Compression problem

[Big Blue]

Hi all,

Was hoping that some of you more mechanically savvy people can shed some light on this issue/treatment.

My '89 FJ has 32,000 miles on it and was running like a champ.  Always meticulously maintained, never beaten on.  It seems now that the power has been diminished quite a bit, and if I had to guess, I'd say a few of the cylinders are not firing quite right/if all.  The bike runs smooth, ie no rough idle, no smoke.  Upon acceleration, the juice just isn't there anymore-the throttle lags, not in the same way as when the cards were gunked-up (you know, that erratic throttle response) just lame.

Any suggestions as to what it could be (probably many things) and what the best next steps would be greatly appreciated.  Thanks for taking the time to read this and for any guidance. 

Ride safe,

Ray

[thuber3040]

oil level?
lifter noise? recently shimmed?
adjustable sprockets on cams?
engine noises any louder than the usual?

[Big Blue]

Thanks for the reply.  Oil level and engine and exhaust noises are normal.  As for the other things that you mentioned, i'm afraid that you have exceeded my technical knowledge base and I have no idea what those things are/mean My usual mechanic has always adjusted things as needed, but I'm afraid I can't vouch for whether or not those things have been done recently.  I don't think so, since I would have seen it on the bill. 

[thuber3040]

I would have your mechanic do a leak down test on the engine to check for loss of compression and or valves not sealing properly, that would be the first step towards an answer I should think. pretty simple, pull the plugs and attach a proper gauge setup and spin engine over.
This was a all of a sudden thing, or just noticed over time?

[Big Blue]

It happened pretty suddenly.  Oil change and new back tire, then never was really the same.  I'll check about those things.  Thanks for your time/input.

[thuber3040]

oil change?, is there a possibility that something is put in wrong, so there is lack of oil flow to the cylinders, that will cause a loss of compression, and will also eat the cylinders, maybe at least change the filter again to check it all inside, unless you have a spin on, I'm going that way asap

[Varget22]

It happened pretty suddenly.  Oil change and new back tire, then never was really the same.  I'll check about those things.  Thanks for your time/input.

Check to make sure you don't have too much oil. Bike level on ground? Let it set for a few minutes, then chect it at the window. Or is the chain too tight? Sit on the bike with your weight on it and make sure you have some slack. Either of these can have a big effect.

[xt550]

Has all the sparkplugs the same colour?
Water or some other foreign objects in fuel filter or carbs?

[Ratchet_72]

If there's too much oil you'll notice some smoking, other than that oil level won't make a noticeable  performance difference. I would go with carb problems/adjustments. The FJ carbs can be some finicky bitches. IMO.  
Compression testing is easy, all you need is a compression tester which is a reasonably priced tool that you really should not be without if you buy or work on a classic motorcycle OR car. Compression shouldn't be an issue on such a low mileage bike
Leakdown testing is a little more complicated but its something that you should put time into teaching yourself. There are tons of resources on the net to do just that a lot better than we can show you.
Make sure your tank is venting properly.
Make sure your carbs are sync'd properly (research threads as we've gone over this many times.)
Clean carbs while on the bike.
Check for stuck float and leaking fuel out of the overflows (more thread research.)