Seca650 No spark

When you say "lose" are you referring to the bolts themselves or the components inside? I can guarantee you the bolts are tightly on. Nevertheless, there is a seal that goes right in there but until I take it apart I will not know. The weird part is that when I go to check the gear oil it doesn't show any sign of getting low. I wonder if I put too much in there in the first place causing a little pressure to build up and therefore a leak. I'm thinking of just cleaning it up to see if more oil leaks out.

 

I don't think it would leak if loose as the unit is sealed and the connection between the swing-arm and housing is simply mechanical. If it were loose, I would think you'd get some weird vibrations and noises from it especially when accelerating and decelerating.

This is what I would do. You might just have a really small leak and you are looking at years of buildup.

If it is leaking, it will be easier to just swap the unit out vs. replacing the seals. There are a few seals and it requires fully dissembling the drive and rebuilding and setting the gear lash etc.

 

Do you mean swap the whole drive shaft unit out?

 

No, after the rear wheel is off, there are just 4 nuts and the shock absorber to remove. Swap the punkin.

depending on the driveshaft configuration, it may or may not come out with the final-drive— some have a retaining clip in the u-joint, others don’t. If there is a retaining clip the driveshaft will stay on the bike. If there isn’t, it will probably pull out with the punkin.

THAT said, the shaft may stay in the bike either way because there is a spring between the end of the shaft and the punkin that usually pushes the two apart when the four nuts are removed.

THAT said, if the shaft DOES come out with the drive, it is NOT attached. Just grab hold and pull it out. If it doesn’t want to release, it’s cuz of a sticky seal on the end of the shaft. Keep wiggling and pulling... it’s just stuck, not fastened.

When you go to reinstall—-

if the driveshaft did not come out, just bolt punkin back on.....you may need to rotate the inner splines just a bit to allow the shaft teeth to line up, but that’s simple.
If the shaft did come out, first you have to reinstall that, and that is a hassle. You’ll need to pull the u-joint boot back so you can access the u-joint and play the “line everything up right so the splines can slide all the way back in first” game. One the shaft is back in, the refer to the above paragraph.

dfox

 

With LA being on total lockdown I figured why not start on some motorcycle projects.

I am about to take apart the drive shaft housing to try and fix the oil leak (see pic). My goal is to replace the oil seal as seen in the diagram. After I remove the wheel and undo the nuts to the shaft housig will the shaft simply come out? Will that seal be easy to get to? This will be a first for me and I'm a little nervous since I love this bike so much.

 

While that seal is important as it keeps grease in the coupler and water/etc. out. It does not do anything to keep oil in the rear end. Look at the diagram for the rear gearbox.

Chacal does have the seal you show above on the shaft. It has metal in it and I had to cut mine off and press the new one on. Wasn’t a full shop press but I had to get creative.

 

Part 14 circled below is the oil seal for the input coupler. It appears you could remove the locking nut (part 17) etc. inside the coupler and pull the coupler (part 15) out and then pry out the seal but I have never done this procedure. Maybe someone else here has?

 

Unfortunately, I'm not sure if the leak is from the rear or front. I've checked the gear oil in the shaft several times to see if it has gotten lower and it hasn't changed one bit. My only guess is that it's coming from somewhere else. But as I think about it does the engine oil make it's way into the shaft drive?

 

What's the punkin?

 

Rear hub/rear gear housing/pumpkin/punkin

sorry, used local term

 

No the engine oil should not be. The shaft stays dry but is greased on both ends. Pull the rubber boot back at the motor and see if there is oil in there. If so then your seal on the motor is bad and could be running down inside the swing arm. I would suspect you’d have leakage at the boot though too.

Have you cleaned it up throughly and ridden to see if there is a significant leak?

 

No, not yet.

 

Would anybody know if the final drive for the Seca 650 is the same as the Seca Turbo and or Maxim. I'm going to do a swap. Can I use the final drive off an xj750 maxim/seca as well?

