Gunson Colortune Issues

it is an oil drain that no one attempts to remove because it shears off, your very lucky it did not. that drain is to remove the last of the oil in motor that will not drain from main oil plug it is a very small amount of oil . it is why when you look at oil spec you see 3 quanities, total oil , oil with filter and oil change only.

and just a little tip . when oil is drained turn on your key to see if oil light comes on . this is a test to see if oil switch is working.

I had a bad diode block and my XK550RJ started to turn over when I did this test.

 

Thanks @XJ550H

Any suggestions on the smoke and no adjustment in the mixture screw? Before it was running rich (yellow/blue) all the time, now it won't run yellow and only runs blue.

btw, it has been Carbtuned so I know that's good to go, but it is slightly erratic where some cylinders will drop in vacuum pressure (1/2) compared to 3/4, but other times they are all the same.

 

Did you put the vacuum caps back on?

 

Can I Carbtune it and Colortune it at the same time? Because the Carbtune tubes would be taking the place of the vacuum caps right?

 

I wouldnt—- we did do a bike with 4 colortunes on it one time... theoretically it would work but it it didn’t really. It sure looked cool though——-

 

Hahaha that’s awesome, good to know though, I’ll see about messing with it tomorrow

 

So been messing with the bike:
Right now it’s warmed up (hot) and if I add the slightest amount of choke it dies instantly. Carbtune readings are posted but still move around some. I am running an auxiliary fuel tank as I tune it.

Colortune still isn’t really working. C1 I have all blue all the time (went out to 5+ turns) and still blue. C2 same deal. C3 I can’t remember lol C4 was yellow/blue but when I went all the way in to bottomed put it was Bunsen blue so 0 turns.

Any ideas? I’d check the valve clearances but I’m worried I’ll damage and have to replace the head gasket. I’ll check them if that’s the only option but I’d prefer if it was something else.

Images are plug 2 and 4. I’ll take it for a ride and plug the plugs and see what they look like.

 

If adjusting the pilot mixture screw has no effect, the your pilot mixture circuit is clogged (typically, internally) or there is some other issue with it (wrong sized jets, o-ring missing, etc.). I assume the spark plugs are black/sooty (rather than oily).

Cylinder 4 is getting fuel from somewhere besides the pilot circuit, either the choke plunger isn't fully seating, the bore or plunger tip is worn, or the fuel levels in the bowls is way too high.

 

Here are the plugs and corresponding turns out.

Initially, it ran the best it ever has, super smooth, great sound, everything. After a few mins, I noticed that it was bogging taking off from a standstill and then when I would really get on it, it would bog and run rough then take off. The long the ride went, the higher the idle would be when at a stop. Starting off it was 1200 and by the end it was around 1700 but wanted to stay higher than that at times.

 

RICH, LEAN, or possibly even ritually UNCLEAN or OBSCENE: THE CARB REBUILDING FAQ:

Let us begin by warning you, though: an engine that is out of synch may perform AS IF it has a lean, or a rich, or a hanging idle, or a no-idle, or a run-away idle, or any variety of different conditions------if your engine (carbs) have not been synched, then that at is the #1 issue that you should attend to first, before you even READ any of the guidelines below and go and try to adjust and fiddle with things and change settings THAT AREN'T THE CAUSE OF THE REAL PROBLEM!!

And here are a couple of very good visuals of how a Hitachi or Mikuni CV ("constant velocity") carb actually works. For those of us who are not intimately familiar with these carbs, these videos provide a great basic understanding of what is actually "going on" with your carbs:









Question #1: Why Isn't It Running Right?:

Below is a semi-useful "general rules-of-thumb" list to help you recognize and diagnose fuel-mixture problems.

All of these descriptions assume that the carburetors are cleaned and operating properly, are stock (no jet kit), the valves are adjusted properly, and the engine has been synched.

If any of the above procedures, tasks, actions, or activities have NOT been checked or performed, then do them first, or otherwise all your other efforts will barely even give you "casino odds" at striking it rich and determining what the real cause(s) of your symptoms are......

Here are the 3 rules you should always follow whenever trying to troubleshoot [i[anytime[/i]:





Typical Symptoms and Causes of a Lean Fuel-Mixture Condition:

- Poor acceleration; the engine feels flat.

- The engine won't respond when the throttle is snapped open, but it picks up speed as the throttle is closed. (A too-large main jet also mimics this symptom.)

- Idle speed falls after you blip the throttle, then creeps back up.

- The engine runs hot, knocks, pings and overheats.

