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XR600 Cough & Die

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Hi there,

Having real issues with my recently purchased XR600, 92. It misfires on idle and when cruising and it seems to have got worse recently. On idle, it's like a loud pop and when cruising its like a small hicup..

Thought I had an issue with the carb when I first bought it as it wouldn't run with choke off, so I have had the carb apart and number of times and have fitted standard jets etc to try and solve that problem - turned out it was me thinking the choke off was at the top position - doh!

Anyway, have swapped over CDI, coil, HT lead from mates bike to rule out those, have swapped around spark plugs. Today I have had the stator out and the pulse generator to see if there was anything obvious - there was a bit of swarf on the magnet of the pulse generator, so could be that, but would be suprised. Also noticed some very slight damage to the inside face of the rotor at one point(the disc with the magnets in it). Not sure what casued this but I don't think it would make a difference to the stator.

My plan tomorrow is try and check the stator for continuity, strip the carb and put the bigger jets back in (it has aftermarket can and air filter on it and had bigger jets in it when I bought it and I understand the problem I have may be caused by running lean)and double, double check there is no airleak and stick it back together.

short vid of the bike running here:

I'm aware it is smoking a bit at the moment, but when I did get it running well recently it stopped and was fine under load.

Questions:

Bike was left standing for 3 years before I bought it, so my biggest worry is that it is a valve issue (i.e. seats corroded) and I have heard stories of cracking of head between valve seats. I guess a compression test would confirm this but any comments?

Is there a good method for testing the stator?

Look forward to hearing some good advice!

Thanks,

Dave

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I was just talking about this with Thumpharder earlier. Check the air cutoff valve and make sure there's no holes in it. Its the diaphram in between the carbs. Thump suggests using a flashlight behind it to see any pin holes. Let us know what you find.

voodoo

Oh and welcome to TT :thumbsup:

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Watched your video..Does your mate have a single carb bike as well..Reason I ask is that your issue with the farting and hiccups sounds very similar to a problem I once had with a set of twin carbs on one of my earlier model 600s..I never could find the problem,,(cleaned the things,,various new internal bits,,no change) so put another set of carbs on it.,,.that fixed it. Check that Aircutt off valve first.,,.if you find no problem there I'd swap carbs over and see if it still does it..

Check that wiring from the Stator as well,,could be some sort of half held together wire down there shorting out as the bike vibrates. Main power wire to the CDI being a prime suspect,, Cut back the external sheathing (not the plastic over the wires),,the other stuff and give them a run over with the eyeometer all the way from the stator to the loom..engine side being more important as they get hot and brittle as well as having mud and sticks etc flying at them,,go all the way into the engine.

Only about one test you can do down there..Meter on Ohms,,setting 200,(RX1),Wire from meter to main wire from Stator,,Red/Black or whatever yours has,, other meter wire to ground of stator..body I assume...Manuals got some sort of answer as to what it should read..

Edited by Horri

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Hi guys, thanks for quick response! My mates bike is a 250, so I don't think his carb will work. Do know someone with a 400 though, but again I assume they have different carb also?

I'll have a good look at the air cut off valve and diaphram, but couldn't see anything when did previous strip down. If its the assembly on the side of the carb, I do think it is a strange design how the cover clamps down on the little o ring. You have to be very careful not to knock it off centre when tightening the cover!

This issue is becoming a bugger to find but we have another go today. Thanks for the advice!

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At the end of the video, the engine stalls following a clacking from the engine. Could be that the auto decompressor on the cam is faulty. Have you adjusted the rocker clearances?

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Is that burning oil smoke from the exhaust? If it only smokes on startup it's not a terminal problem, although the engine won't run well until it has burned the oil from the cylinder.

Yes, double check the valve lash clearances.

Water in the fuel tank can cause sporadic misfires. Try draining and flushing the tank, fuel line, and carburretor bowl then refuelling with new petrol.

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Hmmmm - auto decompressor sounds likely to me. Has anyone else had this problem and think this could be the culprit??!

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Hmmmm - auto decompressor sounds likely to me. Has anyone else had this problem and think this could be the culprit??!

