Any help for an FJ that won't start??

Hi folks,

I've been through the forums on this site front to back for the past 2 months or so. I found you all after purchasing an '85 FJ600. And now I'm asking for some assistance. I bought the bike knowing that it would need some work. The PO told me that the carb bank was taken off because the carbs needed to be synced, and he also provided a set of "aftermarket" carbs (that have no markings on them at all). The air box had been removed in favor of pod filters, the carbs were a complete mess, and the battery box had been all pulled out. I was looking to do some work on a bike, both for fun and for the learning experience (fairly new to bikes), so I took on the challenge.

First on my list was cleaning and rebuilding the carbs. This is something I had done before and was comfortable doing. After determining which set was stock, I cleaned every inch of the carbs, rebuilt them and put in new jets (it has essentially straight pipes on it right now). I discovered that one of the jets had been broken off inside one of my carbs, but some help from a friend who is helping me with the bike quickly remedied that issue. Put the carbs back together, cleaned out the tank and made sure the petcock was working, checked for spark, installed my battery, and tried to start it. It would crank forever and think about starting, but it would never quite get there, even with starter fluid.

So I hit the forums, and discovered the process of checking valve clearances. Not something I had done before, but thanks to you folks, it wasn't too bad a process. I am now 7/8 valves in spec (my I2 is still a hair tight, so I'm getting a different shim for it tonight), put everything back together and tried to start, but to no avail. It fired for a second or two on very high throttle at one point, but I think it might have just been starter fluid. We made sure the carbs were getting gas (which they were) and checked the spark plugs again (good spark). Because I'm new to this, I'm sort of at a loss for where to look next.

I have three initial questions:
#1: Would having 1 tight valve (my I2) keep the whole thing from starting? I was thinking that it would at least start, even if it ran poorly.

#2: I took the pod filters off the bike to go back to a stock airbox, but the airbox is not installed yet. Would that keep me from starting? Again, I assumed that it might run badly without it, but that it would at least run.

#3: I haven't set the float levels on the bike. They looked okay when we were rebuilding the carbs, but obviously that was just a look. Would setting the floats fix this issue?

Any help is appreciated.

 

I've only run into two situations where a bike wouldn't light starter fluid:

1) Very low compression.
2) Ignition timing 180 out, which I don't think you can make an FJ do.

I suppose it's possible you're dumping so much fuel that it is too rich to light the starter fluid, but I'd think you'd see it on your plugs.

One dead cylinder shouldn't keep it from running, even on the carbs.

 

As usual, Carl is right on.

Let's start with a compression test. If you don't have a compression tester, buy or borrow/rent one from the auto parts store. You'll need a 12mm plug hole adapter.

You can't fire a blown-up motor, let's see what's going on. My book says 142psi minimum, 156psi standard and 164psi maximum for the '84-'87 FJ600.

The one tight valve may throw off the reading in that cylinder.

 

Thanks for the responses. I'll get my new shim put in, and then I'll do a compression test. I have a friend who's got a compression tester, so I'll snag it from him. It might be a couple days, but I'll post back with results. Hopefully they aren't too depressing...

 

Quick question:

My understanding (which is limited) of compression testing is that it is best done with the engine warm. I assume that the numbers from the manual are also for a warm engine test. However, I am not able to get the bike to run long enough to warm the engine. Will cold compression testing also work? If so, are the numbers I'm shooting for different than otherwise?

Thanks.

 

The recommendation is "slightly warm" testing cold is fine, the difference should only be a few psi.

The main thing you're looking for is a glaring difference between cylinders, anything more than 10% (14 ~ 15psi.) Overall reading is nowhere near as important, as long as within spec; and it's a pretty wide range.

If they're all within 5 ~ 10 psi of each other and anywhere within range, the motor is "physically fit."

 

Good to know. And again, thanks for the info. I'm really enjoying this process, and it's nice to continue learning as I go. I'll post back with some results when I get a chance to do the compression test.

Josh

 

I forgot, there is one more reason an engine won't light starter fluid:

3) No spark.

Just because a plug will fire outside the engine doesn't mean it will fire inside the engine. New plugs are a cheap, try them.

 

2a) Ignition timing will be 180 out if the plug wires, coil wires, or pickup leads are switched.

