82 xj 650 will not start and compression too high

I have an 82 xj 650 I bought 2 years ago and had two great years of riding, but this year I rode it for two days and now it won't start, and I am having the most unusual symtoms: first the bike would run but was sounding irregular and poor power, like not all pistons firing, then the 1 & 2 cylinders stopped working, then the 1 2&3 cylinders stoped firing, Then only the #2 cylinder was firing, different every time I started the bike , now it won't start, the engine will start to turn over then backfire, I'm getting a spark at each plug, and there is gas on the plugs so fuel is getting in, I drained the carborator float bowls and reprimed the carb, in case float needle stuck , no effect, cannot keep bike going long enough to adjust idle or synch carbs. batery recharged, no effect, checked fuse box all good, did compression test; all 4 cylinders at 150 ?? last year compression was 100. The bike was stored in basement and polished and givel lots of TLC (claned carb float botls of tarnish, inspected floats and float needles and needle set , all good, carb cleaner sprayed into air and fuel jets, cam lobs inspected , fuel filter inspected and cleaned, all good) ,new plugs, new oil and filter, air filter new last summer , cleaned this spring , no obvious exaust obstructions, The only reason I can think for increased copression is if the timing belt broke and exaust valves are not opening , but I am guessing, any suggestions would be gretely apreciated. I love my bike and thios is killing me ......

bikerdave

 

Welcome to the forum Bikerdave!
I can't speculate on the compression issue but I would recommend pulling the carbs and doing a full rebuild. You'll need to check your fuel tank for corrosion also to see if you are getting trash into the carbs. Do you have an in-line filter installed?
I'm sure some members with more experience will chime in and give more detail on what to check.
Later

 

thanksfor the reply, already checked the tank fuel and filter and fuel line , no rust or crud. you may be right about rebuilding the car, it looked good from the under side when I removed the float bowls to clean, but I am new to carbs, I tried to mess with as little as posible as I cleaned but I may have created a problem!!!

Dave

 

Hows your oil level?

 

oil is good just replace oil and filter put in 3 quarts

 

3 quarts is a bit much. IIRC it should be 2300cc or about 2 1/2 quarts.

Still, that's not your problem.

On the compression - you are right at spec. HAPPY DAYS! Your reading from last year was probably incorrect. Or the rings were stuck or you did the valve clearances or something.

I'm not sure I'd tear into the carbs yet. The plugs on these are very touchy. I'd pull each plug, spray it with a shot of starting fluid. Then see if it starts.

I had pulled mine into the garage to do some stuff to it. When I was done it was only running on 1 cylinder. After a whole bunch of messing around I did the starter fluid trick on the plugs. Fired right up, and I've put about 500 miles on since.

 

That sounds great MiCarl , I hate to sound stupid but what is starting fluid? and thanks for the tip on the oil.

Dave

 

New Brunswick? Don't you guys get winter there?

It's an aerosol containing mostly ether. Often used in cold climates to help start a reluctant engine.

Around here it is available in the autoparts section of the major retailers, in the auto parts stores and in the little store inside most gas stations.

It can be used as a diagnostic tool too. If engine won't start a little shot in the air intake will tell you if you have spark.

 

Ohhhh we sure do get winter.....and lots of it. I will check for starting fluid. while I am trying to start the engine I spray in in the air intake ? or spray it inf first then start?

 

Be careful with the amount of starting fluid you squirt in there. Not too much or you can do some serious damage to the engine. Just enough to get it to fire. Think I would do a major cleaning on the plugs or just replace them.

 

The engines and plugs we have are designed to run very hot. Putting around the yard, or just pulling it in from the barn to the garage can foul the plugs quick. I was suggesting a quick squirt on each plug to clean it, let the excess run off before installing. They should just be damp.

You can also hit the air intake under the seat with a 2 second squirt, then try to start. If the bike fires up you know your problem is with the fuel system.

If your problem is with spark the bike won't run on the starting fluid.

 

Wet plugs, increase in compression, changing, ..............
I would guess that your carbs are flooding into your cylinders thru which ever valves are open at the time and due to less combustion chamber area, increasing compression!?

Just a wild guess.... every time the carbs flood the gas doesnt always end up in the oil only.

Has your petcock been in the Prime position? That would do it.

Remember this engine ran and ran well in the recent past, with no modifications since..... what changed?

I'd say the combustion chamber CC volume, maybe by liquid?!

Cheapest easiest thing to try in my opinion.

just my 2 cents

 

Good call Hvnbnd,

Thanks for all the help , I pulled the plugs and let the bike sit for 24 hours to let the gas evaporate out of the cylinders, used some starter fluid (as micarl suggested) and it started well. still rides a bit rough at low speeds but it is running , I am going to synch the carbs next and see if it rids a bit smoother.

Dave