900 Diversion Fuel Consumption Problem

[swedahla]

Hi,

As I'm new to this forum and I'm from Sweden, I apologize for my English. But please, be patient.

I recently bought a D9 -96 and have ride about 4000 km (~2500 miles ?) and is concerned about the consumption of the bike. Typical consumption is somewhere around 30-35 MPG (0,8-0,9 L / 10km). Is this in any way normal or can you provide me with your thoughts on where to troubleshoot.

Thank you for your help,
Regards Martin

[bobh]

Hi and welcome to the forum.

That sounds a bit too thirsty to me - I used to get 50-55 mpg (Imperial gallons, that is - 4.54 litres) with mine.

Assuming your bike is standard and the carbs haven't been tampered with, the two things I'd look for first are:

1. The choke slide may be sticking so the choke is partially on all the time - this is quite common on the D9. Even if that's OK, one or more of the choke needles on the carbs may be sticking and not returning to the off position.

2. Change the air filter, unless you're sure it's been done recently and looks fairly clean.

Can you smell neat petrol around the back of the bike when it's idling, with the engine fully warmed up? That would certainly suggest that it's running too rich.

[mlbv]

I seem to get 150 miles from a tank no matter how I ride, whether doing a long distance at **motorway speeds** or long distance at reasonable speeds, or just taking it easy around town (been using the bike with the dodgy front brake relying mainly on the rear so taking it steady) or riding around town like my hair is on fire... no matter what type of road or riding style it always seems to do the 150 miles per tank which guessing at around three and a half gallons per tank is about 45ish mpg, i say per tank, i always fill up when the needle hits the red, i have no idea how much further i could get on what remains, but it is about 15-16 litres to do the 150 miles... this is completely different from my diesel van which can make nearly 60mpg on the motorway (if i pay constant attention and make the effort) down to around 13mpg flat out (around 145mph)

[GAv]

or riding around town like my hair is on fire... no matter what type of road or riding style it always seems to do the 150 miles per tank which guessing at around three and a half gallons per tank is about 45ish mpg or four gallons per tank is just under 40mpg ... this is completely different from my diesel van which can make nearly 60mpg on the motorway (if i pay constant attention and make the effort) down to around 13mpg flat out (around 145mph)

No offence but if your hair is anything like your icon, it would be a bloodyoming firestorm(only jealous as to the fast receding hairline old Farts like me suffer from), not to mention how would a helmet fit over it
Presumably the caddy is the Racing Van you refer to elsewhere

[mlbv]

yea, I call it the racing van because it is a bit ott for normal road use, it is primarily built for track use as a veg powered toy... and yea, my hair started thinning about a year ago so i had to change my spikes for a more traditional and conservatively styled pink mohichan... in my case, flaming hair really would need a rather aggressive riding style to escape it considering the amount of hairspray i use!!

here is the dirty diesel with dick dastardly smoke screen (which isn't handy when driving past speed cameras, no siree, not me officer!!)

[bluevinny]

Mine manages about 50 mpg when the brake caliper pistons (front and rear) start to bind and approx 55 mpg after the calipers have been stripped and cleaned.

The settings of the pilot screws for each carb should be 1.5 turns out. Are yours set to this value?

[teejayexc]

Balancing the carbs won't hurt either.

[chris900divvy]

Seemed to me mine improved a lot after doing the valve clearances, getting more like 45-50mpg on average now which is way better than what it was at one point I remember it not doing much better than about 38mpg at an absolute best, 30-35 a lot of the time especially when thrashed. Cleaning the air filter always helps, I have a K&N on mine which I can wash and reoil.