 

Welcome aboard! You're gonna love it here. You'll never leave...........

Welcome to Hotel XJ-Fornia.................... (cue the Eagles)

Dave F

 

Ok folks, I've got a little info to share, and I'm hoping that maybe I can get some carbs identified as well.

So I did a compression test, results are as follows:

#1: 135 psi
#2: 120 psi
#3: 120 psi
#4: 75 psi

My manual says cold compression at sea level (I'm at 500 ft) says 100 psi minimum, 135 maximum, 121 standard, with a recommended maximum psi between cylinders of 14. So I'm thinking 1-3 are good. #4 is definitely low.

I'm also wondering if my carbs are actually stock or not. The bike came with two sets of carbs, and we were pretty sure that we had the right bank, but the markings on them are pretty minimal. I've attached some pictures below, maybe someone can verify that these are actual stock carbs? The bike will fire on starter fluid now and then dies after 3-5 seconds, so it feels like it's a fuel issue, which is why we're looking toward carbs, but any other thoughts are encouraged.

 

Anyone have thoughts on these carbs? Or thoughts on whether or not low compression in one cylinder would keep the bike from starting?

 

Low compression on one cylinder won't prevent starting. It can be difficult to even notice one dead hole on a 4 cylinder.

Hard to judge if the carbs are right when holding them unless you have a comparison in the other hand. Darn near impossible with pictures.

Regardless of the low cylinder and whether the carbs are incorrect - it should still light starting fluid.

 

This website and a couple others say it should have mikuni's;
http://www.motorcyclespecs.co.za/model/ ... 0%2084.htm
so those could be the right ones, don't quote me though. Are there any markings at all on the other carbs?

Like the others said, it should run with starting fluid, even minus the one cylinder. Check those floats to make sure it's not overloaded with gas as Carl suggested. Wouldn't hurt to check the coils for proper resistance so you can be sure you're getting a strong spark. Also, I'd try to get that air box back to stock with a stock filter. I only recently discovered how big of a difference it makes with my maxim x. Nearly impossible to get it to run right with a k&n.

 

One other thing:

Low voltage can crank the bike like mad, but not be high enough for the ignition module to function. Not a bad idea to have it jumped to a big battery or a booster box when troubleshooting.

With plugs removed the cranking draw will be reduced and there might be enough voltage for the ignition system to work.

 

Thanks to a couple of crazy work weeks, been a while since I've been able to even think about the bike. However, I did want to post a quick reply.

There are no other markings on the carbs that I have, other than the Mikuni brand that I posted above. I'm assuming that they are the right set, and we'll see if that works out for me or not.

As far as starting goes, it still doesn't want to run, but it will start on the starter fluid. It is acting as if it is starved for fuel, which is interesting, because when I open the drain screws I get plenty of fuel that drains out. I verified my float levels, and they seem to be good. I do know that I have one other thing that might be problematic: I had to replace one of the fuel tees (between carb 3 and 4) and the place I bought the replacement from sent me the wrong tee (there are two different ones, a shorter tee and a longer one). Thought I would try to make it work anyway, and it does fit place okay, but perhaps it's not actually doing its job properly. Once I find a replacement for that and get it in, I'll come back with results.

On the bright side, I've now got all winter to get it going for next season

 

The bike doesn't run on straight gas; it runs on a mixture of gas and air. Getting gas out the drain screws just means gas is getting to the carbs, not that it's mixing right and getting to the engine.

Be patient, you'll find it, and that's what winter is for! ^_^

 

When you cleaned the carbs did you make sure the enrichment jets (hidden in tiny wells on the float bowls) were clear? If these are blocked the "choke" will not have any effect & if you're currently trying to start it with pods then chances are it'd need all the enrichment it can get from cold... Just a thought.

Also, is it possible for the main & idle air jets to be accidentaly reversed on Mikunis like it is with Hitachis?

 

I'd like to revive this thread again...I'm the one helping Josh on this bike. In fact, it is still taking up real estate in my garage! I'm at my limit with 4 bikes in the garage!

One thing I would like to confirm is that the carbs are all stock. I know on some jet kits, the slides have to be drilled out. I'm not sure how this bike is. Can anyone share information about this? If the slides have to be drilled, what size should the be? It might be a stretch, but what size are the stock holes on the slides?

