XJ650 Starting issues

I'll wait for the bike to be running again once I got the new shims in, and then tackle doing that. If only because I don't want to add another project while I'm trying to fix the more important thing (shims/carbs)

Most likely I'll spit some Kroil on them for a few days in a row before I even bother to touch them.

I also have some ACF-50 if that helps

 

Upper and lower rack bracket screws were assembled using thread-locker material, and that's why they are so difficult to remove (and also why the rack kept it's carb-to-carb alignment for 40+ years!).

It is suggested that they also be re-assembled using a low-strength locker fluid.

We've found that the easiest way to remove them is to use an appropriate sized set of vice grips and grab 2 sides of the screw head with end of the vice-grip jaws and give them a little turn.....once you break the thread-locker loose (only takes 1/8 of turn or so) then the screw can be removed with a standard screw driver.

Kroil or penetrating fluid won't really help, as it's not a corrosion issue that has the screws "frozen", it's the thread locker fluid doing it's job........

 

I don't really have a vice nor do I have a place to put a vise, but I can definitely try to see if I can get like an adjustable wrench and grab and twist the head a little bit

I'm assuming applying some heat to them will. I'll also break the locker fluid, but the bottom rail also has some problematic screws. If they accidentally heat up some o-rings or whatever, it doesn't matter because I'm replacing everything anyways

 

"Vise Grip" locking pliers.

 

Oh I got those yah

 

Correct, vice-grip locking pliers.....and you may want to come up on the bolts heads "from the side" rather than straight-on....for example, on the upper rack screws, come in with the top, flat edge of the vice-grip pliers (not the serrated teeth of the plier jaws) from the bottom of rack, and grab a screw head with the pliers as far to the "left" of center as is possible.....since once you firmly "crush" the head of the screw with the pliers, you'll be rotating the pliers counter-clockwise, and you want as much rotational ability (movement) of the pliers as is possible (which will probably be about a 1/8-turn). The handle and long axis of the pliers will be at almost a 90* angle to the horizontal top edge of the carb rack (and to the top edge of the upper rack bracket).

And do some warm-up exercises on your dominant hand, as you'll have to set the "closure pressure" of the vice grip jaws (onto the screw heads) at the maximum amount that you'll be able to squeeze the jaws fully shut ("locked") against the screw heads (hence the word used above, "crush"). Otherwise, the jaws of the pliers will break loose from the screw head.....those screws are loctite-ed in there very tightly!

Once you break the screws loose, then you'll be able to use a standard phillips-drive (or even better, JIS) screwdriver to back the screws out.

 

Nah, i meant the part, where the return spring is attached. im having trouble figuring out where and how it connects to the frame, and how the spring is positioned. i think mine is missing, so ill have to make one. here are the photos. Would be awfully kind of you to send yours. Rock on!

 

I can't seem to find my vice grips, So I'm going to swing over to harbor freight. I also think that the vice grip that I do have is probably too large so I'll get a smaller one. One of the things that I just noticed from taking a better look at this, apparently these already have 40 & 112 jets. 50 & 205 are under the carb hat, and 40 & 112 (side stamping instead of face)

So I'm guessing somebody in the past had already increased the jet size but not the other one

 

It looks like stores around me only have blue loctite, will that be okay instead of purple?

 

The vice trick worked!

Well sort of. I had to hit it with some heat, for a while, and then I was able to get one of them off.

Then, what I did was, I had enough of the screws off of the rail, that I could move the rail back and forth a little bit. Eventually when I was down to the last screw, I twisted the rail a little bit and was finally able to unseize the screw. I don't see anything is stripped

Some of those screws took a inordinate amount of strength.

 

Make sure you use a torque wrench when reassembling.

 

Yes they do! Which is why you may want to use the purple (low-strength) fluid rather than the stronger blue loctite.....which will work just fine, but if you ever have to get into that rack again.....well, you know what you'll be up against!

 

I have carb #1 reassembled, and the new fuel lines and vacuum lines (which was connected to intake #2 anyways??), and 2/3/4 are in the ultrasonic for the next hour.

Questioning if I have enough throttle shaft shim washers. I have pulled six off, and the kit I got only had four.

 

I don't think that I'm going to have time today to do a check of the float levels. I should have it all assembled in the next hour or two.

I noticed with the new metal tip float valves that they don't hang they just sit, there's no little hanger.