Dunno..,possible I suppose.,Yours looks like fuel or electrics to me.. Have you checked the wires through to the Stator with the eyeometer yet..if we don't know what you're doing or have done it's kinda pointless us posting possible causes..Eliminate things one at a time ..ie,,Carb needs a total strip and clean..(most important to rule out fuel)..ie,,each and every hole on the jets and associated tubes needs the wire brush strand treatment and all holes need the compressed air through them..totally needs to be done properly,,carb cleaner is not adequate.,.cheapskates and cheats think it will fix anything..I see you say you used a 400 CDI on your bike,,did you actually have it running with that CDI on it ?? As far as I was aware a 400 CDI shouldn't work on a 600,,,650L,,maybe..My latest build the 89 has a cough and die issue at the moment but no where near as bad as yours..mine can be idling for a couple of minutes then just pop and die,,not sure on what's causing it though I'm looking at a too rich scenario as the plugs pretty black and it has the "I'm too rich" motor/mixture note to the engine as it idles..,,ie,,it's way rich..waiting on a new smaller Pilot to see if that sorts it out..

and no,, I don't think a carb from a 400 will work on a 600.., may do with the correct jetting and a possible manifold spacer adjustment,, pretty sure the 400 run a smaller carb intake size than a 600,, not really 100% sure on that ,,half guessing .,

Edited by Horri

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Right, so finally got time to work on the bike again.

Stuck the side covers back on, stuck some oil in it, started it up with an inline spark tester fitted. It still had the same problem, but it eleminated the electrics as there was a definately a spark when it died.

So stripped the carb, refitted the bigger jets, stuck it together and started it up and it seems to run ok!

However, still have fingers crossed, as was 11.00pm at night when I started it up so didn't have a chance to run it up the road to test.

Question, now need a replacement left side cover gasket (as it split when I removed it) and a replacement oil sump plug as both are leaking slightly - can anyone suggest a good place to get bits (apart from flea bay obviously)?

Thanks for the advice peeps.

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I made a couple of stator gaskets while I was rewinding my stock stator, finally bit the bullet and bought a ricky.

buy some gasket material and just trace the outline...if not cheapcycleparts is good servicehonda as well.

The oil sump plug has an aluminum looking concave washer...maybe try replacing the washer?

cheers

edit: my first stator gasket didnt leak, this one weeps slightly...oh well

ebay is the best bet for buying single or complete gasket sets...fast shipping too...look for k and s kits

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Hi chaps.

Went out for a proper hoon on it last weekend, was excellent fun. Managed to break a clutch level and snap off the guard which protects the stator wires (started the bike back up without realising the chain had come off and the chain rode up into the guard). Its snapped the engine casing which holds the guard on -doh! Anyway, bit of gentle welding will sort that.

Carb is still not great. It starts up and runs ok, generally fine when you accellerate, but when you run at a constant speed it is quite hiccupy. It also used more fule than I expected (about three times the amount of my mates XR250, approx 80 miles on a tank?) - not sure if this is normal.

Gonna strip the carb again, and give it a good clean, take note of the jets that are in it and ask for some advice on that.

Question I have though is can anyone just confirm for me the order of the idle screw components. Reason I question myself is this diagram I found while looking for parts

http://www.cmsnl.com/honda-xr600r-1992-general-export-kph_model6887/partslist/E__1601.html

It shows the spring on the wrong side of the washer and o-ring. I am right in thinking it should be install in order of: o-ring/washer/spring/idle jet??!

Thanks as always.

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spring, washer, oring.

Washer is there to protect the oring from getting crushed, oring to seal and spring to keep pressure so the needle doesnt fall out.

cheers

youre correct above

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Just seen a post confirming o-ring/washer/spring/idle jet is correct so don't need a response on that.

However, another question: With the bigger jets, would you normally set the circlip on the main needle at stock location i.e. third groove down?

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Hey no prob

I have been told many times that you want to get your main jet sorted out first, then you fiddle with the needle position if you have to depending on altitde for example or temp, conditions etc...

I have also been told that the needle really only is a substitute for not having the correct jet, in other words jet first...then if no improvement mess with the needle on clip up or down at a time.