I'm going to adjust the float heights. I know before they were pretty close (within a couple millimeters), but I will get them within specification.

Also I tried installing the airbox, and still doesn't even try to fire up. Some advice on installing the airbox...some people say it is impossible without heating up the airbox removing the engine. I removed the front mounting bolts for the engine, rocked it down slightly, and the airbox will go in. Hopefully this helps someone in the future wondering about this.

Mike

 

First question: way back up the thread, compression test results were posted indicating one really soggy cylinder (75psi) but yet we're worrying about the carbs and trying to start the bike.

Wouldn't it make more sense to further diagnose the bad cylinder before trying to get the bike running? If it's really only making 75psi, then something is wrong and you're going to go to a lot of trouble to 'build' a 3-cylinder motorcycle.

As for the carbs, they are indeed supposed to be Mikunis; and if you're returning it to "more stock" configuration then don't worry about drilling the slides. Unless you have some reason to believe they were drilled then that's most likely not your issue. It does sound as though you have fuel delivery problems still; or possibly a flat battery or saturated plugs.

But if it were me, my primary concern would be determining the fate of the motor. Do a "wet" compression test and see what happens. Like I said, right now you're going to a lot of trouble to get a 3-cylinder motor running.

 

I have a 1982 XJ650 that has the same problem. It's like 45 degress out. I was working on it for about 30 minutes and all I got was a backfire. The gas was purchased 3 weeks ago. I must have gone through 5 cans of carb cleaner to try to get this bike to run. I used 2 cans on the fuel bowls alone. I had the cleaner shooting 25 feet or more. I even ran cleaner through the small pipe that goes into the jet in the fuel bowl getting the small holes on the sides. Compression is left to right 150 145 145 145 using a Mac Tools compression checker. The backwards petcock works as fuel flows freely with PRI. But the engine needs to be running when the petcock is ON or RES. It get nice fat blue spark. Has all of the componets needed to run but it won't start. It refuses to start even with starting fluid. If you read all the posts on this site you will see that the carbs are the main problems. That combined with YICS make this bike almost impossible to get it to run correctly. I am 45 years old and NEVER seen a bike this hard to work on. The engineers of the fuel system should be arrested for their poor design. It doesn't matter my bike is 32 years old there's no excuse for the bike not to run right. I even change the exhaust. The old exhaust had cherry bombs on them. They are now stock. I was worried about backpressure or the lack of it.

 

I would bet that the PO who put those cherry bombs on also changed the jets. What jets are in the carbs now?

 

K-moe, you give the PO too much credit.
altlandf, don't know if you do this but a lot of people start giving some throttle
when these don't start. as soon as you open the throttle you defeat the enrichment circuit. you got to have some fire before you give it throttle

 

Ohferchrissakes here we go again.

altlandf we've already heard your lame rants about Yamaha and Hitachi too many times for it to even be funny any more. We know all too well how you feel about the designs you can't wrap your head around. A typhoon still hasn't hit the Hitachi factory. Darn. Don't hijack the thread of a guy that's struggling with a Mikuni-equipped 600 that you know even less than nothing about. Take it to your own thread.

And Polock's right; once the carbs are properly set up, you don't TOUCH the throttle until it's running.

Now then; back to Josh and Mike's issues with the FJ600...

 

Ok, those are good places to start. I'll do a wet compression test, or maybe even a leakdown test if I have a dead cylinder. Also it is very good to know about not opening the throttle until it is running.

You never know with PO's, so knowing if they have been drilled or modified is something I wanted to figure out. But I agree with bigfitz52, the motor is probably a good place to start for now.

Josh and I are trying to decide if the bike is worth the effort right now, or just cut our losses and move on. I'll post up when I find more...hopefully this weekend.

 

There ya go; that was my point.

Per Josh:

"So I did a compression test, results are as follows:
#1: 135 psi
#2: 120 psi
#3: 120 psi
#4: 75 psi"

Something is amiss in #4. If its valves are in spec, then the "wet" compression test is next. That will at least tell us "valves or rings."

But the sorry truth is, with one cylinder that low, there is something truly wrong. Fixing it will involve at the very least pulling the head; it could be more serious (ring or piston.) In addition, #2 and #3 aren't exactly happy either, "minimum" spec is 142psi for the 600s.