 

It’s the same on quite a few bikes:

https://www.partzilla.com/product/y...?ref=0c166f67cc929f59603e13c229cd7e26ffd09915

 

I believe they are the same

 

Thank you for that. I didn't see the XJ650LJ Turbo model on the list. Would you happen to know if it is the same?

 

It’s a different part number that only lists for the 82/83 turbo. I don’t know if that’s because it’s a different color or gear ratio etc. It may physically fit but I can’t answer that one.

 

Thanks everyone. There's a ton on ebay.


On a different note can anybody tell me what I'm doing wrong with installing my clutch cable. I can't seam to get enough tension. After attaching it I tighten both sides of the cable until I can't anymore and there is still a lot of slack left over (see pics). My last clutch cable did this too so I think I'm doing something wrong. The part number is correct. I should also mention that the spring that goes around the push lever axle right beneath the push lever is broken. Any tips would be great.

 

Well, that spring needs to be replaced. Then there is some preload that you need to put on that lever. You may need to re-index the arm, too. That all said, are you sure the cable is the correct cable? My bet is you have the wrong cable, unless you got it from LEN.

 

Re-indexing the arm made all the difference but you're right about that spring.

 

Your clutch safety switch is also popped out of perch I want to reinstall or replace it

 

That thing has been out for a while. What's it for??

 

it lets you start bike in gear when clutch is pulled in. with it poped out your bike may turn over when in gear with clutch not pulled. if switch has broken and is Open your bike will only start in neutral

 

I've been having an issue with the clutch. When I shift into 2nd gear, unless I find that sweet spot, it makes a ka-lack sound and it kind of hurts my toes. It also does the same thing going into 3rd and then smooths out for 4th and 5th. I tried adjusting the cable by tightening and loosening it. I'm wondering if I need new plates. Any thoughts on what I need to do?

 

I just did a valve check and one valve, the intake, measures at 0.16. It's suppose to be from 0.11 - 0.15. I don't mind fixing it but is it THAT important that I find a shim for that one valve or should I pretty much be okay?

 

do you know what shim you need?

if you use the inch measurement feelers it will be in spec. 0.006 =.15mm and.16mm

 

.16mm is OUT OF SPEC for an intake. You need to pull the shim to find out what size it is and then you need to go up one size.

 

that's what I wanted to hear, thanks

 

Yeah. The shim in there currently is 280. So I believe I need to go up a size to 285. I was just more curious how important/not important it is to change the shim being that all the 7 of the other shims are perfectly in spec.

 

In spec is in spec. Out of spec is out of spec.
If a clearance is out of spec, it needs to be put back in spec.

my concern, though, is this——normal usage dictates tha clearances will diminish, but yours has increased. There’s very few ways that can happen;
1.a wrong shim went in at the factory - unlikely
2.a wrong shim got installed by a PO - possible... there are some incorrect charts out there, but if it’s only one shim, it’s unlikely this is the reason
3. A shim went in that was marked wrong-unlikely but it can happen
4. You have a bent valve or valve stem causing some binding- very possible.

you need to do a compression test to see if it’s low on that cyl. With that great of a clearance, there’s no risk of riding on the cam so theoretically the valve is closed tight. You should have exceptional compression. If it seems to have lower compression, then I’d do a leakdown test to determine if it's that valve or not.

 

It's very possible that my incompetence is the culprit. I actually got the new shim and put it in . A 285 shim should have brought it down to .11mm, however, I couldn't even get a 10mm feeler gauge in there. So, I put back the 280 shim and it measured at .12mm which falls into spec. Why it initially measured at .16mm is beyond me. Nevertheless, I'm a happy man and the bike sounds AWESOME! thanks for your help.

 

could have been some oil under the shim

 

Do you stack feeler gauges to get the number? I have yet to find a set of metric gauges that doesn't require stacking to get some of the numbers. Therefore, I prefer to just use the SAE gauges that are easily obtained with the .001 increments.

 

I stack if needed, but I also wipe down each blade before stacking so there’s no false reading from dirt between the blades

 

Yes, I do stack the gauges. I try to wipe them down every time but maybe I missed something.