- A lean pilot circuit condition can be responsible for a creeping or hanging high idle, where the rpms stay high then slowly drop down to the set point.

- The engine surges or hunts when cruising at part-throttle.

- Popping or spitting through the carb occurs when the throttle is opened. Or popping and spitting occurs through the pipe on deceleration with a closed throttle.

- The engine runs better in warm weather, worse in cool.

- Performance gets worse when the air filter is removed.

- Fuel levels that are too low will cause a lean condition.

- Pilot fuel circuit that are partially or completely clogged.

- Fuel jets that are too small for your application.

- Pilot mixture screws being set too far "in".

- In cases where an overly lean fuel condition is suspected, the application of a small amount of "choke" may decrease or eliminate the symptoms.

- Here's the main reason you don't want to run lean over an extended period of time:

http://www.xjbikes.com/forums/threads/head-gasket-1982-maxim-650.85273/#post-504365

A holed piston. Notice how it's right where the plug fires (the hottest point anyway, and made ultra-hotter by a lean fuel condition).



Typical Symptoms of a Rich Fuel-Mixture Condition:

- Engine acceleration is flat and uneven and loses that "crisp" feel.

- The engine "eight-strokes" as it loads up and skips combustion cycles.

- The engine's idle is rough or lumpy, and the engine won't return to idle without "blipping" the throttle.

- An overly rich pilot mixture is usually the culprit when the idle drops low then slowly recovers.

- The throttle needs to be open continuously to maintain acceleration.

- Black, sooty plugs, a sooty exhaust pipe and black smoke from the tailpipe that stinks of unburned fuel.

- Poor fuel economy.

- The engine works better when cold. Performance falls off as it warms up or the ambient temperature rises.

- Engine performance improves when the air cleaner is removed.

- Fuel levels that are too high will cause a rich condition.

- A choke system that is slightly hung open or has leaky plunger valves. Leaky valves can be determined via a measurement of vacuum using your synch sticks (or vac gauge) --- while watching the gauge, apply a small amount of downward force on the top of the plunger valve. If it vac draw changes, the plunger isn't sealing very well. Over time a small ridge may build up on the tapered brass plunger valve surface (Hitachi carbs) that may be possible to polish out, or a deformity forms on the rubber seals (Mikuni carbs) that may be possible to reform back into shape.

- Fuel jets that are too large for your application.

- Pilot and main FUEL jets being reversed.

- Pilot and main AIR jets being reversed.

- Pilot mixture screws being set too far "out".

- Main jet needle set at too "high” a position (on some Mikuni models), or that has "risen up” within its head cap (on Hitachi models).

- A simple test for an overly-rich condition is to remove the air filter element, and see if performance improves. A very dirty air filter will cause an overly rich condition, AND, even if the filter was in good condition, the great increase in airflow accomplished by removing the air filter will tend to dilute an overly rich fuel mixture, and thus allow you to focus on determining the cause of that situation.



Some common causes of a high idle:

- Engine has not been synched, as each cylinder "fights" the others for dominance, it can lead to a run-away idle situation.

- A lean air-fuel mixture condition, which can be caused by a variety of problems......vacuum leaks, plugged or too-small fuel jets, etc. Old or "stale" gas may also cause a lean fuel-air mixture to occur temporarily (until the fuel is used up!).

- A vacuum leak somewhere in the intake system.....intake boots, internal o-ring seals, etc.

- Mixture screws not properly set or adjusted.

- Vacuum piston sticking or stuck in a partially raised position.

- Idle speed screw set too high, or set to create a "proper" idle speed when the engine was cold (and thus results in a "high idle" once the engine reaches operating temps). The idle speed when the engine is cold should be modulated via the use of the choke (enrichment) control system.

- Butterfly valves opened too far; synch screws out of adjustment.

- Throttle cable wear, adjustment, or throttle lever brackets installed incorrectly or interfering with other nearby objects (cylinder head fins, etc.).

- Choke (enrichment) circuit is stuck "open"....this can occur even if the choke lever is rotated to the fully closed position, if for some reasons the choke plungers are not fully closing (cable wear, cable adjustment, bent finger brackets, or installation problems). In addition, even if the choke plungers are "closing" fully, if the choke plunger valve face or its seat are worn or scarred, this will allow fuel to leak part the plunger and richen the mixture even if the plungers are closed.



Why your engine seems to be schizoid:

A hanging idle---one that stays high and slowly comes down when decelerating---is a sign of lean mixture. The opposite case, where the idle drops dangerously low then rises, is a sign of rich mixture.

A bike that runs better when hot is probably lean, and a bike that runs better when cold is probably rich.

