Up north rider

After talking to driveline, I bought 23cc domes and it made such a huge difference! The cranking psi is now 140(cold). I know I should check it again warm just to make sure it’s not too high but I’m sure it’s pretty safe yet. I didn’t confirm the squish clearance yet either. .051-.055 is the green zone correct? Anyway I thought I’d say it’s running fantastic. I had no idea it would be such a drastic change. The cpi pipes that I have on there (I hate to admit it) kind of sucked for playing around and trail riding but now it seems to have way more mid torque. They almost feel like my old t5’s did but in addition to a lot more top end as well. I haven’t touched the jets yet but we’ll see. The thing rips!

I don’t even know what it means. smh

Lol

So correct me if I’m wrong. Uccr means uncorrected compression ratio?

It is the low port version as well

I’m wondering if I would gain any power from switching from my 24cc to 23 or 22cc domes on my 421 assassin. I don’t plan on running anything higher than pump gas. My cranking psi when I built the motor was around 120. Elevation I ride Is 600-1200 ft.

I made a jumper and did the test. I made sure it was running bad and plugged in the other cdi. Right away it ran great. I confirmed it by replacing it with my old one again. Cdi was the problem. Thanks

If I make a jumper. What do I do with the fifth wire on the cdi on the newer style plug? My old style plug only has four and four on each plug. The new style is four and five.

What do you guys think is wrong with this bike? I have a low rpm miss. It is not throttle position related. It will miss and stutter until it gets on pipe. You have to really work it to get it on pipe as well with the throttle and downshifting. It is also intermittent. It will run perfect for a bit and then it seems as it warms up you’ll hear a mis here and there until it completely misses for about the first half of the rpm range. So far things I have checked are: carbs cleaned (I think 5 times) I also swapped to stock carbs just in case and it still reacted the same even considering the jetting is probably off a decent bit swapped reeds to good working stock one’s I tested the ignition coil/caps. They were good. Just for kicks I swapped ignition coil/wires/caps from another good running machine with the same results I have a brand new OEM stator that I did verify is good with the multimeter and pick up coil gap is set to .020 I have a brand new OEM flywheel that has zero rattle Wiring harness is south Texas banshee looks good and well Leak down test showed Zero drop in pressure for the whole duration of the test (over 13 minutes) compression test showed 124 and 125 psi pipes have good tight oring seals The kill switch and key ignition are ruled out. (not that it would help just desperate lol) The Cdi is really my last thing It could be. My brothers banshees are new style plugs and mine are round old style. So I haven’t tried the swap. After the flywheel and stater setting me back over a 1k I’m hesitant to jump on a new cdi. Although my flywheel was bad so it wasn’t a total loss there. Any advice would be much appreciated!

Well I did the compression test wrong. I didn’t have the throttle open all the way. 126 and 123. I think my fear that I melted it down was misplaced. As you can probably see by now I’m frustrated with this tuning! I feel like I can blow some steam off by telling other people my problems! Sorry haha

Or maybe it makes sense to just get new cylinders considering the cost and wait time of plating. I’ve never done it before but I’ve heard it’s expensive and lengthy. What are the odds of the crank being smoked too? This sucks lol. Also to answer jerzoutlaw I was using 155, 158, 160, 165 mains so nothing crazy small there. But I suppose it only takes one size to small to melt it down, right?

Well, I think I figured out my problem. When I’d get to wot the engine wouldn’t sound smooth and would spin up fast and wouldn’t have as much power as before. So I did a compression test. 124 and 117psi are roughly my readings I’m getting. My engine is a 421 assassin with 24cc pump gas domes. I think I leaned it out with my jetting. The lower psi cylinder also had a torn exhaust o-ring. So multiple factors could have contributed. I didn’t put an hour meter on after I built it but I’d guess it has 20ish hours on it. Live and learn I guess. After I tear down the motor and see what’s wrong is it possible to just order pistons and rings for these nikasil cylinders or do I need them plated again?

Here’s where I’m at. I don’t have my new pilots in yet, but I decided to do a leak down test anyway and I had zero loss in psi. The gauge held solid for more than ten minutes. So that’s good, but I was adjusting the needles and mains last weekend and I had it running nice besides the hesitation near 1/4ish throttle. I took it out for a ride last night and it seems my progress is lost. It doesn’t run the same in the middle or wot. I don’t why I can’t jet this thing. Could this be an electrical problem? What would cause it run great one day and not the next? I’m not a carb expert but it can’t be this hard. Lol Thank you for all the help this far!

I think you are right. I might have been chasing my tail with the needles. I’m trying to set my air screws correctly based what I can get out of the forums. so correct me if I’m doing anything wrong. I purchased a sync tool from fast. I synced my carbs at idle and about an 1/8 throttle. Now to adjust the air screw am I’m supposed to supposed turn it counterclockwise (leaner) until I notice the bike start to build rpms kind of like it would be if you forgot the gas off. Then turn it clockwise(richer) about a 1/4 turn from there? Would that be correct procedure? Anyway, when I lean out the air screws there is zero noticeable difference in idle speed. I’m also blipping the throttle as I’m adjusting so it would adapt. So far I’m 3 turns and nothing has changed. Should I try 52 pilot jets?

So I bought genuine jjh needles to replace the knock off amazon ones. I started on the middle clip position. I was bogging and had lots of blue smoke. I knew I was rich so I kept going up the positions one by one and now I’m at the top again just like before. It’s okay the way it is but you definitely have to brake though a rough patch in the rpm range. It screams on top but mid is not so good. Especially went it gets warmer outside. I’m wondering if my foam filters and air box are choking it out a bit, and I should just switch to k&n clamp on filters. I realize my cpi pipes are a drag pipe but I would think I could at least get this midrange at little smoother. What do you guys think?