Then after getting the right main with some midrange and WOT throttle runs, and plug chops to get a glimpse if your rich or lean then you can mess with the idle jet settings.

For the most part if your not modified you shouldnt have a bigger pilot jet.

You can turn the idle mix screw out or in depending on elevation, and ease of starting.

To adjust you warm up the bike completely(that mean run around town not idle the bike) really get it going.

Then upright with the bike idling high you adjust the screw in and out and get the highest idle possible...then you turn out the screw a smidge.

Thats what I have been told and Im sticking with it.

On my xr600 after many many tries I finally have a solid starter hot or cold and stuck with a stock pilot jet.

Trial and error and effort pays off.

Good luck

christian

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That's great advice.

I have emptied out tank, blown it through with compressor, replaced the in-line fuel filter (ideally I just want this filter, so I want to remove the filter inside the tank except the tap doesn't come off), stripped the carb again and used proper carb cleaner/compressor to ensure all the crap is gone.

I moved the position of the circlip up one (so two down from top of needle), so will see if leaning it out sorts it out (I'll be unhappy if I have to richen it up as the fuel economy already seems a bit high!). Forgot to check the air-cut off diaphragm with a light, but will do this before the carb goes back on.

The jets that are in there now are 155 main, 68 slow (came with the bike). It has a White end can and K&N air filter. Chap at bike shop said it can be a real pain to get it set up running spot on - anyone got similar set up that was successful in tuning it spot on?

Clutch level replaced, went to replace the throttle cable but the replacement cable didn't have correct grommets + the push cable was just as frayed. So now looking for push and pull cable. Think it needs to be Honda standard for the fitting to work at the carb end, but may be wrong.

Also noticed the front brake lever mech is broken (the bracket that supports they underside of the lever which is connected to the master cylinder has snapped). Think I must have done this at the weekend as well. The brake is still functional, so I think I may have to weld this, other wise it is an expensive replacement of the master cylinder.. hmmm.

Oh, I noticed there was a bit of play in the headstock - not looked in the manual about this, but is it an easy job to tighten this up?

Feels like I am getting there (expect for when I stack it and have more things to fix), but can't wait till I get the fueling and throttle control nice and slick!

Will post a few images/video on success!

Cheers.

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good stuff...

About the diaphragm/acv valve...hope you took it out before aquirting carb cleaner in there...that's exactly why they fail! they get eaten up by carb cleaners.

68 pilot seems a bit rich maybe a 65?

About the headstock/stem...loosen the top clamp pinch bolts, jiggle the front end, loosen the big nut on the top clamp(beleive its a 27mm) then release the little tab that keeps the locknut in place...

Give it a few taps clockwise and then put the tab locknut in place...tighten the big nut...

Jiggle and bounce the front end again then tighten the topclamp pinch bolts on the fork tubes...

That should realign ad tighten it up...also its btter of you just regrease and take the whole stem off and check the bearings but its ok to do this for the meantime.

Do not overtighten though as the bike will wallow and track around on its own...

a tap on the handlebars when up right on a stand to eather side is all you need, it should rock from one side to the other on its own...

LASTLY!

IF YOU RIDE IN DIRT GET RID OF THE K AND N FILTER..

Thats probably why you have such a big pilot jet...it flows pretty well but sucks in dirt big time...they are good on street or the track, not offroad.

I would down jet on the pilot and stick a UNI, Twin Air, etc...that is nicely oiled(and dried in the sun) and see what happens

just my 2cents!

enjoy the bike

cheers

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Personally I don't think playing with the jetting's going to sort out the cough and die or hiccup problem.,.Your jetting does seem kinda odd to me..,My semi finished 89 XR600 project with the 100mm XL PIston and CRF250-X mufflers jetted 162/58..,just went down to a 58 from a 62 as it was burbling at idle., I really don't know what's up with your bike but with the smoke etc I'm afraid to say I'd be into a rebore and checking the valves for a leaking seat or something and removing the auto decompressor mechanism from the Cam..,Don't really know if it'd be the issue but it isn't required so remove it to eliminate it..

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