Virago vx 750 Starting problem

Discussion in 'Technical' started by Marco, Mar 9, 2007.

  1. Hi Lads

    Any one familiar of Virago VX 750, i have problemt o get it start,, i know it's its normal problem but all the normal tricks dont work,,,
    I was wondering if any one has or had similar bike b4 and could assitst.


  2. HI Marco.

    As a former motorcycle dealer I did have quite a lot of XV750:s. Generally speaking the first models in the early1980 had many problems but the later models in 1980 and 1990 were quite good. Especially I do not remember that the starting problem was a main problem.

    First of all try to remember when the starting problems started. Did they start after you had your bike in storage for a while? If you got the bike with the problems try to find out whether the bike had been out of use for a while.

    In all these cases the problem is probably that your idle jets are blocked by the additives they put in modern gasoline. It makes up almost concrete like blockings in your idle jets which are very difficult to get rid of.

    Even if you have had your Thai mechanic to clean your carbs mostly they forget the idle jets because they normally are not detachable and very difficult to clean and check if they are open. A normal cleaning of the carbs with a night in a cleaning liquid plus compressor air is not enough.

    To clean the idle jets you can use one piece from an old wire which you unfold or one pcs from a metal brush. Both are small enough to get through the hole of the idle jets but they are to soft and flexible to be used as that. Therefore you put them in a flexible drilling machine and use the revs to get through the hole in the idle jets. It works…. Another way is to put the carburetors into a micro wave cleaning machine if you can find some. Companies working in the aviation industry usually have them.

    To find out if your idle jets are blocked or not is quite easy. Try to start the motorbike, if it not start try to give it “direct injection” (gasoline direct through the carburetor balance screw holes in the manifold or through the air filter). If it starts now and works on higher revs but not on idle revs then the idle jets are blocked and thus the machine will not start.

    After going through this let us say that you try to start and by taking out the sparkplugs we can see that the cylinders get gasoline, the sparkplugs are wet. Now you off course first check that there is a spark when starting. If that is the case we have two possibilities. You have a compression problem or an ignition problem.

    The compression problem can be caused by wrong valve tolerance. Check the valves. It can also be caused by worn out valves or damaged valves or pistons/piston rings worn out or even the cylinder being damaged or worn out. Check the compression using a compressor meter and compare the values to the ones in the Manual.
    Yamaha was not famous for having these kind of problems compared to Kawasaki which all 4 cylinder 1983-1986 models had soft valves which caused start problems when engine was warm.

    Another cause to compression problems could be timing problems. Maybe somebody before have made a mistake when putting together the engine or maybe the cam tensioner have been loose and the cam chain has jumped a tag or two on the sprockets. Anyhow the bike can still work with less power and starting problems. So check the timing.

    Okey when compression problems ruled out we are left with ignition problems. Even if the spark seems good outside the cylinder it maybe not is as good inside he cylinder when high pressure. First check that the ignition sensors are not damaged. Most newer bike do not have any adjustment alternatives anymore. If still not start and the carbs give gasoline (sparks wet) try to start the engine with a car battery. If it starts then you have a power tension problem, bad battery, bad cables or bad starter engine (see below) Change the battery (many Thai or Chinese made batteries are not up to real Yasa performance) , clean the ground cables including the surfaces were they are connected to engine and ground, check the main cable to the starter rely and the starter cable, check for cracks.

    If your starting engine is a little damaged as above or badly damaged you have to do the same thing. Open up the starting motor and see what is left, are the electrical windings burned, are the carbon connections worn out etc. Normally you can not buy spare parts for Japanese starters but in Thailand you can buy same same but different.. One important thing to check when assembling the starter is to clean the surfaces of the starter and the engine. I have had several Yamahas which did not start because the starter was loosing the power to sparks between the starter and the engine when starting and there was no power for the ignition. If your problem is a broken starter you can check if the bike starts when you give car battery power direct to the starter. If it starts now then you have a power consuming starter.

    I think that should be all, sorry if I have been a little too teacher wise but I do not know your background and experience.


    Ps how happy I am that I do not have to touch these old bikes anymore!!!!
  3. Hiko I have a 97 Virago 535, I have notice a miss not constantly uually after I driven around at low rpm for a good distance, then when I try to accelerate I get a miss, when I go to lower gear, the miss clears up quickly/ Ride error or time for new plugs?