 

NOTE: all of the float needles that have a rubber tip also use a retaining clip to secure the needle to the float arm. Please note that the clip can be installed in two different ways (orientations). User experience indicates that the clip should be positioned so that the "open" area of the clip (that part of the clip that snaps over the ridge on the top of the needle) should be oriented towards the "back" of the carbs; in other words, the open area of the clip should be towards the airbox.

By the way, the purpose of this clip is to prevent the rubber tip of the needle from "seizing" within the float valve seat (due to the rubber swelling), or fuel varnish forming around it (and "gluing" it to the brass seat). Since the clip is attached to the float, as the fuel bowl empties the weight of the float pulling down on the needle will tend to overcome any needle tip seizure and prevent that float valve from remaining closed, even as the float bowl empties of fuel.

Metal-tipped needles, although not original on Hitachi carbs, were used on many original Mikuni carbs. The metal needle tips are much less prone to tip seizure and thus metal-tipped needles do not need, nor use (or even accept) the needle retaining clip.

 

Do I need the little metal hanger for the metal tipped float valves?

I have Hitachi carbs, but I got the deluxe kit

Edit: I reread what you posted and it sounds like I don't need them

 

Correct......not only do you not need them, you can't use them, as the metal-tipped needles for either Hitachi or Mikuni carbs do not have the "groove" in the needle case to accept the hanger clip.

 

Finally got these carbs cleaned and reassembled.

Things I noticed:

First time I cleaned carb 1 in the ultrasonic w/ dawn dish soap @ 100F heated water, it was shiny and nice!
When I cleaned carbs 2-4 same as before, they all looked stained afterwards, along with some of the brass. A bummer, but I don't care that much. I only care if the passageways are clear at this point.

Things I did when building:
- Noticed I only got 4 "throttle shaft plastic shim washers" from the deluxe kit. The carbs came with 6 shims. Because of this I reused some shims.
- I need to go back and check, but I had more orings than I needed. I think I had four left over, which is normal apparently.
- I think I may have missed a few throttle shaft shim washers when installing, I think I had a few left over, and I should have used all of them up. Easy enough fix, since nothing is loctite'd yet.
- I think I may have also missed a few throttle shaft seals. Again, easy fix.
- I had some left-over purple loctite from a previous order for the crash guards I can likely make use of for this.
- I dryfit everything without using loctite, or tightening down the lock washers, to make sure I wasn't missing anything and everything went in the right place
- I had some difficulty figuring out which direction the carb 3 throttle cable attachment was placed, because it seemed confusing. Forgot to take a picture of how that's supposed to be setup.
- connecting the sync screws with the tension spring/bolts while connecting each carb is kinda a pain in the ass. I found it was easier to line things up, and then use a metal pick to hold down the bolt and slide the other metal piece in. Not sure if there's an easier way or if it's normal that it's a pain in the ass.
- checked every hole was clear by shining a light through it. I'll spray some carb cleaner through the main/pilot air jets just to be sure
- Noticed it was a massive pain in the ass and a timesink to get the main/pilot air jets back in their holes. Double and triple checked the main #50 was in the middle, and #205 was on the other side (not the screw hole). Using one end of a hex wrench helped to align the tiny screws without stripping anything.
- ensured the float bowl hole was clear by shining a light through it
- Noticed the fuel jets were #40 & #112. Stock is #40 & #110. Probably got increased when someone replaced the exhaust with a 4 into 1.
- Replaced the main/pilot fuel jets with #41 & new #112 (because the new ones have numbers on the face instead of the sides)
- ensured the (I forget the name right now) thin brass tube near the main/pilot fuel jets was clear, but will hit it with carb cleaner later just to be sure
- noticed the o-rings in the idle screws tend to get stuck in the cavity, and I made sure to dig out the old ones so I wasn't double o-ringing in there
- didn't tighten down the idle screws all the way, since I wasn't sure what they needed to be pre-set to, and figured I could do that later.
- checked diaphragms for any rips or tears, they all seem pretty pliable and nice.
- noticed that carb 4, the main jet tube would get a bit stuck on the last millimeter going into the carb body and had to be pushed in, unlike all of the other ones, which went in smoothly.
- replaced all screws (except the spring screws along the back that modify the opening of the butterfly valves?) with hex screws (wish the idle screws were hex too...)
- replaced all o-rings for the fuel supply tubes
- replaced all float bowl gaskets
- replaced all choke plunger dust caps (they were hard as a rock and starting to deteriorate slightly)
- gently etched #1/2/3/4 on the airbox side of the butterfly valves to make sure I remembered the direction of the valves and which one went to which carb
- used 1000 grit sandpaper on the inside cavity where the brass plunger/diaphragm body goes, but did not touch the brass plunger.
- lifted the brass plunger on all carbs after assembly and they dropped back down smoothly and at the same rate