 

I'm working on replacing the fork seals. While I'm at it I thought I'd take a few measurements. According to the manual the spring length is suppose to be 23.86 inches. When I measured my springs they came out to just over 21 inches. Does this mean I need new springs? Would a heavier weight fork oil make up the difference in any way? Could I throw a spacer in there? I think I've seen them done with pvc pipe before.

 

I may be wrong about the length. According to Chacal's catalogue the springs are suppose to be 540.5mm which comes out to just over 21inches like mine so I guess I'm good and the manual is wrong?

 

21.28" straight from my 650 Seca manual

 

540.5mm 21.28 inches from manual 650 seca.

if it is to soft you can go up in oil wt.
or buy new springs

 

yes but only if you know whats in there to start with.

we have a member in recent post who is removing the added pipe because he feels the springs are to stiff. find thread and ask him how long his are

yes you can put a spacer in there.

 

It's interesting when we pick up these old bikes what kind of history it may have had before you bought it. The spring length that I mentioned in the above post were actually the springs of the forks that I purchased, NOT the ones that were currently on my bike. After taking apart MY forks (which I've done once before) to install new fork seals I measured the springs and they were barely 19 inches long!!! Why would someone put the wrong size springs in thier forks! I should've known something was off the first time I took them apart when I saw a pvc pipe as a spacer in there. I'll never learn. This explains why the handling was so poor on my Seca 650! Everyone raved about the handling and I just assumed this was good handling for 1982. It never occured to me that I had the wrong size springs in my forks. I obviously changed them and whoa! It's a whole new bike! I can lean easier in the corners. Oh man! I'm a happy guy. So all is good in my world. Thanks everyone. One more job before I start detailing the bike...new fuse box.

FYI, pvc spacers do NOT work.

 

Yes they do - they "space" don't they? They didn't work in your application, who knows why - what was the rate of this rogue spring? Exactly, who knows. Suspension design is a complicated subject, it ties in machine weight, rake, rider weight, damping oil viscosity, spring rate (as you've found), and damper technology.
This last one is a bit of a misnomer as applied to these ancient designs - it's a wonder they work at all considering what's inside them. So it should come as no surprise that changing one major item could upset this delicate ballance.

 

I just installed RaceTech springs in my Turbo (FZ600 forks) and they were considerably shorter than the OEM springs, necessitating a spacer.
Stiffer springs are a huge upgrade on these old forks. Don't throw out those springs, they are probably Progressive Suspension or RaceTech.

 

I wish I took a picture to compare the two different springs. All I can say is that the bike rides way better since changing back to the original springs. It also stopped tramlining which was a HUGE problem riding on the freeway. Every time I would hit a groove in the road while changing lanes I felt like a quick Hail Mary was in order. The bike would jostle all around like it got tank slapped. I also put 20w fork oil in there and the manual asks for 10w. It's what I happen to have lying around. Anyway, I have an extra pair of Seca 650 forks if anybody wants them.

 

the stiffer springs will certainly give you a more sporting ride, but as you say they will track road imperfections for sure.
Too often these old bikes with the original springs use up half their suspension travel just pulling them off the centre stand.
Personally I like going with the stiffer spring and 10W oil.

 

Because I had leaky fork seals for the past 9 months. Fork oil saturated my brake pads. Do I need new pads now? Is there a way I can salvage the pads I currently have on the bike?

 

Get new ones

 

no get new pads. oil does not work well with brake pads

 

Noted. thanks.

 

Never a dull moment on my Seca 650. My carbs are virgin carburetors. The welch plugs are still in them. Since I got the bike it's always been just slightly lean but not really a big deal. I decided to get the plugs out of there and turn the screws just a hair to get a little richer mixture. I have only done carbs 1 and 2 so far. The first carb came out to a little over 1 1/2 turns. Carb 2 was <1/2 a turn, I kid you not. Factory spec! 1/2 a turn. At first I was going to turn the screws out but I noticed there was a little dirt on the needle of the mixture screw so I'm thinking I should stay at spec and just clean everything up but I'm curious about Carb 2. Should I leave that at spec? only 1/2 a turn out?