Needle supposed to have this many washers?

[system9]

My midrange has been hard to tune in, so I bought some Canadian needles, and needle jets.
Upon removing the "stock" needle, I was a little surprised that there were 3 washers involved. 1 above the clip, and 2 below. Is this normal?

 

[5twins]

BS34s I assume? No that's not correct. Someone added those two lower washers, probably to try and shim the needle higher (richer). The thin washer on top is an original part, it supports the little spring. The sequence should be thin washer on top then the e-clip, then the thick plastic washer .....

 

[system9]

:-(
No wonder I couldn't tune in my midrange.
These are from XS650 special 2
Well, I'm going to use my canadian needles anyway, now that I have them. Thanks for the info.

 

[gggGary]

And with two washers added the spring can bind wedging the needle and the slide might not come down. But you would notice that.............

 

[5twins]

Yes, you would, lol. Those washers you found look to be pretty loose fitting and rather thick. I'm betting they're some small American size. I use metric washers for my needle shimming. The M3 size is a perfect fit and about 1/2mm thick. Needle clip slots on Mikuni needles are 1mm apart so these washers allow you to set in half step increments. Sometimes this is just what you need when moving the needle a full step (1mm) is too much. A lifetime supply in stainless is less than $2 from McMaster-Carr .....

http://www.mcmaster.com/#93475a210/=zt63yh

 

[angus67]

Or if you were lucky enuf....you got a .....bunch .....of plastic ones from........xsjohn.
I think they were quarter steps .
Do you have the matching emulation tube for those Canadian needles?

 

[The Standard]

Researching this in setting up a set of BS34’s for an early bike motor. Running open TT’s and 2.5” long velocity stacks.

My question is the washers I found do fit securely re. ID of the hole in washer. Can’t recall if they were M3’s or SAE. When I mic them they are .62mm thick not the .50mm @5twins advises. Is this increase in thickness significant to pose a negative running condition? I Also went up 2 sizes on the mains and pilots over stock.

Other question is in reinstalling the Retaining plate, I lined up one of the non-screw holes (of the 4 total) with the hole in the bottom of slide but also when tightening down the Retaining plate screws, if I tighten them down all the way it introduces some drag on the slide moving freely in carb body. I backed off the screws a few turns and the slides move freely.

My assumption is the small spring under the Retaining plate keeps tension on the screw from backing out like a lock washer does? Am I correct or is there a spec for how snug to tighten those 2 screws down?

 

[gggGary]

There is only room to add one washer on BS34's with USA spec needles, add more and the spring coil binds, the needle becomes rigid and causes the slide to bind.
Two cents the screws need to be tight.

 

[The Standard]

Thanks for reply on this. Do you mean 2 washers total (above and below E-clip)? Or 2 added to shim?

I just added one .62mm thick washer between the E-clip and plastic disk.

The other washers in setup is that copper “D” shaped washer below plastic disk (with straight edge of washer aligned with pin on bottom of plastic disk) and the washer below the little spring on top of the E-clip.

 

[gggGary]

sorry forgot the pics

 

[gggGary]

there shouldn't be a copper D shape washer below the disk.

 

[gggGary]

The washer get s added between the pill and the clip. If the pill doesn't want to slide a hair dryer will help.

 

[The Standard]

@gggGary,

Thanks for providing pictures. I followed your directions earlier with no issue before posting question. Yep, hair dryer worker perfect in removing the Pill. I added the new shim washer between the clip and plastic pill. I have a washer on top of the clip also (below the small spring) and then 4 hole retainer plate, secured with 2 small screws that the large Return spring sits on.

Do I remove a washer? You have one washer crossed out with the red X.

There should be no washer between the bottom of plastic pill and slide (where needle inserts)?

In the picture above of the bottom of plastic pill there is a little extended pin part of pill. That D-shaped washer I mentioned, assumed was relieved to clear this pin. So I should remove this washer altogether and then tighten the 2 screws that secure the 4-holed retaining plate until fully seated? Of course, snugging not over torquing.