Things left to do:
- I forgot to use the spacers on the enrichment shaft, so I'll need to do that. I also was confused about the orientation of the enrichment linkage
- get two levels and some clamps to align the carbs before loctiting the carbs to the racks, since I don't have a vice and using a glass plate sounds sketchy as hell
- make sure to loctite the butterfly valves
- do a bench sync
- check the float levels, since the old carbs were set to specific distances with rubber tipped float needles, and now are using metal tipped needles, I assume it's going to be slightly off. I'm not convinced the float levels were a problem before, but it's wise to double check it anyways. I should be able to do this with a digital caliper.
- also use some extra tubes to check the float levels. I should also be able to use a digital caliper for this. The hard part is going to be holding the carbs somehow in a way that keeps them level while testing. I don't have a carb stand and I don't think I can afford to spend $170 or whatever on one.

Also:
- Replaced both ignition coils with new aftermarket coils, since they were very slightly out of spec on the battery side, and one of them was showing as OL when measuring the resistance. Both of them had cracked housing. Kept them in case I needed them later.
- noticed replacements had metal things placed around the wire housing that probably would help with fitment, but realized there wasn't a good way to screw them on and they didn't help with grounding, and would probably hurt the wires by bending them back more, so I ignored them

Finally:
- Once the carbs have their float levels set, and are bench sync'd, it's time to go back on the bike
- once the shims come in, I'll replace the out of spec shims, and spin the engine a few times CCW (towards the front) and re-measure the shim clearances to make sure I didn't make any math errors
- Afterwards, do another compression test and see if anything changes with compression (I'd expect the low ones to come up, if they don't come up...lets cross our fingers and hope that doesn't happen please)
- Cross both fingers and toes and start the bike, and do a carbtune pro sync

Am I forgetting anything?

 

as an aside:
once I had disassembled one carb, the rest of the process was pretty rote. It's a fun enough mechanical puzzle, and after having completely disassembled four of them, and then put everything back together, they're actually pretty simple to remember where everything goes. It's just daunting having never done it before, and tedious.

I guess we'll see how setting the floats, bench sync, and carb tuning goes. I probably won't get a colortune, but I might ask the technician I'm bringing the bike to in a few weeks for a sticker to do that for me instead. They tend to work with cafe racers so I'd assume they have one.

I'm going to be pretty satisfied if I do all this and the bike starts up and doesn't piss gas all over the floor or into my crankshaft (though I am going to change the oil after this anyways)

 

Yes, the carb kits come with enough fuel pipe o-rings for both the HSC32 (uses 6) and the HSC33 (uses 10) carbs.....so, 4 leftover for your model!

Whoops, sorry about that...........I can send you the extra shims if you still need them. Your carbs actually uses a total of 7 shims (there should have been 2 packs of 4 shims each....we normally send 8 shims, rather than 7, just because......)

On the HSC32, carbs #1, #2, and #4 use 2 shims per carb (one on each side), and the #3 carb uses only 1 shim. Thus, on HSC32 model carbs, there are a total of 7 shims used per entire carb rack. On the "other" side of the #3 carb, there's that really thick plastic spacer bushing that acts like a seal shim for that side of the carb body.

On threaded items that don't have "starter" threads, turn the fastener counter-clockwise (like you are removing it) and the threads will semi-automatically align themselves (you'll know it / feel it when it happens) and then start tightening them.

Ummm....not recommended. You need a perfectly flat surface to place the carb throats (or the airbox throats) onto so that the carbs stay FLAT....as in "really flat". Otherwise, the carb bodies will tend to start "walking" (twisting) in relation to each other when you go to install the upper or lower rack screws......and this throws off the alignment between the 4 throttle shafts, and that results in (at best) some butterflies staying open more than others, or some butterflies that can't ever close completely.

You have to get all 4 throttle shafts in a perfectly "straight thru" alignment with each other......imagine a perfect-fit (about 3/8") metal rod stuck thru all 4 carbs where the throttle shafts would be fitted......that's what you're shooting for. Now imagine one (or more) of the carb bodies twisting a bit while you're tightening down rack bracket screws.....while each individual carb body will still be "correct", all 4 will not be in alignment, and the overlap and meshing of those throttle shaft end brackets (which hold those pain-in-the-butt synch screws) won't be in proper alignment with each other, either.

