4xv running issues just off idle.

[galaxian]

Hi guys,
I have owned a 99 bike from new and its been off the road for the last 6 years, got another bike and sort of lost interest due to a running issue I couldn't resolve. This is not a problem caused by old fuel not being drained, in fact after buying a new battery it burst into life after about 2 seconds and ran on all four cylinders exactly as it did before it was put away. (I did drain the old fuel, new oil, filters etc before mot last month)
From around 10 thousand miles it has had a worsening issue from just off idle to approx 3.5 thousand RPM, it does this with the standard end can or my Demon aftermarket can (no difference), it stutters and vibrates then runs fine to the redline. I cleaned jets and cleaned with carb cleaner, new genuine air filter, new plugs, 2nd hand set of coils and leads, no difference.
I then read about the the potential issues with wear on the emulsion tubes, so I bought a set from Dynojet, but damaged one of the carbs when disassembling them.
So I then purchased a set of low mileage 5JJ carbs, hoping all my problems would disappear, but no difference.
Stuck it the back of the shed after mot ran out in 2014.
I assume its running a little rich, so set the air screws 2 turns out last week, but it made no detectable difference.
Last week I opened up the carbs and installed a Yambits rebuild kit, reset the air screws to 3 1/8 turns out and no difference, except it wont idle nice but that may be just the need for a carb sync as it ok when actually moving.

Any ideas where I look next ?

Thanks,

Colin.

PS totally standard, no mods apart from the end can.


https://yambits.co.uk/yzf-r1-float-valv ... 89358.html

[R1Clarky]

i had a not dissimilar issue which turned out to be exup valve related, one of the cable sheath retainers had rusted off so exup operation has severely hampered.... worth checking just in case ( thanks again jompers me ol monkey mate for cheap as f**k headers [emoji6]) good luck bud oh & welcome in....piccys when yer can pal

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[R1ch]

i had a not dissimilar issue which turned out to be exup valve related, one of the cable sheath retainers had rusted off so exup operation has severely hampered.... worth checking just in case ( thanks again jompers me ol monkey mate for cheap as f**k headers [emoji6]) good luck bud oh & welcome in....piccys when yer can pal

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2nd'ed.. sounds like exup valve

[galaxian]

Thanks guys,I will give it another check, I did check it before and it was moving as expected a number of years back,was fine then with the same symptoms. Was going to do it again a few weeks ago but the cover bolts have siezed, I broke one off, and decided to leave the others alone as I'm 100% sure they will twist off as well.

[R15UTT]

Might as well try the other bolts Col' . It's only a chrome cover . & then you can see if the Exup V'v is working . The bolts can be another project for when the running is sorted . Go for it . From another Colin . Look for a cobalt drill if too hard for HSS drills to drill out broken bolts .

[galaxian]

Will do, have the carbs off and hope to pick up some Allen bolts for the float bowls tomorrow, will be the weekend before I get to look at the exup.
I will report back what I find.
Cheers guys.

[Moise]

It would definitely be worth checking the EXUP valve. But it doesn't open until about 4000 rpm, so it might not be the problem.

When you turn the engine off, it opens part way, I assume to allow exhaust gas in the headers to escape. That's probably the easiest way to check if it is working. Some say that it fully opens and closes when you turn on the ignition, but not on the 4xv.

If it's not the carbs and the EXUP, it has to be the ignition. I assume you're tried new plugs?

Edit: You might find the idle improves if you refit the original mixture screws. I have no idea why these are included in carb service kits.

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[galaxian]

Hi Moise, yes I have changed the plugs In the past and no change, bought another set of coils and plug caps as well.
I'll try and balance my carbs and if no luck with the idle I'll put the original screws back in.
I am fairly sure I will find the exup working. Bought a crank sensor years ago, but never got around to fitting it, not sure where it is now..

[Moise]

When the problem started, what was the rev range where it happened? You've said it worsened - did the problem change, or does it now happen over a wider range?

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[galaxian]

Hi Moise, the issue got progressively worse, same problem and instead of just feeling like a little 'miss' about 2000 rpm, it got more pronounced and lasts up to maybe 3500 or so. Obviously worse when under load using higher gears, no fun at all with a passenger in town.

