Archive for the ‘carb’ Tag

XS650: Yamaha Racing Tips   Leave a comment

This manual first appeared in 1972. Here is the 1973 revised edition. Includes Section 11. XS750(650) Racing Special.

The OW72 motor was developed to take this and the then relevant associated tuning knowledge to another level.

Racing Part numbers referenced in this are found in the Yamaha Racing Parts Book.

 

Yamaha Racing Tips … mostly for the 2 stroke program … includes Section 11 XS750(650) Racing Special

 

YRT contents

 

YRT contents

 

YRT warning

 

Here are the sections. Relevant to XS650s are Sections 1 and 11 …

  1. Using a degree wheel,
  2. Tips for cutting parts,
  3. Cylinder Head mods,
  4. Porting mods,
  5. Piston mods,
  6. Rotary Valve mods,
  7. Con Rod mods,
  8. Expansion Chambers,
  9. Spark Plug selection,
  10. Carb Adjustments

Posted July 22, 2013 by xscafe in Manaul - Literature, Manual - Other

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XS650: Troubleshooting Manual   Leave a comment

If you have ended here and not where you want to go – VOU HAVE A VIRUS ON YOUR COMPUTER … do us both a favour and scroll back to my blog post Virus. Please read this then do a search as suggested.

Yamaha Troubleshooting Manual

In 3 languages. English. French. German

Troubleshooting Manual

Yamaha Troubleshooting Manual

Trouble Shooting

– hopefully this can prove organic … comments and suggestions – correcting, extending
– an engine is basically an air pump – 4 stroke …  suck, squeeze, bang, blow
– add fuel, timing and spark = internal combustion engine
– break this system anywhere and you wont get much action

– so your engine turns over ? wont start
– what have you done ? what have you changed, altered, played with, unfixed ?
– air ? fuel ? spark ? …all in the correct ammount and moment ?
– don’t panic…turn the key and petcock/s off, step back …take a breath-deep, go do something you really enjoy for a couple of minutes…

  •  fuses ? kill switch ?
  •  battery ? 12.6 V ? put it on charge, brushes ? check charging system
  • power to coil/s ? points spark ? plugs ?
  • filters ?
  • fuel to carbs ? bowls ? cylinders ? floods ?
  • compression ? leak-down test ?

·

  •    adjust your cam chain … can readjust warm once you get her running
  •       set your tappets
  •       set your points if you have them .. plugs

 

– once you get this far she should be at least spitting and farting enough to attempt setting your carbs …

  • if she wont idle, look for air leaks ? atu ? massage her pilot jet circuits
  • once you can get idle, do the idle speed screw/pilot air screw dance
  • smooth transition through to full throttle ?
  • synchronise

Electric Troubleshooting

Carburetor Troubleshooting

Starting System Troubleshooting

Engine Troubleshooting

Oil Troubleshooting

Clutch and Gearbox Troubleshooting

Frame Troubleshooting

XS650: Amal Single Carb   Leave a comment

Melv from Greensand Foundry has produced single carb manifolds for an Amal. Nice simple carbs.

Carb exiting to the left …

I made this manifold because I had lots of requests from people asking for a cast 2 into 1 that will fit in a standard frame loop. I made this to fit an Amal MK1 concentric, but will be making these to fit other carbs in the future. The Amal carb has a rubber o ring that seals against the machined face of the manifold!!!!!

Straight mounted carb …

He states: This is the first time I started the bike in 4 months. It usually starts first kick but the battery was flat!!!!! This is my straight mounted 1-2 manifold made to fit a standard XS CV carb. Internal bore diameter is 33.0mm. I made this because a number of people wanted it … personally I don’t like the standard XS carbs so adapted it to fit a trusty old Amal MK1 930 Concentric. My range of XS parts is listed on UK ebay!!!!!.

The jetting/settings on the twin Amal 930’s is   Main jet #140   Needle jet#106   Throttle valve (or slide) #3 1/2   throttle needle is 2 indent (which is the 2 small engraved lines above the clip grooves) and the clip position is second groove down or midway.

For the straight mounted 1-2 everything is the same apart from the main jet which is a #170.

See his other stuff here and here.

Amal site.

Notes On Rebuilding the Amal Mark 1 Concentric Carburetter.

This old tractor. Amal info.

Hitchcocks Amal.