A proper decision!

It's a better practice to verify the FUEL LEVELS, rather than simply checking the FLOAT HEIGHTS (what you called "float levels"). Proper fuel levels in the bowls are just as important as proper valve shim clearances, and mixture screw settings, and engine synch in terms of carb tuning.

https://www.xj4ever.com/setting fuel levels.pdf

And yes, fuel level setting is kind of a pain in the bowl, but.......typically you only have to do it once, and it remains pretty constant until the next time the fuel inlet valves are changed (or needles changed).

 

You also should inspect the rubber diaphragms for pinholes......in a darkened room, use a strong light behind the diaphragms and look at the diaphragms from the other side, and see if any light is shining thru. Pinholes will allow air (vacuum) to leak from one side of the diaphragm to the other side, and decrease the responsiveness of the piston to the vacuum signal.

 

If you have a good formica countertop, it may be flat enough to assemble the carbs on. Check flatness with a straight edge.

 

She doesn't, and I think she'd be angry if I put the carbs on the kitchen counter lol.

I could also use a known straight piece of stiff metal, and some clamps (ergo why I was initially thinking to use two stiff things of metal to sandwich the carbs between, and then use clamps to hold it in place. A table vice probably also would work to keep things from shifting.)

if the carbs are flat along their carb bodies on a true surface and they're stopped from moving, they shouldn't shift when the upper and lower rails are tightened, I assume.

 

That's what one would think, but unfortunately....not true!

The holes in the rack bracket are just a tiny bit (fractions of a mm) offset of true centers of the carb body threaded holes, and thus screwing the adjacent carb bodies together creates a repulsive tension......the carb bodies try to "run away" (gently) from each other.....and that's what causes the twisting effect. Without a completely level surface, the carb bodies will try to twist or "walk" away from each other.....amd unless restrained/constrained to their absolutely proper alignment with each other, you'll get some of the issues discussed previously. Clamping the carb throats and the airbox throats togther (each against a flat-and-true straight surface is ideal, but doing so might (will likely) interfere with installing the screws.....otherwise, it's an ideal solution.

Even with a flat piece of something that one end or other can be placed upon, you'll find when installing/tightening rack bracket screws you'll still need to put hand pressure on the "other" end (face) of the carbs to keep them all in alignment (flat against the surface) .

Pieces of somewhat thick glass (window glass, which you can get in small pieces at Home Depot, etc.) is about the cheapest truly flat surface which can be purchased (plate glass is remarkably flat due to the way it's produced).

 

I guess what I'm worried about is getting a plate of glass and pressing the carb along it, and then when I tighten one it shifts anyways, or the glass breaks.

I wonder if there's like a YouTube video of how someone did it?

I assume you'd need to tighten all of the screws within 10 minutes or so, I'm just not certain that I'm visualizing this process correctly. I'd imagine even against the plate of glass, you would tighten one and then it shifts all the others slightly.

https://www.xj4ever.com/hitachi throttle shaft seals.pdf

Page 28 was what I was originally talking about, sandwiching the carbs together as you tighten the rails

 

Always a possibility........but if you get the thick glass (1/8") then unless you start beating it with a hammer, it won't break unless you drop it on the floor........


I spent about 1/2-houron youtube looking for videos of "carb rack reassembly" and couldn't find a single one where (when they had actually taken the carb rack apart) that shows or mentions using and alignment plate (like Yamaha tells and shows on page 75 of the XJ650 service manual). Of course, some of the videos were for other model carbs, and what was most surprising is that only 2 of the 30 or so "complete rebuild" videos did the "expert" replace the throttle shaft seals while the racks were apart. I mean, many of these carbs that were being worked on are closing in on almost 50 years old! How in the world that they think that 50-year old pieces of rubber are still going to be viable enough to re-use....especially after going thru the entire effort to break the rack apart and re-assemble.....is beyond me....


But after a moment's reflection, I thought "let's see what mezzmo has to say"....he's very professional and anally-retentive (in a good way) about such things, and sure enough, right in the middle of his carb assembly video....in which he, unlike all the others, actually replace the throttle shaft seals (and installs them the right way, too)...right there at about the 14:00 minute mark, he tells and shows the importance of keeping the faces in alignment when tightening the rack bracket screws:

 

I feel like I have watched that rebuild series so many times. I guess it's time to watch it again.

I really wish that I had the space and the shop tool access like he does.

Edit: yeah what he did to his carbs is literally what I was going to do lol

Also anti seize and no loctite??