    Stating this little bugger is touchy:

    First starting the bike really drains the battery, I had to put the headlight iopn a sperate swith so I can turn it off when I start the bike is has been very effective.

    The other thing I put it on full choke when I first start it in the morning regardless of the weather a soon a the engine first I take the choke off and it's happy.

    The other thing I had to adjust to was the elecric fuel pump one I turn the key on I start it immediately, or I will flood it everytime.

    I have been given the battery a little charge weekly a part of the normal upkeep. Today I hxd to start it three times in about ten mins. Third time the battery was gone. Since I had ridden a 100 KLMs before this it should nothave a had a problem. When it was push started kicked right over.

    When I go home charged the battery and it just sucked up the power, I think it is time for a new battery. So I either have a charging problem. I'll start with a new battery and see what happens. I've only had the bike for about three month but the battery looks pretty old.
  4. Hiko & Ray

    1st of all,, wow that was like walk through instructions, clad that u are here,, well ray actually point out my problem as well,,,

    well bike was packed 3 monjths, no battery inside,,, came back and try to start it,, no luck,,,then got wife behind the wheel in the car, pull started it and i had this same problem like Ray explaned,, in normal starting rpms no problem,, bike run slow and good, when trying to increase trottle,, miss and engine gets either too much air or fuel,(did not checked) so what did i do,,, i did run bike in slow speed with 1st gear got well and tryed to increase speed no luck but i chifted to 2nd and 3rd and 4th and 5th,, little by little icreasing the speed so after 20 minutes bike run like angel,, so it's running, so i took her to road, and run abt 20km's with full speed and no problem,,, next morning i came to garage and tryed to start turn the key(Yeah i have key start) starter say Clack clack, nothing else,, then after few try nothing,, power i now 9.7v but it wont start, Push Start is no problem, engine start but i think it's in the carbs, or start engine...what is diagnose from there?

  5. Hi Marco,

    Better get a new battery as this is always the weak link in the chain,and the first thing to suspect, sometimes, even if the battery is strong enough to turn the engine, it may not have enough juice left for the ignition of the engine.
  6. Good morning HIKO,

    Absolutly enjoyed your being "teacher wise" even though the problem described is not - for the time being, one that I have. Would appreciate reading more on any mechanical subject when you've the time and inclination.

    Nice job.

  7. Thank You David for the nice worlds.

    Let us start with Rays problem. In principle the XV 535, also sold as 500 CC Xv500, was a very good machine, never had any problems and your machine is supposed to be a 97. Your bike should not have any problem if not some mechaninc has caused them.

    First of all change plugs the cost is less than the beers I drink while writing this, at least one possible problem less. Avoid to buy resistor plugs even if they are recomended. Normal plugs without resistor are more cheap and reliable and your neighbour does not have to look at TV when you are driving motorbike...

    If this does not help you probably have a carburator problem. Theoretically you could have a loose cable or sidestand killer that activates when you accelerate but I do not buy that.

    Ok which model do you have, do you have the tank under your seat or a real tank? The gasoline pump and the carburators are different depending on that and the gasoline piping system is very complicated in both cases. Check up which model you have and check how the pipes goes.

    The carburators are not same and the California model differs radically but the functions are the same. Since your bike runs well on iddle revs the idle jets are ok and the next jet is the air jet or probably the pilot jet on the XV535. This can be cleaned and adjusted. It is situated next to the diagram covers under a rubber. Look in the manual for correct values and do not try any extreme values. Since your bike revs up when you put a smaller gear you probably doesnt get gasoline enough when accelerating. There is also small diagram in the carburator but I do not remember if that is some kind of accelerator pump. Check it but be careful not do damage the diagram, they are expensive and can not be repaired (except for in Thailand) The rest of the carburator has nothing to do with your problem and the only adjustable part is the needle jet.

    Of course you must check the carburator fittings, no cracs in the rubber manifold or the rubbers to the aircleaner.

    Your starting problems are probably many problems together.

    First of all buy a new battery. It is not a very expensive item a 12N12 battery you should get for 1000 Baht if you have a sealed battery it will cost you more but you could try to find one from a computer shop. They are by far more cheap there. Do not buy junk batteries only known japanese brand and If you want the best buy Japanese Yasa. After you have bought the battery charge it slowly, if you have a car charger like you probably have, put the battery in cold water while charging. Before using the battery on your bike check that you generator charges enough approx 13 volt and that the regulator work. Otherwise you will have battery problems very soon again.

    If your bike now starts every day be happy but your problems are not over. First of all your bike should automatically close down your light when starting Probably one wire from the ignition knob should go to a rele that closes down he light. Check because the less you have of homemaid solutions the happier you will be in the long run.

    The next thing to check and repair into original order is your gasoline pump. First of all I cant understand how it will have fleeding when off but not when merchanically put on by you? Is your pump original? The pump should go on and off according to the gasoline level in the carburator. Do not try to modify it.

    If the bike still starts to empty the battery when starting you have a bad starter or bad cables. Check the thick red and black cables and their surfaces were they are connected. If ok then you have to take up the starter. Original spare parts are not normally available but Thailand can do....

    Now everything should be ok and throw away your family mart charger....


    Marco you have to wait a while I run out of beer... And pls inform me what year model about you have.
  8. Good Advice changed the plugs today put in a new dry cell battery now a very happy 535. It's the model with the tank under the seat.
  9. Forgot the mechanic put a meter on the bike while it was running producing 13 volts, so I should be in business for a while. I had the mechnic go though and tighten the front end while I was there, not a probelm yet just starting to feel a little loose. Cost for everything was 1200 Baht.

    Funny part the bike set for a we hours while the battry was being charged, the mechanic felt it was idling to slow so he adjusted the idle while it wa cold, big mistake when it warmed up, it was idling at abou 3K. Finally found the settign screw hidden behind some pretty chrome and every this is back the way it should be.

    Every now and then you do run into a Thai MEchanic that takes pride in his work and is careful about what he does. This one is located at the Yamaha parts store down town, the work he does is excellent, if he doesn't know he just tells you he can't do it instead of taking his best shot. He is probably the best around here on electrical. I have taken bike into the shop for four years. He have developed a friendship of sorts, when I go in there he either does tthe work himself or supervises the work on my bikes. He is actaully the shop manager.

    The problem that usually happen are in trouble shooting since he speaks very little english and the same for me with Thai.

    I did notice something differnt on the ride last weekend then heard it again tonight when I pulled in a clicking noise from the rear end. not constant someone said it had something to do with the rear brake and not toworry about it. Should I worry LOL Brakes are working fine.
  10. All great advice but when you have checked everything else and the problem is still there, pull the starter motor out. You will find a wire clip on the throw out gear. When these get weak the starter motor won't work properly so you need to replace the spring
  11. Morning Hino

    thanx again for intresting reading,,,regarding my bike it's 96 body with 97 engine, but i tooked today for one of the bike shops here in Ubon and when i drove inside garage,, guys face went smiles,, and he said that he got that bike in originally to Ubon and he knows whole story, i asked if's long story and he said YES, so i go there later today ad get whole story,, [xx(]

    So have to wait and see...
  12. So how's the bike coming coming, mine is very happy these days, just got to find the click hopefully Monday.
  13. Same here, took it for the "Boys nd getting it out Monday,,, running like FINNISH Bear
  14. HIKO

    Just got bike back from the garage and intresting story,, what i actually would not dicovered.
    Voltage regulator was distroying my battery as soon i start to drive, as i mention, I could start the bike by pulling it and then driving,,, after stoping,,, bike did not start..

    Regulator pushing 16V+ to my battery even not running yet, turn on head lights, no effect to lower down voltage, well guys take a look on it and found out that it has been connected incorrectly and now it's working like a swiss clock,, any how my engine was completely over hauled same time,, feel soo good to be on the SADDLE again...
  15. Before using the battery on your bike check that you generator charges enough approx 13 volt and that the regulator work. Otherwise you will have battery problems very soon again.

    Didn"t I tell You!!!!!

  16. Yes you did indeed...and i didnt, but now i know..thnx for that...
  18. Thanks for all your help Hiko, enjoy Cambodia

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