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F650GS 2002 Single Spark issues / mods / improvements?

3K views 15 replies 3 participants last post by  Andy.I 
#1 ·
Hi Chaps,

My F650GS 2002 Single Spark, which I've owned for a couple of years, seems to be running well (touch wood!) but I'm mulling over possible issues / mods / improvements as follows...

I'm getting 55MPG with what I think is normal riding: 75-80 on motorways and 50-65 on A/B roads. I'm not unhappy with the consumption but I've noticed that the (standard) exhausts look a bit sooty- if I run my finger inside it's definitely black (but not wet). Is this normal and if not, what can be done about it?

After losing my rear duck's arse hatch last year I bought a replacement but so far haven't fitted it because it looks as if it might go AWOL again. The two sections of the duck's arse (or whatever we should call it) don't fit together properly in spite of having the little cross-piece add-on fitted. Is there any solution to this or should I just make a lanyard for the hatch?

Checking the oil level is almost impossible, because even with a bright torch I can't see the through the sight glass! I'm sure this was an accepted issue because the twin-spark oil cap has an integral dipstick - would one be a direct replacement or should I modify my oil cap and add a dipstick?

My mate JayDee1942 (see his recent thread on solving his twin-spark's refusal to rev over 4000rpm) has opened out the tiny coolant level peephole in the cladding with a dremel so he can actually see the coolant level. That's rather a clever mod as I've been removing the cladding to do this but I still have to remove the cladding to check the battery acid level, which is a complete PITA. Does using a sealed battery mean this laborious chore becomes unneccesary?

The hand protectors are riveted to metal bracket which clamp round the bars. Is it a difficult job to drill out these rivets so I can get the brackets blasted and painted and then refasten them with nuts and bolts?

I had a problem with the a chain tensioning bolt working loose which resulted in the plate through which it runs in the rear of the swinging arm being destroyed and from what I have read this is quite common. What's the best method of prevention - loctite or using nylock nuts?

Is there any function to the "possum scraper" addition to the chainguard or is it just a styling affection which can be discarded?

The headlight - what headlight? I have bought a pair of LED halo/spotlights and I am debating how to mount them. I know that there is a bracket which bolts under the top yoke which enables you to mount running lights but are there any drawings or dimensions available?

This bike has only done 17k so I'm keeping my eye on the water pump and the rear suspension linkage but I don't think there's any need to be particularly concerned yet, but any other tips would be gratefully received!

Thanks in advance!
 
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#2 ·
I can only comment on some of the issues.

55 mpg does seem a bit low for an F650GS but it depends on how hard you ride it. If you are worried about the engine running a bit rich, I would check the state of the spark plug after a long run - the electrodes should be a light brown in colour. Black sooty deposits would indicate a rich mixture.

I found it almost impossible to check the coolant level on my F650GS using the sight glass - I wouldn't be surprised if the earlier oil level sight glass was similarly useless. If I had the earlier F650GS and couldn't use the oil level sight glass, I would probably have just knocked up a suitable dipstick (calibrate against sight glass level) to poke through the filler cap - it's not as though you have to check the oil level very often. Alternatively, it looks as though the later filler cap with built in dipstick will fit.

Modern Gel batteries are maintenance free and don't need to be checked - in fact, there's nothing to check!

I replaced my water pump at ~10k miles purely as a preventative measure so I didn't find myself constantly worrying about it. The problem is that the outer water seal relies on the grease between the two seals to lubricate it and there's no way of easily checking this grease or replacing it. After 14 years, I was doubtful that the grease was still in good condition and so replacing the pump removed all this doubt. That said, having to take off the clutch cover to remove the water pump impellor was a complete pain.

I took the rear suspension bearings apart to check them after I got the bike and they were all in very good condition. However, the same couldn't be said for the swinging arm bearings. Water had got into one of them and it had seized up. I would therefore recommend doing the same checks on yours but replacing the seals at the same time (basically made out of felt if I remember correctly and relatively cheap).
 
#3 ·
Thanks for the reply.

Initially I thought that 55MPG was a bit thirstly but then I rationalised that JayDee1942's twin-spark does 65MPG so this was the the downside of the less efficient burning of a single-spark. I shall try using a less vigorous wrist action and see what happens, and indeed, a plug chop might be a good idea. However, if it is running rich I'm a bit confused about what can be done to lean it out.