But sometimes a bike that can be adjusted "just right" when cool, but actually starts exhibiting signs of running lean (hanging idle) as it warms up. And if the idle speed is then re-adjusted while the engine is warm, but eventually falls and the bike dies (especially when sitting at a stop light). Or if the pilot screws are adjusted, then it's too rich when cold---all in direct contradiction of the above observations.

Experience shows that this is a sign of worn throttle shaft seals.....the aluminum carb bodies expand with the heat, but the steel throttle shafts---resting comfortably in a nice cool airflow---don't heat up and therefore don't expand. Once the shaft seals get old and hard, they no longer are able to flex and fill the gap.....so the carb starts drawing air around the shafts, leaning it out.



Why does my engine sometimes backfire when I first turn on the key (without attempting to start the engine)?:

- When you kill the engine, the intakes will still have some remaining (un-burned) air-fuel mixture remaining in them. Upon powering up the bike (turning the key on), the ignition system will apply 12 volts to the coils, thus charging them. Of course, that constant current is not good for the coils, so a few seconds later (if the engine is not started) the TCI shuts down the coils by grounding them (to protect the coils from overheating) which cuts the current to the coils and thus triggers a spark to the plugs. If there is enough un-burned fuel in the intake manifolds or the combustion chambers, and if the valves are held open by the camshafts, a backfire thru the exhaust header and/or thru the intake manifolds/carbs/airbox can result.



Why is my engine hard to start, and using the choke makes no difference?:

Most probably, the starter jets --- which are tiny, and are down inside the carb bowl ---- are plugged up with fuel varnish or the like.



Why does my engine run poorly (or is hard to start) after it is fully warmed up?:

This could be due to leaking throttle shaft seals (where extra seal-to-carb body clearance occurs after the carbs warm up and expand), or, it could point to valve shim clearances that are dangerously tight (the clearances close up after the engine gets fully warmed up).



Why are my plugs carbon-fouled (dry, sooty black deposits)?:

- Carbon fouling is the result of incomplete combustion----for any reason. It is most often associated with an overly rich fuel mixture (whatever the cause), but can also be caused by an overly lean fuel mixture (or poor spark, etc.) In a lean-mixture condition, most of the un-burnt mixture gets pumped out the tailpipe, but some fuel droplets remain in the cylinder and add themselves to the next intake charge. That's not a very precise way of metering the mixture, so when it's finally rich enough for a spark to ignite, that particular charge may be too rich, resulting in incomplete combustion and plug fouling. So carbon-fouled plugs can be due to rich or lean conditions.......your Colortune spark plug will tell you for sure. If you have a light blue or white-ish flame, intermittent flame, and/or intermittent flashes of yellow within an otherwise white-ish flame, then your fuel mixture is too lean.

And by the way.........if the spark that happens to ignite this overly-rich mixture is the "wasted spark" (which occurs in each cylinder at the top of the exhaust stroke, it will occur JUST AS THE INTAKE VALVE IS OPENING ---- so the backfire pressure wave may be directed back up the intake tract!



Why are my plugs oil-fouled (wet, oily black deposits)?:

- worn or broken piston rings, excessive wear or damage to cylinders, *leaking intake valve stem seals.

* while bluish smoke from the exhaust can be caused by worn exhaust valve seals, that situation will not foul your spark plugs. Consider what happens: oil pools above the valve guides, and coats the valve stems every time they rise. These stem "seals" really aren't seals, they are more like wipers, and their function is mainly to wipe off the excess oil from the valve stem. Now, when these stem seals get old and hard, they leave an excess amount of oil on the valve stem, which then drops down into the path of the exhaust gas flow as the valve opens and the oil is evaporated off, leaving blue smoke from the exhaust. But note that none of that oil ever enters the combustion chamber, so it can't foul the plugs.

Of course, any excessive oil coating an intake valve stem will end up going through the cylinder, but intake valve stem seals rarely fail on these engines. Unlike the exhaust valves, which are constantly baked by superheated exhaust gas, the intake valves are bathed in cool and moist (with gasoline) air.



Why is the inside of my carbs covered with a brownish-green goo?:

When fuel mixes with water and sits around for a while, this is the result. Nasty looking, nasty smelling, and you can bet that the tiny passages inside the carb body are plugged solid with this stuff! Definitely time for a full rebuild.......




