greg_in_london

Well I've got an Odyssey battery on long term loan from a friend and it has been absolutely marvellous - no more starting problems at all, so if I can have a PC680 as part of this deal then yes, please. Do you have anyidea what shipping to the UK would be ? Could I mix the order and add in a PC310 ? Assuming it's all okay I can pay by PayPal straight away. PS Sorry for leaving this so late - I mainly post in Tech Talk and hadn't noticed this.

Hi Jeremy, Yes, I checked the vacuum advance the way you suggested - set the tickover to 2000 rpm and then sucked on the vacuum advance and tickover increased noticeably. My Venture has done just over 54,000 miles, so there may well be wear in the emulsion tubes, especially as there seemed to be some fuel escaping when the slides are closed. Last time I asked about prices, they were silly money, but if I can get some at a sensible price I will try them out. I noticed at tickover, though, that the butterflies are completely closed. I can be sure of this because I used a squirty can of carb cleaner, and this actually pooled in the inlet and did not pass the butterfly. I was quite surprised by the effectiveness of the seal, but it does mean that I could be sure that I was only investigating the pilot mix circuit. [i know I also said I saw some petrol escaping from the main/needle jet, but this didn't pool. Maybe it was an optical illusion after all. I can't explain that.] I didn't check the coasting enrichment diaphragms, but it doesn't pop on the over-run and under the circumstances, I don't feel I need to enrich the system any more, so if they're not functioning correctly, I don't think they're critical. Talking to the guy who runs the Venture UK club and website, nobody is getting 37 - 40mpg (US) (45mpg UK) here at those speeds (or even going slower, in fact).

I reckon it would affect your petrol mileage, but an overhigh fuel level can lead to a tickover rising in traffic/when warm. You can check the fuel level without taking the carbs out. You connect a clear tube to the drain hoses and open the drain screw a couple of turns. There's a mark halfway up the side of the carb housing. With the engine running, the level in the tube should rise to 14mm below this mark. You can check all four in ten minutes if the screws undo okay. I wish I was getting 40mpg - US or UK. Some people are getting better, though....

It may be that your pistons are seized - after all, if the linked front brake is still working, then the fluid return valve is likely not the problem. The standard linked system (which I think is awful and should be removed, but it's up to you) has lots of restrictions in it - a restrictor valve to reduce pressue on he front brake and a proportioning valve which reduces braking power at the back when you're slowing down and between these a lazy piston gets every opportunity to stick. While it's apart, push down on the brake pedal and see if the pistons move freely. (Don't keep doing this or you will drop the piston onto the floor. This would make the job easier to do - cleaning the piston - thoroughly, but a bigger job) If it begins to move, but is corroded, try cleaning it with an old toothbrush and brake fluid (put some goggles on or be careful). If you have some (red) ruber grease, lubricate the piston with that before you puch it home again. You may have to do one piston first, then push it back and hold it in place with vice/mole - grips while you do the second one. As to the metal plate - the manual shows a spring above the pads and says to change it when the pads are changed. I have always refitted these without a problem. On bikes which have the additional plate, I refit it the way it came off. It doesn't seem to be important, though, and the manual does not mention it at all - sorry I can't help more. I'll see if mine has them when I fit a new back tyre. (This afternoon or during the week)

I would investigate the fuel level if you have a problem with tickover rising like that. Obviously balance the carbs first, but if the screws aren't seized, it is not difficult to check if you use a bit of battery overflow/breather clear pipe. (The proper tool or glass tube would be easier to use, but only if it's available.) Having said that, I've had funny results adjusting my fuel level (see the petrol/gas mileage thread) - I'd now check the level two or three times on different days to make sure I'm getting a true reading. If the fuel level is too high, then that my be your problem. If you're taking the carbs off anyway, though, it's certainly worth checking. NB - check the fuel level on the bike to decide whether or not to adjust, and clean out the pilot air jets while you're at it.