[satnav]

Oct 31, 2015 20:23:41 GMT mlbv said:

I seem to get 150 miles from a tank no matter how I ride, whether doing a long distance at **motorway speeds** or long distance at reasonable speeds, or just taking it easy around town (been using the bike with the dodgy front brake relying mainly on the rear so taking it steady) or riding around town like my hair is on fire... no matter what type of road or riding style it always seems to do the 150 miles per tank which guessing at around three and a half gallons per tank is about 45ish mpg, i say per tank, i always fill up when the needle hits the red, i have no idea how much further i could get on what remains, but it is about 15-16 litres to do the 150 miles... this is completely different from my diesel van which can make nearly 60mpg on the motorway (if i pay constant attention and make the effort) down to around 13mpg flat out (around 145mph)

You have a fuel gauge that works!?

I have to rely on the trip on the speedo. I know the fuel light will come on somewhere around 165-170 miles.

[satnav]

Oct 29, 2015 9:35:41 GMT swedahla said:

Hi,

As I'm new to this forum and I'm from Sweden, I apologize for my English. But please, be patient.

I recently bought a D9 -96 and have ride about 4000 km (~2500 miles ?) and is concerned about the consumption of the bike. Typical consumption is somewhere around 30-35 MPG (0,8-0,9 L / 10km). Is this in any way normal or can you provide me with your thoughts on where to troubleshoot.

Thank you for your help,
Regards Martin

No need to apologise for your English.

1) It is certainly better than our Swedish, and

2) probably better than most of the UK's natural inhabitants.

[swedahla]

Thanks for your answers!

I will lookup the choke and carbs. Will be back with new info later

[cam7777]

Just for reference, my commute is mainly dual carriageway.

I filled the tank, then covered 180.5 miles, filled up again with 14.32 litres which equated to 57.3mpg.

[swedahla]

OK, here is some other information for trying to solve this:

Checked the plugs today, all black and dry. Not oil. Does this automatically mean that the problem is inside the carbs, saying that the air filter is perfectly new ?

Checked the pilot screws about a month ago, they were set to about ½ turn out. Tried setting them to 1½ and the consumption is the same....

Will do a carb sync probably this weekend. Cant get any results until at least mid of March though, cause of winter conditions in Sweden

[swedahla]

Nov 13, 2015 9:09:52 GMT cam7777 said:

Just for reference, my commute is mainly dual carriageway.

I filled the tank, then covered 180.5 miles, filled up again with 14.32 litres which equated to 57.3mpg.

Oh great dream....for me...

[GAv]

Hi I have family connections in Denmark, and have visited your lovely country many times.

Anyway another contributory factor with your Nike, may be the rear calliper binding, even the fronts, as they tend to do on XJ 900s that would effect the fuel consumption.
To me sooty plugs is not too a bad a sign, as oily ones indicate too rich a mixture, but even so, you might like to try a drop or two of RedX,in the petrol tank which often works wonders cleaning carbon deposits.
Crud in the Float chambers, even the Venturi bowls to the main jets ,can cause problems, but generally they affect starting and restrict the bike revving(my 650 twin carbed Sachs, for instance wasn't revving till I had the whole thing apart, and found cruddy deposits under the diaphragms rubbers), like plaque one gets on teath, rampant, she now runs fine again, however being a betting man, I would be tempted to put my money on the brakes causing drag and ruining you mileage.

Good luck with it Anyways.

[chris900divvy]

Feb 24, 2016 16:24:13 GMT swedahla said:

OK, here is some other information for trying to solve this:

Checked the plugs today, all black and dry. Not oil. Does this automatically mean that the problem is inside the carbs, saying that the air filter is perfectly new ?

Checked the pilot screws about a month ago, they were set to about ½ turn out. Tried setting them to 1½ and the consumption is the same....

Will do a carb sync probably this weekend. Cant get any results until at least mid of March though, cause of winter conditions in Sweden

Carb sync will probably help, they can go off quite a lot if they haven't been done in some time and you'll appreciate the difference in smoothness after. Also maybe have a look at your air filter at the same time, and as said is the choke returning properly? I did my valve clearances a few months ago when I had the engine out to do the gearbox, seemed to me I was getting improved consumption after that maybe 45-50mpg a lot of the time whereas before that it was similar to what you say you are getting. The brakes do get sticky with a bit of muck behind the seals, well worth checking that too I'd say just a toothbrush and some brake cleaning spray with the pistons eased out a little should sort that.

