Deepinnaharta Depression: JiangWayne's 26mm ExpChmbr Pipe

[Wheelman-111]

Greetings:

I'm running an 8. Installing a brand-new one this evening didn't change the 2-minute cold symptom. You may be correct about the need to jet up a size. Trouble is my 150 was my biggest. Fortunately Mikuni jets are easy to obtain.

[808BMW]

I had to up both pilot and main compared to my v8 tune. Weights are at 30g if memory serves me, but my trans is different so it may be a moot point.

[Wheelman-111]

Greetings:

Now y'see? This is why I love this place so much. I was about to hunt for a 155-160 main jet, but it probably would've taken me a month to figure out that I need to reinstall my bigger pilot. Thanks, dawgs!

[Wheelman-111]

Greetings:

Honda-san can order Mikuni jets in the needed sizes - all the way up to 175. Unfortunately thay have to order them in 4-packs. Curses! Anybody need Mikuni jets? I'll have 155, 160 and 165 for mere pennies a pop. They look awfully similar to the Arreche ones I have, too.

[bakaracer]

arreche carbs uses mikuni main jets.

[Wheelman-111]

Greetings:

I forgot who wanted the spare Mikuni jets! The 165s came in today. I expect the 155-160 later in the week. I'll try the big jump from 150 to 165 just to see if it's too much. The Pilot jets from Mikuni are very different from the Arreche pilots, but the main jets are indeed identical. Thanks again Bakaracer. Funny that the Arreche 17.5mm ran mains in the 100-110 range but the Mikuni TM24 requires 150+ in this application.

[Wheelman-111]

Greetings:

Screwed in the 165 (only one of 3 that arrived) and re-installed the 15 pilot that was too big for year V8 exhaust. It wasn't quite as cold as it's been, so another variable. Warmup was easier needed less choke time. Did need to readjust the air screw out a little. I moved the needle clip back to the middle.



Power was stronger, but a bit fussy at part-throttle. Not too much smoke. Temps never got above 300 - was 350 before. Plug no longer white, but not enough cook time to tell.

The weird sound at WOT was gone. Something tells me it's a good thing it's been cold or I would have seized the bore. It was pretty lean with the 150 main jet

I'll decide if I need to try the 160 when it arrives. Thanks for the heads-up, Bakaracer.

[bakaracer]

I'm glad to help. what is it doing at part throttle?

[Wheelman-111]

Greetings:

Quoth Bakaracer:

what is it doing at part throttle?

Nothing real bad... in certain positions the engine seems to hunt for RPMs up and down a little. It's resolved by cracking it open a little more. I may need to move the needle clip up a little more with this big jet. At WOT it pulls well past 9500 now without the Wa-wa-Wa-wa. I can't wait for a chance for another GPS run!

[elitedio]

While you had the stinger off the pipe I would bury it into the fat part of the chamber(obviously using a new section of pipe). It will really help with noise and not hurt the power. Now to read the last three pages of posts.

I have mig welded stainless with my normal gas and wire.

[Wheelman-111]

Greetings:

Quoth the Esteemed EliteDio:

While you had the stinger off the pipe I would bury it into the fat part of the chamber(obviously using a new section of pipe). It will really help with noise and not hurt the power.

Not sure what you mean there, pard. Remember I have absolutely no skill with Molten Metal, other than to set stuff on fire.

Oh, and who needs Mikuni jets? 155-160-165 for $10 a set. Fits Arreche and ?? too.

[Wheelman-111]

Greetings:

Tonight I rectified another nagging issue with the JW 26mm chamber. The header flange couldn't be centered over the port due to the welded-on spacers at the engine mount bracket. II didn't want to risk cracking the flange by ham-fisted leverage, but I was in a hurry to install it at first, so I left it a little off-center.

However I know the importance of air flow at stratospheric RPM, so tonight I used trusty Roto-Zip cutoff wheel to separate the spot welds, then reamed out the holes in the needed down-and-forward direction. I slipped the intact spacers back behind the bracket, and the oval holes now left enough slack to install the pipe with the flange dead-center.

In the process, I swapped the aftermarket Ruckus variator's ramp plate for a sharply-angled SEF item.

Testing around the block revealed a markedly-increased RPM due I believe to the steeper slope those 5.6-gram rollers now have to negotiate. It had been pulling 8500-9100 with the other plate. How high it goes now I cannot say. CURSE the Early Darkness and non-illuminated Tiny-Tach!!

The Good News was that the exhaust seemed to support the higher revs. The Bad News is that I may have to richen the main back to 165 from 160. (I did richen the needle up a click, solving the cold-blooded issue from this morning.) What say you?

[Wheelman-111]

Greetings:

I didn't get to whack it open and keep it there for long, but acceptable performance returned even during the warm-up thanks to raising the needle to one click below full-rich. Still 160 main. Speeds on Deepinnaharta freeway easily buried speedo needle, which I have determined = 55+. How much + I can't say, but all the heart was back. I should start packing GPS every day.

It turns out that RPM wasn't as high as I thought, but higher than with the flatter ramp plate that came with the Ruckus Aftermarket Vario, which was flat like a saucer. The SEF is decidedly more like a bowl. RPMs at WOT from cruise speed slowly rose from 8800 to 9100 when I had to let off for traffic. Those figures were 8100-8500 before. Still lower revs than I was seeing with the Polini-for-Dio variator with these same 5.6-gram weights, however.

[elitedio]

I am always impressed with the amount of work that you put into your scooter Wheelman. I envy your weather.

Why don't you just add in a bicycle speedometer? They can be calibrated to within one part per 1000.

I think that a lot of running issues that you are encountering are do to and air density changes. Putting an expansion chamber on an engine really demands a lot more accuracy in jetting than the box exhaust that they come with. I bet if you were to compensate for air density on each ride you would not have as much fluctuation. Myself, I just keep it rich enough to keep itself from burning up.

I bet the guys in Hawaii don't have to deal with as much fluctuation in jetting requirements as we do in the middle of the country.

Keep ringdinging.

[Wheelman-111]

Greetings:

I thank you for your kind comments, means a lot coming from you, O Grand Master of the Dark Chamber Arts. Wish I could weld... Scooter Tunage keeps my few remaining synapses entertained. I'm sure you're right about the hyper-sensitivity to air temps. (and humidity, and barometric pressure...) Tuning a shade rich sure cures most of these symptoms. After April or so we can count on low 80s in the AM, High 90s riding home.

I don't know why I've put off installing a bike speedometer. Being also a road bike enthusiast, I may even have a castoff or two lying around. I'm partial to the wireless variety now, but not sure how the engine electrical field would affect readings. My current Cateye won't even record from tha back wheel on my Cannondale. Most of my bike speedos can be calibrated almost to the Cm. (one ten-thousandth!) You put a paint dot on a tire, roll it out and measure the distance, punch it into the head unit. Won't predict tire growth at speed, however. \

One certain disadvantage is the lack of night lighting, which is already a source of frustration with the TinyTach. At least my GPS lights up.