Honda-SOHC

Hi, my commuting bike is a 98 Yamaha 900s Diversion that is doing me proud in all weathers.

My problem is, that according to every specification I look at, the tank should hold 24 litres, giving a range of about 240 miles. I get about 10 miles to the litre so my consumption seems spot on, but I ran out of fuel after 135 miles the other day and it took about 14 litres to refill it.

I can’t say for certain how much fuel was left in the tank when it “ran out”, so it might’ve been that there was ten litres left in there.

There is no reserve setting on the fuel tap, only on or off. It is not a vacuum operated tap. There is an electric fuel pump.

The bike has a fuel gauge and low fuel warning light. As appears to be normal for this model, the fuel gauge is not reliable, so I use the odometer for my remaining range calculations. Apart from the light check at start up, I have never seen the low fuel light on.

When the weather improves, I am going to empty the tank and take the fuel tap off to see if there is an extended pipe or something inside that is reducing the amount of available fuel.

Another thing is that maybe the tank has had a huge dent in it that has been very well filled and repainted, but I doubt it’s this.

Anybody had any experience of this reduced range/fuel tank capacity on this model, or any other?

I understand why you’d say that. However I can’t imagine it would be possible to make a bendy guitar string go through a hole which was smaller than it.
Anyhow, I’ve replaced the slow idle jets with 38’s and balanced the carbs. It’s much improved but coughs a bit going up the road, lacking power. Once revs are at about 3500 it’s much better. That’d be Main jet though at that stage.
The exhaust still indicates running rich, any attempt to put a filter in the airbox makes that worse.
I’m contemplating dropping the needle to lean that off, currently needles are on the middle setting.
Vacuum gauges are on about 8 inches which if I’ve converted correctly equates to the book 16-24 cm HG

If you’ve measured 8 inches of water, then that’s about 1.5 cm of mercury. 16cm of mercury is about 85 inches of water !

Quote from: jon stead on October 06, 2019, 07:02:12 PM

Quote from: K2-K6 on October 06, 2019, 06:56:24 PM

Unsure what it looks like.

But found this for sale https://www.ebay.co.uk/itm/1995-YAMAHA-XJ900-DIVERSION-PETROL-FUEL-PUMP/392177364511?_trkparms=aid=1110001&algo=SPLICE.SIM&ao=2&asc=20160323102634&meid=9b376a3e351c4bb386664e582a46642e&pid=100623&rk=3&rkt=6&sd=183914917986&itm=392177364511&pmt=0&noa=1&pg=2047675&_trksid=p2047675.c100623.m-1&redirect=mobile

Which may help.

Thanks for the link. I’ve seen pumps on eBay, and yes that’s the one, I’d like to fix the one I’ve got though. So I need to find a clip that will go securely into a groove on a 5mm diameter shaft.

I'm just thinking in the absence of your missing bit it could help to get another example.  Sometimes arrangements like this have a "washer" with a recess in it that when pushed over the thrust side of the clip  would encapsulate it and prevent it's falling off. If anything like that had also been lost it may leave you vulnerable to further failure too.
I like to fix things like this too but can't see from diagrams available that level of detail to help out.

Yup, that’s what I’ll be doing. First thing I’ll do is whip the points cover off it and see how it activates the points.
I’ve been thinking about this today, and it might be that there isn’t a clip at all, and that the plate if one of the contacts, had to locate in the groove on the spindle.

1998 Yamaha XJ900 Diversion fuel pump gave up the ghost. Upon inspection I found there’s a clip missing from the 5mm diameter solenoid spindle. The clip opens the points when the solenoid is energised and the spindle displaces.

Has anybody got any idea what this clip looks like?

I can find round wire clips, online, but only down to 6mm diameter shafts. An external circlip, that small, is not an option.

I’ve fitted a E clip for now, but this is loose fitting and I had to crimp the clip closed to stop it falling off. I’d prefer a more secure clip, but what?

On mine there was no electrical supply whilst cranking the engine over. As Bryan says, the engine needs to be physically running before the fuel pump gets an electric supply.

I’m going to make a simple jump lead up and keep it under the seat in case I ever run out of fuel somewhere and need to fill the carbs before restarting the engine.

Got the bike running. Rigged up temporary 12v supply to the fuel pump, filled carbs up, started bike, ran good. Stopped bike, started again just to see if it would. Stopped bike. Removed temp supply, reconnected to original supply, started engine. Ran it for 5 minutes without issue. Took it out for a ride and it was good. Thankfully.
Now I need to sort out the retention o rings for the needle assemblies

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Ok so local mechanic who has a good reputation has had bike for a day and is convinced this is a valve problem. Says he has heard similar sounds/symptoms on other bikes down to slightly bent valves that stick when warmed up.

Am now thinking that maybe I have accidentally slightly bent the 1 and 2 exhaust valves when I reassembled after the head gasket change.

This all seems logical as this problem only started after the head gasket change and am sure nothing else was changed, valve timing is correct.

Also thinking back I seem to remember I had a bit of a struggle getting the rocker cover to go on back easily even though I thought I had wound back the adjusters as far as I could.

Started another thread now as this is getting off track

If you have bent a valve whilst putting the rocker cover back on, it’s possible you’ve cracked a valve guide as well. I know because I did it! A very costly mistake.