Hi Turbodan.
I tried to PM you but the page won't respond. Your bike sounds like a 175 and starts the same way.
That's how they should be at least.
Good informative clip.
I'll leave it at that .

 

It usually is one or two kicks cold or hot. Stuffed cases improve intake signal, starting is one time you really notice a difference. 

It would really kick ass with a proper pipe. The MX360 pipe is better than nothing but a modern pipe with a long, tapered header and fat midsection would be a substantial improvement.

Kudos on getting your bike running so well Turbodan. Would love to get mine running that good but some of the mods you've done are either over my skill set or would cost more than I'm willing to spend. I remember reading in another thread that you had tried all sorts of jetting changes and that none of that helped much. I'm getting ready to go up one size on the pilot jet, have one on order.

Right now it is has stock #50 in it and I'm going up only one size to a 52.5. I don't know if that's something you tried or not but thought I'd give it a go. My reasoning behind this swap is that the absolute worst surging I get is right after returning to a fully closed throttle position while still at speed. It seems odd that it will idle just fine with throttle closed while the bike is standing still but surges like a madman at the same throttle position while the bike is rolling. Too me is seems to be starving for fuel under those conditons, not sure why but think it might have something do with scavenging.

Trying to make sense of it but I do tend to over-think things sometimes. Anyway, at closed throttle the pilot pretty much runs things and though it's influence is reduced, still has a significant effect at part throttle and low cruiseing speed so thought it'd be a good place to start. I should say that I'm not really looking for perfection, just want to get rid of or at least dampen the surging thing. Othewise the bike starts easy enough, revs up through the gears fine, and has more power than an old fart like me needs anyway so not looking to make a race bike out of it or anything. Just wanting to get it running like I remember it ran, even if my memory is lieing to me.......

Wow. What a difference.

I remember that carburetion issue well.  I went up to a 60 pilot with the stock carb.  Raised the needle until it was choking on fuel.  It would be pig rich at idle and still so lean at a cruise that it would ping and surge.  Detonation was strong and sustained anywhere near or above 5000 RPM.  Doesn't make any sense, the same jetting circuits are in operation during these conditions and yet it is lean at a cruise and rich at idle.  You can make sure there are no air leaks, that's easy enough.  These will exacerbate the issue but even if you get it sealed up tight you won't eliminate it.

Enjoyed everyones videos that they posted here so I took another one of my stock DT360, it has a few thousand miles on the stock bore so try to ignore the piston rattle! 


"80% of carburetor problems are ignition related" is a phrase I think of when I think about the issues people have with their DT360s, capacitors cant last 40 years. I think the first step to getting a smooth running DT360 is to get a good strong ignition system from the likes of VAPE or REX. My bike above uses a Fireplug CDI box with a stock pulser coil, it works but you MUST make sure pulser measures 100-95 ohms at 75F room temp, the Vape and Rexs system replace this entirely.
Either way, anyone with issues I strongly suggest looking as close as you can into the ignition system.
My bike is stock otherwise and will cruise from low speed like 20mph up to 60mph with no bucking, surging, 4 stroking, or pinging. I was having these issues as shown in the last video I posted to this forum, then I replace ignition, now its smooth as ever.

Congratualtions on getting it running so great! And all stock other than the Fireplug CDI, is that correct?

I checked my pulser while I had everything apart and I can't remember exactly what it was but thinking it was right at 100 ohms or very close to it. I do remember feeling pretty happy about the test results, so the Fireplug might be an option for me if I can't get it sorted out with the smaller tweaks I've been experimenting with.

I was almost certain I'd read somewhere of at least one stock DT360 running great and yours is likely it. Actually thinking I read of a couple more that ran well stock, so there may be more out there. And sorry if people are tired of hearing this but I'll say it one more time, I'm almost certain my bike ran great before I parked it all those years ago, without any of the crazy bucking surging crap going on. Honestly don't see how I could not have noticed that or forgotten how bad it was. Either way, I'm going to keep piddling around with it and if everything else fails I may have to bite the bullet and buy the new CDI.

Part of my hesitation on buying one right now, (besides the cost) is that the bike runs so well under all conditions except at closed or low throttle when cruiseing. The only igniton related suspect that I'm thinking might cause this would be the auto advance system which I'm a bit fuzzy about but working at getting a better understanding of.

Thanks for posting the great video Akara! Good to know that there is at least one stock DT360 out there that doesn't get squirrely at steady speed or when getting off the throttle.

If the advance is wandering you can certainly check it with a timing light.  Anything is possible with vintage electronics, though I have the original CDI on my 1970 Kawasaki, working just as well as it ever did.  Had a few 78's with the original stuff running like a clock too.  Failure or erratic behavior is not assured due to age, but over time it does become increasingly likely.

Akara1 - bike sounds terrific, didn’t hear any four stroking, perhaps it’s your superb resto, throttle control and flat terrain?

turbodan - what mods would you recommend to a completely stock bike that runs perfectly shitty as designed like mine knowing that I love her as is?  The guts are solid and I have zero desire to mess with anything that’s internal cause it is all right and solid.  Reeds?  Carb?  Ignition?

Again I like my angry gal as is because despite all the drama she doesn’t knock no matter how hard or long or hot I ride her. So I am looking for an easy tweak or two to improve, no OC stuffing!

They're getting rare now, and I don't know whether or not fitment would cure Jack's and others' issues, but a common fix for the DT360A's somewhat temperamental cdi set up was to completely replace it with the points system from the same year DT250A. I guess that, nowadays, this might be as expensive as fitting a Rex or Vape system!