Seca650 No spark

if that is where it works thats where its set.

mix screw is used to change the opening size/flow throughm the little hole in the carb throat. it fine tunes the circuit. then the 2-1/2 turn starting point is not used

could be that when the orings were new 1/2 turn was 2-1/2 turns, that spec is just a starting point.
could be the lower threads are gummed up not allowing you to go lower 38 years untouched.

could also be you have a set of carbs with corse threads on the mixture screw

xj4ever
Thus the standard advice of using the 2.5-to-3 turns out (from bottoming) as a "starting point" for the idle mixture screw setting is really based on the use of the fine-pitched screws; the earlier coarse-pitch screws would need to be initially set at about 1.5-to-2 turns out as an initial starting point.

 

Thanks for replying. I just managed to remove the plug for Carb 3 and 4. Carb 3 was just under 3 full turns and Carb 4 was just under 4turns! And both those spark plugs look lean! I like your idea that maybe it was gummed up on Carb 2 not allowing it to fully seat but my instinct while turning the screw doesn't tell me that was it. Who knows.
I may just put them ALL at 2.5 and see what happens. Mixture screws have been the one thing no one can really tell how to do even with the Colortune. It seems experience on those things are the best teacher.

 

I just ordered a CarbTune but earlier I would check the plugs and make small adjustments to the screws after a ride. I really can't tell much from engine sounds to make adjustments because there is no discernable change while even making radical screw adjustments. At the Carb Clinic a CarbTune was use and lo and behold, all cylinders were bunsen blue. Lucky. CarbTune on the way still because I will need it on my son's Kawasaki.

 

That Was the Colortune. And yes, you had dialed them in pretty good by plug chops

 

Nice catch on the typo. Thanks for setting the record straight. I also hate when things don't to make sense.

 

Are the respective gauge wires the same for either side of the fuse box? I'm getting all the materials I need to replace the fuse box. I had ordered one of Len's kits last time I did this and I have a lot of the wires left over. For some reason I feel like one of the wires, maybe the brown wire, is a larger gauge on one side then it's opposites.

 

Can someoe please please PLEASE tell me why my front calipers are dragging. No matter what combination I put them on in the end they just drag all day. The funny thing is that they were working fine before. I took the pistons out and polished them up. There was no calcification inside the piston chamber but I took the seals out to inspect them and they're fine. I cleaned and lubed up the caliper sleeve so now they move nice and freely. I bled the brake lines and put fresh brake fluid. Not to mention messed up my new paint job on the Master Cylinder from constantly filling it up with brake fluid, grrrrrr. I also took a piece of thin guitar string and went into that little pin hole in the Master Cylinder to make sure that is clean. .
As far as reinstalling I would first tighten the axle then I would squeeze the brake lever to allow the calipers to find it's center before tightening the pinch bolts but after I squeeze the brake they would not retract enough to stop putting pressure on the rotor. They just squeeze up and never let go. I put on brand new steel braided brake lines about a year ago. Everything is clean with no leaks. What in the heck is going on? What am I missing? If I could have all the time back that I have put into installing calipers I'm almost sure it would be close to a year. Someone please help me.

 

From what you have written, there still seems to be pressure on the brakes. Test it by letting pressure out of one of the bleeder bolt and see if they let lose. If they do, then you may have to take the MC all the way apart to make sure there is no blockage??? When you put new clear fluid in the MC when you pump the lever you don't see any cloudy fluid come up from the little hole? That would be a sign there is stuff on the plunger inside the MC still.

If letting fluid out of the bleeder bolt does not fix the issue, see if you can move the calibers with your hands. As you pull and push them do they move freely?

You didn't put new bake disks on the bike? Something too thick? Just trying to help you find the issue.

 

I may be overthinking this. A friend of mine just said that it's fine so I'm not going to worry about this. Thanks for responding.

 

what did you lube it with? and removed seals but never replaced with new?

 

Sil-glyde from Napa Auto Parts. I kept the seals as they didn't seem to hinder the action of the piston going back and forth.

