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R1 Carburation All Gone To Shit!


exuprob

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I thought I'd go out for a final ride the other day so fished the bike out and started to warm it up and noticed it was only running on 3, popping and banging and generally running like a sack of poo.

Went for a short ride to see if it was just old fuel or a blockage that might clear but no such luck. Low end fueling was very rough, opening the throttle from closed was a very hit or miss affair and on a constant throttle at sub 5k engine speeds its was all very jerky BUT above this point it went well, pretty much up to full throttle it felt as good as it always does.

Got home and started to hunt for a problem. First job was to spray the down pipes with WD40 with the engine ticking over, 1,2 and 4 burnt it straight off in a cloud of smoke but number 3 it just steamed a bit and ran down to the collector. Removed the tank, airbox and coils and pulled the lead from number 3 and popped in an old plug and got a good spark (after refitting the coils) so its probably fueling.

Carbs come off tonight but anyone got any pointers to watch out for??

Bike is a '99 R1 4xv.

Cheers

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Thanks for the replies.

Carbs are on the bench so I'll give them a proper clean and blow them through. Had the float bowl off no.3 and all looks ok, no dirt or crud but I'll delve deeper this morning.

I change the plugs pretty much yearly so Ive popped in a used set and there was no improvement.

I'll keep at it.

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It was the throttle position sensor when the fuelling went odd on my 4XV. Fortunately a local dealer had a couple left over, from a recall for another model, one of them fitted and worked fine.

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Had a go at the carbs this morning and they sparkly clean, didnt find any crud anywhere and the only thing I needed to do was re seat a diaphram (spelling) on the troublesome number 3 cyl. Might have been that I suppose.

Had a sudden fret though and did a compression test and all 4 were within 1 psi at 155 psi across the board so its a carb fault.

Cant refit them though as found one throttle cable had frayed so need to find another. Bugger!

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Had a go at the carbs this morning and they sparkly clean, didnt find any crud anywhere and the only thing I needed to do was re seat a diaphram (spelling) on the troublesome number 3 cyl. Might have been that I suppose.

Had a sudden fret though and did a compression test and all 4 were within 1 psi at 155 psi across the board so its a carb fault.

Cant refit them though as found one throttle cable had frayed so need to find another. Bugger!

I might have a spare throttle cable/s in the garage for the 4xv. I'll have a look when i get home. If i have, you can have it for the cost of postage of you like?

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Really? That would be great, big thanks.

No probs. I'll have to check what condition it's in. I can't remember if i got it as a good condition spare when i replaced the clipon/throttle tube on my old R1, or took it off becasue it was frayed.

I'll post a picture back up here tonight and let you know.

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The ones I have only have one strand adrift on one cable. Do you know if you can split them ie are the two cables exactly the same so I can use my one good one and one of yours?

Big thanks for digging these out for me.

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Bugger.

I also double checked the compression to as, even though theyre all consistant, they seemed a bit low so borrowed a mates gauge and got low 190's within 5 psi difference.

Seems my old Motrax Comp tester has been dropped once too many times!!

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Ok, spent 3 1/2 hours on it today and made no headway whatsoever.

Fitted new throttle cables, carbs have been blown through and throughly cleaned but I didnt find anything amiss so got them ready to refit. Popped them on, rigged up an external feed to the fuel pump so I didnt have to refit the tank and......no change.

Took the plug from no.2 and swapped it to no.3...no change.

Removed no.3 carb slide and needle and swapped with no.1... no change.

Swapped just the needles...nope

Swapped the dyno jet needle on no.3 with a standard needle...no change

Re checked spark at troublesome no.3 and good strong spark.

Running out of options. I'm thinking of swapping the coils round to see if the fault moves but at the moment its just not firing reliably on no.3 cylinder.

Valve clearances maybe? Bikes covered 19k or so but could be a tight clearance messing up idle and low speed but allows the cylinder to chime in when the throttles opened further I suppose. Clearances on these is a pain as the rad needs draining down but I'm seriously running out of options.

Ultrasonic carb clean?

Bike is a stock 99 4XV R1 except for a carbon can and a dyno jet kit. Bikes been running fine on the dynojet kit and pipe for 4 years or so.

Anyone got any ideas?

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What about the ht lead and cap? I think swapping the coils isn't a bad idea, just to prove the leads and caps aren't doing anything they shouldn't when fitted. Shame you weren't a bit more local, could of nicked some bits off mine to test with.

