Running Really Bad

Hi Just been Trying to My XJ650 to run better, at the moment Starts fine idles no Problem, take it out it quite sluggish till about 3000 Rpm, then pulls like a train, does not go much above 5000 rpm, and after about 10 - 15 mins it gets all popping and dies and difficult to idle and start.

Any Suggestions are Welcome,

Many Thanks

Gary

 

start with a compression test.
Make sure all the valve clearances are in spec.
Church of clean and rebuild of carbs
bench sync,
wet set floats to spec
new spark plugs
make sure battery is good and charged
in line fuel filter
Petco*k working as designed
running vacuum sync
colortune air fuel mixture.

There are write ups on all topics. There are no short cuts to getting the bike to run correctly.

 

Valves first; it sounds like the classic symptoms of a motor in need of a valve adjustment (if it's not too late.)

 

got to the bottom of the problem Today..!, Yippee!

Well i hope so,

Already Done the Shim Thing
Carbs Cleaned
Bench Balanced
Float Heights Done
Inner Tubed the Intakes
New Plugs

Only when i started to Colour Tune, it wouldn't adjust Orange Flame
we had a Air Leak in the System,
This is when we started to find the issue,
Replaced the Vacuum Blanking Plugs, started it up and pulled them off individually, No2 and No4, No Change, tightened up jubilee clips on the Intakes, Nothing, Placed my Rubber gloved finger over the End of the Butterfly on No$ Shaft, Revs Started To Rise,
So I Think That There Must be An Air Leak on the Shaft.

Any Suggestions on how to fix will be much appreciated

Gary.

 

That would be throttle shaft seals.

The rack has to be broken down, and each carb will need to have its individual butterfly and shaft removed so that the seals on the shafts can be replaced.

There are (2) seals per carb, eight in all. The only two that can be easily accessed are the very outermost two, on the outsides of carbs #1 and #4.

 

get the throttle shaft seals from Chacal......& tear the carb rack apart to replace, if you do it right the first time, you will only be doing it once.....be patient, be methodical......follow the instructions.....

http://www.xj4ever.com/hitachi%20thrott ... 0seals.pdf

 

Cheers for the Advise Guys, Parts Ordered from Chacal, He's a Good Guy, Really Helpful.

Will have to get on with some other tasks while i wait for the Parts,

Fingers crossed this will be it Fixed and Ready to Go!, and i can go out enjoy the bike, the weather is starting to turn a bit Winterey so i hope i can, get a few days before it gets too Bad, But we might get better Weather in the New Independent Scotland Who Knows?

 

You might as well change the fuel o-rings while you have the rack apart....see chacal for the fuel o-rings as well.......now is the time to do it when you are replacing the throttle shaft o-rings....

Just a suggestion....

 

Totally, I Get what your Saying,

But I Think I'll Burn that Bridge When I Come To It.

LOL!

 

The bridge is already on fire....just saying..

I tore my carbs down, did the church of clean, replaced and put back on bike.

Wouldn't idle...

Tore down replaced throttle shaft seals, Len suggested fuel rail o-rings...I ignored suggestion..

3 months later, fuel rails were leaking badly.

Again, carbs off the bike and tore apart.

30+ year old rubber o-rings need to be replaced sooner than later....

 

Got everything back together, color-tuned and balanced Carbs,

Went out for a test and got More Issues!

Going along Fine Gets to 3000 rpm jumps up to 4000 rpm, Throttle will not shut Down constant 2000 rpm,

get it back in the drive and Revs Hanging / Increasing at Idle

Please Help?

Shims Done
Float Heights Done
Inner-Tubed Inlets
Throttle Shaft Seals Done
Carbs Stripped and Cleaned

 

Adjust your idle speed screw.... The big knurled on that sticks out between the center two bowls---- turn it counter clockwise to drop the rpms. If it all the way out already, then your butterflies are not closing correctly. Could be upside down, or a spring binding, or bench sync not done quite right first.....

But check the idle speed screw first---

 

Not Idle Screw, wish it was, Took great Care With Butterfly's (see Pics)
will have to strip carbs again.

 

Is the idle screw all the way out and still revs high?

Was the idle normal during the first carb balance (sync)?

Normally, balancing should not be done until the bike is fully warmed, like a 10 mile ride. Then put a fan on the motor and re-balance / colortune the carbs.