 

Check that the return port in the master cylinder isn't clogged.
Get new seals.

 

I'm pretty sure the brake calipers are fine. A friend told me to feel the rotors after a ride to see if they're hot. They're cold. Not going to worry.

So now I'm on to the rear shocks. I still have the original shocks on my bike. How do these things go bad? Does the spring just get so depressed that they have no more give? Can they be rebuilt? I don't think these shocks have oil in them. I'd much rather stay stock in the interest of money but I also don't want to kill my butt. If anybody can educate me on rear shock performance that'd be great.

 

oil leaks out springs get weak not rebuildable

 

Breaks >>> engine. Stopping is the most important.

 

How would I know there is no more oil in them? It's the same oil from 38 years ago? Doesn't it go bad? Oddly enough there isn't a whole lot of info on rear shocks on the internet. I'm surprised.

 

If the oil is low the back end will bounce while you ride, almost like a pogo-stick.

Mineral oil does not go bad, but the rubber seals age and then stuff leaks out. Wear also adds small bits of metal and plastic to the oil, which hampers performance.

 

oil leaks out with every stroke if your lucky you will see it on the pavement before its all gone.
your not going to find any rebuild info they were not made to be rebuilt.

 

Just did a compression test with my 650 and also checked the plugs. overall I'm pretty satisfied with the bike. I'm planning on doing a cross-country trip on my Seca 650 next may. Anyway, here are the results of my compression test:

#1) 131 psi
#2) 140
#3) 129
#4) 141

Also, I took a pic of the spark plugs while they were out of the bike. Look a little lean to me but what do you guys think?
Thanks in advance.
MrSeca

 

It seems there are so many discrepancies with float height and everything I find is so unclear so I just need to put this to rest in my head. Referring to the picture below am I trying to get the fuel level to match with the yellow, green, or red dot?

 

you measure down from the edge of the carb body (green dot)

http://xjbikes.wikidot.com/carb-specs wet sets specs listed in link

all 650 and 750
Fuel Level in float bowls: 3mm +/- 1mm (.118" +/- .039")
so 3mm down from the lip(green dot)

range is 2mm to 4 mm below lip

 

for the 900
Fuel Level in float bowls: 5.0mm +/- 1mm (.197" +/- .039")
so 5mm down from lip 4 to 6 mm using +- spec

 

As per a couple lengthy phone calls, I think we got some direction going, and some things cleared up to do

 

yes sir. I believe my problems are stemming from the float heights. I thought I knew what I was doing. I'll be readjusting those heights soon. Thank you again.

 

I seem to have a fracture in one of the pipes coming of the oil cooler. I beleive they're made out of aluminum. Any ideas how to remedy that situation?

I've found some stock oil cooler lines to an xj750's, xj600, and xj900. Would any of those work?

 

Get a new one

 

oil cooler pipe ends are brass, solder it up.


sorry just seen its the oil cooler end thats fractured. the actual pipe union is steel, the solid pipe is brass.
the oil cooler coupler is aluminium

 

Are there any tutorials regarding changing the swing arm bearings? I want to know if I can do it without removing the drive shaft inside the swing arm.

 

I removed the swing arm. I disconnected the four bolts under the drive shaft boot and took it off so I could lubricate the drive shaft splines at the same time. With the drive shaft on the bench you can remove the bearing race on the drive shaft side easier. That is how I did mine.

 

Was it easy to take the drive shaft out of the swing arm?

 

Yes.

 

Disconnect the universal joint by removing the four bolts and the four nuts holding the hub to the swinging arm. On reassembly fit the universal joint to the shaft splines before fitting the assembly to the frame otherwise it will be much more difficult to get the splines on the driveshaft to align with the splines on the joint. Use Moly grease on the splines.