Posted February 1, 2012 by xscafe in Carb - Amal

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XS650: VM34SC Mikuni   Leave a comment

Yamaha’s Racing Tips Manual, 1974, suggested using VM34SC Mikunis. Round slide. Magnesium bodied. No Power Jet/Accelerator Pump/Beschleunigungspumpe.

Today, TM’s are supposed to provide significant performance improvements. Flat slides and the jet blocks help create a smooth bore effect. Air flows faster and smoother through the TM Series venturi. Higher air flow velocity gives a stronger vacuum at the needle jet needle. Provides more precise metering and better throttle response.

For known geographic and climatic conditions.

However, I do a fair bit of touring. Low to High altitude. For this I actually prefer the original BS series carbs. They automatically adjust themselves for air pressure. Easier to keep tuned.

… VM34SC carb … XS750(650) Racing … adjustments … jet needle 6F9 (#2 clip position)

 

… carb adjustments

 

… carb .. VM34SC … adjustment

 

… VM34SC carb … 3/4-full throttle adj … main jet

 

 

… VM34SC carb … 1/4-3/4 throttle adj … needle jet

 

… VM34SC carb … 1/8 – 1/2 throttle adj … slide adj and cutaway

 

 

… VM34SC carb … 0-1/8 throttle adj … air mixture screw – pilot jet

 

 

… VM34SC carb … idle speed screw

Posted December 21, 2011 by xscafe in Carb - VM

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XS650: Carb Heaven   Leave a comment

1:1 – In the beginning was created the heaven and the earth.
1:2 – And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit moved upon the face of the waters.
1:3 – Calling, ‘Let there be light’: and there was light.
And not before time too! Sonar never really worked for me. No fun riding the XS by white cane.
Ever wondered where carbs go when they die.
Carb Heaven? Sonic bubble bath. Soda spa. Queen Joan Jetts.
Or Carb Hell? Oxidation soup. Vacuum Patches.  Dysync city.
Function change? Why not …
  • dual eyes … halogen

halogen eyes

 

simple really

 

coloured and polished variations

 

Where are you  going to hide all the spaghetti?

Mount as you wish.

  • stop/tail … led

 

ol led eye

 

here’s lookin at you … led

 

Not really my cupoftea, but (?) … rcknrllrog on fleabay

Posted October 13, 2011 by xscafe in Elec - Lights

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XS650: Carb Boots and Diaphragms   1 comment

Some time ago I had to rebuild my carbs, BS34s from a 3L1 motor, was really no big deal, they had been sitting a while so I cleaned them and tarted em up. Rejetted, new needles. boots, diaphragms etc.

The original Yamaha boots were hard and cracking after just 30 odd years. Anyway I ordered new boots etc and installed the carbs. After 3 months the boots had cracked to shit on the outside and begun to melt on the inside. WTF? And European fuels dont have the same ethanol content as North American-I see the other day that this will be changing in the near future. This was my first experience with that particular supplier I cant even bring myself to name, but we all know who he is with his cheap chinese crap.

 

damage like this

 

and this

 

Anyway, to cut a short story longer, JBM Industries came to the rescue. Theyve been making stuff for the aircraft industry.

These boots dont use the original metal cage and will secure your carbs unsupported. They make BS38 boots both straight and angled flange and BS34 boots. Also the diaphragms.

 

 

NOTE. These will have no problems with ethanol containing fuels.

My BS38s are running great. It’s a shame as I prefer the BS34s. I guess it’s good that Paypal is my friend.

JBM’s first carb diaphragms were for our Mikuni CV BS 38mm. Next were those for the BS 34’s. They’ve gone on to design and manufacture parts and compression molding tooling for a variety of vintage motorcycle carburetors. Don James, head of JBM, uses only a specified quality TSR heat cured compression molded rubber compound. (Not that crap recycled, zero quality control crap we are becoming used to from my favourite low service partner). Molds, tooling and production are all done ‘in house’.

TSR … Technically Specified Rubber, a system for describing rubber compound formulations. Graded according to dirt, ash, nitrogen, volatile matter content and the Plasticity Retention Index (PRI).

A first rate design, tooling and molding operation with excellent customer service!

Cost is very reasonable. Reflects a lack of ‘middlemen, mark-up merchants’  (distribution/wholesale/retail links). Products sold directly at a reasonable margin to the customer/user. A sound business model.

JBM Industries – thumbs-up – keep up the good work guys.

Posted January 10, 2011 by xscafe in Carb - Boots

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