Well, I think I know what my problem is, but I wouldn't mind some confirmations of my suspicions...

I read Doc_V's post today about throttle lag, and that described EXACTLY what I've been having for the past couple days since I did all my intake work. Let me start with the recent work.

I was running very rich and couldn't get past 35 MPG to save my life. With the choke on, the smell of raw gas was overwhelming. Plugs in the front jug were black, back jug were good. They are Iridiums with maybe 500 miles on them. The jetting WAS:

DJ 190 Main
37.5 pilot
DJ needle, clip on 4 from blunt end
PMS out 3

So, to fix my problems, last weekend I did the following:

Rejetted carb (again)
Ported manifold (again)
lapped/resurfaced manifold flanges & sealed with original OEM o-rings and Hylomar
brand new tight vacuum cap & silicone on nipple on top of manifold
Changed jetting to my previous settings:

DJ 175 Main
35 pilot
DJ needle, clip on 3.5 from blunt end (3rd clip w/ two washers)
PMS 2.5 out

After all the work, it started much easier, but I was getting occasional pops/farts through the carb and consistent hesitation & lurching when just barely rolling off a closed throttle...maybe 1/8th of a twist. Bike was fully warmed and choke off. More throttle made everything go away except for a very sporadic carb pop. Now what I tried was pulling the choke out to the first click when I was holding the throttle in that problem area just off closed. It was like a jet assist when the choke hit the first click...the bike pulled forward with more power, the uneven engine sound smoothed out, and it ran GREAT. Throttle was responsive, no hesitation, no nothing. Push the choke back in and the exhaust tone got slightly raspier again and the hesitation & pops come back.

OK, so at this point I'm thinking I'm lean on the PMS/idle circuit...

So then I turn the PMS out to 3 turns. A little better, but not much. So I turn it out to 3.5. A little better again, but not good. SO I get home tonight and hop off the bike, left it idling, walked into the garage and got my starting fluid spray and sprayed one side of the manifold and the engine dropped way down in RPM and almost died. So I spray the other manifold/jug mating surface...again the RPMs drop and the engine almost quits.

SO NOW it seems to me that maybe my o-rings shouldn't have been reused, because it sounds to me like I've got a bad vacuum leak. Don't know if it makes a difference, but when I sprayed the starter spray on the manifold I did it from the fuel pump side (I'm pumpless) and it's a wide spray (straw doesn't fit). I don't know if some of the spray could have gotten into the carb throat from the back side, but the air cleaner was on so I'm thinking not...

OK, so...thoughts? Does it seem my reasoning is sound? Did I miss something here? Just want some feedback before I rip it all apart tomorrow and redo it all with the oversize o-rings...I know some have had problems with those, but I've got 4 new ones to try and no way to get OEM o-rings any time soon.

Thanks in advance,

RK

Hey RK ,
Looks like you are headed in the right direction. You Won't get to the bottom of the carb issue until after all the leaks are resolved.If it dropped enough to nearly die from spraying it from the left side of the bike , chances are it's a legit vacuum leak. Personally , I never reused the original o-rings , I used the fatter ones from Napa (can't recall the part #) and that always sealed it up tight. Once you have that resolved , tweeking the carb will yield the results you're looking for. BB

Big Bear wrote:
Hey RK ,
Looks like you are headed in the right direction. You Won't get to the bottom of the carb issue until after all the leaks are resolved.If it dropped enough to nearly die from spraying it from the left side of the bike , chances are it's a legit vacuum leak. Personally , I never reused the original o-rings , I used the fatter ones from Napa (can't recall the part #) and that always sealed it up tight. Once you have that resolved , tweeking the carb will yield the results you're looking for. BB

Thanks, BB...that's kinda what I thought....stupid o-rings...stupid me.

Hey, and it's good to see you around once in a while!

RK

Hmmm, surprised the hymalar didn't seal it?? Oh well, ca-ca happens. When you do the reinstall, make sure each screw seats to the flange by hand, don't let 1 screw bind at all, might have to jiggle the manifold a bit if 1 does. Once they are all in, then in a criss-cross pattern tighten 1/4 turn at a time. I know, a pain to do 1/4 turn, but it helps to ensure that nothing gets out of skew.

and the DJ175 is kind of on the small size, better to have a 167.5 or 170 Mikuni, or it's DJ equivalent which is closer to a 180 or 183? Guess you can look at the conversion chart in the tech article section

Also use flat washers on the bolts to spread the torque over a wider area.

