briggs 3.5 HP stretched/chopped/lowered murray cruiser

G

gbginger

New Member
thought i would go ahead a start a build thread. going to be using a briggs 3.5HP motor. still trying to get all the parts i need to start on this project. going to be using a stormey archer 3 speed internal hub for the motor. its going to be a long process and I'm sure a lot of problems along the way.. i have already ran into a few. biggest problem i see is going to be getting the hub to fit in my rear dropouts. I'm not sure its wide enough to fit the hub so I'm going to have to come up with something.
this is how i bought the bike for 30 bucks then went to chopped the back end off and added 5 inches along with a new support for my rear seat.this is how she sits right now.
 
i am going to cut the down tub to fit the motor so it sits lower and more forward on the bike. i just sat it inside the frame just to get a look and this is the plan for my jackshaft set up and how I'm going to run everything.
also going to be using a stormey archer front drum break. can anyone tell me how big of a problem it will be if i grind down my flywheel fins? will it throw my balance way off?
 
I broke off all the fins on a aluminum Gc160 flywheel. Then took a angle grinder to get em pretty close to flat. Next fired up engine ...let it spin at a slow speed then grab a file and press evenly against flywheel. This will get it smooth and even ..
 
MotoMagz said:
I broke off all the fins on a aluminum Gc160 flywheel. Then took a angle grinder to get em pretty close to flat. Next fired up engine ...let it spin at a slow speed then grab a file and press evenly against flywheel. This will get it smooth and even ..
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this is exactly how I'm going to do it! thanks
 
MEASURE TWICE said:
The way you DIY and modded the seat post / frame, also with added support, very nice!
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thanks. wish i would have bought a tig welder a long time ago. the first try at it all i used was JB weld and some pipe i bought at ace hardware haha it worked for a while i guess.
 
How Koool! You doing a good job,love the old Briggs builds. How about finding a old Schwinn or other brand ( Schwinn has the best curve )girls bike and taking the down tube and fitting it in yours would give you a lot more room for the motor..............Curt
 
Great job on the frame mods. Going to be a real cool build.
If you tilt the motor forward, it will lower it considerably and fit without replacing the tube. I've been squeezing 5hp Briggs motors into stock frames for years. Although, the drop loop frame and upright engine has a more vintage look.

 
msrfan said:
Great job on the frame mods. Going to be a real cool build.
If you tilt the motor forward, it will lower it considerably and fit without replacing the tube. I've been squeezing 5hp Briggs motors into stock frames for years. Although, the drop loop frame and upright engine has a more vintage look.

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this motor has to be sitting upright. i just can't imagine it any other way. i don't see it being to big of a problem cutting the tube and bending it back to get the motor to sit just right
 
Excited to follow your build. I love any Briggs powered bike in every configuration. Keep plugging and it'll get done.
 
You might think about lubrication when tilting the engine. I think I did the max the amount of degrees tilt that Briggs say can be done.

My engine is aft tilted to fit on my build. The problem I found is that the oil breather is more likely to have oil sloshed up into that area and not just blow by mist.

Most would warn me not to put less oil in the crankcase to compensate, but I have done that and use 1/4 to 1/3 less fill. The inside of the crankcase I have pictures from when I overhauled the Briggs 80202 0420 3hp 4 stroke of mine, it shows the splasher fork getting a longer time in to oil sump due to the angle, so that is my rational to be Ok with somewhat less oil fill. I have ran the engine hard trail riding and have not blown it up.

If I had known eariler though that others had tilted forward the engine and no problems with lubrication and I could have fit the engine that way without too much modding, I would have done it that way.

MT
 
gbginger

Just sent you an email, you are approx. 20 miles from me. Nice build. Looking at your jackshaft mock-up, you are apparently aware of the "Staton" grooved freewheel adapter that uses the $5. 3 prong sprocket and freewheel sprocket adapter. It is a great system and saves a lot of cost for a shifter build.

You could use a regular rear wheel with a 5 or 7 speed cluster and install a rear derailleur and have a nice shifter mab that you will like.

Have you done more on your build? Thanks for sharing.

Ron
 
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headtrama said:
Here is a picture of my Briggs powered bike.
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And when Andy say's "Briggs powered" here.......he's not joking as that thing is Unlimited Class material!!! That bike seriously rivals my 212cc build in every aspect and is top-notch in detailing. Not too mention 20+ HP Briggs!

Did I mention that already? :D
 
wow.. that is clean. sorry i haven't updated in a while. i work offshore and just did 8 weeks. should be having some updates soon.. made my manifold for the the carb I'm using. H30 tecumesh carb. it really seems like it sucks down the fuel but it runs and idles. vibrates like crazy
 
Is that a real Tecumseh H30? I may be going to get a imitation I saw on Ebay of one as low as 15 bucks, but I see original H30 for about 55 bucks in USA ship from North Carolina free shipping.
 
its a knock off H30 got it off amazon for 17 bucks i think.. seems to be working pretty good. it idles and runs.
 
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