Author Topic: Overflow tubes  (Read 9280 times)

Offline bikerterp

  • Newbie
  • *
  • Posts: 5
Overflow tubes
« on: June 18, 2011, 10:29:31 PM »
Hi all,

Picked up my 2000 a week ago.  Rode it home from the PO about 450 miles and found that I was only doing about 4000 rpms at about 70 mph.

Even though the PO didnt tell me about it... I'm guessing he probably didn't know, he wasn't the original owner...I'm guessing there was a 7th gear mod done on the bike.  Can anybody confirm this suspicion?

It also got me thinking about what else may have been done.  How would I be able to tell if overflow tubes were installed?  Is there an easy way without tearing everything apart?

Thanks for any insight you may have.

 

Offline George R. Young

  • Moderator
  • Full Member
  • *****
  • Posts: 624
  • Country: ca
    • Concours 2001 Farkles
Re: Overflow tubes
« Reply #1 on: June 18, 2011, 11:07:07 PM »
It's fairly easy to remove the float bowl from an outside carb without having to take the carbs off the engine.
65 CB160 (67-69), 69 350GTR (69-72), 72 R5, 73 RD350 (73-84), 82 XZ550 Vision (84-03), 01 Concours C10 (03-19), 89 EX250 (11-14), 00 SV650S (14-16), 03 SV650S (19-)

Offline timmerz

  • Full Member
  • ***
  • Posts: 151
Re: Overflow tubes
« Reply #2 on: June 18, 2011, 11:27:08 PM »
My '91 is stock and says about 4k at 70 also...it's speedo error, really doing 63 or 64 mph...in order to get a real 70 mph (gps proven) I need 4200 rpm...

Offline bikerterp

  • Newbie
  • *
  • Posts: 5
Re: Overflow tubes
« Reply #3 on: June 18, 2011, 11:29:59 PM »
Well, some of us are more gifted in the ways of the wrench than others, lol.  I was hoping for an easier, more visual way without having to pick up a screwdriver.  Guess I'll have to get my fingernails dirty, lol.

Offline syntor

  • Jr. Member
  • **
  • Posts: 46
  • Country: 00
Re: Overflow tubes
« Reply #4 on: June 19, 2011, 01:29:18 AM »


  How would I be able to tell if overflow tubes were installed?  Is there an easy way without tearing everything apart?


Just get a piece of plastic tube, put one end over the drain nipple on the carb bowl, and the other end in your mouth.

Blow down the tube, all will be revealed.

Offline Steve in Sunny Fla

  • Full Member
  • ***
  • Posts: 1123
  • Country: 00
    • Shoodaben Engineering
Re: Overflow tubes
« Reply #5 on: June 19, 2011, 07:22:54 AM »
 I was gonna say the same thing syntor said - he beat me to it! if it has overflows, the air you blow will go right into the bowl unimpeded.

  I guess I need to get on the "sticker" thing so folks with 7th gears can ID them  - i'm thinking a big 7 inside a gear, stuck on the round part of the 7th gear unit?

 Bikerterp, take the bike out with a gps and run 80 mph. with the 7th gear you should be around 4400 rpm. HTH, Steve
« Last Edit: June 20, 2011, 04:04:31 AM by Steve in Sunny Fla »

Offline anycleavers

  • Jr. Member
  • **
  • Posts: 84
  • Country: us
Re: Overflow tubes
« Reply #6 on: June 19, 2011, 02:38:03 PM »
On my '97, at exactly 4000rpm my speed reads 66mph, flat highway.
"Always take the long way home."

Offline mach1charlie

  • Jr. Member
  • **
  • Posts: 45
  • Country: 00
  • Lone Wolf... No Club
Re: Overflow tubes
« Reply #7 on: June 19, 2011, 02:52:21 PM »
Could be "gold wing' size tires?
Real men have tire irons, and use them.

Charlie

Offline bikerterp

  • Newbie
  • *
  • Posts: 5
Re: Overflow tubes
« Reply #8 on: June 19, 2011, 03:16:31 PM »
Thanks all, I'll give those things a look.