My point is that there is no sense in wasting time and money on the carbs right now when you're dealing with a motor with one or more bad cylinders. Diagnose that; then decide if you want to explore fixing it, replacing the motor, or giving up on this particular bike.

Carb service alone won't "fix" this one. It's got a sick mill.

 

I suggest you add a couple of teaspoons of oil to your 4th cylinder and redo the compression test on that one cylinder. That way, at least you know if you might be dealing with a ring issue vs a valve issue.

 

They're all a bit low for that motor; I'd "wet-test" them all.

 

Sometimes just hearing the engine run will brighten your day - how to force-start a motorcycle:

Get a snow-free bit of road, downhill, and a friend to push,
Fully charge the battery,
Dry your plugs and blow-out any "wetness" in the CYL's
fog a SMALL amount of Starting Fluid in the airbox,
Grab a helmet and bump it in 2nd gear, throttle closed, choke "ON".

It'll light off - you may have to vary the choke and Ether amounts.

 

I wouldn't be trying to actually fire this one up (yet) it's only making 75psi in one cylinder. It would not only be an exercise in futility, it could further exacerbate whatever the problem is.

 

Sorry for the delayed response here...

I ran a standard compression test again, and revealed roughly the same numbers again - 130, 115, 125, and 70psi. A leakdown test reveals 5% leakage by the piston rings on cylinders 1-3, and 45% on cylinder 4.

Is it worth tearing into it to see the condition of the cylinders and pistons, and maybe get lucky and only have to install new rings? Sometimes I hate digging deeper into problematic engines, because it seems like I always find more things wrong than what I originally guess. And like we mentioned earlier, even with a good engine there are still other problems...carbs, brakes, possibly chain/sprockets, and I'm sure that list will continue to grow.

 

If you tear it down all you are out is time. The alternative is finding a good-used mill to transplant, which is going to cost you more than just your time.

 

I didn't see the results of the 'wet' compression tests, why don't you think the lack of comp' on 4 is valves ?

 

Seriously.

I went back and re-read the thread.

Right now we have an incomplete diagnosis; and if you pull it apart now you've lost a valuable opportunity to find more out first.

ARE THE VALVES IN SPEC OR NOT? Major question as it can throw off your compression readings (and a leak-down test even) if they aren't.

Do a "WET" compression test; the leak-down test is valuable, but a wet compression test will give us additional clues.

If any valve clearances are more than slightly tight, get them in spec and re-test BEFORE you tear into the motor.

-Yes, it might need rings.
-But it could just be some horribly out of spec valves.
-Or it may have a burnt valve or two; which is a lot cheaper to fix than new rings and cylinder honing, etc.

As of right now, you don't have enough information; don't flush away the chance to gain more insight by tearing it apart prematurely.

Especially if you're trying to do this as economically as possible.

 

We adjusted the valves and they are within spec with one exception. I think on #2 or #3 we had one with no clearance to start with, so it was a guessing game which shim to order (Josh, correct me if I'm wrong). I think we were one size off, so while we have clearance it is a little on the tight side.

What will a wet compression test do that the leakdown wont? Tell us it isn't the rings when it really is part of the problem? My understanding is that you do a regular compression test, and if it fails then the oil will narrow down that it isn't the rings that are the problem. Oil added + higher compression on a regular test means rings. Oil added + no change in compression means something else (head gasket, valves, or other head-specific problems).

I'm struggling to make sense of the advice on here, and not trying to make it a pain for you guys.

 

A wet test focuses on determining whether the rings are sealing or not. A leakdown test can be used to focus on the valves, when done wet. The perennial trouble with a leakdown test comes when there are leaks at multiple locations. It just gets incredibly difficult to hear where the leak is coming from, which is why I usually do a leakdown test wet, and after doing a normal wet-test to eliminate the rings as a leak source.

 

I ran a wet compression test and got these numbers: 150, 120, 140, 150psi. A wet leakdown on #4 reveals 12% leakage, and it still looks like rings. Maybe the oil isn't completely sealing the rings?

 

Or the valves need lapped. Or a little of both.

I'd be more concerned about #2. Are either of its valves out of spec still?

