Dont just remove the spark plug cap on electronic ignition models, you must ground the cap to earth with a spare plug or you can fry the coil or the TCI
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Need some help with carbs and motor issues.
- Thread starter rustynail99
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- carburetors engine
Dont just remove the spark plug cap on electronic ignition models, you must ground the cap to earth with a spare plug or you can fry the coil or the TCI
Mellowyellow
XS650 Addict
I just skimmed through this forum but if your idle is high it might be a cracked carb holder (rubber between carb and engine).
rustynail99
XS650 Addict
thanks Ady66 i will definitely take a look at that. thanks also to everyone else, i will mess with all that and see how it goes and report back.
Rusty
Rusty
rustynail99;
Everyone has given you good advice on the high idle.
As previously stated, the butterflys must be able to close completely i.e. no gap left at all. Do that by leaving the butterfly screws loose while they close against the carb body, then tighten. Why is that important, you ask.
If the butterflys can't close completely, it will be impossible to adjust the air/fuel mixture when using the dead cylinder method. The butterflys must be able to close far enough that they block off the 3 by-pass holes. When the by-pass holes are blocked off, the pilot screw is the only path controlling the air/fuel mixture. You'll know you have it right when you can lower the engine speed (with the idle speed screw) to only 300 or 400 rpm (one one cylinder firing). At that rpm you can easily adjust the pilot screw for the highest/smoothest idle.
Everyone has given you good advice on the high idle.
As previously stated, the butterflys must be able to close completely i.e. no gap left at all. Do that by leaving the butterfly screws loose while they close against the carb body, then tighten. Why is that important, you ask.
If the butterflys can't close completely, it will be impossible to adjust the air/fuel mixture when using the dead cylinder method. The butterflys must be able to close far enough that they block off the 3 by-pass holes. When the by-pass holes are blocked off, the pilot screw is the only path controlling the air/fuel mixture. You'll know you have it right when you can lower the engine speed (with the idle speed screw) to only 300 or 400 rpm (one one cylinder firing). At that rpm you can easily adjust the pilot screw for the highest/smoothest idle.
rustynail99
XS650 Addict
ok so i was able to adjust the fuel/air mixture screw and was able to get the right cylinder to about 1,500 which is much much better but the butterfly is still not closing all the way and the left cylinder is still not firing even when i kept adjusting the mixture screw out. so it seems like it might be in the valves or cam chain, or some other carb issue. i saw that inxs said he was writing up some tech articles about that and some of the other stuff yamaman had suggested looking at. i was just wondering if those will be put in the tech section and if they were up yet and i am just missing them somewhere. thanks again for all the help and i feel like with the help from you guys i can hopefully get this thing running smooth sooner rather then later. thanks.
Rusty
Rusty
rustynail99
XS650 Addict
your the man inxs! that is a great tech article going there! it would be great to have this at the top of the tech list because it covers so much. hopefully armed with this info, my clymer manual, and the xs carb guide ill be good to go! thanks. ill keep you posted!
Rusty
Rusty
Gordon
XS650 Junkie
rusty, when you check the left cylinder, you should either ground that plug wire, or use an old plug holding it against the cylinder head or case. You will burn up a coil if you don't. Next ,do you have vacuum barb's on the inlet's? If so, are they capped & are the cap's good?
On the butterfly's, I separate the 2 carbs from each other, then loosen the 2 screw's and slide the butterfly's around until they are as close to being centered as possible. This give's you the least amount of 'gap' .( the idle speed screw is also backed way out).I don't know if the 'dead cylinder method' of syncing the carb'shas made it's way into the tech section yet, but, in a nut shell, you disable one cylinder by grounding that spark plug wire, get the cylinder that's runningset to the best it will run using the mix & idle speed screw's, then doing the same for the other cyl. Then reset idle speed using the idle speed screw.
On the butterfly's, I separate the 2 carbs from each other, then loosen the 2 screw's and slide the butterfly's around until they are as close to being centered as possible. This give's you the least amount of 'gap' .( the idle speed screw is also backed way out).I don't know if the 'dead cylinder method' of syncing the carb'shas made it's way into the tech section yet, but, in a nut shell, you disable one cylinder by grounding that spark plug wire, get the cylinder that's runningset to the best it will run using the mix & idle speed screw's, then doing the same for the other cyl. Then reset idle speed using the idle speed screw.
rustynail99;
You probably have several problems. You need to fight one battle at a time, solve it and then move on to the next one.