[swedahla]

Thanks for your response.

Will have a go with the RedX or similar(not sure we have RedX in Sweden). Actually I haven't looked at the rear brake at all. GOOD idea. Get back later tonight after having a go with them.

Yeah, I believe the valve clearance is in the plan before the season starts here. Was thinking of doing that before starting any sync or carb cleaning.

[chris900divvy]

You just need to be careful to support the bosses on the oil cooler when unfastening the lines on it as it needs to come off to get at the valve cover. There are tools for doing the shims but I managed to do it with just a couple of screwdrivers.

[swedahla]

Feb 25, 2016 10:39:10 GMT chris900divvy said:

You just need to be careful to support the bosses on the oil cooler when unfastening the lines on it as it needs to come off to get at the valve cover. There are tools for doing the shims but I managed to do it with just a couple of screwdrivers.

Actually I've booked a time at a shop for the valve check. I believe that's worth it.

After that sync carbs (perhaps a hard clean as well before), new spark plugs and air filter. Wish me luck

[swedahla]

Feb 24, 2016 16:43:06 GMT GAv said:

Hi I have family connections in Denmark, and have visited your lovely country many times.

Anyway another contributory factor with your Nike, may be the rear calliper binding, even the fronts, as they tend to do on XJ 900s that would effect the fuel consumption.
To me sooty plugs is not too a bad a sign, as oily ones indicate too rich a mixture, but even so, you might like to try a drop or two of RedX,in the petrol tank which often works wonders cleaning carbon deposits.
Crud in the Float chambers, even the Venturi bowls to the main jets ,can cause problems, but generally they affect starting and restrict the bike revving(my 650 twin carbed Sachs, for instance wasn't revving till I had the whole thing apart, and found cruddy deposits under the diaphragms rubbers), like plaque one gets on teath, rampant, she now runs fine again, however being a betting man, I would be tempted to put my money on the brakes causing drag and ruining you mileage.

Good luck with it Anyways.

Thanks for this tip, I've now cleaned front and rear calipers and I believe there as free as possible now.

Actually, after doing a refill the other day, I had ran 75 km, and just got in about 4 liters in the tank. I believe that some improvements have been made thanks to you guys.

Just valve check tomorrow and after that carb sync. Hopefully everything works smooth afterwards.

[GAv]

Great and then hopefully you start to enjoy your machine in full measure.

[swedahla]

OK, valve check, sync carbs done (by the shop). He's really nice this guy and told med that the carbs are getting a bit rich even after sync. He suggested, if I wanted to, repair or replace carbs.

Two questions,
A: How difficult is it to repair(gaskets, float needle etc) the carbs on my own? I'm a bit handy. Think a repair-kit is available for about 60-70 pounds on ebay.
B: If replacing (I believe this is a risk if I cant get a brand new set of carbs), how common is this sort of "brake down" on the carbs? Is it worth £200 for used carbs and still have the possibility that this "new" used one also gonna crack?

[GAv]

Well it depends if you are keeping the bike long term, in which case the new carbs sound a good bet. You say you are handy, it is often getting the things out, then often the Philips headed screws are tight ( I had to use Mole grips on the Twin Suzuki ones on my Sachs 650, after taking the balancer pipes off to get a grip on them. It was worth it as I had taken the float bowel covers off whilst still on the bike.

Not realising there was a third jet on each side,hiding from the two protruding ones, but my optimism the problem was solved was short lived, as it still wouldn't rev up.
Taking the things out again, no mean feat as I had had to take the back wheel out to replace non standard K&N filters with the huge air box in. Then getting the carbs on and off with freezing hands, so the carbs join the two inlets back and front in a limited space can be trying.

I had a Virago VTwin engined Sachs that was very unreliable as it would alternate between running on one cylinder and occassionally two, after yet another taking it off(the single carb ironically)situation, even after buying a Virago carb from EBay that leaked like a siv or cullinder, and I sold the whole machine for spares or repairs.
Everyone I speak to reckons the carbs on them play up, particularly after winter lay ups.