What are my fuel levels supposed to be?:

Here's the Holy Grail on this subject:

http://www.xj4ever.com/setting fuel levels.pdf

And here’s a good visual guide to some problems that you might run into:

http://www.xjbikes.com/forums/threads/setting-the-floats-mikuni-not-gettin-any-readings-fixed.40395

and here’s a wonderful video from TurpentyneTV that shows the whole process in excruciating detail:





Fuel Level Cheat Sheet:

Here's the proper fuel-level settings by model when using the "clear-tube" method of measurement:


Hitachi all HSC32 series models:

NOTE: all of the following models used HSC32 carbs:
XJ650 Maxim, Midnight Maxim, XJ650RJ Seca (non-turbo), XJ650 Euro all use HSC32 carbs (various versions)
XJ750 all USA 1981-83 models use HSC32 version 5G200 (Seca) and 15R00 (Maxim and Midnight Maxim)
XJ750 all Canadian 1981-83 models use HSC32 version 5H200 (Seca) and 15T00 (Maxim and Midnight Maxim)
XJ750 UK/Europe 11M models, XJ750 Police models 24L and 37H use HSC32 version 5N100

-Fuel level measured via the clear-tube gauge: 3mm +/- 1mm (.12 +/- .04 inches)

-Float height: 17.5 +/- 0.5mm

 

I double checked the fuel levels and they were all dead on except 4 which I adjusted to proper spec (1MM +/-1MM) I’ll post a pic of what it was and you can tell me if it’s off.

I posted the jet sizes earlier and they are all basically brand new.

 

I removed the airfilter and within a little bit it was running better and smoother. Took her for a ride and super responsive, just wanted to run like it’s supposed to. Ive attached a pic of my air filter which got flooded with gas a few times due to the leaky petcock. Would this dirty filter make that much difference? And how bad is it to run it without the filter?

 

It's hard to tell from the picture, since it wasn't taken "level" with the fluid at the top of the tube, but, it still looks like it is too low......it's should be 1mm +/- 1mm front the base of the carb body, and it's the "dip" in the fluid that is the measurment point (fluids "ride up" on the sides of a tube, and the risen sides are not the actual fluid level, it's the bottom (base) of the "U" shape that the fluid makes which is the real fluid level in the bowl (and thus the reference point for measuring).

Make sure you check your AIR JETS (under the rubber vac piston diaphragm) to make sure they are placed correctly (the Haynes manual has the jets reversed in their picture),,,,,,the PILOT air jet (in the forward position) is the larger of the two, the MAIN air jet (center hole) is the smaller of the two.

 

That filter isn't all that dirty, but if it got fuel-soaked it's not passing air properly (the paper turned to mush, blocking the pores) . Restricted airflow = richeens up the fuel mixture.

Terrible idea, you'll wear out the rings in a few thousand miles or so (depending how dirty/dusty/gritty the air is around you).

 

I haven’t taken apart the top of the carbs since they were rebuilt by hogfiddles so I’m pretty sure he didn’t switch them, but I could check just to be sure.

That makes sense about the filter. Looks like I’ll probably be ordering one then

 

I doubt I mixed them up. But check anyway. Sounds like your air filter needs to be replaced..... did you ever install the snorkel? I recall that was missing but I don’t recall if I sent it to you Or if I put it in here....

 

Yup the snorkel is in place. I’ll probably get a new filter then and see what it does from there. It shouldn’t flood anymore with the on/off shutoff so I won’t have to replace it for a while.

 

How much will the octane rating in the fuel effect how the bikes runs/behaves? I was told by someone to run high test in it, but I saw somewhere that hogfiddles runs 87 octane with no problem. Will that throw off my tune at all?

 

It shouldn't.........octane ratings are (basically) a measure of resistance to detonation (pre-ignition, a/k/a engine pinging or knock), it's the ability of the fuel to not self-ignite due to high combustion temps caused by high-compression ratios (and other factors) of some engines. XJ engines aren't all that of high-compression (about 9.2-to-1 or thereabouts) and don't really benefit from higher octanes, but it won't hurt anything (besides your wallet)......

 

I run 87 in all my bikes.

 

Okay, ordered an air filter, but my bike didn't come with horns...I ordered some last year off eBay that look in great shape, but they won't sound. Any suggestions to check them or the wiring on the bike to make sure I have power? The horn wires are on the bike, but someone removed them for some stupid reason.

 

Hook the horn up to a battery wit one wire, the momentarily touch the otherwise to the terminal. You’ll know either way very quickly. Then try the other. If either is good, hook it back up on the bike

 

Hook the horns up directly to the battery (use some short runs of jumper wires, etc.) ....either terminal on the horn can be either positive (or negative). If they don't work hooked directly to the battery, well........

Whoops, quick-draw Fiddles beat me to it!

