Hi Again all. I feel like im posting on here constantly, but making good progress on my build with the holiday period and its throwing up more and more questions

I bought a second hand GSXR TB set up with a fast dan inlet manifold from big-vee-twin on here. Great guy to deal with, the bits were all as described and arrived next day so happy bunny. I've looked through big-vee-twin's past threads and he changed to Jenvey's due to trouble balancing the GSXR throttle bodies as well as the well known on off issues with bike throttles.
With most of my driving on track ill see how I go first with the current throttle linkage and possibly look to going to a modified one to get more of a progressive throttle travel, but thats one for the future.

Now to my question: How important is it to have the Throttle bodies lined up spot on with the inlet manifold and the distances between TB and manifold exactly the same accross the 4 TBs? Ive trial fitted the set I have and 2 of the 4 are spaced pretty well bang on to match, however the other 2 are out by 1-2mm compared to the inlet manifold ports. This should be easily fixed by adding a couple of small washers to space one and trimming the current spacer on the other, however I wonder if this could be part of the issue with struggling to get them balanced?
The other question is how large a gap to leave between the inlet and the TB? This is covered by hoses, but should they be as tight together as possible? The TB and Inlet came separate with the hoses clamped to the inlet, but from the marking on the hoses where they sat on the TB lip the gaps between the inlet and TB were around 50mm and also weren't consistent accross the 4 TB's. Again how accurate does this have to be and would it cause balance issues by being out by 10MM one to the next?

Ill add some photos later on to help out my description if I get the chance and thanks again for all the help

Balance is about air flow, as the runner to number one is slightly longer due to being cranked to miss the top pulley, they will never be exact same length. I tried to get them as close as possible and to minimise the gap, main thing is to make sure you get them sealed properly.

I used a manometer to balance them plugged into each spare vacuum port.

It is quite a fiddly and repetitive process going up and down each body getting them aligned to the TB closest to the idle adjuster.

The only real issue I had was that my car is for the road and I found them a bit on and off when driving slowly, as you say, but the car wasn't that bad to drive.

I came into a bit of money and did the upgrade, I was always going to go for Jenveys anyway.

Hi there. To combat the on/off low throttle response I made a larger diameter pulley and offset it to give a rising rate cable pull. The centre of rotation on the pics below is between the four small bolts holding it to the standard pulley. It works a treat.
The change of angle of the cable end is catered for by a small rod end fitting.

Nice piece of work there spyder! I'll save the pics in case I need to do similar

Very happy with what I got for the money Vee-Twin, just trying to get it as good as possible before I fit it. I appreciate it'll never be as good as a car specific jenvey kit and I may well end up down that route in the future once its all up and running.

The alignment of the worst one (cylinder 2 from memory) is shown below. I was just concerned that the offset of that one in particular would disrupt the airflow enough to make a difference. It shouldn't be a big deal to sort with a relatively small washer on that one and a slight trim on the next spacer to re align again


Description

[Edited on 31/12/15 by gav2612]

That's not ideal and will effect flow. I'd be tweaking the spacing to align that a bit better if it was mine

Ian