 

Driveshaft just slides out of the u-joint.
The trickier part is lining it up to put it back in… But I would recommend taking the rear gear off, install the swingarm, then reinstall the rear gear and the driveshaft

 

Be aware that the driveshaft splines (at the u-joint end) has a small (very small) wire CIRCLIP (two, actually) that restrains any forward or rearward movement of the driveshaft in relation to the cross-joint......the circlip behind the u-joint (on the driveshaft) isn't a concern when removing the driveshaft from the joint, but the forward circlip will prevent the shaft from being extracted towards the rear. It's small, and it's embedded within the splines, and it's tough to see and to remove with the parts still on the bike (boot must be removed, things must be clean (so you can see it), a very small pick and lots of patience (and a good supply of curse words) are required.

 

Some have that, some dont

 

That is correct, I believe that the 900's are one of the models that do use the "forward" retaining circlip.

 

I didn't know about that, the driveshaft was easy to remove on my machine. Now l am thinking a PO mabe removed it or is it damaged. Need to check it now before l run it.

 

Here they are. Number 41.

 

Well, perhaps not all of the 900's used the before-and-after clips..............as Dave pointed out, not all models used the "forward" clip, and the driveshafts on such models do not have the machined land for the clip, either. The later model XJ900's may not have used that forward clip either, just not sure.........the Norte Americano XJ900 models did use the forward clip.

When you think about it, the rear clip is actually more important, as it's the only thing preventing the driveshaft from moving up into the cross-joint....a Very Bad Thing. The forward circlip prevents rear-ward movement of the driveshaft, which is already constrained by the final drive unit.....which is probably why some earlier models didn't use it, but then I guess it was decided that it's not an expensive part to add (and to machine the groove for it into the shaft), and it's a good idea to have one there, too.......

 

My machine is a 4BB1 sold in 1991 so perhaps it does not have the forward clip. As long as nothing can be damaged and as you state the rear clip is more important thanks Len.

 

I just replaced my original XJ650 Seca final drive with the Turbo’s final drive.
I couldn’t pull the drive shaft out of the original so I used the Turbo’s drive shaft to. It was in 2 easy pieces, did I miss a circlip I wonder?

 

The turbo drive shaft I used came from own Turbo which was all pretty much original so I think the 2 650 Seca’s differ there.
I would remember removing the clip if it was there

 

Here is a schematic from the 650 seca which has three clips.

https://www.cmsnl.com/yamaha-xj650r-seca-1982-c-usa_model8877/partslist/D-06.html

The 900f has two on this schematic has parts 34 and 35.

https://www.cmsnl.com/yamaha-xj900f-1992-4bb2-france-224bb-351f2_model38008/partslist/0025.html

So is it clip 36 on the 650 that @chacal is referring to? Looks like it is not the full circumference of the groove it will sit in which might make it easier to remove.

I could remove the driveshaft of my 900f easily from the universal joint splines. But the 650 Seca non turbo has three clips parts 34, 35 and 36. I wonder @Simmy if that is the reason you could not remove the shaft from the universal joint splines? I could not find details on the Turbo driveshaft. Do any of you have a schematic on it to see how many clips are there? These internet links are not working on my phone but are on my computer.

 

My u joint just slipped right off the drive shaft.
I have currently disassembled the engine block on my xj900 (replacing cracked starter clutch). After removing the engine, I went to inspect the u-joint and the thing just slipped right off the drive shaft splines. No circlip whatsoever. After looking on a parts diagram it DOES show that they're supposed to be there, but I didn't have any issues with the drive shaft prior to engine disassembly so I just assume the driveshaft is just going to slip back on to the u joint and I feel I don't have to worry about any circlips.

 

I didn't say that.
The drive shaft slipped right out of the U-joint on both standard 650 Seca and the Turbo.
The drive shaft was clipped to the final drive on the standard 650 Seca but not on the Turbo.
Rather than determine how it was fastened together I just replaced the final drive and the driveshaft, from one which was clipped together (RJ) with one in 2 pieces (LJ).
The schematics do show clip #36 for the RJ and not there on the LJ but also list it as unavailable.
All those parts slip all the way down the driveshaft to the final drive end, in the schematic it could be misinterpreted to look like they belong at the U-joint end.

 

Good points I misunderstood what you meant.