While nothing to write home about, those numbers aren't horrible from a cold motor that hasn't run in a while. Cylinders #1, 3 and 4 are within 10% of each other. If #2 still has some tight valves, get them in spec and re-test. Spin the motor a whole bunch to blow as much of the oil out as possible and get a "semi-wet" test. If they're all within 10% of each other you can try firing it up and see what happens. If it will run, even raggedy, get it slightly warm and re-test.

Meanwhile, if finances are a concern, do some research before you pull it apart. Figure out what rings would cost (if you can find them) and what the next oversize pistons (with rings) cost; plus call around and get some prices on boring/honing. Check pricing and availability on the necessary gaskets (or sets) and valve stem seals. Make sure you can find everything you'd need.

Then add it all up and decide if it would be cheaper to go shopping for another motor, or a parts bike with a better motor than it would be to do a valve job and/or top-end rebuild on this one.

 

I think #2 might have one valve out of spec by a couple thousandths. We have tried running it already in its current state, and has no sign of life in it whatsoever. That is why I was wondering about the carburetors and trying to understand what exactly it is that we have. I have no idea what has been done to them, and what concerns me is there was an extra set of carburetors included with the bike. They are different than the ones we believe are the stock carbs. So now I am suspicious of a previous owner who is a tinkerer, and wondering what the heck he's (or she's) done to the bike.

Josh is looking into what rings cost. My gut feeling is get rid of the bike altogether, before it turns into a money pit. Maybe Josh can part it out, or sell it to someone and get back most of his money. We're due for a talk on the bike's current situation. I think at this point, I don't have a lot of time to invest in a project like this one.

 

What you say may be true...or even more likely it isn't. Nothing short of a complete rebuild could create the "money-pit" you're talking about. This is not a car, nor is it a complicated motorcycle. More than likely whatever is wrong will cost you way less than a new bike, way less than a rebuild, and way less than a 2 hour trip to the ER!

Come on don't give up yet. How can you be so sure ii's an expensive fix when at this point you're not sure what is wrong. Your comment about the PO, and the mismatched carbs is a red-flag that says "CLUELESS PO SCREWS UP ANOTHER CLASSIC!!" But more importantly it also means that your road to fixing it might be much easier (read that cheaper) than you are currently imagining.

I can't tell you how many times I have picked up a "Basket Case" only to find out it was a relatively easy fix. Last year I bought a BMW that the PO was clearly wanting to unload because they thought it was terminal. They had taken it to 4 mechanics to fix the "CHECK" light believing it was an engine problem-ALL of the mechanics investigated and told the PO the engine was fine but they all also told her that they couldn't get the "Check Engine" light to go off. Well that "CHECK" light is NOT a "Check Engine" indicator-instead that light is a courtesy feature of BMW's that was ONLY indicating a burnt-out brake light bulb. So $2.75 later I had it fixed-I now have a BMW worth $4000 that I purchased for $1600!! I've had this very same type of experience with every Yamaha I've either purchased or helped fix over the last several years.

Let this site and members get you back on the road to believing! IT CAN BE DONE.

 

It depends on your definition of "money pit."

We were just discussing this in another thread. http://xjbikes.com/Forums/viewtopic/p=4 ... tml#400972

A basic yet complete recommissioning will run around $600 ~ $800 by the time all is said and done. For parts and a couple of tools; with you doing all the work. And assuming you have a good motor to begin with. A lot of folks consider this a "money pit" when in fact it's just what it costs to reverse the neglected maintenance and is to be expected regardless of what the bike cost to begin with.

So that expenditure was already going to be necessary although nobody may have realized it yet.

If you're going to do a top end rebuild, add another $600 or so to the price tag once all is said and done.

Josh needs to understand that this same basic cost-benefit equation will be present for ANY OLD BIKE he finds, not just XJ/FJ series Yamahas. Any bike more than about 6 or maybe 8 years old is going to require "recommissioning" to be safe and reliable; and there are costs associated with that. An old bike IS NOT an old car. You can usually start driving most old used cars whilst you whittle away at the "problems." Not so with old bikes. You have to do all of the "catch up" work FIRST.

You can probably fix this bike. But it's not gonna happen for a couple hundred bucks, even if the motor is salvageable. We haven't even begun to discuss things like brakes.

Please don't tear the motor apart unless you're prepared to go all-out and fix it. Sell it (complete) to someone better prepared to take on the task.