The current battery doesn't seem to have been damaged by the two full discharges it suffered due to the relay problem a few months ago but when it finally expires I'll fit a sealed battery. I currently have a makeshift dipstick hanging on the garage wall for periodic oil checks but when I fit the new battery I'll open out the coolant sight port and also adapt the filler cap to include a dipstick. That, coupled with an external electrical socket will allow charging through an Optimiser or using a photovoltaic panel should mean removing the plastic just for services to get at the air filter etc.

The water pump is behaving at the moment but I've got my eyes on it and plan to replace it next winter. There's no play in the swinging arm bearings either but I've got replacement parts ready if it deteriorates, and these include rubber seals, not felt ones.
 
#4 ·
Agree with suggestions already posted, look at preventative check on suspension/ SWinging arm not just bearings, but seals too, as these deteriorate , let in water, not well greased from manufacture =wear like SHB

Re seeming rich mixture look at air filter, clogged? Dirty, collapsed? especially if never replaced with your low mileage, bit of a bugger to get too :(
MPG on borderline of low for this model, depends how you ride, hilly area etc, check rear brake not binding , well known fault, rubber cover on brake slave cylinder deteriorates, lets in water, piston sticks, I know from experience . Ok when set off, but didn't release fully during rides, eventually had to prise pads open to get home :-(
hand protectors - drilling rivets out and replacing with bolts doable, take it easy so drill doesn't slip, replace with rivets if got rivet gun, or nylock nuts and/or Spring washers with bolts as belt n braces job, h/ bars vibration .. .. . . .
suggest same with chain adjuster, loctite works ok, but remember it's an adjuster
 
#5 ·
Thanks, I recently checked the air filter when I had the bike apart to sort out the load relief relay problem - it had been recently renewed. However, even if the air filter were partially restricted shouldn't the fuel injection system balance the fuel mixture and the result would be decreased performance rather then a rich mixture? I live in south lincolnshire so hills are few and far between and I have no brake binding problems although I'm aware of the possibilities of getting them.

WRT the handgrips, as long as there are no gotchas with removing the rivets, and although I've got a rivet gun, I think the hand protectors will look better with stainless torx screws with nylocks underneath rather than rivets! :)

When threadlocking the chain adjusters you have to take the bolts right out, treat them and then wind them back every time they are used. I read somewhere that nylocks were not a good idea although I don't understand why; perhaps aerotite nuts could be used?
 
#6 ·
What a motorcycle fuel injection engine relies on is the O2 sensor in the exhaust to tell it whether the fuel-air mixture is correct. In principle, if this is not working correctly then you could end up with a rich (or a lean) mixture. I would do a spark plug colour test first to try to establish whether there is a problem or not.

Nyloc nuts are reusable and would be fine for this application especially as all you want it to do is to stop the adjuster bolt from unscrewing.
 
#7 ·
'Morning AWJDT,

JayDee and I came to the conclusion yesterday that after a plug check the first quick-and-dirty (cheap-and-easy) test should be the O2/lambda sensor change - on offer for £20 on Ebay, with a 2-year warranty. Has anybody got any experience on using unbadged lambda sensors?

After reading up on them it appears that the major difference between many is just the electrical plug rather then the sensor itself!

Regarding the chain tensioners, I concur with you - lock nuts it is then!
 
#8 ·
To keep everything in perspective, I've just had a look at the average mpg figures reported for different model years for the F650GS. For 2002, the figure was 50 mpg compared with 60 mpg for my 2006 model. On this basis, your 2002 model petrol consumption looks pretty good compared with the average for that year! At 55 mpg, that's still a range on a full tank of petrol of over 200 miles which isn't too bad.
 
#11 ·
personally think these ave imperial MPG realistic , my single spark from records goes from 60-70 mpg, depending on long motorway runs to Scotland/Lakes or local town runs. I don't dawdle .. . ..
Twin sparks are a bit more efficient
 
#12 ·
Hi Chaps,

I have checked my plug and can confirm that my GS is definitely running on the rich side.

I've been reading a lot about O2 sensors and it's all very interesting...

