Converting motorcycle throttle bodies

Paul Illick · Post by **Paul Illick** » Wed Sep 28, 2005 5:26 am

The machining on that adapter you drew isn't so simple, and it won't be cheap. Check cutting off the flanges of the T4 manifolds and re-welding as was suggested, which should be cheapest and still do what you need. Welding is cheaper than machining. Then use the rubber boots that came with the Suzuki TB's, simple enough.

For the linkage look at BMW R-series motorcycle throttle cables. The R's were the horizontally opposed engines with a carburetor on either side of the engine, so they used split cables. One side of the cable has an adjuster to lengthen the outside tube so you can balance them side to side. Then leave the TB pairs on each side of your engine linked and use that cable, one end to each side. Alternatively I think that some of the English performance parts places (Tweeks, Redline, etc) have split automotive cables that were used on the old TR3's or Europas or something. Or try Pierce Manifolds in Gilroy, who have something similar but automotive and probably a bit more expensive.

76bug · Post by **76bug** » Tue Oct 04, 2005 5:12 pm

hello ben is there any progress with the throttle bodies? im on ebay now looking for a set

76bug · Post by **76bug** » Thu Feb 09, 2006 3:17 pm

hey there how are u goin with the throttle bodies?

John_S · Post by **John_S** » Sun May 21, 2006 1:30 pm

just noticed this thread as i've just got hold of some motorbike tb's (could be off a vmax i'm told) there 40mm in diameter , and i'm going to attempt to put em on a 2110cc aircooled engine

John

www.autoelectricsolutions.co.uk

Post by **Piledriver** » Mon May 22, 2006 4:08 pm

Paul Illick wrote:The machining on that adapter you drew isn't so simple, and it won't be cheap. Check cutting off the flanges of the T4 manifolds and re-welding as was suggested, which should be cheapest and still do what you need. Welding is cheaper than machining. Then use the rubber boots that came with the Suzuki TB's, simple enough.

For the linkage look at BMW R-series motorcycle throttle cables. The R's were the horizontally opposed engines with a carburetor on either side of the engine, so they used split cables. One side of the cable has an adjuster to lengthen the outside tube so you can balance them side to side. Then leave the TB pairs on each side of your engine linked and use that cable, one end to each side. Alternatively I think that some of the English performance parts places (Tweeks, Redline, etc) have split automotive cables that were used on the old TR3's or Europas or something. Or try Pierce Manifolds in Gilroy, who have something similar but automotive and probably a bit more expensive.

With very little work, those work great on Webers as well, made my own from JY MC parts and ran them with no need to adjust anything for years.

Someone should be selling them for ACVWs.

Wally · Post by **Wally** » Tue Jun 06, 2006 12:31 pm

Anybody found out already which motorcycle TB's are closest to the IDF pattern??

Tnx,
Walter

John_S · Post by **John_S** » Sat Oct 14, 2006 11:42 pm

i've got my megasquirt system up and running.
2110cc aircooled , FK-8 camshft (over 1/2 inch of lift)
and i've used CBR900 throttle bodies.
I must admit the difference in centre to centre between these and IDF is within 2mm

if u want pictures i can post some

John

slowtwitch · Post by **slowtwitch** » Sun Oct 15, 2006 2:49 am

John,

post some pics. I'm working on a set of MC throttle bodies also.

pete

76bug · Post by **76bug** » Sun Oct 15, 2006 3:37 pm

hello john i would love to see some pics of your setup. im in the final stages of seting my motor bike t/b's they are off a gsxr1200

Wally · Post by **Wally** » Sun Oct 15, 2006 11:41 pm

John_S wrote: i've used CBR900 throttle bodies.
I must admit the difference in centre to centre between these and IDF is within 2mm

if u want pictures i can post some

John

Cool, thats the closest to IDF-pattern I have seen so far!

Yes, some pics as how you mounted the TB's to the manifolds would be excellent!

TIA,
Walter

slowtwitch · Post by **slowtwitch** » Wed Oct 18, 2006 3:42 pm

OK, here is my feeble attempt at adapting MC throttle bodies. These are Honda VFR TB's. A buddy of mine gave them to me, so I figured I give it a shot

Anyway, they are 36mm and there was about a 2mm difference, center to center, compare to Dell's. I milled the fit off center on the adaptors, 1mm.

pete

76bug · Post by **76bug** » Wed Oct 18, 2006 3:49 pm

nice work slowtwitch, how r u going with the linkages??? im finding this the most challenging part. ill post a picture of my setup tomorrow

slowtwitch · Post by **slowtwitch** » Wed Oct 18, 2006 4:19 pm

Thanks 76bug,

I still have to drill and tap the mounting holes and polish things up.

As for the linkage, I'm going with a cable setup that I have been working on.
It's kinda of universal, it will work with these TB's and my Dell's and hopefully, it will be easier to setup than hex bar linkage.

Oh, don't mind the engine in the pic. It's just used for mocking up my parts. It doesn't even have any pistons in it

pete

Wally · Post by **Wally** » Thu Oct 19, 2006 11:35 pm

Excellent work! tnx for the pictures

I am also a little afraid the rubber connection between TB's and manifold might give an inaccurate linkage (flex of the rubber hoses), but I can't tell how stiff the set-up is from here

Tnx,
Walter

MattKab · Post by **MattKab** » Tue Oct 24, 2006 9:07 am

Nothing feeble about that attempt!

Wally's concern would be almost eliminated with the proposed cable linkage.. a great idea

Did that rail in the mock-up pic come with those bodies?