'82 XJ650R Seca questions...

I've bought an '82 Seca as my first bike and while it runs great despite a small head seep I do have some questions that I'm hoping people can answer for me.

1) Twice now on a grassy hill I've stalled this thing and no matter how much gas I give it the tail end seems locked up until I point her downhill. I'm not sure where to look for this problem.

2) Someone replaced the speedo before I got it and it's a 120mph one while all the ones online I've seen are 80 mph. That the speedo doesn't read right does not surprise me. I take it there's never been a 120mph speedo and someone put an RD250 one in there or something?

3) I can't seem to turn the choke all the way off without killing the bike. My normal idle is around 1500 but I can open the choke and it will drop to about 1100 but then I have stall problems with the bike when stopping. I'm betting this is gummed up carb jets but I'd like someone else's opinion.

All-in-all I love the bike! When I got it it ran horrible in the lower ranges especially when taking off. That turned out to be someone had put float #1 upside down. (Yes - it was upside down.) No gas for carb #1 made her of course run like crap. Once I fixed that it was hard to keep the bike under me when taking off! ;-)

I'd say I got a deal for $500...

 

Welcome aboard! Yep , you got a deal for $500.
Ok first the stalling and running downhill. Ran into this before and it turned out to be the float level was too low. Point the bike downhill and the fuel that rushes forward heads for the cylinders.
2. Speedo. A law was passed back in the 80's mandating that all M.C. speedo's only read up to 85. So a 120 might work if the RPM of the speedo matches the gear in the front fork.
3. Choke, the choke on these engines is actually an enrichment circuit. It adds fuel to the mixture instead of restricting air. So it sounds like your carbs are starving your engine of fuel. There is a links section on this website where you can find sites that will greatly help you in cleaning the carbs. You may get by with a Seafoam treatment and a check of the float levels. Seafoam is a carb cleaner that we have found to work quite well while not harming anything in our fuel systems. Initial treatment is half a can in one gallon of gas. run the engine smokes , denoting that the Seafoam has entered the carbs and let it sit over night. Next day fil the tnk with fuel to dilute the Seafoam for riding and ride for at least 50 miles. If the bike's performance improves keep going. If not pull and clean the carbs.

 

Thanks! I think it was a pretty good deal!

I don't think that's what's happening. The bike runs just fine but won't move when stuck on an uphill. It's almost like the rear is locked as if the u-joint were locked up or something. The minute I take load off the tail it'll move again.

I suspected this so maybe the gear I have coming from E-bay will make a difference. But I doubt it's the right one as it's off a Seca Turbo of the same year. I ordered it before I realized the speedometer was wrong. I'm watching a gauge cluster up for auction right now that has the right speedo in it. Hopefully that won't cost me too much.

I'll have to look for Seafoam but adjusting the carbs is something I definitely have to do as someone replaced the air box with individual cleaners. After reading through the forums so far I realize that without re-adjusting the carbs this might be part of my problem.

 

[quote="nimitz
I don't think that's what's happening. The bike runs just fine but won't move when stuck on an uphill. It's almost like the rear is locked as if the u-joint were locked up or something. The minute I take load off the tail it'll move again.[/quote]

Haven't heard of this before. Ujoint may be it. Does it try to move or does it kill the engine if you let the clutch out?

 

It tries to move a little but yeahit basically kills when I let the clutch out.

 

Well that pretty much leaves the clutch out. So it would appear that either the driveshaft ujoint or the final drive has a problem. Not my area of expertise. I can suggest the ujoint be checked for play. Quick check is to put the bike on the center stand, put bike in gear and rotate wheel to see if the ujoint has excessive play. Other way is to also remove the ujoint boot and visually check. Other than that, Robert may be the one needed here.

 

Nimitz, you mention an ability to let the clutch out when pointed down hill but stalling when facing up hill. I'm in agreement with BlueMax, he hit the nail on the head with your floats. Physical failure of the rear end is just about unheard of (with the exception of someone monkeying with it, in which case all bets are off). You need to verify the soundness of the rear end if you are able to confirm the float settings are correct (and it sounds like you've been in the carbs already so I'm expecting you'll verify that). Given that the boob before you was running the floats upsidedown (How in the Heck???), I'm laying odds the rest of the carbs are screwed up in one fashion or another. A through going through is indicated (check jet sizes and locations, complete cleaning and verify the settings of the air/fuel screws).
I'm afraid your recommendation is going to be a sour note, BlueMax. I'm not any more enlightened than you are on this one Max. I am thinking that the shaft joint is jamming up when placed under load. Bad bearings or the yolk is loose (bolts or the spline, take your pick, either one is bad news). I'd love to be able to be there, this is a brain teaser for sure.

 

It's not a stall per-se but as if I'd killed the engine using the kill switch. It's that sudden. And she accellerates up hills just fine - I just can't get her moving again if I kill her on a hill.

