dr. occa <-------------what the hell is this popping?

[4agshoob]

its in the exhaust , the stoitch reads rich at idle , but goes ideal on revs and holds strait while cruising down the road.....what is that popping (0:49)? possible burnt valve?(again at 1:25)


edit* test drove it, and it goes strait to lean while accelerating , till i get to top end then it balances out. wtf?

[CBR_TOY]

motor looks awesome.... also, i know nothing about carbs ha ha

[4agshoob]

lmao...and thanks =]

ok , so after a few more runs i did notice that it only leans out between 1/8 throttle and 1/2 throttle. according to the link i posted on the carb essentials thread page here on this forum , the needle valves and slides control this area , so tomorrow im gonna raise the needles 1 height and see if it helps. because at WOT top end the thing screams , and runs right at ideal, and rich at idle , also rich while rolling idle , but as soon as i start to get into it , it bogs and goes to lean , if i step down on it , it picks up and goes away, so assumption is needles need to be backed out a bit, am i correct?

[dr.occa]

If it bogs at initial acceleration, it could be lean bog. You can try opening the needles but I'm not sure that will solve your transition from idle circuit to main circuit.

The popping sounds like it could be timing. Have you gotten your timing adjusted properly/ideal for your setup? How much advance are you running at idle and what fuel grade are you running?

Are the carbs outfitted with accelerator pump jets?

[4agshoob]

yes on accelerator pump jets.

timing is still locked out at 32 degrees advanced. the controller should be here any day now.

im running 87 octane , should i be running more? its only a stock bigport right now, i wont be swapping the head for another week or 2.

[mooreofit]

doesnt sound to bad justin. good luck with the bugs.

[dr.occa]

yes on accelerator pump jets.

timing is still locked out at 32 degrees advanced. the controller should be here any day now.

im running 87 octane , should i be running more? its only a stock bigport right now, i wont be swapping the head for another week or 2.

What size are the acc. pump jets?

Also, don't fret too much on the rich lean mixture at the moment. Speaking from experience: without a proper timing curve you're not going to get the air fuel mixture right from idle>acceleration to wot. You can't unless you have on the fly fuel modulating otherwise known as fuel injection . And even then, it won't be idle without proper timing.

[mooreofit]

p.s. i thought that that popping was a lean issue. at least i thought i read that on the megamanual a few years back when tuning my megasquirt.

also my car did not like a stoich afr at idle. it would run like crap and die.it liked the afr in the 12's. also dont tune for an afr at idle tune for the highest manifold vacuum reading you can achieve.

[Clos]

if it's easy, you could check your idle/main jets see if something fromt he gas got in there and clogged them, i had that on my bike, started popping and would run right, pulled off carbs, pulled jets out, dipped in carb cleaner bucket, and voila. vroom vroom. are the carbs sync'd? (if your running 2/4 carbs.)

[4agshoob]

yes , carbs are synched. i read on a few bike forums that the cvk factory mix screw setting was 3 turns out , i have mine now at 3.5. in the vid they were 2.5 out. also in the vid , the needle depth for the slides were clipped at the third position down , i moved them to the 4th position down (in turn meaning jet needle pulls out further, earlier = more fuel). now i can accelerate fully and it stays a step into "rich" , or high "ideal" (sunpro led guage, and bosch 1 wire sensor).

the only time it goes over to lean, is exactly at 1/8th throttle, and it goes so lean it goes off the gauge. but i can say it doesnt bog now like before ,theres just a little blip in that one section of throttle , and i think dr. occa is right , its just wierd spot in the timing/fuel ratio.

as for the pump jets, im lost. hell im not even sure it has accelerator pumps. im not sure if it was for the model i have or not, ill look more into it.

as for lean alan , its only doing it on one cylinder , i did catch that , but ever since i pulled them off and reset the screws, and needles, its dissapeared. so im assuming i had one carb leaner than the rest. and again i am running on locked out timing.

clos-i just cleaned them before install, and i have dual filters on the line, one between the tank and pump , back in the rear , and another right before the FPR.

i got some goodies in the mail today to throw in the glove box with the 6-al......probably install it tomorrow.



ill post some detail pics , or "timeline" in the appropriate area.

[Clos]

awesomeness,

[mooreofit]

good stuff man hope this fixes the issue.

[dr.occa]

After you can get some proper timing thrown at it it should help give you a better picture of how the motor's running and where it needs attention.

[4agshoob]

yep its showing lean in multiple areas now , and spits out the carbs every now and then , addressing this issue tomorrow.

[4agshoob]

okay, so the keihins have #35 pilots, and had #150 mains. i was still running out of juice past 5k rpms. so i backed the slide needles out to their lowest slot , and still didnt have enough juice past 5500.

so did some toying and found that the mikunis main jets are for the the most part interchangable with the keihins. since the previous owners had drilled the mikuni mains out to #215-ish, i figured it was worth a shot. i swapped out the jets , and dropped the needles to the 3rd clip position (theres 6), and reset all the set screws back to 3 turns out.

on 1/4 throttle blips , it would lean a little and spit out of the carbs. so i backed each mix screw out an additional 1/4 turn.

OMG!! the car pulls so freaking hard all the way to 6500 rpm's. mid range torque is way better than my EFI big port in the coupe , and it has all that head work. 2nd gear, about 40 mph, blip the throttle a few times , and your sideways , with plenty of power to keep it there. the car runs very strong!! i think alot may also have to do with the MSD advance controller as well.....so i cant wait to see how its gonna perform when i swap the worked head from the big port in the coupe onto this engine. raised compression , better flow, and cams oh my!

but......i cant get it away from this rich idle. the transitioning spot between pilot jets, and needle slides is inevitable which tells me the tuning is dead on. if i go to smaller pilots ill be back at the same 1/4 throttle lean problem. i dont mind the rich idle.....it just takes about 20-30 seconds of steady cranking to get the motor to turn over, and to start firing, and turning under its own power, and unfortunatly the way the choke on the these keihins work , they dump fuel instead of restricting it. so i have to figure out a way too, lean it up upon cranking while the motor is warm.

any suggestions?

btw, i have the intake cam retarded 4 degrees.....