Roadmaster Project

[MEASURE TWICE]

The sound I recall is like I did the same a long time ago, but also had a muffler on the end too. The current one I am building the muffler is the spark arrestor muffler, so it looks a bit bigger than the tube ore other types.

I was wondering the attachment point on the back, is that a self made bracket.

I was thinking I would have a few points, maybe 3 or 4 to hold the pipe on my build to take stress of the 1/2 inch pipe, and the mechanical advantage stress it could put on the threads on the exhaust output of the engine. I'm not sure about a Helicoil that big for an exhaust thread 1/2 inch if it were to get stripped. Probably so other way involving welding and the metal is a low temp melt, so it would be difficult.

Nice looking frame and the generator roller in front and light. Is that a drum brake hub in the front, or specifically only for the speedometer? I noticed it is the old type with cable that goes to the speedometer.

The picture I post of what I'm doing on my bike:
The hoses I will trim down when I am near finished. The Washing Machine Pulley is just taped on while I have the paint fully curing on the clamp parts for the rear wheel, it will be centered when it is back in place.

I got a 45 degree bend I am going to put some where so that I have the pipe at the rear wheel area level. I think I saw you used one of those. I got a couple more lock nuts so I can have the bends where I want them and tight.

Measure Twice

 

[Tinsmith]

Wonderful job!! Dan

 

[Gbrebes]

Thanks for the response guys.

Briggsbikeer: I am going to stick with the primitive rope pull for now. Maybe someday I will get it together to install a kickstart.

MeasureTwice: I made the muffler bracket myself. I currently only have one mount at near the rear wheel axle, but your comments have made me consider one more bracket near the seatpost tube. I can get a close up picture of the bracket if you would like. Its basically a doubled over "P" shape strap. In reference to the front wheel, I do have a drum brake hub, as well as an old fashioned cable driven speedometer. This is more for show than actual accurate speed. The speedometer only goes up to 40 mph.

I tried to ride the bike this evening, but it didn't go so well. I still have not got the carburetor adjusted properly. The motor could not get up to very high rpms. Also, the clutch was not really driving the back pulley very well. Either the clutch has a fairly high engagement rpm, or the back belt was too loose. So the ride was more pedaling than actual motoring, but the bike did move on its own power for a 20 yards or so. I will try it again hopefully in the light of day tomorrow or Friday.

 

[MEASURE TWICE]

The clutch I think I see as the one that is on the jackshaft? The engine is I think like mine about 3hp 4stroke Briggs? The centrifugal clutch is a belt type. You only use the 2ea belts for motor drive; the chain is only for pedals.

Knowing this if true, then I think the centrifugal clutch belt type I am just thinking is about the same as the comet minibike clutch I have one mine which is for #35 chain. I also have a centrifugal clutch for v-belt, but it was going to be used on the crankshaft of the engine and was a different diameter, I think a bit smaller than the shaft on the 3hp Briggs aluminum.

I have cast iron 5S Briggs that it fits probably 1/4 inch shaft, but wanted to have more power and lighter so I decided clutch on aluminum 3hp Briggs and chain clutch to jack shaft then pulleys v-belt to wheel.

I have 8.3 to 1 ratio gear down. I am nearing getting ready to ride it but I am still making the cover for chain and cover for the delicate homemade linkages to the carb throttle mechanism. I don't want to get my leg chewed up or the carb linkage smashed.

The idle I spoke with a Briggs rep once about my carb and engine, he said I think 1750 rpm idle. He also said about 1800-2000 rpm is where the clutch start and then is fully engaged. I know with the 8.3 to 1 ratio I calculated that it if fully engaged and not slipping at the clutch or pulleys for the v-belt, it would be going about 18 mph. That was for the calculation for 2000 rpm, so range of speed when fully enguaged is 18 to ?. Figure the engines go maybe rpm max to about 3000 rpm so 30mph top end.

If this is the range of speed, it could be OK except for wanting it really to start out at 5mph when fully enguaged and then just have a trade off for less top end speed. Just I need to find some used sproket not too badly worn, or a bigger washing machine pulley to use on the rear wheel!

I would have hoped it would be slower, because how can you go like 5mph or less to make sharp turns in the woods, possibly going uphill a little. It is for off roading only this build motor bike, no pedals.

I know this seems way too high a gear ratio. I found the large sprockets to buy are expensive, and somewhere between $30 and $60 at Granger. I am going to just see first what happens. Then if necessary maybe I will buy a larger sprocket for the jack shaft. The other way I know works is push start, no clutch and I had two motor bikes with a 2hp and another with a 3hp that worked that way. All I would have to do is put parts I already own, pulleys, then I would have two v-belts.

I used the Link Belt brand that I have enough adjustment and can add and remove links, besides moving the rear wheel or jackshaft forward and aft to adjust and have had it tight enough so while holding the jack shaft still, I could not turn the rear wheel.

Let me know what you find out trying it again.

Measure Twice

 

[Goldy]

Been watching this...An awesome looking build, the lines just scream "classic motorcycle!"
Very, very, very well done! Have you considered painting it yet, or are you going to leave it as is?

 

[Gbrebes]

Thanks for the feedback Goldy. I have a lot of respect for you and your bike builds. As for the paint, I always imagined it black with a white tank, sort of like an old Triumph or like your bsa bike, but I have been considering an olive green. For now though, I am just going to leave it metal. Painting is so time consuming and labor intensive, I am just not ready to have the bike out of commission for that long. I still haven't really got it running well yet. I took it for a short ride, but it would not reach full rpms and would barely move on its own power. I do not know if my clutch is working correctly or not. My tank had some debris inside left over from brazing it and the debris clogged my petcock/fuel filter. The tank also has two tiny leaks, so I need to re-braze it, clean it out on the inside somehow and re-assemble.