Okay -so I've been looking at the manual to get my head around the problems, but feel that I'm not 100% sure about how all the fuel circuits relate to each other. The carburettor companies (ie mikuni) give advice on how to ajust their carbs, but concentrate on much simpler models, which obviously is little help to us. One point that I'll come back to later is that there was a small amount of petrol visibly trickling out of the main/needle jet at tickover, even though there was the idle mixture was set well enough that the slides remained closed. I think it was a trick of the light, but it looked as if the needle itself pulsed in/out. Right - back to the plot. Below is a picture of the venture carb: http://i252.photobucket.com/albums/hh10/greg_in_london/venture/venturecarb.jpg Air flows in from above through the pilot air jet (2) and travels to where it meets fuel coming through the pilot fuel jet. They bubble together (stop me if I get too technical) and travel together along the long dotted tube over to the other side (it doesn't actually go outside the carb - it's just easier to see this way) where the pilot screw controls how much is let in. [For those with sharp eyes, there is a dotted air feed in just after the pilot air jet which comes from the coasting enrichment valve. When you are coasting, vacuum rises and this air feed is blocked off, hopefully enriching the mixture - if you didn't spot this, ignore this paragraph, it just complicates matters] Now, rightly or wrongly it seems to me that this pilot fuel jet seems to be determining most of the mixture and that the pilot screw seems to be controlling how much mixture is allowed in, rather than the composition of the mixture itself - a way of making it look as if they're allowing home mechanics to make changes without allowing them to make much difference. Below I've shown the detail of the mixing area itself (sorry if the text is not easy to read): http://i252.photobucket.com/albums/hh10/greg_in_london/venture/pilotjet.jpg Now when I first saw this pilot fuel jet, I thought it was adjustable, but looking more closely (at the diagram at least - my jet block did not want to come out of the carb and I didn't want to force it) I see that it's just an ordinary screw in jet. On the other hand, different carbs have different jets and I wonder if this could be a clue as to why some riders report quite respectable fuel economy while others do not - regardless of how the throttle is used. Here are some examples (thanks to the technical download section of the UK Venture Club http://www.yamahaventureclub.co.uk ): 1983XVZ12TK pilot fuel jet 42.5 1983XVZ12TDK pilot fuel jet 42.5 1984XVZ12LKC2 pilot fuel jet 42.5 1985XVZ12DN pilot fuel jet 37.5 19861987XVZ13DSSCTTC 37.5 1987XVZ13TTC pilot fuel jet 37.5 This shows me that there is some variation between years on carb specs, but I wonder if there wasn't more between markets, nor whether the changes were for emissons or to resolve any particular problem. This next information is from my 83-85 Yamaha service manual XVZ12TK carb 26H 00 - fuel jet 42.5 main air jet 65 XVZ12TDK carb 26H 00 - fuel jet 42.5 main air jet 65 XVZ12L (XVZ12DL) carb 41 R00 - fuel jet 37.5 main air jet 55 I haven't found any model numbers on the carbs, so presume that the only way to tell is from your bikes serial number (or by dismantling and checking the jet number - but as I said, my jet block didn't want to come out easily, so I didn't force it) serial numbers were: XVZ12L 41R-000101 XVZ12DL 41V-000101 XVZ12KC2 47R-000101 XVZ12DKC2 47T-000101 XVZ12TDK 31M-000101 XVZ12TK 26H-000101 Obviously I'm wondering if there is a link between which jet people have and what mpg they get tp see if this could be worth experimenting with. If I make changes I may also see about buying new emulsion/mixer tubes at the same time if they're available at reasonable prices. Mine is 41V-000125, by the way.

I've said it before, but it's still funny how different countries have different takes on this. In the UK a trailer equipped with an over-run brake is supposed to have a cable which is designed to snap once it has put the (hand)brake on on the trailer, if the hitch comes apart. Possibly the assumption is that the rig is most likely to come apart when the trailer is still stationary. This system prevents it rolling away out of control. If it comes off when towing, the brakes will go on, protecting pedestrians (do you have them in the US?). 'Security' chains don't seem to be encouraged at all.

