What Next...Carb Mods or Mushrooms?

[Hal the Elder]

Well...I've got my intake restriction opened up to match the carb venturi and the intake port, and I've got a Hi-Flow muffler insert installed, and I've got the cam gear advanced one tooth.

What should my next priority be...Re-jetting the Carb or ordering the Mushroom Valve Lifters?

My throttle response seems to be OK, but since I live at 3000 ft. elevation, (where the air is thinner), do you think this would cause my fuel/air mixture to be a bit on the rich side?

Thanks...
HAL & OSCAR

 

[KilroyCD]

Hal, I'm going to make this suggestion because of my lifters going bad in less than 300 miles. Do the mushroom lifters first, then worry about the mixture. You may also find that (if you take care of the mixture first), because the 'shrooms hold the valves open longer the mixture may need to be changed yet again.

 

[Quenton Guenther]

Hi Hal & Oscar,
Guess what? Chances are if you change the valve timing [mushroom lifters] you will also effect the air/fuel requirements slightly.

BTW, we called the machine shop today and asked about obtaining more mushroom lifters. The reply was "we will call you if we get an opening in the near future". We may run out if the demand doesn't slow down. I was only able to get 25 sets for my stock, and I shipped out almost 1/3 of them this morning.

Have fun,

 

[Hal the Elder]

Good Point, Kilroy!

A DANGED good point!

Mushrooms next, then! (You hear that, Quenton?)

Thanks...
HAL

 

[Hal the Elder]

OK Then, Dr. Q...

What do you need from me to ship me a pair NOW?

Thanks...
HAL & OSCAR

 

[Quenton Guenther]

Hi Hal, send me a PM [private message] with your shipping address.

Have fun,

 

[Kep1a]

May I also suggest Hal If you are going to do any other upgrades do them now. Before you do your jetting.

You know like...

1. Copper head gasket (a must have).
2. Milling the head .70 for more compression.
3. Polishing that combustion chamber.
4. Match porting and massaging the valve pockets.
5. 3 angle valve job.
6. machine the spark plug hole for a shorter 10mm plug without the threads protruding into the combustion chamber.
7. Any other things you may want to do that will change how it performs.

I have not done all of the above myself but they are things you should consider if you are going to do this proper.

Then you can jet that thing once and be done with it.

Note; You also may notice it to be more cold natured once the jetting is done.

Kep1a

 

[Hal the Elder]

Hey Kep1a:

I'm not a performance enthusiast at all...just a Reliability enthusiast!

I have no appetite for cruising at over 25 MPH, where I feel comfortable. I actually feel the MOST contented at 20 MPH!

This old man DOES NOT feel comfortable at 30 MPH and above on a motorized bicycle!

I'll leave my engine strictly stock, with the exception of replacing those components that are prone to early wear.

That's it!

Thanks anyway...
HAL

 

[Kep1a]

Well the copper head gasket and the shorter spark plug conversion and machining the spark plug hole is a must IMHO!

But the rest is optional if your head has a true flat surface (mine was not). All the rest really only becomes something to consider doing because you are already that far and at the machine shop anyway. Performance also makes for easy starting, cooler operating temperatures, smoother throttle response and idling. Not all of this is for go fast mods. Some like the plug and copper gasket are upgrades for long term reliability issues on that motor.

Kep

 

[Hal the Elder]

Not Interested!

HEY KEP1A:

I have no true Machine Shop...it's more like a Hobby Workshop.

I have no Milling Machine, only a 9"x20" Metal Lathe, a 1/2" Drill Press, a 12" Disc Sander, a 12" Band Saw, a 6" Bench Grinder, an 8" Table Saw, a 3/8" Drill, a 1/2" Drill, a Portable Grinder, a Jig Saw, a Scroll Saw, a large Vise, and an AM/FM/Cassette Player.

I'm from the non-adventurous school that says: "LEAVE IT STOCK!" I'll bet there are plenty of Whizzer owners who are enjoying their bikes just as they came from the factory.

I've already made what I hope will be the extent of all present and future modifications to Oscar, except for the insurance policy of the Mushroom Valve Lifters.

I'll leave the hot-rod stuff like milling the head and polishing the combustion chamber to those younger guys in their 60's who take their bikes to the Bonneville Salt Flats on weekends!

Thanks again, KEP1A...
HAL