02GF74
|
| posted on 8/5/06 at 09:02 AM |
|
|
DIY throttle bodies
I know this hads been asked before but I don't recall a definite reply.
Surely it is not that difficult to make your onw throttle bodies or midify say bit os side draught weber/delorto carbs?
In effect a tube in which a throttle disc turns (hard part is accuraty so it seals) then a tapped hole for the injector.
Surely that is it? (apart from maybe a vacuum take off but that is just a tiny hole right?)
|
|
|
|
|
nick205
|
| posted on 8/5/06 at 09:11 AM |
|
|
Do you need an idle bypass too to let enough air through for the engine to idle when the butterflies are closed?
|
|
|
02GF74
|
| posted on 8/5/06 at 09:14 AM |
|
|
quote:
Originally posted by nick205
Do you need an idle bypass too to let enough air through for the engine to idle when the butterflies are closed?
err why? use the method SU and other carbs use; that is a small screw to push on the spindle to open the disc up; shouldn't be that difficult
to do???
|
|
|
nick205
|
| posted on 8/5/06 at 09:19 AM |
|
|
makes sense  and simpler too
are you planning to have a go?
|
|
|
MikeRJ
|
| posted on 8/5/06 at 09:23 AM |
|
|
The precision required when making throttle bodies is well beyond the average DIYer IMO. Don't forget that the butterfly has to be the perfect
shape to seal the throttle bodywithout binding etc. (not circular!) and the throttle spindle bearings have to be sealed to prevent any vacuum (or
pressure) leaks. This implies the bushes/bearings for the butterfly spidle have to be absolutely concentric and accurately located.
You can indeed convert a pair of old DCOE carbs to throttle bodies, Dave Walker covered this conversion many years ago in CCC magazine. However
"old" DCOE's are often knackered and probably need rebushing etc. With the price of bike TB's it's hardly worth the
effort IMO.
|
|
|
02GF74
|
| posted on 8/5/06 at 09:44 AM |
|
|
quote:
Originally posted by MikeRJ
Don't forget that the butterfly has to be the perfect shape to seal the throttle bodywithout binding etc. (not circular!)
quote:
spindles and discs can be bought so nbot a problem; but this is:
quote:
the bushes/bearings for the butterfly spidle have to be absolutely concentric and accurately located.
but again the butterfly discs have slotted holes so can be moved within the spindle so I reckon it is not that a precise job?
|
|
|
02GF74
|
| posted on 8/5/06 at 09:51 AM |
|
|
quote:
Originally posted by nick205
makes sense and simpler too
are you planning to have a go?
not really; just more curious as to why they are so £££ and whether it is possible with a bit of ingenuity.
|
|
|
MikeRJ
|
| posted on 8/5/06 at 09:57 AM |
|
|
You might be able to buy the butterflies, but they are designed to fit in a very accurately machined housing. The chances of being able to buy a bit
of tube off the shelf with exactly the right internal diamater would be slim I'd have thought.
Put it this way, it doesn't take much wear to make a carb/throttle body start misbehaving.
If you have access to a lathe/milling machine and are skilled in their use then I reckon it wouldn't be too bad a job, especialy if you buy the
spindle and butterfly. If you are hoping to drill through a bit of steel tube on a pillar drill and bung a butterfly in I reckon you will have your
work cut out...
|
|
|
Bob C
|
| posted on 8/5/06 at 11:36 AM |
|
|
BTW DCOE main spindles run on wee ballraces (replaceable if necessary) with sealing washers. these things are pretty fix uppable, even basket cases
Bob
|
|
|
MikeRJ
|
| posted on 8/5/06 at 12:23 PM |
|
|
quote:
Originally posted by Bob C
BTW DCOE main spindles run on wee ballraces (replaceable if necessary) with sealing washers. these things are pretty fix uppable, even basket cases
Bob
Absolutely. My point was that by the time you've shelled out for a knackered pair of DCOE's and the repair kits you might as well have
gone for bike TB's and saved a load of hassle.
|
|
|