 

[The Standard]

It also looks like in your picture above there is some grease on the needle/pill. Is that necessary for protection of the pill friction fit? When I used the hair dryer it came off fairly easy with gentle rotating the pill back-and-forth and slid back on with slight friction after installing the washer. Hair dryer procedure not needed to reinstall the pill.

 

[5twins]

Since you've increased the main and pilot jet sizes, you may not need to do this needle shimming at all. Your new larger jets will bleed over into the midrange and make it richer. Two up on the pilots may be a bit much. You can make the idle circuit a little richer than just one up on the pilot jet by reducing the air jet size. It has less of an affect than a pilot jet change so can be used for fine tuning the circuit. You can obtain a richness level more than one size up on the pilot jet but less than two sizes up.

 

[The Standard]

Thanks 5twins,

Yes I read another post on the Forum here where a member with similar intake/exhaust setup just went up one size on both mains and pilots and reported bike was running great with that combo, after trying the Heiden kit and some other combos.

Thread was “BS34 Jetting for Modifications” Thread starter jpdevol Start date Jun 12, 2022

Smallest Main I have is a 137.5 (stock I removed was 132.5) but I do have a 45 Pilot which is one up.

I don’t have any diff size Air jets, so will see how bike runs with this setup first.

I’ll try it with the needle shimmed and see if too much.

Bike ran good with open TT pipes and K&N pleated filters on stock jetting but with adding the velocity stacks concerned about being too lean and burning a piston.

In looking at the various parts diag for BS34’s none have a washer (D-shaped) under the Plastic ring. Wonder if PO added. Its super thin (like .25mm) so don’t think much richening was aim in installing.

 

[The Standard]

That’s unless you think with the 137.5 Mains I’ll still get the bleedover that accomplishes the same thing as shimming needle.

I also pulled the brass plugs to gain access to the idle air/fuel adjustment. Set baseline adjustment at 3 turns out.

 

[5twins]

Yes, what you need to understand is that the three circuits in your carb overlap the ones next to them slightly. This means that changing one will affect a portion of the one next to it ......

Yes, two up on the mains will do this, as will one up on the pilots. Pretty much any change will, but whether it's enough to correct the lean midrange, well, only testing will tell you that. I think Gary's needle shim trick is mainly for all stock bikes. Many experience a flat spot just off idle and the shim fixes that. I never needed to do it on my '83 because I didn't have that flat spot. But, I also changed some jets even though it was almost stock. I went up one on the mains because I read even a totally stock BS34 equipped bike runs better that way. I left the stock pilots in but reduced the air jets by two sizes (to a #130). This put some color back on the plugs. They had been very clean, too clean, lol. As I mentioned, the bike was almost stock. I thought it was until I took a closer look and discovered the P.O. had drilled extra holes in the ends of the mufflers. This made the already borderline too lean carbs even leaner and prompted my need to do some jet tinkering. It ran nice with the tweaks.

Eventually I did the typical "pipes and pods" mod, and that required more jetting changes. I went up another size on the mains (to 137.5) and did one up on the pilots. With the larger pilot, the two down on the air jets proved to be a bit much, so I went back up one. As I mentioned earlier, the air jet is good for fine tuning and "tuning" the plug color or "smoke ring" .....

I like to get the ring so it covers no more than about the bottom 1/4 of the porcelain. I had that with my jetting when the bike was nearly stock but after the mods, the ring had climbed up to cover about half of the porcelain. Increasing the air jet one size brought it back down to where I like it (about 1/4 coverage). I'm still one size smaller than stock, but with the one size larger pilot, two down on the air jet was just a little too much. I like this about the BS34s, the ability to fine tune the idle circuit and plug color using the air jet. You can't do this on the BS38s, the air jet is pressed in and can't be changed.

 

[Paul Sutton]

There are several available washer sizes and these are referred to as "Forms". The "M3 Form A Washer" is the one with the 0.5mm thickness.

M3 Form A
Internal Diameter - 3.2mm
Outside Diameter - 7mm
Thickness - 0.5mm

 

[5twins]

The ones I use can vary a little in thickness. I mike them out and if need be, sand the "fat" one down a little. It only takes a few swipes on some 600 wet/dry paper .....