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1999 BMW Funduro problem(s).
Greetings
I've been having a devil of a time getting my newly acquired 1999 BMW "Funduro" to run properly and I'm hoping someone can help me out. The bike was not well-maintained, but I have done my best to clean it up and replace neglected parts. In its current state, the bike will not run properly below 4000 RPM, so we can rule out any regulator issues. It will start fairly easily enough (even when cold) but the idle is erratic. If I twist the throttle VERY SLOWLY, the engine speed will increase until about 2000 RPM's whereon it will stop increasing, or may even decrease a bit. As I continue to twist, the engine speed will eventually increase beyond 2000 RPM but there is another point around 3000 - 3500 rpm where it will become erratic again. Once it gets above 4000 RPM, the engine runs well and pulls strong. When I bought it, the PO claimed that the choke cable was "sticky"...but in fact, it had broken off at the plastic hub and the choke plunger was actually seized inside its bore. Once I got that repaired, I also discovered that the screwdriver slot one of the pilot jets had been stripped, so I had to use a screw extractor to get that one out for cleaning. Since I didn't want to put a broken jet back in, I opted to replace them both but since they are an odd size (#41.3) I went to the next size up which is a #42.5 Float level is set as per the manual. Mixture screws set to 3½ turns as per the manual. Main jets are stock #132.5 Mileage is terrible...about 25 miles per gallon (about 10L/100km) I have been across various forums and Facebook groups trying to solve these issues...to no avail. One member mentioned that his mileage was bad until he replaced his spark plug boots, so I thought that I might be having an ignition issue, and I replaced ONE of my spark plug boots (I only had one spare). The other day, I disconnected one of my ignition coils (so that only ONE spark plug would be firing) and started the engine. It ran roughly and needed choke to stay running - this was the "new" spark plug boot. I repeated the test with the other spark plug (original) and it ran better. So I measured the resistance of the NEW boot and found it to be over 20K ohms...that's too much. The original boot was 13K ohms (closer to spec). I ended up replacing the NEW boot with its old counterpart, but noticed that its resistance was over 4 MEG ohms, so I had to clean it up to get it back to within spec. To make a long story short, I've ordered two NEW plug boots and they should be here within a week or two. With the two original spark plug boots back on the bike, I was able to start it but it still ran quite rough, so I turned IN the mixture screw on the LEFT side carb, since I can't adjust the RIGHT side when the engine is running. The further I turned it IN, the better the engine ran...until I reached the bottom of its travel. The LEFT side mixture screw is fully closed and the engine runs "better" than when it is set to factory recommendations. Right side is set to 3½ turns as per the manual. This is what I find the most perplexing because the ONLY parts which are not OEM are the two pilot jets and I can't see how going up only ONE size would have such a devastating effect on overall operation. I have two carb kits coming from Holland (hpefully, they will get here this month) which includes new pilot jets (supposedly the proper size), new needles and emulsion tubes, new float valve and seats, and new slide guides. If this doesn't get it working, then I am really at a loss as to how to proceed. In summary: Factory recommended settings make it run worse. Only non-OEM parts are the pilot jets. Floats are properly set and are NOT water-logged, each one weighs 7g. Fresh fuel. Fuel flow is good and strong...no blockages anywhere. Engine speed will hang at 2000 RPM and dropoff, when gently accelerated. Engine runs well above 4000 RPM but mileage is terrible. No tears, holes or leaks in carb manifolds when installed. Air filter is clean. Valve timing has been checked and valve clearance is good. SPark plugs are new, although the boots are suspect and will be replaced. |
Wow, that's been quite the odyssey!
I know NOTHING about the F650, other than they're well regarded and generally very reliable, only issue I know of is water pumps fail. I think you're on the right track, but would be checking coils and general ignition wiring while you're waiting for carb bits. I've gone down the wrong rabbit hole myself more than once. Plug caps are only the (second) last thing in the electrical chain... Does the spark look FAT and GOOD? How's the starting - is the battery good? Mixture screw - improving until it can't go in any further - hmmm, suspicious! These might be very susceptible to pilot jetting changes. Put the damaged one back in, just not tight so you can be sure to get it back out easily. OR just put the one good one you have in. Does one carb do low speed only and the other cuts in at higher speeds? (Like I said I know nothing of these things) IF that's the case make sure the low speed one is 100% as best you can. It should then run clean to half throttle-ish. If they both work together all the way, scrap that idea! Fascinating issue, I look forward to hearing the result. And nice to see someone else from the 'Wack here, welcome! |
What's the "Wack"?