It was however such a lovely comfortable ride, despite only being a 125  I wanted more power, so got a Suzuki engine(single pot)d one done up as a Street tracker as they are as rare as Chicken's teeth, but after a year gathering bits it is back as stock.
Well nearly, as the guy shortened the down pipe so I made a CBR 600 RR Honda one fit instead, which makes it run now smoother at top end,  than when it had a gloriously noisy megaphone type one , used it on the road beforehand ,well 3 years back.
It spent the next two in a shed.

Now after taking the top covers off revealed the rubber diaphragms ( so like Zenith carbs)were good but the main two needle jets that go into the Venturi, were caked in crud(a polite slang term for s*it.) inevitable if unused. Also flushing the petrol tank is a good idea too.

Of course there are 4 ( mikuni Solex carbs on a D9 and they are relatively straightforward to refurbish
www.ebay.co.uk/itm/85-90-YAMAHA-XJ900-CARB-REPAIR-KIT-4-REPAIR-KITS-INCLUDE-CI-XJ900ACR-/261585601433?hash=item3ce7b78399:g:gJwAAOSw-jhUCskk

Good luck whatever you decide to do.

[m40man]

Mar 21, 2016 16:58:51 GMT swedahla said:

Two questions,
A: How difficult is it to repair(gaskets, float needle etc) the carbs on my own? I'm a bit handy. Think a repair-kit is available for about 60-70 pounds on ebay.
B: If replacing (I believe this is a risk if I cant get a brand new set of carbs), how common is this sort of "brake down" on the carbs? Is it worth £200 for used carbs and still have the possibility that this "new" used one also gonna crack?

1. Repair - You maybe just mean clean, & maybe replace some or all jets. Possibly a split diaphragm. It's not too difficult, it's just taking bits off & making sure they are clean & putting them back, or swapping them for new bits.

2. Replacing: With new = too pricey (around £550 if you can find any). Secondhand: May be no better than the ones you have, could be worse if they've sat on a parts shelf for months, nicely drying out & deteriorating.

Some carb parts can wear out a bit, or may have been damaged by previous folks being a bit heavy-handed with past cleaning. But mostly the carbs just need a good clean - taking each jet out & making sure it's as clean as you can get it, that no passages are blocked. That none of the floats have punctures, that none of the diaphragms are perished / split.

........... at least, this is my experience, having cleaned a few carbs over the years.

[swedahla]

Mar 21, 2016 22:45:27 GMT m40man said:

1. Repair - You maybe just mean clean, & maybe replace some or all jets. Possibly a split diaphragm. It's not too difficult, it's just taking bits off & making sure they are clean & putting them back, or swapping them for new bits.

2. Replacing: With new = too pricey (around £550 if you can find any). Secondhand: May be no better than the ones you have, could be worse if they've sat on a parts shelf for months, nicely drying out & deteriorating.

Some carb parts can wear out a bit, or may have been damaged by previous folks being a bit heavy-handed with past cleaning. But mostly the carbs just need a good clean - taking each jet out & making sure it's as clean as you can get it, that no passages are blocked. That none of the floats have punctures, that none of the diaphragms are perished / split.

........... at least, this is my experience, having cleaned a few carbs over the years.

Yeah I believe your right about nr 2. I will try to make a "repair" with a kit like this, www.ebay.co.uk/itm/like/4x-Carburetor-Repair-Kits-Gasket-Float-Needle-f-Yamaha-XJ-900-S-Diversion/231862288006?hlpht=true&ops=true&viphx=1&_trksid=p5197.c100068.m2280&_trkparms=ao%3D1%26asc%3D20140211130857%26meid%3Dc9a5c6bbba1a4b568103c907ceb01a82%26pid%3D100068%26clkid%3D4165672313005871756&_qi=RTM2063723

I'll try to take some photos and tell you how it proceed