Untold

Hi there Reesy, your problem sounds familiar. I have just rebuilt a pre-div XJ600 for commuting on, and after I got the engine running, it leaked fuel at a scary rate in the same way. I fixed it by installing new float needle valves. The problem is that the float needles have a rubber tip and it perishes over time. When it hardens, it fails to seal when the float is up, allowing petrol to leak past. It is really hard to tell if this has happened just by looking at the needles. It will only happen when the engine is running because the petcock only opens when there is vacuum from the intake manifold, allowing fuel into the float bowls. Its fine when not running (unless petcock has problems). I used Tourmax carb refurb kits from wemoto. And I wrote about it here: http://www.rolandbeverley.is-a-geek.com/blog/?m=201101 Check posts for Jan 27th and onward. Hope this helps!

I tried to, but could not find one today of the right size (biggest in Halfrauds is 12mm). In the end we got a pack of M10 nuts and bolts from Focus DIY for about a fiver, threaded them together and used a spanner. The top caps popped right out Just finished test riding it and all seems to be well

I am probably asking about something that everyone else knows, but having searched the forum and the internet with no luck I thought I'd ask here. I am replacing the badly pitted forks on my '89 XJ600 with less pitted ones from ebay. They have arrived complete but I don't know if the oil level (or quality) is ok so would like to replace it before installing. The problem is I don't have a tool to remove the top caps. They seem to need an enormous hex bit, 20 or 21mm diameter. Apparently they have new seals, so don't need to take anything else apart except remove the top caps and springs to pour in and measure oil level. Does anyone have a trick, or know of a tool for removing these top caps? I thought perhaps a bolt head or nut with a spanner might do it, but need to go acquire a bolt. Any suggestions gratefully received

I understand your frustration. There is a little pitting on the forks on my XJ, but unfortunately there is the odd bur as well. They ate through new oil seals in two weeks. Looking at the costs and difficulty in fixing the problem, I am wondering if its even worth fixing the bike since it will also need a new chain and sprockets pretty soon. I have had a very glum day pondering the situation. Will contact the breakers tomorrow and arrange to go and see what they have got....

Hi, I have an '89 XJ and I think it has the same engine as the Radian, which means its air cooled right? If you can't find a fuel problem, could it be overheating? Check your oil cooler to see if its hot when the bike quits. If its cool, then maybe there is a blockage in the oil system that is causing the engine to overheat? I'm no expert, but it might be worth checking.

Well, I swapped over the plugs and got the same result. Cylinder 1 takes ages to heat up, but I shut off the choke and continued warming it up. The number 1 downpipe slowly warmed (much more quickly than the head) so I know there is ignition there. I suspected the idle jet in cylinder one might have been clogged. It was seized in the carb when I first tried to clean it so I could not guarantee it was as clean as the others. I went and bought a better screwdriver, took the carbs off, got it out (finally) and cleaned it thoroughly. There seems to be an improvement in smoothness, but its not quite there. I oiled the carb pistons which helped the throttle response, it doesn't feel "lumpy" now, just not exactly smooth. I think the carbs still need balancing. I have heard from a couple of (older) fettlers about using a tube and your ear to synch carbs. I might try that as I have nothing to lose really. Though I doubt it will be easy on the Mikunis because of the bypass that handles airflow at idle... (where do you put the tube?) Will take it for a ride later and see if it performs better on the road now too. As for the lights, after cleaning every connector and spending ages trying to trace the fault, I found that if I tapped the fuse box, the lights came on will have to check all the wires and connections to/in the box and fix whatever is loose! Nice not to have to spend any more money on it though

Thanks Kieran. Its good to hear that someone else had a similar problem and fixed it so easily! My bike passed its MOT only a week or so ago and the lights were all fine on Wednesday, so I am hoping its just a loose connection. I'll give all the plugs a good clean this weekend and WD40 them.

Thanks for the reply. Will try swapping the plugs, but all the pipes were equally toasty after a ride. Certainly sensible to eliminate the ignition from the list of potential problems tho. Like your suggestion for balancing will have to locate some lock-ups.. The local bike man quoted me £50-£60 to sort it, but I could get a set of four cheapo gauges from ebay, delivered for £35 so I'm tempted to learn the tricks myself. As for lighting, the fuses appear to be fine... I have no headlight, full beam or dipped, no parking light and no tail light. Passing flash switch does nothing either, but the brake light is fine for front and back brakes. Very limited visual check on wiring (under tank only) did not reveal any problems. Wondering if some relay module could have gone? Trying to find a wiring diagram...