I also just purchased a comet clutch that I would like to switch out, but I have to work out my mounting for that.

Anyway, I will probably paint it someday, just not sure when.

Gilbert

 

[Goldy]

Paint or not, it's pretty damn awesome! I'll be watching for future updates...I hope you get it running as good as it looks.

Goldy

 

[harry76]

If Grebes does get his bike going as well as it looks, hes gonna be getting a LOT of speeding tickets!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[Norman]

Since you are building a hand built bike I thought you might like seeing this.

Here is a couple of photos of a hand built bike from the Netherlands I looked at while at one of the bike show in Sturgis this year

The engine is an over head valve waterpump engine that must be sort of common in that country. I really like the bike and the guy who built it was very friendly. He talked out this bike for quite some time, I don't remember his name. he was going for an early board track racer. The tranny is all hand made along with the clutch. To see this in the real would blow you away.

 

[harry76]

Man that is sweet, but no pedals.... but it is so nice. Shame you cant remember his name, id love to see more pics and maybe read about it. Dont suppose you have any links?

 

[Norman]

You can hot rod the h ell out of a briggs there's racing cams, pistons, billet rods
one thing to look for for a 5 hp engine is a cast iron 3.5 hp flywheel it will allow that engine to rev very fast. High lift cams with high pressure springs will allow almost 9,000 rpms but you need to do a lot of work to make it live at that rpms the billet rod and racing piston is a must along with the high pressure valve spring. I've got an alcohol burner 5 hp that will turn 9,000 rpm running alcohol.
I copied a friends blue printed racing briggs, mine would out run his engine. My clutch is set up to engage at 3400 rpm, the max rpm for a stock briggs.
You can also do thing to the valves along with the ports, decking the block and reworking the head is all part of the game. Doing it right the engine is capable of 18hp on alcohol. A tilly pumper carb will help. When you whack the throttle wide open it looks like a toilet flushing when looking in the carb. I know quite a few vodoo things to do to an old flathead briggs.

 

[monark]

spot on! a really nice bike,i drooled a little on the laptop when i heard the sound,perfect! thanks for your reply on my own thread,on the right path.

 

[Gbrebes]

I am currently trying to repair the frame. I had a crack develop in the downtube in between the bottom bracket and the rear of the motor mount. I will try and take some pics of the repair process, then I will post some new pics of the bike in its current state with a rear rack and tool box in between the seatpost and the rear fender.

Gilbert

 

[Gbrebes]

Got some work done on the frame repair. I have a photo (bad quality) of the crack. I cut out the downtube right at the crack and ahead of the front motor mount. I then bent up a new downtube with a bit deeper of a loop, because my motor just barely fit under the crossbar before and it was difficult to access the spark plug.

I then put internal sleeves as well as external sleeves on the two new joints and re-brazed it. I made a one piece motor mount and made the new "gussets", they turned out to be fairly large and the frame is heavier, but I think that the frame won't crack again, at least not under the engine. I will weld on the gusset on the other side of the frame, then I will add a strut to support the motor mount at the front. I will also fashion a bracket on the crossbar to bolt onto the engine near the head somewhere.

Not very exciting pictures, but I am really excited to be this far along, it has taken me quite a while due to the fact that I only have between 9pm and 12pm at night to work on it.
I will post more pictures when I finish.

Gilbert

 

[briggsbiker]

Hey Gilbert, how's it going? So did you ever get that engine running better since the race?

 

[Gbrebes]

Not really. I tore it down and hand milled the head and the block. I thought I was leaking compression out of the head gasket, so I replaced it. It ran a little better. I bought another 5hp briggs and plan on rebuilding it, I might have a professional do it because I am not completely confident in my machinist skills.

Gilbert

 

[Kestrel Motors Inc.]

Hey Gbrebes! That's really cool! I'm doing a similar build only with a 1 1/2 horse Clinton. I'm looking at your jack-shaft as a guide for mine. I look forward to seeing this one painted up and done!

 

[briggsbiker]

Not really. I tore it down and hand milled the head and the block. I thought I was leaking compression out of the head gasket, so I replaced it. It ran a little better. I bought another 5hp briggs and plan on rebuilding it, I might have a professional do it because I am not completely confident in my machinist skills.

Gilbert

Haha that's funny you say that cuz I was thinking of doing the same thing to my engine. My machinist skills are not at that level but I'm still gonna give it a shot. ever since the race my bike hasn't ran the same it's a little sluggish.

 

[Gbrebes]

Got some more work done. Finished up the motor mount and added an upper mount. Man, this stuff takes so much longer than planned. It took a bunch of late nights in the "Shack", my little 8 x 12 shed.

 

[Gbrebes]

I also worked on fabricating a new headlight. I have always wanted an old fashioned looking bullet headlight, but I could never find the right one, so I decided to build my own. I got my inspiration from an old luxor headlight like this

I bought a forklift utility light that fits the par36 bulbs I like to use. I then added a cone to the back and fabricated some fins for the grill. The final product is not exactly what I was hoping for, the rear teardrop section still looks too pointy to me. But I will use it anyway and maybe try it again later.

I still need to fabricate a mounting bracket for the light, then I have to re-mount my battery box and wires. After that I should be ready for the road again. I will take more pictures of the bike all back together.

Gilbert