Got my carbs torn apart, but it looks like the previous owner mixed up some of the springs and the jets. I think its got all of its original jets because they have the Keihin logo stamped into them, the slow jets are all 38, and the main jets are 112 and 115, I believe the larger jets go on the rear cylinders, but I want to double check. I also forget which end the longer springs go on, front or rear. The emulsifier tubes are different too, the holes are in slightly different spots for front and rear banks. This will be the third set of V4 carbs I’ve rebuilt, but it’s been a while.
This was the arrangement of them on the bike when I pulled them. I want to say the front tubes are the ones with the 5 holes and the rear has 4?
I fitted a jet kit to my RE, they get you to drill the holes on the bottom of the of the pistons and cut the springs for a quicker throttle response and fit their new jets. Idle jets are now #40’s and my mains are all #140’s. Essentially making all the different jets and springs irrelevant. The bike runs so much better now after getting the idle adjustment and ballancing perfect, pulls harder in the lower-mid range rpms. Top end may be a tad better but I don’t run at high rpms much…mid range in the 4-8k rpm range is where this engine likes to run…the V-4 is all about the torque.
Just out of curiosity, why do the longer ones go in the back? I had read on the V4MuscleBike forum that the short ones went in the rear to help make the rear bank run richer. (I’m assuming less spring=less resistance on the piston so the needle unsheathes faster allowing more fuel sooner)
I’m still new-ish to carburetors so the more I can learn the better
If you have two springs that are identical in every parameter i.e., wire diameter, pitch, material etc. but one is shorter than the other, then the shorter spring will have a higher rate (stiffer).
Two things I have always struggled to understand fully are suspension and carburation.
Why the springs differ in length baffles me,especially when the springs on the RE are all the same length.
The mains are also all the same size
If you fit a dynajet kit to the interceptor,the springs and jets are the same for all 4 carbs.
Previous experience has shown that mixing springs/emulsion tubes and jets causes problems
