A 550 Newbie With Questions

Brought a 81 XJ 550 Seca with 25K (hoping it's not 125K, air cooled engines don't usually last that long, right?) last week.

Want to replace several items on the bike, beginning with the chain. The chain has been stretched to the max and still is loose, plus it's all rusty. The rear sprocket is worn but the front sprocket looks alright.

Now, I'm trying to figure what to do, buy chain and only the rear sprocket or chain and both sprockets. Next question, the rear sprocket on 81 seca has 46 teeth. So far I haven't been able to find a 46-tooth gear, only 45-tooth gears. I know about the gear ratio, but does it matter which gear count if I use the same chain, 530 x 104?

Lastly, should I opt for an o-ring chain or should an ordinary chain do? I know the former probably will last longer but is it worth the extra cost?

Where should I purchase the parts? Old Bike Barn or is there a cheaper site?

I have several more questions regarding the Seca but this will do for now.

Thanks for your time and hope I will like the bike as much as some of you seem to like yours.

 

Aircooled motors can last alot longer than 125K if they are looked after (regular filter and oil changes) unless they are HDs

One tooth should not matter and in the case of a 45 will gear up the bike slightly.

O ring chains last alot longer (up to 10 times longer maybe more) than normal chains, (this is why dirt bikes use them, a normal chain on a dirt bike is a waste of time) and is well worthg the extra cost. Only use o ring safe lube. Might as well replace both sprokets. You might have to use 1 less link.

 

Thanks.

Do all new chains come with a removeable link or should I purchase a tool to break and/or join the links? If I wanted to remove 1 link from the chain, I would have to use the tool anyway?

Yes, I'm new to the world of motorcycle mechanic.

 

You could also try BikeBandit.com and DennisKirk.com. IMHO, both are good sites with great prices.

 

According to most mfr's, a "Heavy Duty" chain will last 2X as long as a "standard" chain. A Heavy Duty aftermarket chain is the MINIMUM I'd opt for. They seem to run about $25-$50. Depending on mfr, O ring chains seem to be rated as lasting 8X longer than a std chain, and run about $80-$120 for a 530x104.

The front sprocket is the cheapest of the 3 parts. Plus if you replace both sprockets, at least you know they are a matched set (same mfr).

The aftermarket only seems to offer a 45 tooth rear (instead of the stock 46 tooth). Yet, you can find 3 variations on the front sprocket (15, 16, or 17 tooth available- 16 tooth is stock).
If you get the 45 tooth rear, and 16 tooth front, you're gear ratio only lowers by 3%. This will give you 3% lower rpm's at any given speed. In theory a lower ratio should give you better top end, but you probably wont notice the 3% difference.

 

Thanks for all your responses. Decided to go with a 16 and 45 combination along with a heavy duty chain, rather than an o-ring chain.

While taking the wheel apart, I discovered that a PO allowed the chain to stretch (or it could had been a wrong size in the first place) to the max AND still jump the gear and grind the aluminum housing next to the gear on the wheel. Also, the rubber protective shield on the gear shift shaft has been worn down about a half way. :roll:

Now, with new set of questions. Everytime I start up, the cylinder number two won't fire (the exhaust stack is cold). I know there are sparks because I get shocked whenever I try pull the cap off the plug. Maybe the carb is out of synch, too rich or lean?

I noticed this upon buying the bike and pointed it out to the PO and all he did was pull the cap off and turn the engine off (I guess from being shocked himself) then turn the engine back on. It worked then but I tried that myself later, didn't work for me.

Oh, one more thing. When the clutch lever is depressed down all the way, is the drive gear supposed to be completely detached as in turning loose or not turning at all because the gear on the Seca still turns with a small force (enough to prevent it from going forward in 1st) but with the bike on stand, it will turn. Is it supposed to be like in the car, completely neutral when depressed or is it allowed to still drive even when depressed completely (yes, I adjusted the cable to the max and to the stop).

Thanks for your help.