Offline Nosmo

  • Full Member
  • ***
  • Posts: 254
  • Country: us
  • "We're all in this together." - Red Green
Re: Overflow tubes
« Reply #9 on: June 19, 2011, 09:30:58 PM »
I have Steve's aforementioned "7th fear" mod (nice Freudian slip, by the way, Steve), and the "Wing-size" Michelin Pilot GT's and my bike shows 3520 RPM at 65 MPH (indicated) in 6th gear.  Before the mod it showed 4000 even at that speed. Steve's GPS method should be more accurate, it will correct for all that tire, speedo, tach error.
A life undreamed is a waste.  A dream unlived is a sin.

Offline SteveJ.

  • Arena
  • Full Member
  • ***
  • Posts: 806
  • Country: us
Re: Overflow tubes
« Reply #10 on: June 20, 2011, 01:31:18 PM »
Nosmo, I like yer sig line. :thumbs:
Perfection Is A Fantasy, Improvement Is Possible(Margie J)
America's Seaplane City
'99 Conk: 234k mi, '98 KLR650, both gone, '15 Versys 650LT: 74k mi
COG 5603, IBA 19921, CBMMA 50 (Cheap B@st@rds Motorcycle Maintenance Assoc, 18 year member)

Offline syntor

  • Jr. Member
  • **
  • Posts: 46
  • Country: 00
Re: Overflow tubes
« Reply #11 on: June 24, 2011, 04:24:19 PM »
Here's a question for those of us with overflow tubes.  :)

Why do we also need the carb vent tubes, you know the ones that have a clear plastic tube that comes up and over the top of the chassis?

I can't see any reason not to remove the plastic tube and just cap it at the carb.
After all, the carb will now vent out the overflow tube.

Offline Daytona_Mike

  • Arena
  • Full Member
  • ***
  • Posts: 825
  • Country: us
Re: Overflow tubes
« Reply #12 on: June 24, 2011, 09:00:22 PM »
Here's a question for those of us with overflow tubes.  :)

Why do we also need the carb vent tubes, you know the ones that have a clear plastic tube that comes up and over the top of the chassis?

I can't see any reason not to remove the plastic tube and just cap it at the carb.
After all, the carb will now vent out the overflow tube.
No it wont. The over flow tubes are way to tiny to effectively vent air. Just look at the size of the vent tubes. Over tubes are meant for liquid.
If you still have fuel in the tank, you are not lost yet
Most motorcycle problems are caused by the nut that connects the handlebars to the saddle

Offline George R. Young

  • Moderator
  • Full Member
  • *****
  • Posts: 624
  • Country: ca
    • Concours 2001 Farkles
Re: Overflow tubes
« Reply #13 on: June 25, 2011, 01:39:17 PM »
I found the bike harder to start after installing overflow tubes, I think because the more volatile gas vapour stuff ran out the bottom. Anyway, I now have overflow tubes, with external drain tubes attached to the bowl nipples, with a turn up at the end, and a couple of drops of oil in there to seal them. Then the stock vent tubes are needed to allow air in. And it is easier to start.
65 CB160 (67-69), 69 350GTR (69-72), 72 R5, 73 RD350 (73-84), 82 XZ550 Vision (84-03), 01 Concours C10 (03-19), 89 EX250 (11-14), 00 SV650S (14-16), 03 SV650S (19-)

Offline medicevans

  • Full Member
  • ***
  • Posts: 137
Re: Overflow tubes
« Reply #14 on: June 27, 2011, 04:31:45 PM »
Me too George. Mine wouldn't start unless I flipped it to prime for a couple of seconds first. Made a loop in the rubber overflow hose and put a couple drops of oil at the bottom of the loop and no more "no/slow start" problems.

Offline snarf

  • Arena
  • Full Member
  • ***
  • Posts: 827
  • Country: 00
Re: Overflow tubes
« Reply #15 on: June 27, 2011, 06:12:03 PM »
My 86 is a good 10 mph off.70 is almost exactly 4k.
2002 Conc
1986 Conc "The spirit of COG"

"We did not become the men that we are because we were Sailors, soldiers or cops; we became Sailors, soldiers and cops because of the men we are."

Offline Gitbox

  • Full Member
  • ***
  • Posts: 143
  • Country: us
Re: Overflow tubes
« Reply #16 on: June 30, 2011, 07:35:43 PM »
Heck, I'll chime in: my 2000 has Steve's 7th gear and the speedo does indeed read 80mph at 4400rpm.
2008 Yamaha FJR1300A
2004 Yamaha FJR1300 (sold)
2000 Kawasaki Concours ZG-1000 (sold)