Keep us posted. I'd be interested to hear what you find. I bought the starting fluid to test mine, but when I found the loose connection, I figured that was it and took the stuff back. May need to try that after all.

Good luck.

Erbman02 wrote:
Hmmm, surprised the hymalar didn't seal it?? Oh well, ca-ca happens. When you do the reinstall, make sure each screw seats to the flange by hand, don't let 1 screw bind at all, might have to jiggle the manifold a bit if 1 does. Once they are all in, then in a criss-cross pattern tighten 1/4 turn at a time. I know, a pain to do 1/4 turn, but it helps to ensure that nothing gets out of skew.

and the DJ175 is kind of on the small size, better to have a 167.5 or 170 Mikuni, or it's DJ equivalent which is closer to a 180 or 183? Guess you can look at the conversion chart in the tech article section

Erb--

I'm surprised it didn't seal, too, because that's exactly how I did it...finger tight on all 4, criss-cross tighten, then torque to 10 lbs. Unfortunately, the next size up in DJ jet I have is the 190, which is equivalent to about a Mikuni 179...big, but still smaller than stock.

Now, I do also have the leftover parts laying around of a jet kit that came with a Hypercharger, and the needle in it is brand new...is that a Baron's/Mikuni needle, for all intents & purposes? I could put it in and I could try to find some Mikuni jets at a local cycle shop. I'm not sure how many different thread sizes and variations there are in Mikuni jets...would I just ask for a 170 jet for a CV40?

Thanks,

RK

Mikuni main jets are all the same , the round head with screwdriver slot in them. You should be able to get exactly what you want from any reliable bike shop. BB

RK,if your current/newest carb setup still has the slight lean cond you describe after you get inatke sealed up then try this.

Put pms out to 2.75-3 turns from light seat,then remove 1 thin washer and the move needle clip to the 4th slot from top/blint end . That should effectively get you an additonal .5 step more rich going from your current 3.5 with 2 thin washers to 4th slot with 1 washer.

I had similar lean situation comming off idle & when crusing at low speed/in low throttle position and doing that fixed it.

That was at 5k miles and 10k miles later its till running great in all throttle postions and comming off ilde too. I maybe get 1-2max carb spits comming off idle from a stoplight when riding all day long which i think is pretty normal/tollerable for your avg lrg old school air cooled carb's v-twin.

In mixed riding cond in hilly areas riding 2 up/bags loaded/tall windscreen/31T pulley i consistantly get 38-38.5mpg & on open road crusing at 65-68mph (70mph at times) riding 2up get approx 40-40.5mpg.

Scott

Big Bear wrote:
Hey RK ,
Looks like you are headed in the right direction. You Won't get to the bottom of the carb issue until after all the leaks are resolved.If it dropped enough to nearly die from spraying it from the left side of the bike , chances are it's a legit vacuum leak. Personally , I never reused the original o-rings , I used the fatter ones from Napa (can't recall the part #) and that always sealed it up tight. Once you have that resolved , tweeking the carb will yield the results you're looking for. BB
=====================

Heres what i found (pasted below) in a post here in RSC on aftermarket replacement intake seal pt#'s.

Scott

======================



54.0 x 2.5mm or 2 1/8 X 1 15/16 X 3/32

Federal-Mogul Oil Seals #135, 136 is the number for oversize O-rings. 135 is the stock size.

NAPA#: BK 7272136

Attributes: Material:Buna-N-Nitrile Dimensions:2" I.D. x 2-3/16" O.D. x 3/32" W Contents:5 O-Rings

NAPA may or may not have them.

You can order them - http://www.allorings.com

You want to get the Viton material and 136 size.

If you have a John Deere dealer near you - U42111

Don't use the Ace Hardware ones they melt from the heat even though they seal.

You'll need a Dremel to grind out the little nubs in the O ring chanel.