Mikuni Carbs Type2, Type3, and Type4

[david premo]

Hi Ron,
With regard to getting full throttle, either you have the incorrect ratio in your linkage or your foot pedal is not at the correct “resting” height. Years ago when I was taking a Roadster out for a test drive with the owner in the car, I noticed it was not getting full throttle. So I pulled to the side of the road mid test drive, put my foot under the foot pedal and lifted up to what I felt was about the correct height. I took off and hit full throttle and car ran great. The guy told me he had no idea his car was so fast. The is also a limit bolt just under the pedal, remove it and see if that gives you enough range to get full throttle.
Dave

[Gregs672000]

Yep, what Dave SAID! I did a dyno session with 80% throttle. Unfortunately mine was already at full throw and the pedal had no more adjustment left on the floor. Now that I've got full throttle the car is far more powerful than I thought!

[eastmedia]

Thanks. I will try the simple stuff first. No doubt after mashing the accelerator for 53 years, theres some adjustment to be made.

[eastmedia]

Accelerator pedal was loose. Also adjusted the stop. That gave me all the pull needed.
On another note, as i was warming it in the driveway, one of the carbs backfired, and lit the foam air cleaner on fire. Lucky i was near a hose. What a bad design. Need to get some proper filters.

[Solex68]

Accelerator pedal was loose. Also adjusted the stop. That gave me all the pull needed.
On another note, as i was warming it in the driveway, one of the carbs backfired, and lit the foam air cleaner on fire. Lucky i was near a hose. What a bad design. Need to get some proper filters.

Wow. Now that will inspire me to get a fire extinguisher!

[Gregs672000]

Wow. I've had carbs snarf when cold or lean but never had a flame! I'd investigate as to why that may happen. I've seen it occur when people were trying to get an engine to fire up with the timing out. How could it fire off the fuel in the intake tract when all valves are closed creating a sealed chamber and no access to spark unless it fired out of sequence or something else lit it off? Experts chime in?

[david premo]

The popping through the carb is a lean condition for the RPM it was at.

[Gregs672000]

The popping through the carb is a lean condition for the RPM it was at.

For sure, seen that Happen! I re-read the post, and i though it was idling. But maybe he was reving it up to warm up... pop! Wonder if the pumps are working fully too?

[eastmedia]

Yes, it was cold stumbling, rev to get the fuel flowing. once its warm, it idles well. I increased the idle and it seems a bit better now.
It does pop a bit on the way back down from higher RPM.
chokes aren't hooked up yet. switched to new filters.

filters.jpg

[Gregs672000]

Love em! Totally changes the sound, doesn't it? I've always loved the look combined with the fined R valve cover. Are you able to run any air horns inside the filters? I know they are tight as I've looked to run similar set ups. They make some nice, short, fully radiused ones that will work great.

Are you familiar with tuning these carbs?