These carbs (there are two) are neither staged nor synch'd...they both operate on the same shaft. Neither the manual, nor any online resources I've found (and I've dug through many) make any mention of synchronizing the carbs. There are two intake valves and it appears that each carb feeds a valve. As far as I can tell, the coils are within spec and pass visual inspection in terms of cracks or arcing. But the spark plug boots are a known weak-link; the fact that one measured 4+ Megohms and could be brought to within spec with a light cleaning, attests to that. I've thought about replacing the broken pilot jet, but I fear that I may ave damaged it during the extraction...I have it downstairs and will inspect it later...I only need to worry about the actual HOLE size, yes? It's a non-bleed type Mikuni jet as show here: https://mikunioz.com/shop/n151-067-p...v=13b249c5dfa9 But this is the perplexing part because many other models out there can withstand an increase (or decrease) in pilot jet sizes, in order to aid cold-starting, or improve mileage without creating problems in overall running...but I suppose this model could be sensitive to changes. As I said: This is the ONLY change made from the stock setup...so it is plausible. In its own way, it IS a fascinating issue but all things being equal, I'd sooner be riding...and considering that I sold a perfectly functional, reliable and solid bike to get this one, is particularly upsetting. |
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Note that some people have dumped the two carbs and gone to a single one! I wouldn't do it on a well running bike, but if the carbs are toast and the price is prohibitive to replace, it's a possible option. Quote:
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Considering that the plug caps are known failure-points and are slated for replacement, I'll consider this as a MUST DO before going forward. Quote:
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https://cdn-images.imagevenue.com/6e...ME16K37V_o.png |
A few thoughts I have:
3.5 turns seems a lot to me too but it's not critical , and if that's what the manuals say... It affects the tickover/low revs and your bad running implies deeper problems. If it's running rich no surprise there's improvement with a mixture screw fully in. Have you checked the diaphragms? Any hole/crack will affect pick-up. And the seal on the diaphragm cover. Have you checked the inlet manifold(s) for cracks? If the bike is running, spray some brake/carb cleaner in the area and see if the revs drop. If so there's an air-leak. Not necessarily the manifold of course. Maybe the choke bore? Is there a little filter on the fuel input pipe? (like a DR) Has a prevous owner been tinkering? Maybe an o-ring is missing, jets are wrong, needle is too low. Worth checking a schematic to verify. I expect a refurb kit will be a great improvement and a reassuring baseline. Apply lots of carb cleaner and let it soak. Then compressed air if you have it available. Hopefully you'll be able to rule out the plug connectors soon. [Edit] Maybe some heat from a soldering iron to help move the broken jet. |
I'll just add something which is *probably* irrelevant:
A while ago I had a problem with my KLR which everyone, including me and every amateur or pro mechanic I consulted, believed was a fuel or ignition problem. Lots of carb/fuel line/filter/electric/electronic adjustments followed. Then one day in Texas, on a test run after extensive work by a dealership, I heard a "clunk" which seemed to come from beneath and behind me. It turned out the entire thing was caused by a loose muffler baffle--fixed by replacing the whole thing under warranty. So: just a reminder that sometimes we get over-focused on one partial piece, forgetting that bike mechanics are a system and may benefit from systems thinking. Probably not what you're experiencing, but maybe.... |
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Lots of good ideas there! A note on diaphragms - the hole can be TINY - stretch it and hold it up to the light. Easily missed. I've also become a fan of ultrasonic cleaners, bought one a year ago, absolutely fantastic for small stuff like carburetors. Stuff comes out looking like new. A really big one would be nice but just can't justify it. |
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I bought these from Dellorto in the Netherlands and they claim their kits are made in Japan, so here's hoping I get some quality parts! |
Just received confirmation that the spark plug boots are en route and should be here by July 7th...Canada Post is still sitting on my carb kits, so who knows when they'll arrive.
We are set to take off for another couple of weeks holidays on the 6th, so either way I'll miss both packages...they'll have to wait until we get back. In the meantime, I've got an RV to prep so this "project" will be taking a back seat for a while. I've been dealing with this for 4 months...I need a break from this headache. (But still interested in any advice/opinions anyone is willing to share)... |
Burn it!
Petrol + matches will save you polishing this Aprillia made @#$% before the water pump, head gasket, reg-rec, undersized chain, corrosion etc. etc. get chance to ruin your day further. Assuming you enjoy pain, has https://f650.com/ anything useful to say in their FAQ'S ? Used (I went for the petrol and matches solution after a little stroll in the desert courtesy of the chocolate teapot water pump design in 2003) to be the best resource. Andy |
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...and I don't get a lot of replies on that forum either. Believe me, if I had insured it for fire and theft, it would have been "stolen" and left burning in a ditch a LOOOOONG time ago! |
...a revelation, perhaps?