Well - feedback from the trip to Le Mans. The racing (what we saw of it) was good, Team Alf's finished the race, which was good as we sort of supported them (which means we looked at their pit when the pit lane was open on Friday and looked out to see if bike 59 was still going round), the partying was excellent and we met up with a few people from last year. As I had the bagpipes with me, I had a good way of meeting lots of others without the lack of spoken French being too great an issue. The weather was variable - there was some sunshine and while it rained, it didn't stay for so long that you got soaked. But what about fuel consumption ..... well it was a good job that there was more petrol available than other years. After all the work, resetting float heights, fiddling with pilot screws, balancing carbs and blowing out jets, it was using more petrol than when I began. I was getting around about 25-27mpg (UK - 22mpg US ?)), no matter what speed I was travelling at. That meant that I mostly refilled every 60-80 miles with 11-14 litres or thereabouts. If I'm now getting the same mpg at 50mph (awful) as at 80mph (tolerable) that suggests that the main jets are fine, but carburation at lower throttle openings is wrong. That's obviously a wind-up for me. I'm not going to have the carbs again for a little while at least, but I do feel that I should be able to make some sort of improvement. I think I would like to look up which pilot air/fuel screw jets are fitted in the different models in the jet block. I couldn't see how to take the jet block out when I was cleaning the carbs - obviously the screws come out, but I didn't want to use too much force to try and lever it out - but from looking at the manual, it appears that this jet may determine the mixture (and it may be thraded and so could be adjustable ???), while the main pilot screw adjusts how much of this mixture is fed in (with the coroallary that there is an airbypass which mixes with it via the cosating enrichment circuit) rather than the mixture itself. Anybody selling any shares in an oil/petrol company ?

Funny how people have diferent perspectives: good engine, wheels, forks, running gear and I'd say it's easily worth £300 if you've got the space. That's without mentioning pick-ups, tci, coils and carbs (how much is a set of diaphragms ?). Mind you, if you feel that 20-50,000 is high mileage then you're on a different wavelength to me - I wouldn't expect to need engine spares until at least 80,000 and preferably 150,000 miles or more. The spares to me would be a guarantee of no nasty (read expensive) surprises in the maintenance stakes.

That looks useful - especially as I can do it without taking the carbs off again. Thanks - I'll try it today.

A quick update: It's not been such good news. Although I checked the float level when it was back on the bike, it seems to have 'settled' at a different level. Adjusting the pilot screws had been fine out of town, but in traffic I had a bad misfire and fuel consumption was appalling. 65 miles to 15.5 litres / 3 1/2 gallon (UK) / 4 US gallon - that's 18-19 mpg (UK) - ouch. I've reset the pilot mixture screws to where they were - 2 3/4 turns out and balanced the carbs (not far out anyway). What is most disappointing is that using the Colortune, no matter what I did I had the same blue flame. I know I should be happy that the flame is that colour, but I could do nothing to change it, which either means that Yamaha designed the carb so you cannot adjust it, or something is blocked. It needs to be ready for a trip (Le Mans) in a couple of days, too. As I've pointed out, if your venture is not economical, it doesn't matter how slowly you ride, you won't get good mpg and at night in France petrol stops are few and far between.

Sorry Squeeze - you get 32-36 mpg(US) ~ 40mpg (UK) travelling at 85-90mph. Other people get 28-30mpg(US) 35mpg (UK) travelling at 65mph. That tells me (assuming everyone is even slightly accurate in their mpg estimates) that the biggest influence is not the rider's right wrist, but is somewhere else. (Although obviously we can all make consumption worse when we choose to....)

Hi Spyderhead - yes it's pretty galling when the car does better than the bike on juice. I wish I could believe that it was all down to aerodynamics, but so often you see bike produced in one spec, that then uses more petrol when it is tuned and then even more when it is detuned for a later 'retro' model. Retailers often don't even claim to have an idea about economy as they seem to think bikes are for 'leisure' and not for transport/travelling. I don't know how to move it up their agenda, other than to keep asking when I'm in their showrooms. GeorgeS - I've read about this on other threads on another forum (XJBikes.com) but when I just checked couldn't find it. Someone as I recall gave a guesstimate of how 2mm float level equated to turns of the pilot screw, but obviously that would be specific to the make/model. Setting it right is certainly the best place to start getting the mis right, though. Too low and you may not get enough fuel at high revs and too high and it will be flooding/too rich both at low revs and through the range. Mine certainly seems happy now I've got it right, but as it was low before (& therefore probably lean), it may not improve mpg.

I've been assuming that Canadian posters are talking US mpg when they quote what they get to the gallon - but that's not logical, is it ? Do you use the US 3.8l or the Imperial/UK 4.5l gallon ? Can$5 or Can$5.88 / gallon still sounds pretty good - I've just filled up at the 'ultra-cheap' supermarket (ASDA - equivalent to Wal-Mart) and it was £1.04.9 per litre - £4.76 per gallon, thats US$9.40 or Can$9.57 for a UK gallon (about $8 per US gallon). Anyway, back to the plot. Yesterday I had the carbs back on and the floats correctly set. I went for a test run down to Rochester to visit Valhalla's shop (he has set up the UK Venture Owners' Club) and it ran very nicely. I've filled up with fuel again and will see what I'm getting to the gallon as soon as I can get out of London. At the moment, though, it is starting very easily from cold without choke, which is a sign that it is running rich (especially as I RAISED the float level), so I have twice screwed the pilot screws in by 1/4 turn on each carb. This should improve fuel consumption and response is (even) better. On the motorway it was certainly running well - I kept drifting up to 80mph, which considering the sidecar is fair progress. Maaybe it's because I didn't have the trailer... I've just received a new Colortune in the post to have a look at the colour of the combustion flame to see if I can adjust any further. I'd have preferred if there were a colour chart with it, but there's not. I'll keep you posted on any improvements or otherwise.

Hey - good to see another sidecar - so that's be about 33-35 mpg (UK). Did you ride the bike solo before you put the sidecar on ? Do you remember what you got then ? There's part of me that thinks you have to expect really bad mpg with an outfit, but another part (that actually used to get the wallet out of the pocket at the petrol station) that says there wasn't that great a difference between solo and combed up. Going from 33-35mpg solo to 30mpg with a chair would makes sense, except that if it were possible to get 50mpg solo (on the same or a different bike) then low 40s mpg should be possible with the sidecar on (and driven moderately). Just looking for that magic formula.

Gene-B - that's 50mpg (UK) - what shade of black does it have to be and does it matter if the moon is out ?? wkboard - I'm working on it, but anyone who has good mpg has no reason to check theirs out so the rest of us are working blind. I took it slowly today - the carbs are ready to go back on, but I haven't done it yet. I've just ordered a 12mm Colortune kit so I can check the mixture. BTW I was told that the M6 bolts on the exhausts were for checking CO levels. Is there a sensor that goes in - lambda sensors all seem to be M18 - much bigger.

Hmm, can't say that I've noticed that, although I've had some bikes with pretty flexible front ends over the years. Left disc on the '84 is the linked brake, right only for the handlebar. I presume that you use both. (I junked the standard system ages ago.) As to left and right turns, unless you turn several circles while you are out, there will be no difference in mileage - whereas the turn one way will seem longer, it will be a less acute turn - will be closer to a straight line. A turn the other way will seem shorter, but will be more acute - more of a bend and more strain on the tyres (and you'll lean further). It evens out. I still say that he needs to check for problems - this isn't normal - and make sure his tyres are safe.

One of the two columns that hold the float pivot was damaged. I had drilled and wired it so it couldn't move, so that might actually might not have been the problem - I didn't try putting it back on to find out, though, it's just too much hassle getting the tank off and the carbs out. I don't think there's anything much wrong with my diaphragms, but they must harden before they crack and they are quite old. By the way, what's this Sea Foam that some of you have mentioned - I've googled it and just come up with funny colour schemes. Presumably a petrol additive ? Over here we have redex, but that seems pretty useless, even though they claim the world for it.

Hmmm - if the tyre's wearing badly are you sure that you want to keep it on the bike ? There's an outside chance that it's a freak tyre and you'll never have to worry again. If you feel that there's something badly wrong with the geometry, why are you still riding it. If you feel that there's nothing wrong, double check everything that you've checked already (including the frame - some early ones broke/rotted away - can anyone say where) and if there's nout wrong change the tyre. If the bike feels wrong, but you can't find anything and need to get to work, be very very careful, but wouldn't it be safer on good tyres ?? I'm presuming that the last tyre wore normally and the back tyre has even wear.

Hi Gigawhiskey That's the sort of thing I've wondered about. I have seen big improvements on a bike after reinstalling a camchain, but that was more likely due to a previous owner than the factory. (Not an XVZ) If there were something that could have been wrongly installed, surely someone would have noticed by now, though. I know that they're a tough engine and simply don't need to be pulled apart , but surely someone would have had tocheck the valve timing or how some gears go together - if there are two ways two parts could mate together there would be a technical note somewhere saying 'WARNING' - don't mess this up. The other, related, possibility is that Yamaha could have been sourcing some of its parts from two places, or using different parts in different markets, or have tried one design and switched to another, but used up the stock of old parts. Could it be that some engines have slightly different cam profiles than others, with different valve timings and/or durations ? [Are V-max cams the same ?] Surely Yamaha could have come clean on this by now (albeit unofficially) if something like this happened - or maybe it's so long ago they've all forgotten/retired. Maybe I've just added a new conspiracy theory - oops. Hipshot - the whole world uses Celsius - just remember '0' is freezing and after that it gets better. 20'C is room temp. 100'C and the kettle's boiling. Gearhead - thanks for explaining that - I hadn't realised that it was a pilot air jet that was blocked and thought it pumped extra fuel in. My commuter is an XTZ660 which also has that valve. Before I changed the carb on that I was getting low 30s mpg (UK), afterwards 57mpg, but popping on the over-run. I might switch the valve over from the old carbs if it won't push the mpg down again. Bobcat - I know what you mean about the air breather - I have an XJ750 that was breathing badly that I swear sucked up oil, but whether it's better to have one probably depends where you are. Some people say a slight vacuum in the cases is a tuning bonus, others that it helps drive out moisture. Parts suppliers recommend a filter if it vents to the air. I don't think it's a big thing though. I might try it after I've used all my other ideas, but won't hold my breath on it making a diference ! I'd happily try new diaphragms, but they're not exactly cheap and mine seem okay. If anyone wants to lend some new ones for an experiment though ... Nope ?? Oh well never mind. RandyA - well 44mpg is over 50mpg (UK) If that's in traffic or on litle twisty roads then that's quite acceptable. If it was on the freeway - 40mph - wouldn't you have been run of the road by trucks ? Plan for today - reset carb floats and reinstall. I might try and check those plenum chambers if I can think of a way of doing it. I don't think blowing pressure in would be a good idea would it ? *pop*

Thanks Gearhead, I've checked the float levels and will adjust them tomorrow (food beckons now) - before I checked them last time the level was too high, now it's a little too low. I do find these carbs confusing - I really don't quite understand the coasting enrichment valve and so leave it alone. Whether it can be a cause of extra fuel consumption I don't know. From checking the manual, it looks as if the mixture is defined by the air jet and the jet block and the pilot screw determines how much of the mixture is drawn in, rather than setting the mixture - unless the purge holes let lots of air in - or maybe I'm just confusing myself. I'll try sucking on the pipe at 2000 rpm - I wouldn't have thought of it because I'd have expected there to be plenty of vacuum already (more than me sucking, anyway) - after I put it back together tomorrow.

Hmmm, Bobcat - not quite sure what you're getting at here - when you're travelling at 80-90 mph you're getting significantly more to the gallon that some of us get at 50-55mph. It doesn't support the idea that it's dependant on riding style - tou're sure you're not just showing off ?? Either way you're saying that 40 to the US gallon (50mpg UK) is attainable - what do I have to do to get it ? Back to the plot: I pulled off the carburettors today to get at the vacuum advance/retard. I couldn't check for holding a vacuum other than by sucking on it and checking the vacuum against my lip, but it seemed okay. I did try checking it could hold pressure by pumping 10-12psi (manual says okay to at least 600mm Hg, so won't damage it) and it only lost pressure at the speed that the pump does anyway whne I put my finger over the end. So far as I can check it's airtight, then. I checked the output voltage and it was about 2V. I've leant out/given away/had stolen my better multimeters and I've not much faith in the accuracy of the one I was using, but it should be close enough. I pressurised the unit to 10-12 psi, but the output voltage rose only to 3V, rather than 4.9v that the manual says. By just sucking on the tube I was able to drop the voltage to 1v. When people have said they'd had problems it has been down to a dodgy connection or complete failure. Does this sound like a failing unit or is it within normal functioning range ? Are the exact voltages critical ? I could delay rebuilding it until I grab hold of a better meter, but if it's not critical could just put it back together - after all there won't be positive pressure much of the time, will there ?

Yeah BJBoomer - it was a typo - or at least a moment of misplacing some fingers when I was counting:bighug:....... Gearhead: Every now and then I think about how much weight I can be pulling and think 'Hey, it's not so bad' - but there really was not much difference in mpg when I put the sidecar on ~ 4-5 mpg maximum ~ and from experience a trailer does not affect mpg very much when you're on the flat and away from town traffic. (In stop/start traffic or through the hills, yes, but not as much as you'd expect) If no-one else had said that they get much better mpg I would just put up with it, but if it is possible to get better mileage I'd like to know how. I'm going to fiddle with the vacuum advance/retard tomorrow - if it only makes 1-2 mpg difference that's still a help, but more would be better..... Remember one of the first posts said that on average riders were getting 40-47 mpg US (45-55mpg UK) and that's an awful lot more than I ever managed. Let's hope I can find that Holy Grail.

Fuel capacity is 19-20 litres, that's 3 1/2 UK gallons or 4.3 US gallons. [Edit:correction, see below, that's 4.4 gallons, or 5.3 US gallons] A while ago we had a long holiday across to the Czech republic. We were keeping the speed steady (didn't want a breakdown a long way from home) and were travelling at 55-60mph on the autobahns and 50-ish on other roads. We had plenty of time to check out the mpg without any significant acceleration, just kicking back, listening to the stereo, comparing miles to what the speedo said and checking out the scenery. 2100 miles in 20 days. I had the bleed valve set to bypass so the radiator hardly got warm (was jammed when I first investigated it) and hoped that the mpg would get better when I replaced it and running temperature increased, but it didn't make a difference.

Hi JimBob, I'm as sure as I can be that my speedo is accurate, but if it were exaggerating the mileage, I would be believing that I was doing better mpg than I am, surely. If I ride steadily I get 30mpg (that's 25mpg US) and used to get up to 35 mpg solo (thats about 29mpg US). If I up the speed it drops - I don'tknow how much 'cause I can't afford it.... :mo money:If you're getting 37-38 mpg (US) and think you could get 45mpg, that 45-55mpg (UK) then you're getting 50% more than me. Why ? Bigin - I checked the float on my carbs in the Autumn. I can't say they're spot on, but they're much closer than they were. I checked the heights externally, figured out how much to adjust one to get a float height and set the others the same. The manual says that you have to check with the engine running and I'm going to do that again this week. The carbs are fairly well balanced. I use either a Morgan tuner with the stainless steel rods or a mercury gauge - should be no problem. New air filter, clean oil every couple of thousand miles, newish plugs, pumped up tyres. So far as I know a good spark - the old plugs all look okay if maybe just slightly rich. And in any case - there seem to be plenty of riders who get the same mpg and cannot get any more just by restraint - what is different about the bikes of those who get more ? AllenH - it's frustrating isn't it - ruins what could be a much better bike, even if at your worst you're still getting better than me. How do we get rid of that thirsty little gremlin who's inside the tank slurping it up ?