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its either sparks, fuel or compression. can you isolate which pot is missing by spraying something on the exhs? you could pull the plugs and see which one makes no difference. also try running it without an airbox and squirt brake cleaner into the trumpets to see if it chimes in on the duff pot. if it does then its fuel.

if not then try a compression check

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Thanks for that Alex, would be really useful to just swop bits over until I found what was wrong.

Its no.3 cyl thats playing up. It only seems to be at low revs/idle/small throttle openings that it plays up. The no.3 down pipe does get warm but definitely not as hot as the others. Cant seem to get the problem to move to other cyls either.

Compression check was initially low but perked up with a swap to a mate tester, all 4 cylinders are within 5 psi of each other so I would surmise if it was low compression then it would effect all 4 cylinders equally.

Have had to wander off and have a think as nothing seems to make even a small difference.

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Nope, not yet. The water feed to the thermostat that runs through the cam cover makes it a bit of a pain so was going to try all other options before I do them.

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If you have cleaned the carbs (swapping carb parts over is not a good idea imo due to the differences in wear) Anyhow..

Id be inclined to test or swap the coil packs over and see if the problem moves.

Then after that id do the valve clearances.

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  • 2 weeks later...

Dont think its this but have heard of this before.

Had the carbs off again, carefully set everything as per book, carb cleaned and blown through with an air line (compressors gone mad too!) , swapped the coils for a set of known good ones and swapped the plugs again....same.

Changes the small wiring loom from coils to bikes loom and suddenly much better. Not entirely sure if thats problem solved as I didnt actually find a fault but bikes running far better now.

Fingers crossed.

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My R6 of similar year had the exact same symptoms, caused by a faulty coil, but it tested within spec, and sparked off the bike.

But in the cylinder it wasn't running correctly.

I tried a set of 4 off a good known engine from a friend and it worked and ran perfect.

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  • 4 months later...

Ok, thread back from the dead!!!

The bike is still suffering with this problem which is rough idle and lumpy running at very small throttle openings but open the throttle a fraction further and the bike goes as it should. This problem started very suddenly, took bike out for a spin and covered 100 miles or so and all was fine, parked it in the garage for a week and when it was started it ran rough and nothing Ive done has changed this.

Ive done the valve clearances, compression checked, new plugs, tried different coils and had the carbs ultra sonically cleaned by budgetboy (and a superb job he did too, carbs look like brand new) but nothing has made any difference.

To me it feels as though the pilot drillings/jets may still be blocked due to only very small throttle openings being effected but Ive got no real way of testing this apart from buying another set of carbs and trying them as it still feels like a fueling problem to me so maybe thats the way forwards.

Any ideas would be greatly appreciatted as Ive run out of my own!

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Heres what i think.

1.) Put the carb back to standard (needles and main jets) see if problem goes away.

2.) Get your carbs balanced with a carb tuner to make sure each one is in sync.I can only bench balance which is close but id still get the carbtune done.

3.) make sure idle is set at 1100 rpm +/- 50rpm (warm)

4.) make sure you have no snags in your throttle cables as this will cause jerky takeoffs.If they are worn get new,not 2nd hand.

5.) make sure choke cable operate properly,again sticky cable lube or replace.

Start and ride...

OR....

6.) Book a dyno and see whats what.As i said,, mucking about with jets and needles is all well and good but its all guess work.And without it being on a dyno you are grabbing at straws.

Personally i would go with Number 1.to 5. I don't think (IMO) you will get the full use out of the dynojet kit without going on a dyno.(Thats why your kit has many jets in it) I also think it will run better standard with what you have on your bike,, but its just an educated guess. Try it and see as its only 20-30 mins work.

A video would also help in this matter :icon_salut:

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Dont want to sound patronising, but you've spent a small fortune trying to fix it.

Take it to a dealer you trust, who will probably diagnose and fix it for half of what you have already spent on it.

Sometimes we have to admit defeat.

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Dont want to sound patronising, but you've spent a small fortune trying to fix it.

Take it to a dealer you trust, who will probably diagnose and fix it for half of what you have already spent on it.

Sometimes we have to admit defeat.

Or they'll go over the same ground again and charge the op handsomely for it. I honestly believe that there's virtually nothing the collective pb mind can't sort out, the knowledge here is as good as any dealer.

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