Carb model differences 81 - post 85?

[motoboy66]

So.. Here's an example of stupidity and cack handedness that I don't normally do.

As part of my total "restoration" (I use the term lightly) I had to rebuild the carbs on the 81 R65. The o rings were either split or square, jets were turning green with corrosion etc..

The mixture tubes were seized so badly I had to partially drill them and finish with a dremel with a diamond tipped grinder. I had tried heat, kroil, everything.. they weren't shifting.

The first one I had a go at I thought was weakened sufficiently that i'd try an extractor tool. Bad move. Felt like it was going but ended up splitting the carb body. Second one i just kept going at with the grinder and got it out after an hour or so of very careful work.

So.. Had a go at soldering with an acid based solder. No chance. Tried with a bit of "universal" brazing flux i had knocking around. Nope.

Had a look online an interesting patent came up from the 50s about using Tricresyl Phosphate as a flux. Aha! Keep searching and discover it's a neurotoxin and pretty damn nasty and not really possible to purchase in this country at least, probably for good reason.

So tried the plastic padding leak fix stuff. Supposed to be good for emergency repairs on petrol tanks etc but wasn't sure how it would deal with being permanently submerged in a float bowl.

Short answer, it didn't do well. It didn't melt but had gone soft and my theory is it was letting fuel getting sucked up past the main jet and into the idle circuit as I've had a total headache with the RH cylinder running rich, popping, backfiring.. you name it.

So i've decided my only option is to replace the body on this side.

The carb model is a 64/32/308.

I've found a supplier here with a new body here at a ridiculously cheap price (£20) but they state is from 1985 onwards for R80 , still 32mm, with a model number of 64/32/354A.  It's probably a ridiculous question as although it appears physically very similar I'm sure it has totally different mixture characteristics. Has anyone had experience with both carb models and are they very different?  

Or does anyone have a spare 64/32/308 body they are willing to sell?

And a picture of my stupidity for posterity:

[Tony Smith]

I feel your pain.

But, I'd buy the new body and then kit it out with the same jets etc. that you started with. Have a very close look at the "piston" and if they are different use the one from your old carb.

Only person who will ever know is you and I'd reckon you will not have any trouble getting the engine running correctly.

[Luca]

Also, if for some reason you were having trouble balancing the carbs, you could buy a new body for the other side too and swap the guts in that one as well.

[motoboy66]

After having a peek at the other parts they sell it gets confusing - slide pistons seem to be 81-83 then 83-85. so I might be stuffed straight away. Checking with a couple of other breakers here and awaiting call backs.
Found complete carbs from £60 which might be safer but still are different model numbers. Seems crazy how many variants of bing model there are listed for the R65!

[Barry]

Worth a look here to check the detail including slide part numbers for each version of the carbs.


http://www.bingpower.de/en/service/tuning-manuals/

[georgesgiralt]

IMHO, and I'm not a bing expert but got a BMW factory manual, the carbs are all the same on post 81 bikes. Only difference is jetting and on later ones the way the needle is affixed into the slide.
Jetting has chnaged a lot during the years (81,82,83 ..., then for Europe and different for USA...) so marking had to follow the changes. This explains the number of P/N they had.

[motoboy66]

Have ordered a second hand 64/32/308 body at £60 and the 354a body at £20 and will check out both and return one. Will report my findings later in the week!

[Mike V]

Worth a look here to check the detail including slide part numbers for each version of the carbs.


http://www.bingpower.de/en/service/tuning-manuals/

Barry,

Where do you find all this stuff?! I say we vote Barry as our Primary Technical Data Depository Officer.

-Mike V.

[georgesgiralt]

Unfortunately, the 307 and 308 are not listed ...  

[Barry]

Thanks Mike,

I stumbled across that years ago. Once I've found something I remember it exists and then know where to look it up when needed.

I'm sure I've posted that link before though.

[montmil]

...Once I've found something I remember it exists and then know where to look it up when needed.

Sure, I also remember my crap exists. Knowing where it is; that's the nut to crack.

[motoboy66]

Who's up for a game of spot the difference?!

307 is the old, 354a the obnoxiously clean one.

[motoboy66]

Apart from the different vacuum take off port there seem to be only very subtle cosmetic differences at points in the casting and nothing that affects the old hardware and jets working.

Slide piston fits and works perfectly with the old dome top. Float bowl is exact fit.

Of course the proof is in the pudding and I haven't yet received the new o rings to test it out..

[Barry]

The most interesting difference for me is the enricher ports. Hopefully the changes make it work better.

[motoboy66]

Very good Barry! Missed that!