Canada Post sent me a notice that they're holding something at their office...it's probably my carb kits, but since my spark plug boots aren't scheduled to be here until next Friday (when we're gone), I'm not in too much of a rush to pick it up. The Canada Day long weekend means that I'll probably have to wait until Tuesday, anyway...
So just to streamline things a bit, I thought I'd pull the carbs tonight and get them ready for my makeshift ultra-sound cleaner (bucket with orbital sander attached) tomorrow. Removed the carbs from the bike (I'm getting REALLY good at this) and started prepping them for the bath. I removed the choke plunger and for some reason, it appealed to me to compare it to the old one. As you may recall, the original was stuck in its bore by way of a "sticky choke cable". This is when I noticed that the one I've been using does NOT match the stock part. It is about 3 mm shorter and the stud in the middle is shorter as well. So could the "new" one have been the problem? I'm thinking that if the plunger is not long enough to close off the port, it would allow an overly-rich mixture through all the time. This could account for the lousy mileage AND the rough running...and why the engine would run better when the mixture screw is closed off completely, yet run like crap in the off-idle position. And if the stud isn't long enough to bottom out, or to do whatever it does, this could also account for some issues I'm experiencing, right? Well the kits are here, so I'll install them when we get back...a carb rebuild never hurt. And I'm still waiting for the plug boots...replacing a known weak-link is always a good idea. So I guess I lied...the idle jets are NOT the only non-stock items in the carb...the choke plunger is too! But could this have been the problem all along? Hoping that it is...wouldn't that be wonderful, or am I dreaming? Here are some pics for comparison. The STOCK plunger is the top one...the shorter bottom one is what I've been using. https://cdn-images.imagevenue.com/8c...ME16KB8G_o.JPG https://cdn-images.imagevenue.com/fe...ME16KB8H_o.JPG |
Interesting! Always worth doing a careful comparison when installing new parts, even if it's a "genuine" part things may change.
It might be perfectly fine - or not - you'll need to inspect / measure the hole it goes into to determine that, but it's worth putting the old one back in and see what happens. Good luck! |
Premature jubilation...
So I tested my theory this morning by placing each of the plungers into the bore and it doesn't appear as though either of them block or unblock any port or passageway to a greater or lesser extent.
The only possibility would be that the shorter one might not seal the port completely, but the amount of travel in the plunger cable suggests that there is more than enough. Back to the drawing board... |
There were endless variations. The short screen and tall screen carbed bikes had other differences, yet they superseded some parts all the way from short screen to the carbed bikes. I recall a bit of waterpump that looked wrong but fitted and worked.
Zero proof, but my feeling is that your choke plungers change the amount the lever moves? A solution to a problem no one really had? Can you close the choke by other means? Shims and an extra O-ring? A cold Rotax is impossible to start without but leave it parked in the sun and it will. If you can start it with the choke sealed off and it runs better you have the answer. Thank you for reminding me how much I love my OBD reader :devil2: Andy |
So I started on the carb rebuild(s) yesterday morning...dismantled each one completely and set the old parts into cups marked LEFT and RIGHT, just in case I needed to reuse any of them.
Put some HOT water into a small bucket, along with a few drops of DAWN dishsoap, placed the twin carbs into the liquid...closed the lid and mounted my B&D Jigsaw to the top with some Duc-tape...turned it on and left everything for 15 minutes in my homemade Ultrasonic cleaner. Then, a quick rinse and dry with compressed air and then got down to it...everything was going great...turns out the the float valve I had installed to replace the worn one, was a bit shorter than the original...but it still seemed to do it's job, so who knows? Had to reset the float level on that particular side....double-checked them both and set them to parallel with the carb body. Idle jets supplied were #41.3, so I set the NEW mixture-screws to 3 ¼ turns (thought I'd leave myself a little bit of wiggle room) but the main jets were #140 so I put the old ones (#132.5) back in. The slide guides are nice and new...but the emulsion tubes (venturi tubes) would not fit...they were physically too large to slide into their holders. I measured the diameter of the old ones: 7.02 mm New ones were 7.06 to 7.09 depending on where I measured them. So I mounted one in a drill and spun it while holding some fine emery cloth on the threaded hub that holds the main jet. When I had finished polishing off the silver coating, they fit like a glove! New needles with clips on the middle groove as per the manual. Everything went together well, aside from the emulsion tubes... Back on the bike a short while later...cranked her over a few times and she started (on choke) and took off on a higher than usual idle....good sign! Let her warm up for several minutes and then kicked OFF the choke..she stayed idling...good sign! Left her to idle for a few more minutes then started s-l-o-w-l-y opening the throttle....the hesitation/dip at 2000 RPM seems to be gone. RPM continued to increase, proportional to throttle position...I may be dreaming, but it looks as though the stumble between 3500 - 4000 is no longer there either, but I'll have to wait and test drive it first. So now this thing has the equivalent of 2 new carbs on it...and I'm 99.9% certain that everything went together properly; there were no parts left over and no "old" parts used (other than the stock main jets and the choke plunger). At this point, I think it's safe to say that whatever problem may persist, it is likely NOT carb-related. Still need to replace the spark plug boots before calling it done, but our impending holiday and the delayed delivery means this will have to wait for another couple of weeks. Crossing my fingers... |
great job - Sounds promising - that may be all of it solved! Ride it!