Did you take great care in installing the butterfly's (throttle plate)? The clearance holes in the throttle plate are quite a bit larger than the screws to allow for tolerances to enable the throttle plate to center in the carburetor bore in order to completely close.

To install the throttle plate, hold the throttle plate against the flat portion of the throttle shaft while the throttle plate is fully closed in the carburetor bore, then secure the screws.

 

Went Through Everything Again, Stripped Cleaned Bench Sync Etc.

Tick-over to 3000 Rpm everything's fine
Gets to 3000 Rpm then it wants to rip your arms off, Mini Power-Band thinks it's an RD350LC
Gets to 4000 / 5000 Rpm Rev Jump up and it like the clutch is dragging,
Clears up above 5000 Rpm but does not pull Clean,

Checked the Needle for Wear no real sign, checked Jet Size 110
Any suggestions Most Welcome

Gary

 

Did you pull the emulsion tubes out to check the metering holes?

 

Re-read some of your earlier posts where a PO was very creative in grinding valve shims, and you had valve clearances way out of spec (too loose). So given that there could be some more PO related issues.

K-moe's question is good, hopefully you pulled and cleaned the emulsion tubes during the cleaning.

Is the hanging idle still present?

The jets say 110, but are they really? The PO could have done some drilling?

Did you check to see if the needle jet that extends into the main jet was not shimmed by the PO? They are not adjustable as in clips to move the needle up and down, but shim washers can be added to move the needle up to go to a richer mixture.




Since the gallery is no longer present, and I could not find any photo of your bike: does it have the stock exhaust and air filter box - no pods?

How about electrical - new plugs, a quick ohm check of the coil secondary resistance to verify plug caps are OK?

 

Emulation Tubes Pulled and Cleaned,
Needles No Shims,
Motad 4-1 Exhaust,
New Plug Caps 5k Resistor, Cut Back Leads
New Plugs Not R,

This is an Unknown for Sure, But Throwing $90.00 For New Jets May Not Fix It.


Motad 4 into 1


Stock Air Box

 

Yea, I would not want to throw $90 away either and would attempt to diagnose the issue more before doing that.

How many miles on the bike?

Did you happen to do a compression test after adjusting the valves?

What about the hanging idle, is that still a problem?

By not pulling clean, is it missing?

Does it backfire / pop in deceleration?

Does it have the stock air filter also and is the lid present?

Link to information overload hour for lots of informative reading. In reference to main jet sizes it recommends going up +4 for the 4-into-1 exhaust, however, it also states that typically no jet changes are required for aftermarket exhaust changes... so I am a bit confused on that one.

http://www.xjbikes.com/forums/index.php?threads/the-information-overload-hour.27544/

 

ARe these carbs equipped with the two extra air jets on both sides of their "mouth" (airbox side) alos called compensation jets? There are not of the same size and they are often mixed up due to a mistake in the service manual, maybe that's your case?

THey can be seen on this picture:

 

I thought this was the mistake in the Haynes manual:

A - larger hole is the pilot air jet, they have "A" labeled as main air jet
B- smaller hole is the main air jet - they have "B" labeled as pilot air jet


The POSITIONS of these two Jets, in the photograph appearing on pg. 123, are CORRECT.
3 Holes - Right side looking down and in.
LABELING of the 2 Jets is NOT Correct.

Also thought you would never make it through color tune if these two were swapped?

 

Have you checked the intake manifold gaskets? I had a similar problem with a hanging idle, i made some gaskets for it and that problem went away. Now it won't idle but that is a different story. Have you tried the propane or starter fluid test around your manifolds?

 

$90 for a set of jets? That's ludicrous! Get 'em here for $3.29 a pop:

http://jetsrus.com/a_jets_by_carburetor_type/jets_hitachi_main_4H7.html

Ordered from these guys a couple times and never had a problem.

 

Sorted was Running Lean

No Just, Really Sluggish

Yeah a Little Bit

Yes

I got +4 for 4-1 Exhaust = 4
Add up all the main fuel jet size increases and subtract 2 sizes. =2
- 2 for stock Air Box + 4-1 exhaust =0

Yeah That's Been Checked Too!

Thanks for all you help but i my thoughts on this are:

The Weather is on the Turn not many days before it becomes to wet to go out and have Fun
So Just Going to Ride it, it not the best but In A Couple of Days I Won't Even Notice, "Over Come and Adapt"
And Deal With This Next Summer.

That's Some Good Prices even With Int. Shipping And Tax.

Thanks again.
will Keep you posted about any developments