13B-RX3

Jetsrus sells the JJH for like $6 each. Sent from my SM-G965U using Tapatalk

The bike is an RD400 (air cooled) mild port, pipes, stock compression. Carbs are pwk 30mm (oko) needle is a GJH. When I originally started the bike I had 155 main jets. I put about 100 miles on the bike before I started running it hard. With the 155 it seemed very rich, didn't want to come on the pipe at all. 1 dropped down to a 150 and it got better but still wasn't 100% clean. Went to a 148 and it was clean and felt good. I put about another 300 miles on it, not running it too hard, while I dialed the needle in. Once it felt like everything was good, I wanted to make sure before I started adding timing. After the first plug chop I realized it was lean. I went up one size on the L and 2 on the R (150L, 152R) after I did another chop it seemed even leaner. I just got back from a third chop. I put 155 mains in just to see what would happen and it ran good. Didn't come on the pipe as violently but seemed like it pulled harder. I'm guessing it's still a little lean, but y'all have way more experience at this than me. I don't know why it wouldn't run before with the 155mj but does now. Either the rings weren't seated or the needle was way off to begin with (JJH). it seems like it's responding to a jet change now, so if it's still lean I'll order some more jets. Sorry if I'm talking in circles. Any advise would be greatly appreciated! Sent from my SM-G965U using Tapatalk

A little better pic Sent from my SM-G965U using Tapatalk

Photos didn't load Sent from my SM-G965U using Tapatalk

Last weekend I did a plug chop to verify jetting, these are the plugs. L&R were at full throttle, through the gears to the top of 5th (102mph). 3/8 was through the gears at 3/8 throttle for about a mile, and 3/4 was through the gears at 3/4 throttle, for a mile as well. Both 3/8 and 3/4 were only done on the left cylinder. IMO both the right and left cylinders looked lean at full throttle, the right more so than the left. I went up one main size on the left and two on the right. It also looked lean at 3/8, compared to 3/4. I went one taper shallower and dropped a clip on the needle. Picked up a little low end and dropped a little top end (seat of the pants) as expected by me. This weekend I wanted to get another plug chop in just for giggles. Everything was done the same other than the location and it appears to be leaner everywhere, even though I had richened 3/8 and full throttle. For the first test it was 77f and today it was 80f. I don't understand why it seems like I'm getting the opposite results of what I'm expecting. The only thing I can think of is that I did the chop today after a longer ride to warm it up. Maybe it was a little hot, I did notice a small amount of boiling in the fuel lines. The first pic is from the previous weekend and the rest were from this weekend. Oh, p.s. Let's pretend that this is an air cooled Yamaha twin [emoji16] Sent from my SM-G965U using Tapatalk

Good to know. The RDs suffer from the same flat spot.

Definitely not prepared for a rebuild! I was thinking that it wouldn't be a bad idea to run a little less timing in the 4000-5000 range than the maps that have been posted. When cruising that is primarily the rpm range i will be at and possibly could build excessive heat over time. On your original post, you mentioned the flat spot. I'm assuming you are talking about the flat spot at 5000rpm?

Thank you! I'm starting to see a pattern. Apparently they aren't very prone to detonation in the 3500-5500 range. I'm guessing that 8500-10000 is the area that you don't want to get carried away in. With the points i was running flat 17 degrees and i didn't get any evidence of detonation . So i theory, within reason, as long as i keep the top end below 17ish, i should be safe for now? Thanks everyone for the input!

The ignition was $170ish. My bike was originally point ignition so i had to buy coils, pickups, rotor, etc. I spent right at $300 on my conversion. Worth every penny IMO. Lots of features!

Thanks everyone. I don't want to get too far off topic. After all i didn't start this thread. Maybe I'll start another thread for all my toys. To get it back on track, here is a video of the ignition working with the banshee map.

I don't actually know, we blew up the transmission on the dyno. Going off the weight of the car and the trap speed, it's just shy of 1000rwhp.

Here you go. And the inside view. That was a horrible pass, spun so bad the shift light didn't go out on the shift. trapped 173mph

Sorry, wrong map. This is the one Sent from my SM-G965U using Tapatalk

Perfect, thank you! Blue line is the map i'm leaning towards, red is stock banshee +2 from 0-2000. Any suggestions, advise? Sent from my SM-G965U using Tapatalk

I cant figure out how to post a picture, but the map i was leaning towards would be the equivalent to a banshee map that was +2 from 0-2000, +7 from 2000-5500, +4 from 6000-9000, then back to +0 at 10000. Interestingly enough, that map is very similar to an 84 RZ350 map except for -3 from 6000-9000. The RZ map is much more aggressive. I wonder if it's because of the PV? Yes it is. That's the weapon i choose if i really want to roll my socks up and down.

Thank you for the reply. Exactly the kind of info i was looking for. Trying to learn more theory than specifics. The bike is actually an RD400. Similar to a banshee but nobody has done much with ignition, other than bolt on an off the shelf ignition with limited to no adjustability. I'm running a Ignitech ignition and have limitless control over the timing map. Looking at other "similar" engines, the timing curve varies drastically. From banshees, rz350, tz250s, rd500s, etc. They all go about it differently. I like the look of he Dynatek curves. I'n my mind, it makes more sense to not pull timing until the bike comes on the pipe, but all of the maps i have looked at peak at 3500rpm. I am trust trying to learn where it is safe to add timing and what areas i should avoid.

What would an ideal curve look like? I recently bought an aftermarket programmable ignition for my "bike". I realize every combination is different and i would have to rent a dyno to get it perfect, bu that's not in the cards currently. As of right now i have a stock banshee timing curve loaded, but i can change it however i want. I am not vary familiar with 2 stroke timing theory and just need a little guidance.