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Looks as though my enthusiasm was misplaced...
Got back from a couple of weeks holidays...was able to forget this albatross for a while. Got home and decided to change out the spark plug boots. That went easily enough; so now I have resistor-type boots with NON-resistor plugs. She started easily enough and idled nicely while under choke...idling higher than usual which is good, but when I shut off the choke and tried to rev her up a bit...she wouldn't go past 3000 RPM....stuttering and coughing as if there were no more fuel. If I revved her quickly, she would go over 3000, but not if I went "casually" as if I were driving. After browsing forums for as long as I have, I suspected that the regulator might be the issue and sure enough....the Molex plug was hotter than a fire cracker and some of the wiring looked burnt. I tried to repair the Molex connections to no avail, then decided to scrap it and replace with bullet connectors since I have a lot of those. In the end, I just decided to replace the voltage regulator. Funny thing though...I've never had problems getting it over 3000 before...but under closer inspection, the Molex connections were quite cooked and corroded...as if this has been going on for some time. Given the age of the bike, I suppose the regulator could be defective...but why was I able to actually ride it for a while, if the reg was faulty? I actually had someone coming to look at it this week...this means any potential sale will get postponed for another month (since I'm going on holidays again)...and parts won't be here for 2 weeks. It's as if this bike is cursed...I know that people keep telling me that "once I get things worked out, it will be great" but as I explained to my wife; I don't trust this bike...I don't have ANY faith in its ability to get me to and from anywhere....and I've developed an outright hatred of it, as a machine. My happiest day, will be the day I see it loaded onto a trailer and driven away. |
Not that it helps you but the R/R is a known weak point. IIRC it's one of the bits like the chain and forks where Aprillia decided 125cc spec parts would be fine.
The gradual breakdown is always possible with analogue electrics. Works for a second, doesn't work, works again.... you only notice when the gaps are big enough. The connector cooking is more symptom than cause. Good Luck with the sale. Hope you find a masochistic mechanic who can get some pleasure taking it to bits over the winter. Andy |
Wouldn't it be something, if THAT was the problem all along?
This is the only bike I've ever hated...came close with a 2009 Kawasaki Super Sherpa once. The next owner won't have to do anything...by the time I sell it, I will have worked out all of the bugs and THEY will get the bike that I was hoping for in March. |
I once had a Rover 3500 P6 - beautiful leather, hand rubbed oak dash, smooth V8.
Would just stop. Randomly. POS [emoji2957] Sent from my iPhone using Tapatalk |
So I reasoned that if ONE side of the Molex connector was cooked and corroded, the other side must be too...so I installed bullet connectors onto the existing connections and fired her up just to see if it made a difference.
Apparently not, within minutes the regulator was too hot to touch, and the bullets were starting to heat up as well. Good thing I ordered a new regulator....AND a battery. I swear, this thing will be burning in a ditch somewhere soon..... |
Tried that....didn't work!
Replaced the voltage regulator today...didn't make one bit of difference.
The dead-spot between 3000 - 3500 remains...taunting and mocking me each time I start the damn thing. I have NEVER hated a machine more than this one... |
Does the regulator and connectors still get very hot? Is the electrical issue solved?
Leaving the dead spot to solve? |
The regulator gets warm...not as hot as the one I replaced.
The dead spot(s) come and go as they please...acting up today, will probably be gone tomorrow, only to return again the next day...this is the most frustrating machine I've ever owned. It's official...this POS has broken me...I give up. I'll be looking for a shop to repair it over the next few weeks. Going on holidays and when I return, I'll be looking at getting a new Honda.....NEVER looking at another German bike again. My riding season for this year is a write-off...all thanks to ONE unscrupulous pr*ck that sold me this POS. I swear, if I could get away with it...............:censored::censored::censored: |
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