Apparently the business-end of the sensor is a sintered porous ceramic which allows O2 to diffuse though it to make contact with a pair of electrodes which produce a potential difference somewhere between 0V and 1V, depending upon the level of O2, and this voltage instructs the ECU to increase or decrease the fuel mixture. It makes sense to me that the sensor will have a finite life because its function will depend upon the porosity of the ceramic which will become increasingly blocked by exhaust deposits. While these sensors are supposed to last 100,000+ miles we all know about the bath tub failure curve don't we?

There are numerous videos on Youtube claiming that we have been convinced / hoodwinked / brainwashed into believeing that O2 sensors fail completely and need to be replaced, rather than regularly cleaned - possibly becauase it's a quick and easy fix - although this is relatively easy process. These videos O2 sensors being soaked overnight in petrol, thinners, carb cleaner etc and then residual deposits being removed by an ultrasonic cleaner. A general recommendation is that they should be cleaned every 10-15k kmiles, ie at every service. This makes sense to me because the porous ceramic will eventually become blocked with all the carbon and whatever deposits in the exhaust, and that regular cleaning should slow down the blocking process.

As it looks as if my O2 sensor is not working properly I will try cleaning and report back my findings.

Has anybody else any experience of this matter to add to the thread?
 
#13 ·
There was another fall at the first hurdle yesterday!

JayDee arrived for a BBQ with a brand new O2 removal tool in his pocket. We grovelled under the bike, slid the tool onto the O2 sensor and it was so slack that it rotated around the hex flats without gripping - a vernier showed it to be 33mm, not 32mm. I sorted out an old 22mm ring spanner and attempted to grind it open but my angle grinder made very heavy work of it so I gave up and decided I needed to buy a suitable tool.

This leads me to the following question: the various tools seem to fall into several basic designs and variations thereof:

1) a deep socket like a plug socket but with a slot down the side and 3/8 or 1/2 inch drive square such as Ebay item 190754427966

2) a flat open-ring crowfoot spanner for either 3/8 or 1/2 inch drive square such as Ebay item 163663425378

3) a cranked open ring crowfoot spanner for 3/8 or 1/2 inch drive square such as Ebay item 183726054782

4) a deep open-ring with a pivoting breaker bar such as Ebay item 392534151835

I can see possible difficulties arising with any of these types of tool due to the awkwardness of access and limited space: would any of you chaps with experience of removing and replacing the O2 sensor kindly advise me as to which type of tool is most suitable please?

Thanks in advance.
 
#14 ·
I thought I found a definitive answer to my question on https://f650gs.crossroadz.com.au/ExhaustRepair.html and I bought such a tool.

This morning JayDee and I discovered this tool wouldn't fit because the sumpdrain plug was in the way. :roll:

JayDee had brought his 22mm slogging ring with him but this wouldn't fit either because there wasn't enough clearance between the frame's front down member and the sensor to get it onto the hexagon flats.
However, we discovered that a 22mm cranked ring spanner could be slid over the electrical connector and with a couple of minutes' heat from a blowlamp the sensor was extracted and the replacement was fitted. :sunny:

We reset the ECU, topped up with fuel and set the trip; the engine seems to run just as it did before but I'll judge future consumption from facts and figures.

More to follow...
 
#16 ·
I have done 187.4 miles since I last filled up and zeroed the trip, with a mixture of gentle country roads and some rather spirited riding where I was, ahem, making good progress. ;-)

It has just taken 13.8 litres to fill to the brim again and I make this 62MPG so it looks as if I've had a result and I'm well happy.

To me the engine's performance was the same as ever but the frugality stands out.

The only significant thing to report from this experience is that you don't need a special tool; a blowlamp, a bit of alloy as a heat shield to protect the frame's paintwork and a 22mm ring spanner does the job, along with some sidecutters to cut the cable ties and some replacement cable ties.

While I was at it I degreased the underside of the engine and frame which seem to collect chain oil and I replaced the sump guard torx screws and washers with stainless items.

Note that my comment about not needing a special tool and that a cranked ring spanner if all one needs applies to my 2002 single spark model although I don't see why it shouldn't apply to a twin spark but as I'm informed that its exhaust pipe is 2mm greater diameter so it is conceivable that this could make a difference. Maybe a twin spark owner can confirm this?

Thank you for the information and suggestions chaps.
 
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