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Author Topic: '75 Yamaha XS500 Cafe Project - Open Throttle  (Read 94558 times)

Offline JRK5892

  • Posts: 9755
    • The Powder Pro
what you think i can do about it? you think that gettin rid of the V stacks will work?

here is a shot of her out yesterday with the wife on her fighter... made it a few miles!
Joe
"your life is an occasion, Stand up to it"
www.thepowderpro.com

recent builds: Hd street bob, TX cafe, KZ bratt, Goldwing tour, bratt wing, st fighter, road king, vriago bobber, chop, FXD, 1200 sporty, 1200xl sporty, GSXR, Royal enfield.. and more

Offline SrgtBear

  • Posts: 843
  • The arsenic has oddly shaped feet...
Do you only start having problems when the engine gets fully warmed up?

« Last Edit: Jul 19, 2010, 18:48:33 by SrgtBear »
Ted

Kawasaki Kaiju (怪獣) - 79 KZ650 - 700cc Bore Cam Rocket - http://www.dotheton.com/forum/index.php?topic=39748.0
75 Yamaha XS500B Cafe - Completed - http://www.dotheton.com/forum/index.php?topic=14392.0
74 Honda XL 125 - Original - http://www.dotheton.com/forum/index.php?topic=25706.0

Offline JRK5892

  • Posts: 9755
    • The Powder Pro
nope cold, warm, midway... just all though the range, tried over 5 diff jets, i refuse to change my exhaust (it sounds wicked and i got to much time into making it) but i will put on the stock air box if i have to! this thing is driving me nuts that it looks so sick and i can not ride it! just blows!
Joe
"your life is an occasion, Stand up to it"
www.thepowderpro.com

recent builds: Hd street bob, TX cafe, KZ bratt, Goldwing tour, bratt wing, st fighter, road king, vriago bobber, chop, FXD, 1200 sporty, 1200xl sporty, GSXR, Royal enfield.. and more

Offline Swagger

  • DTT SUPPORTER
  • *
  • Posts: 5513
  • Putting boot to ass since 1967!
Srgt: Meant to say before: That plating looks outstanding, really takes the engine u pa notch or two!

Joe: Best thing you could do.....
1) add some length to the exhaust. It'll help, trust me.....plus by adding some length you can probably get rid of some/all of your back pressure by removing the lolipop.

2a) VM30 carbs. You cna get'm pretty cheap and there's enough info out there that getting them jetted is pretty easy. Hell, grab yourself a couple dial-a-jets and have external control! This really is the best long term solution, the vacuum carbs just suck in an open flowing system

2b) Put your stock airbox back on. I know it sucks but htis will at least allow the carbs to work as designed. There will be enough restriction on the inlet to allow the vacuum from the engine to properly operate the slide. 

2c) you can try drilling out the little 'vent' hole in the slide to help it work a little better with less vacuum. The old Dynojet kits used to include the drillbit for doing that....

But really, the VMs are the ticket mate!
.....there's no way that little rice cooker is going 100m/h when the work need to get up to those speeds includes a big fuck off fairing shaped like a giant cock. ~Staffy

Weiner tetanus is nothing to scoff at. ~JustinLonghorn

Offline JRK5892

  • Posts: 9755
    • The Powder Pro
man i am sorry for the thread jack....

you thinking these would do it?

http://cgi.ebay.com/ebaymotors/Mikuni-Carbs-VM30-Tricked-Out-Yamaha-RD400-_W0QQcmdZViewItemQQhashZitem3a5ce10ddeQQitemZ250666356190QQptZMotorcyclesQ5fPartsQ5fAccessories


i am just worried about the stock airbox... mainly cause i have no fn clue where it is!
Joe
"your life is an occasion, Stand up to it"
www.thepowderpro.com

recent builds: Hd street bob, TX cafe, KZ bratt, Goldwing tour, bratt wing, st fighter, road king, vriago bobber, chop, FXD, 1200 sporty, 1200xl sporty, GSXR, Royal enfield.. and more

Offline SrgtBear

  • Posts: 843
  • The arsenic has oddly shaped feet...
haha. i don't mind at all.  This is all useful information that I will need once I get to tuning.
Ted

Kawasaki Kaiju (怪獣) - 79 KZ650 - 700cc Bore Cam Rocket - http://www.dotheton.com/forum/index.php?topic=39748.0
75 Yamaha XS500B Cafe - Completed - http://www.dotheton.com/forum/index.php?topic=14392.0
74 Honda XL 125 - Original - http://www.dotheton.com/forum/index.php?topic=25706.0

Offline Swagger

  • DTT SUPPORTER
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  • Posts: 5513
  • Putting boot to ass since 1967!
Srgt: You're a good sport!

Those can be made to work though they are set up for a 2-stroke but I believe all you need to do is un-shroud the needle seat. PJ will be able to tell you exactly, I haven't done it but I read something and remember him mentioning it.
.....there's no way that little rice cooker is going 100m/h when the work need to get up to those speeds includes a big fuck off fairing shaped like a giant cock. ~Staffy

Weiner tetanus is nothing to scoff at. ~JustinLonghorn

Offline JRK5892

  • Posts: 9755
    • The Powder Pro
i will first try  the pods, i got so much work into these carbs i would be sick if i could not use them.  keep trying over and over right! ha ha ha what is the dial thing you are talking about?
Joe
"your life is an occasion, Stand up to it"
www.thepowderpro.com

recent builds: Hd street bob, TX cafe, KZ bratt, Goldwing tour, bratt wing, st fighter, road king, vriago bobber, chop, FXD, 1200 sporty, 1200xl sporty, GSXR, Royal enfield.. and more

Offline Swagger

  • DTT SUPPORTER
  • *
  • Posts: 5513
  • Putting boot to ass since 1967!
Ok, option 3)
make a piece like your exh. lolipop that fits inside the neck of the carb on the inlet side that'll help create some vacuum.

http://www.thunderproducts.com/dial_a_jet.htm
nifty!!!
.....there's no way that little rice cooker is going 100m/h when the work need to get up to those speeds includes a big fuck off fairing shaped like a giant cock. ~Staffy

Weiner tetanus is nothing to scoff at. ~JustinLonghorn

Offline SrgtBear

  • Posts: 843
  • The arsenic has oddly shaped feet...
Here is a whole thread on pod filters:
http://pnwriders.com/mechanical-technical/127667-pod-filters.html

According to these guys looks like the stock airbox is the way to go if you don't want power band problems.  Personally I think they are a heap of tin when it comes to the cosmetics.  Keep me posted if you fix it and dial it in.
Ted

Kawasaki Kaiju (怪獣) - 79 KZ650 - 700cc Bore Cam Rocket - http://www.dotheton.com/forum/index.php?topic=39748.0
75 Yamaha XS500B Cafe - Completed - http://www.dotheton.com/forum/index.php?topic=14392.0
74 Honda XL 125 - Original - http://www.dotheton.com/forum/index.php?topic=25706.0