Hello everyone. Quick rundown. This is a type IV in a 912...so a 913?

Here's the story. This engine was in a 914 and ran well with a no name dizzy and Weber 44's. Since I was putting it in a 912 I made a few changes. I got Tangerine's 4-2-1 exhaust and got rid of the no name distributor for a bluetooth 123Ignition. I also thought the 44's may be a little big so I used some 40's from the 912.

Engine 2056 with webcam 86.
Weber 40's
185 air.
F7 emulsion.
130 main.
52 idle.
32 venturi.

123 Ignition bluetooth.
0-1000 RPM 12*
1000-3500 RPM 28* to 6000

First time starting up it held an idle but the exhaust got so hot and popping out the exhaust that I couldn't even set the idle air or check the timing with a timing light. I literally got a blister from just grazing the header. The AFR was hovering at 10:1. The head temp was under 200 and oil temp never even moved the needle, but it was so hot it just wouldn't run. I ran a couple of house fans and tried again. I did get it to idle for a minute by adjusting the air idle screws but wouldn't rev high enough to check timing. This brings me to the 123 Ignition. Here is a picture of the rotor with green light just turning on and pointing a half an inch past #1 plug wire. Does that mean it's retarded too much? Prior to all this I confirmed TDC and checked the valves.
Any thoughts?


Click to view attachment
Click to view attachment

The blue masking tape with the white line is where the #1 plug wire is when the cap is on.
Thanks Jeff.

You are too lean for that motor and the vents you are running,start by upping the idles 57 or 60,one indication is when the air idle screw makes little difference and are screwed out too far .
With the correct idle jets you will notice much improved starting and idle,once you get that right you will most likely need to increase main jet size too due to your added displacement and cam,head spec comes into play also.
CB Performance and others have a jetting guides which is a good starting point,I think this is based on what was supplied with the carbs from new,when the engine is modified you have to experiment further,good luck.

I was thinking I was lean also because the exhaust was really hot but AFR reading is at 10:1 at idle. Have 60 idle jets and F11 tubes I'm going to try.

It sounds like you are rich and retarded.


...I mean, not you personally, but your motor.

Extra fuel + late timing means some of your fuel isnt burning until its exiting into the pipes (hence the pops and extra heat in the exhaust)

Lol. Just changed jets to F11, 200 air and 60 idle 135 mains.
I know you shouldn’t change so much at one time but I’m going for it.
Gunna fire it up now. Bee back soon.
Jeff.

Will be interesting to see,you should be getting close but I would tend to keep the air correctors you had before,the emulsion tubes you originally had are odd as F11 is standard fitment so you will be good there.
Waiting .

Ok, just back from the garage. Made the jetting changes and fired right up and sounded good. Was able to set timing with timing light, still learning the 123Ignition. AFR readings at 11:1 now, a little better.

However...#3 cylinder exhaust is not nearly as hot as the others, #3 intake manifold not very hot either, maybe it's not firing? I'm thinking it's only running on three cylinders. I pull the plug wire while running and no drop in idle. Pull the plug and I do have a spark.

I better check all cylinders. Pulled #1 when running and no drop or change in RPM. Pulled #2 and had a big drop in RPM. Pulled #4 slight drop in RPM. I think I'm only running on two cylinders #2 and #4. The engine will run with only #2, #4 plugged in but not on #1, #3.

So how did this go from a jetting and timing issue to only running on two cylinder issue.

I have read this before.

"the firing order conundrum issues, 1,4,3,2 and the theory of , that when
2 fires, it depletes 1 which is next
or when 4 fires. it depletes 3 next, (same side depletion theory)

At idle, how does each cyl respond to it's respective idle air mixture screw? Set them all at 3 turns out from lightly seated. Start fresh with a common setting. Where are the air by-pass screws set? The 'shotgun' approach is futile. If you don't have one, I suggest you get a CB performance Weber manual. are the little O-rings for the IAMS in place?

Hey rhodyguy. The air bypass screws are lightly seated and all pull equal with the uni-syn. I started with idle air mixture screw 1 turn out and it started to stall any more turns out. If I understand the idle circuit this should mean the idle jets are to rich. AFR at idle back at 10:1 and doesn't change at any RPM. I know I did too many changes at once but at least it idles now so I am able to start a organized approach or SWAG. I'm gunna do this over this weekend. I'm not convinced the the linkage wasn't coming into play, I have Tangerine's cable throttle linkage and don't think all the slack was out.

Ok some progress ,whats the condition of your leads,I run the best I can buy,copper leads don't cut it with other than a stock system,and what do have ?

They are Bosch ultra premium opti-layer copper core 7mm.

Start from the start,you are adding too many factors into what is fairly simple process,firstly set your timing to a reasonable setting,then disconnect the linkage system from the carbs,run the air idles out around 2.5 turns,the uni-syn is not for this job,its for setting even vacuum on the throats via the airbleed screws so do that next,if ok work on getting the linkage even after reconnecting .
Report back.

Hey porschetub. I agree with you about adding too many factors, but there was no way the timing could be set because it ran so horrible, couldn't rev or hold an idle. After the jetting changes it runs well enough for the timing to be set. Now I can start a logical tuning sequence. I did disconnect the linkage, it's Tangerine's cable throttle system, one of the cables still had some drag and I think it didn't let the throttle close all the way, my bad.
2.5 turns out would not even run, I ended up starting at one turn out. From everything Iv'e read anything more than 1.5 turns out and the idles are too big.
I'm gunna give it another go this weekend.