Barkwindjammer, you were right about the carbs, they are totally out of whack! Felt the downpipes while warming up. They all warmed up at different rates except number 1 which didn't seem to heat up at all! It was hot after I rode to work, so I have to assume ignition is ok in that one and its a carb problem. Still. Thanks for your help, its such an easy way to spot a problem and I would not have thought of it. Now whether to get my own vacuum gauge or get a pro to do it? And in an unrelated issue, when I arrived at work the headlight and taillight weren't working a few teething problems to sort out still! I expect a plug got dislodged somewhere, or maybe the bulbs gave up after so long in storage, but together?

Ah, just looked up how to balance carbs. Looks like you don't have to touch the air screws, its all about manifold vacuum and adjustment of the throttle links to the butterfly valves to make it the same everywhere. Sorry to state the obvious to everyone, I feel like I'm the only one who doesn't know this sort of thing, but this is great because there is now a chance of sorting it out. There seem to be a few balancers on ebay. Any recommendations?

Hmm. Balancing them is going to be tricky, unless I can match cylinders 3 and 4 to 1 and 2? (the screws on 3 and 4 are fine (counting cylinders from left to right of bike)). I might need to source some parts on ebay as those screws are well and truly stuck, I tried soaking them in WD40 every day for a week and it had no effect. Carb cleaner likewise. Will try and remember to check how the downpipes heat up tomorrow morning - good idea.

Hi All! First I just wanted to announce to the world that I got my '89 XJ600 back on the road after 10 years storage in someone's garage I just got it MOT'd and rode it a couple of times today. Bike feels good, balanced and comfy. It handles better than I'd expected. There seems to be plenty of power (gears seem very close together..), throttle response is ok, it just sounds a bit rough, a bit lumpy. I cleaned the carbs using solvent and cleared all the passages, especially the jets, but there could be a bit of residue still in there. It is possible the ignition is not at its best either (old HT leads and plugs, though I gapped them). The question is, do you think it will improve after a few good runs? (using redex to try and help the carbs) Or could there be something fundamentally wrong that I've missed? Idle is a bit uneven, but I'd expect that. Two of the air screws are not adjustable, they are totally seized and I've damaged the screw heads in my frustration, but due to the size of the venturi compared to those screws, they can't have an affect above idle speed can they? If all is well I'll commute on it tomorrow, thats a 30 mile round trip. I'm a little nervous because today was my first day on a bike since an accident about 5 years ago!! All ideas welcome.

Thats a good idea. I have taken the carbs off now to look at the choke problem, so will try this after the rebuild. The inlet rubbers are cracked on the outside in places, but look in good condition on the inside. I am not sure if these have caused an air leak. The worst crack (outside) is shown in the first photo, the inside (hard to photograph) is in the second photo. It looks smooth and the rubber seems ok. I'm sure I could seal them with something just to be sure. Worst of the cracks: And the interior: Inconclusive. Carbs are still the prime suspects. At least there were similar petrol traces in each of the rubbers after running, so it looks like all carbs are working to some extent.

I was wondering about those. They are not perfect by any means. I was thinking a coating of silicone sealant might keep them going a bit longer? I could test the theory by greasing them up really well and see if that helps. (I don't have any silicone at the moment) I tried connecting the vacuum hoses to the other cylinders to see if that made a difference. One of the rubbers it was previously connected to looked rather dodgy. But this made no difference. If they are generally affecting the running of the engine, the air leak must be very bad as the throttle control barely does anything. I also have to check the choke passages in the carbs. At the moment, only full choke seems to do anything, partial choke is useless even when hot. This doesn't seem right, so maybe something inside is blocked? I realised this is the only part of the carbs I have not taken apart and cleaned. Silly to overlook this I know.

Thanks for the welcome! I had not realised I could post pictures yet. Foamy, it has some rust and the odd dodgy fix, but I just hope it will get through an MoT. Hopefully will eliminate some lines of enquiry on the troublesome engine tomorrow. Might even fix something! Will let you know how I get on.