[R15UTT]

Will do, have the carbs off and hope to pick up some Allen bolts for the float bowls tomorrow, will be the weekend before I get to look at the exup.
I will report back what I find.
Cheers guys.

thumb up. I'D SAY THUMBS , BUT LOST ONE IN '96,

[Moise]

Hi Moise, the issue got progressively worse, same problem and instead of just feeling like a little 'miss' about 2000 rpm, it got more pronounced and lasts up to maybe 3500 or so. Obviously worse when under load using higher gears, no fun at all with a passenger in town.

My 4xv does something similar at low revs if you give it too much throttle, say 2000 to 2500 rpm. It's OK at a steady speed, but is not happy if I open the throttle too far - runs rough and vibrates. I usually just change down.

But your bike sounds worse than that. Is your cam chain tensioner OK?

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[galaxian]

It does it with any throttle input, how do I check the tensioner ?
Thanks

[Moise]

It does it with any throttle input, how do I check the tensioner ?
Thanks

That's different to what I have then. I doubt it's the CCT in that case.

Must be ignition, especially if it happens for any throttle setting. I have a few thoughts, but will post later as I should be working! (Friday morning in NZ).

[galaxian]

Thanks, I won't be able to look at the bike until the weekend, I'll be putting my carbs back on, and if I can find my CarbtuneTool, balancing the carbs, then snapping off the exup cover bolts, lol, to check 100% it's working.

[Moise]

Thanks, I won't be able to look at the bike until the weekend, I'll be putting my carbs back on, and if I can find my CarbtuneTool, balancing the carbs, then snapping off the exup cover bolts, lol, to check 100% it's working.

Do check the EXUP cables are adjusted correctly. The procedure is in the service manual, although 1.5 mm for the free play might be a bit tight

[malr1]

Everyone is correct in what they say especially after the bike has been laid up for 6 years. Seeing as it's a misfire you're kind of describing, I would also remove the coil packs, take off the plug caps and cut back the leads about an inch and then refit the caps. The leads corrode at the caps but clean up easy. When I did mine, because of rough running, I couldn't believe the difference it made.
Let us all know how you get on.

[malr1]

Thanks, I won't be able to look at the bike until the weekend, I'll be putting my carbs back on, and if I can find my CarbtuneTool, balancing the carbs, then snapping off the exup cover bolts, lol, to check 100% it's working.

If you're balancing the carbs, you will have the tank off. You can see the Exup servo motor with the tank off and will be able to see the pulley move when you blip the throttle.
Ride it to Dorset from Northern Ireland, I'll fix it for you.

[galaxian]

I have always seen the motor and cable move perfect fine, I just haven't actually watched the valve turn under the cover.

[galaxian]

That would be a nice run to Dorset if the weather stayed as it is up here today

[Moise]

If changing the coils and plug leads made no difference, then it is unlikely to be the HT side of the coils. It would still be worth checking the leads where they connect to the spark plug caps as malr1 suggested, as this is a common problem on the 4xv and 5jj. Also check the wiring to the coils and the connector by the carbs. The ignition system on the carbed R1's is a bit marginal, so it is important that the the coils are getting the full 12V. You can't check the voltage with a meter, as the coils are only powered when the engine is running.

[galaxian]

I did read a post regarding this, someone had wired 12v directly from the battery. The coil connector close to the TPS is nice and clean, I lubed with a little acf50 to keep corrosion away.

[galaxian]

Had a busy day, but did have time to look at the exup, it moves fine, and there is just enough slop in the cable for me to freely move it by hand slightly, so cover back on using the one bolt I managed to free.
Double checked the air screws were 3 1/8 turns out.
Put the standard can back on just for fun.
Weather forecast is too good tomorrow to work on it so will go for a spin.

[galaxian]

Runs a little better with the standard can, but very rich, started with no choke and needs a little throttle when starting warm.
Maybe turn back the air screws a turn ??

[newsh]

Standard setting for the screws is 2.5 turns out from lightly seated.

What pilot jets does it have in it? The earlier bikes had #17.5s. They run better with #15s.