79cc Sportsman Flyer build

GoldenMotor.com

Tom from Rubicon

Well-Known Member
Apr 4, 2016
2,757
5,941
113
72
Rubicon, Wisconsin
Sounds like you're weather is as flaky as ours Tom. May Bank Holiday weekend here in the UK (followed by another for next Saturday's Charlie/Camilla Coronation) and I'm stuck indoors watching the Snooker World Championship thanks to yet more rain. The E-bike carrier for my Saab (now UK registered) that was supposed to be delivered last Wednesday still hasn't showed up, so my planned weekend trip over to the Lake District in Cumbria is postponed. Been that kind of cold, wet spring where I haven't been able to squeeze-in anywhere near the bike rides I was looking forward to. But the forecast for next week says 'a mini heatwave is on the way', so fingers crossed...
Hi Pete,
I was just standing at the stove turning our ham and potato hash and there was a brief snow shower mixing in with the cold rain. 35F

Tom
 

Tom from Rubicon

Well-Known Member
Apr 4, 2016
2,757
5,941
113
72
Rubicon, Wisconsin
How about an update on your motor upgrades Tom and your opinion of your efforts after this amount of time?

Rick C.
Hi Rick,
Sorry but no update to report. I never got the carburetor fuel feed adjusted so that the engine would not stall under load. Too lean I think.
I ran out of riding weather last year, and this year? We take a long time warming up here in SE Wisconsin.
Snow showers as I write.

Tom
 

fasteddy

Well-Known Member
Feb 13, 2009
7,426
4,848
113
British Columbia Canada
Mom always said the weather here in British Columbia was like the weather in the U.K. This spring has been wet and upper 40's to the upper 50's. The past few days were in the low 60's and yesterday it was 78F. That's a mid summer temperature. Today at 8am, it's 54 and overcast which is normal. It will rain of course. Tomorrow is supposed to be a repeat and then sunny and in the 70's for a couple of days.

Steve.
 

indian22

Well-Known Member
Dec 31, 2014
4,722
7,697
113
Oklahoma
Hi Rick,
Sorry but no update to report. I never got the carburetor fuel feed adjusted so that the engine would not stall under load. Too lean I think.
I ran out of riding weather last year, and this year? We take a long time warming up here in SE Wisconsin.
Snow showers as I write.

Tom
Thanks. I thought I might have missed some posts Tom, but look forward to hearing your progres.

Rick C.
 

Tom from Rubicon

Well-Known Member
Apr 4, 2016
2,757
5,941
113
72
Rubicon, Wisconsin
Hi Rick,
I understand your concerns. Notices of watched threads has for some time been iffy.

There is a air screw which as I understand it controls fuel mixture enrichment from 1/2 to full throttle.
I don't have a good understanding of the mechanics of carburetors. The Mikuni manual seems to make me think I need to open up that (air) circuit to enrich the fuel mixture. So why do they call it an air screw?
Is it the nomenclature that is tripping me up?
I would like to get this sorted out.
Tom
 

Tom from Rubicon

Well-Known Member
Apr 4, 2016
2,757
5,941
113
72
Rubicon, Wisconsin
Hey Steve,
Good to hear from you. We all excepting Rick have been laying low over the winter months.
How is your health holding up?
Mona last saw her Oncologist a month ago and she is still in remission and well.
As mentioned above, I need to get the bloody Flyer carb sorted out.
Still waiting patiently for your TriCars tyres to touch ground. I know you were sorting out your work space.

I found a deceased mouse last week. I dare not speculate how it was in repose before I spied it.
And mouse droppings, everywhere! I really do not like mouse droppings.
Mona just called, so good night.

Tom
 

indian22

Well-Known Member
Dec 31, 2014
4,722
7,697
113
Oklahoma
Tom I hope you bought a real Mikuni and received same. The counterfeits are just that and not replicas. They have authentic looking branding, but not the machining. I have one a (VM 24) I think, which I never got running right. The idle/air circuit is on the front, intake side of the carb. I close this gently then back off one &1/2 turns and that gets me close on an actual Mikuni, the clones I haven't a clue.....

Warm weather down here so it's slowly coming your way.

Rick C.
 

fasteddy

Well-Known Member
Feb 13, 2009
7,426
4,848
113
British Columbia Canada
Hi Tom,
Great news about Mona. What a relief for you both. Not much different for me. Still trying to get one foot in front of the other some days and it's good other days.

I have been in the garage when I can cleaning it up and condensing junk so it can be thrown out. I've run out of space to put things away. My brother and I bought one of those tissue paper tin sheds but first we need to get a wood floor put together to set it on. With the winds we get and the wet snow falls it will need all the help it can get to hold together. This will give us a little space in the garage and there are plans to get a small dumpster/skip so we can toss a bunch of the crap lying around here.

I've been working on the camper getting it ready for a trip to Silverbear's for a Bike Camp. It's been 9 years since the last one. Need to get the paint for the Epic in a couple of weeks and the metal to finish Silverbear's fenders. We are 2-3 weeks behind what we should be as far as spring weather is concerned. Ever one is I think.

Steve.
 

Tom from Rubicon

Well-Known Member
Apr 4, 2016
2,757
5,941
113
72
Rubicon, Wisconsin
Tom I hope you bought a real Mikuni and received same. The counterfeits are just that and not replicas. They have authentic looking branding, but not the machining. I have one a (VM 24) I think, which I never got running right. The idle/air circuit is on the front, intake side of the carb. I close this gently then back off one &1/2 turns and that gets me close on an actual Mikuni, the clones I haven't a clue.....

Warm weather down here so it's slowly coming your way.

Rick C.
The 19mm clone unadjusted carb functioned well on the unmodified 79cc engine. but 3 hp on that heavy bike is a flat ground rider only.
Main jet mods never mattered and last year I was all over the map trying. I have not queried the fella at AGK. Now is the time. Or figure out a 212cc in this frame which is more than strong enough.
Plan A is a stock genuine 19mm Mikuni.

Tom
 

indian22

Well-Known Member
Dec 31, 2014
4,722
7,697
113
Oklahoma
Good reports are pure joy, Pete.

I'm hoping the modified 79cc will reveal a couple more hp for you, once running.

I live in hilly terrain, some rather substantial grades, so even casual paced rides challenge single speed, centrifugal clutch builds with small displacement 4 cycle engines. I like the 212cc Predator a lot and it makes sense on the Sportsman, but I'd sure like to see the 79cc come to life!

Rick C.
 

Mossy

Well-Known Member
May 20, 2022
1,128
818
113
Good reports are pure joy, Pete.

I'm hoping the modified 79cc will reveal a couple more hp for you, once running.

I live in hilly terrain, some rather substantial grades, so even casual paced rides challenge single speed, centrifugal clutch builds with small displacement 4 cycle engines. I like the 212cc Predator a lot and it makes sense on the Sportsman, but I'd sure like to see the 79cc come to life!

Rick C.
This is what I'm working on 79cc ... Degree8 on ebay has your parts.. pwk needle jets ;)
 

Attachments

Tom from Rubicon

Well-Known Member
Apr 4, 2016
2,757
5,941
113
72
Rubicon, Wisconsin
Tony, here is a link to the origin of this lovely adaptation of a Farmall Cub Tractor.
Guy Turns Old Tractor Into Badass Motorcycle » TwistedSifter
I think the oil can mounted behind to tractor tool box is what makes this build so right.
And you can get a rusty butt from the heavy duty saddle. As far as the frame is concerned?
I suspect it is a low cost proof of concept prototype. ;)

Tom
 
Last edited: