock length rod and a Burris raptor piston is also a good choice. Good machine work will be the key. Line bore and hone with a torque plate,good valve job with NEW aftermarket guides. Briggs guides are weak and wear quickly. Finding a good shop that has the proper equipment to do this would be worth it in the long run. Anyway thanks for your purchase and I hope you enjoy it. I do have lots of briggs parts including the sheetmetal to go with that engine.
 
Clayon

Clayon

#11
#11
I'll be watching your build Eric. :thumbsup: I just built a 5hp B&S FH I/C myself. I used a Dyno 94ss cam along with dual spring valve springs from Rieken's Racing, but I removed the inner spring and just used the outer spring. I haven't run it yet because I am having some clearance issues with the ARC adjustable billet flywheel, so watch for that.
 
CarPlayLB

CarPlayLB

Well-Known Member
#12
#12
Damnit Clayon!...get out the grinder and whirl away at that thing! Knock thosde off so we can hear it! I want you to lead the way for me!
 
CarPlayLB

CarPlayLB

Well-Known Member
#13
#13
tim mclaughlin said:
CarPlaylb, You will need the new style recoil with that crank.The kind that uses a cup rather than a starter clutch. The lifter area may or may not need welded. That depends on the camshaft used. A stock (gas) animal carb works well on a mild build. E.C. carburetors makes a nice intake for this purpose. The dyno 107ss cam is a nice cam for this application. No need for welding lifter bores with this cam and at .315 in. lift the head will need no modifications. ARC stock length rod and a Burris raptor piston is also a good choice. Good machine work will be the key. Line bore and hone with a torque plate,good valve job with NEW aftermarket guides. Briggs guides are weak and wear quickly. Finding a good shop that has the proper equipment to do this would be worth it in the long run. Anyway thanks for your purchase and I hope you enjoy it. I do have lots of briggs parts including the sheetmetal to go with that engine.
Click to expand...
Tim...I did not get this from you...appears as if I git this from your wife! I am looking forward to this build. I will send you a PM.

Thanks again
 
S

slow greg

#15
#15
Briggs 5hp help

Eric since your in long beach give terry nash or dwight a call at Nashs karts in upland ca (909) 981 9611 he has all the parts and info you need and everything will work.... hes ex IKF briggs and stratton champ..he also does those re sleeved 3" bore clone engines.....a great machine shop and speaks vintage mini bike and go kart ...well worth the time and effort
 
CarPlayLB

CarPlayLB

Well-Known Member
#17
#17
slow greg said:
Eric since your in long beach give terry nash or dwight a call at Nashs karts in upland ca (909) 981 9611 he has all the parts and info you need and everything will work.... hes ex IKF briggs and stratton champ..he also does those re sleeved 3" bore clone engines.....a great machine shop and speaks vintage mini bike and go kart ...well worth the time and effort
Click to expand...
Thanks Greg...I will certainly look him up. I sent you a PM
 
CarPlayLB

CarPlayLB

Well-Known Member
#19
#19
I am still a parts collector. I have my billet rod (anyone have a billet flywheel for sale?), a Crane Cams 91004 (pretty mild cam), lifters, blower housing and pull start, billet intake...etc.
DAMN JEFF CLARK! Him and his "Bungholio" got me into this



I am too flippin cheap to have this done, so I bought a polisher and all the bits that go with it. Probably spent double what it would cost to have it done, but I can always do other stuff now too!
Give Jeff some props...this is hard work!
 
vwfan79

vwfan79

Active Member
#20
#20
I too just bought a I/C dual bearing block and will be doing a build with it, I already have all the parts just have to do the work. I built one for my build off bike and used a kool bore block I had lying there and ended up seizing the crank to the block. I will be using a .300 lift cam, billet lifters, arc rod, 22mm Mikuni, 3hp flywheel and coil, ss valves, dual springs (only outers), copper head gasket. With that setup I had to cut the lifter bores for the billet lifters, didn't have any problem with it breaking and there was no welding. The motor I seized got rode hard and just couldn't take the heat with the bushing block. With my gearing it would push my bike about 50.
 
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