 

Okay, that's what I thought so I tried it over the weekend and neither horn works. Thanks for confirming my suspicions though!

 

Alrighty, so I have the new airfilter in (thanks chacal!) and been playing with the idle mix and then carb synch. I normally ride around 30-40 mins but took it for an hour 15min ride (longest yet) and it ran great at first but as the bike got hotter and hotter it ran worse and worse. It wanted to die at idle without the throttle held on and lacked power overall. I almost didn't make it back! I'll post pics of the plugs, but I still can't get the Colortune to work. Most of the screws can go all the way in or out and it doesn't change the color away from bunsen blue.

Another weird thing...after this latest adjustment after the bike warms up it wants to rev and stay high, but if I apply either brake...the idle will drop back down to where it's supposed to be...what's up with that?!?! It's been an issue before, but that was before the latest round of new parts and repairs.

 

Pics are of C2-3-4 in that order. I forgot to get a pic of C1.

 

The pilot fuel circuit is clogged for some reason.........either the jet, or internally, or the o-ring is missing/damaged in the mixture screw bore.

 

I know I cleaned the pilot fuel circuit and jet (that's the one in the side of the bowl that everyone misses the first time correct?), but the o-ring could very well be the issue. I just unscrew it all the way out to check correct? Anything I can do to test that?

 

No, the small passage thru the BOWL is part of the starter (choke) system (the brass tube that drops down from the bottom of the carb body fits into that passage in the bowl, and is also part of the choke system). The pilot fuel circuit jet is one of the two (the smaller of the two) brass jets screwed into the bottom of the carb body., and it leads eventually to the passage that the pilot mixture screw controls:

http://www.xj4ever.com/inside your carbs.pdf

Yes, you can unscrew the mixture screws all the way and there is (in this order) a spring, a flat washer, and at the bottom of this crackerjack box is the o-ring.

 

Ah, okay, I'll screw it and see what happens. If I add the slightest amount of enricher it does race away so it's definitely slightly lean. I'll have a look see but I'll probably end up ordering something from you in the near future

 

Thanks for the PDF, that's the first time I've seen that and it was super helpful!

 

All of them looked like this, some came out with the screw, others I needed to pick out with a small hook.

do those look good or do I need to replace them? And what’s the next step: take carbs off and double check the idle jet passage?

 

If the tiny o-rings are not cracked and in otherwise good shape, they look good to me but I'm no expert.

 

They look a little pancaked, but they are still rubbery and not cracked or anything like that. Pretty sure they are less than 5 years old.
What's the best/easiest way to clean the idle jet passage? When I double checked the carbs (see previous posts/pics) I removed the jets and soaked everything in carb cleaner and it all looked good. There very well could be a blocked passage, but I don't know how to clean those internal passages besides what I already did.

@hogfiddles

 

Carb cleaner sprayed into the passage and then blown through with compressed air is one option. I think there are some tiny pipe cleaners that people have had luck with. Maybe something like this? https://www.amazon.com/Carburetor-Cleaner-Cleaning-Brushes-Small/dp/B075J7M7B4

 

I’d just replace the o-rings if there’s ANY question.....
Passages—Yup, lots of spray, and lots of compressed air. I typically use 2-3 cans per rack AFTER the dip. Then compressed air. I make sure that when I spray, I see a good amount of spray come out somewhere else. I spray through EVERY hole, regardless of whether spray came out of it already........spray in every hole, it better come out somewhere. Then the same thing with air. I have my air set at 100psi, and I use a pistol-style with a small tube, and also a rubber tip kind, to make sure I can get into every hole and have a seal so I can hear if air comes out some where or not..... air goes in EVERY hole, it better come out somewhere.

 

So I think I figured it out: the vacuum line caps have deteriorated so they no longer seal super well. The
“bubble” at the top of the tubes had actually formed a slight area that air could leak by so instead of pushing them all the way down I only pressed them halfway down and put the clamps right over that section instead of at the base of the vacuum tube. Two rides (each over an hour) and no high idle of any kind!

Note: this was after I’ve tried the starter fluid trick to find air leaks (twice) and I got no change in RPM. My guess is since the tube is so far up the rubber cap (and the leak was so small) that the fuel didn’t get siphoned up.

Thank you all for your help! I’m very glad to have my bike running like it should after so many years of tinkering.

 

Ahem......

 

For the record, they were on just non functioning

Anyone have a suggestion on a windscreen? I’m 6-1 so I need one that doesn’t just direct the wind into my helmet but don’t want one as tall as a sky scraper either

 

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