Hello. I have got a 1986 XJ600 (pre-Diversion). I bought it from a mate who kept it in his garden, not moving, for a year. It has had some work done on it but is not MOT'd taxed and on the road. But I still have some problems.

Riding home from a rally I was really enjoying it getting used to going quicker etc and managed to go up to a certain speed which is the fastest I've ever gone. Then I got problems. The bike started lurching back and forth and the rev counter was going all over the place. Bit scary, I slowed down and it kept doing it until it loudly backfired and seemed okay. I kept going and it happened again so I made sure I didn't go too quick the rest of the way back.

It has already had problems with revving all over the shop. When I stop it would rev anywhere between 1500 and 3000 and would change as well! I was told that air leaking in to the rubbery bits after the carburettors is common, and they've now been coated in electrical tape and the idle speed altered, which has greatly improved it. Also the caps for the spark plugs have been replaced.

This morning the thing would not start! While it sounded like it was making the effort the engine did not turn over. I stuck the battery charger on it for five minutes and tried again while it was attached - no change. So I packed away and was ready to brave the bus. Thought I'd give it one last try without the charger - surprise - it works but intermittently ticks over with no revs and making a weird low pitched noise. It does this sometimes when just started and will get over it after running for a couple of minutes.

So anyway well done if you read all that. I just want to know whether anyone has similar experiences with bikes of this age, specifically this model, and therefore might have an educated idea about what is causing all these problems!

Update: Happened again this morning. Found the tape round the rubbery bit between carburettor and engine had fallen off - replaced it and it ran fine. So I guess I may need to replace that part after all. Does anyone know what it's actually called though?

Update: Does anyone know where to get inlet manifolds for a pre-Diversion XJ600 online? Or have an approximate idea of price? I can only find Diversions!

Oh yeh and you will all be pleased to hear that this is my last comment on the matter (unless someone replies that is).

Update (sorry)

Anyone got an old igniter unit they wish to part with?

the intake manifolds are known as carb holders, or carb boots, and mine are all cracked and nasty too. You can get them from places like bikebandit.com or denniskirk.com, just input your specific model and they usually go for around $10-$60 each. If you order them specifically for your model it can get pricey, but if you measure the diameters and such, you may be able to get cheaper universal ones that will fit. good Luck, please tell how it goes, cuz my FZ-600 is all whacky with the stuff you mentioned too, (same engine as XJ adn YX Radians).

In my experience of my current XJ600 and previous kwak, the rev counter going all over the place, and power dropping out and coming back in was a failure of the coils, because one coil supplies a pulse that gets interpretted as the engine's revs for the dash.