I'm going to dig into the rear end this weekend hopefully. At the very least I'm going to change out the oil in there with some GL-4 if I can find some locally. I should probably do a full oil change because I haven't done one yet - my bad.

That would not surprise me one bit as I'm unable to get the bike to run with the choke fully off. And it was only the number 1 carb that I found the float upside down on. But yeah I'm going to have to take those apart and clean the heck out of them. Which means I need a colortune, a YICS tool, and some carb sticks. Anybody want to put together a Carb Clinic out in the Midwest?

That said I've decided to leave the pods on there if I'm going to tune the carb. The air box is already out of there and that leaves me space to mount other geeky things like a small maintenance charger and maybe even a remote mp3 player with speakers on tank. (Yep. Me==geek.)

Like I said, I'll dig into it. I'm sure I'll be able to find the cause.

As for the info - any info is better than none. At the very least it's nice to know that I'm not out here all alone with this model bike. ;-)

 

You dont need a yics tool, an 82 seca did not have this feature.

 

Not quite correct firebrick, the 82 SILVER Seca didn't have YICS but later in the year, Yamaha relased the 82 RED Seca that did have YICS.

Rob

 

Indeed. Mine is silver and it suddenly occurs to me that I don't recall seeing a YICS logo on it. But as usual I'll check just to make sure before I do the carbs.

 

AH, but this was the RJC model (had one) and as the Red Rose commercial used to say; "only in Canada?........pitty"

All Yamaha mechanical speedometers are geared the same, you can install one from another model without issues assuming the unit itself is working as it should. More likely is that you have the wrong gear unit and or the cable needs to be lubed or replaced. Is it reading high or low?

 

It's reading low and responding slowly. And since this speedometer reads 120 instead of 80 max speed I have a hard time believeing that it will match the standard gear. I have another gear coming but I've already lubed the cable to no avail so I don't see a new gear making a difference.

The speedometer looks like it's out of an RD250 but put into the XJ "can". I'll post a picture maybe when I get a chance to set up my gallery.

 

Reading too slow is a common problem with old speedos that tend to slow down when the grease inside dries up. A 120 is just an 80 with a wider scale. If it's reading too slow it needs to be cleaned and lubed. That usually means you have to get it open in order to spray some degreaser on the gears inside then a shot of light oil or WD-40 will usually get it going again.

 

So what you're saying is that I should wait on buying the gauge cluster off E-Bay? :wink:

I was going to wait and try the other speedo gear anyway.

I don't understand the whole range thing though because I know you have to match speedo gears in cars to the speedometer or they won't read right. Why isn't that the case here?

 

Dunno about cars but all Yamaha mechanical speedometers operate on 2245rpm = 60mph. All bikes of the (same model) regardless of the market they were sold in (whether displaying in miles or kilometers) have the same drive gears. On a metric one the internal gearing is the same for the speedometer but different on the odometer. On a US 85mph speedometer the internal gearing to the speedometer will be different in order for it to operate though the full range of motion. If any of the components become dry due to lack of lube there will be an error. Lube your drive unit, put on a new cable (sometimes they are beyond lubing) and failing that the speedometer will either need replacing or need to be taken apart and lubed.

 

Yeah but my speedometer is definitely the wrong model. After looking through many pictures it's almost certainly off an RD250.

If it's designed for a drive gear from an RD250 then lubing it shouldn't make a difference. Or at least that's my thinking anyway.

Regardless I'll try your suggestions but I'm just trying to get a better picture in my head to understand the concept.

 

It suddenly occurs to me to ask if a gear from and RD250 will fit the front wheel of my JX. Is that possible?

All-in-all it would be a plus to have a 120mph speedometer even if I'll likely never have the bike up to that speed. :wink:

 

Bingo! I found the damn thing on E-Bay!

Here is what I've got speedo wise on that bike:

http://shorterlink.org/1012

Weird. Someone put a really really old speedo on that bike to replace the original. :?

 

You are missing the point. ALL speedometer units are driven at the same speed, the difference in drive gear units is to account for different size (diamter) or wheel/tire combo's. If you have the stock front wheel and correct size tire fitted, the correct drive gear then you can install any speedometer unit and assuming it is working as it should it will read correctly regardless of whether it is the stock 85mph one or something else.

That said you have something from an RD or XS series that doesn't match you tachometer. Since it isn't working correctly and doesn't match, if it were me I would change it to something that will match up to the tach in appearance. The models you can look at at from the years 1978 and 1979 (earlier will look like what you have and later will be 85mph)

XS650 - 120mph
XS750 - 140mph
XS850 - 140mph
XS1100 - 160mph
XS400 - 120mph
SR500 - 120mph
RD400 - 120mph (1979 only)

 

Ok. Think I've got that now.

The speedo doesn't look out of place so I suspect someone switched it into the right cover but as I said I need to dig a little and take pictures.

Regardless this is all pointing me to my first inclination which was to replace the gear cluster alltogether. Either that or get/make a digital.