Do a compression test on both cylinders...........that is a must! Focus on finding out why the left cylinder is not firing before chasing other things. Eliminate simple things............change the spark plug for a new one, change the spark plugs leads. If you have the original ignition coils, its best to replace them with a modern single (dual output) coil.............will give much better spark. If you don't know how old the points are...........just replace them with new ones.
You probably have several problems. You need to fight one battle at a time, solve it and then move on to the next one.
Do a compression test on both cylinders...........that is a must! Focus on finding out why the left cylinder is not firing before chasing other things. Eliminate simple things............change the spark plug for a new one, change the spark plugs leads. If you have the original ignition coils, its best to replace them with a modern single (dual output) coil.............will give much better spark. If you don't know how old the points are...........just replace them with new ones.
rustynail99
XS650 Addict
ok guys, it seems like my xs might have the plague. we finally were able to get the compression tester adapter to do the compression test. so i went out to the shop to try and fire it up before we tested it. unfortunately when i went to start it gas started pouring out of the right carb out the intake. this is the first time that this has happened since i had taken them apart and cleaned them. and the bike wouldnt fire up at all...awesome. so we did a compression test by putting the gauge in and kicking it over without it starting up until the gauge plateaued. the left side (non running side) was getting about 90 and the right side was getting about 60. im not sure if this is the proper way to test the compression but that was as high of a reading that we could get which didnt seem very good since they were so different and seemed very very low. so if this is not a proper reading please set my ass straight! thanks.
Rusty
Rusty
rustynail99
XS650 Addict
also, im pretty sure im just going to do a top end job because it probably needs it anyway and certainty wont hurt to do it. so my question is i am on a shoe string budget and cant really afford to just drop it off at the shop and have them do it all. so how difficult is it to do a topend, what speacialty tools would i need, am i taking on more then i can chew if i try and do it myself? it doesnt seem terribly difficult but what do i know. thanks again guys.
Rusty
Rusty
Compression test needs to have the throttle butterflys wide open and the carb slides held open. Also make sure the valve clearances are correct, allowing the valves to seat fully.
If those compression readings are correct, and considering it has 18000 miles, then its time for a top end re-build.
There's tons of postings on top-end re-builds on the web. Do some searching. You won't know what parts need replacing until you open it up. As a guess, parts and some labour costs (rebore/hone) might be $300 to $400. When you have the engine out of the frame, you'll want to inspect other things such as the clutch. Plan on replacing rings,front cam chain guide, cam chain, gaskets, oil seals, o-rings. If cylinders are worn excessively, you'll also need to buy new oversize pistons.
Some things you need:
Torque wrench
Valve spring compessor
Clutch holding tool
Micrometer
Feeler gauges
Vernier caliper
Valve lapping tool and compound
3bond 1104 gasket sealant
Lacquer thinner
You don't need a ring compressor, as the rings can be put on easily by hand.
If you get into it, the guys here will answer specific questions.
If those compression readings are correct, and considering it has 18000 miles, then its time for a top end re-build.
There's tons of postings on top-end re-builds on the web. Do some searching. You won't know what parts need replacing until you open it up. As a guess, parts and some labour costs (rebore/hone) might be $300 to $400. When you have the engine out of the frame, you'll want to inspect other things such as the clutch. Plan on replacing rings,front cam chain guide, cam chain, gaskets, oil seals, o-rings. If cylinders are worn excessively, you'll also need to buy new oversize pistons.
Some things you need:
Torque wrench
Valve spring compessor
Clutch holding tool
Micrometer
Feeler gauges
Vernier caliper
Valve lapping tool and compound
3bond 1104 gasket sealant
Lacquer thinner
You don't need a ring compressor, as the rings can be put on easily by hand.
If you get into it, the guys here will answer specific questions.
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- compression and leakdown testing when done correctly can give you a very good idea of what youre up against
rustynail99, Which bike is this we are talking about, The white one is a 78/79 Special with points and will have brass flots in the carbs, here is a good referece for year and model carburetors, http://www.xs650.org.au/XS-TX650 Carburetor Evolution.htm
You could have a stuck float or it could have developed a hole . you need to remove and check or sometimes a tap on the bowl, (gently), will get it unstuck.
You need to slow down and start from the beginning.............. Do one thing at a time and don't get confused with tying to sort all of your problems at once.............. You had the bike running with the carbs , so you should get the carbs fixed first and then get the motor running as good as you can . .............I say this because if you jump from problem to problem before fixing them as you go then you will not know what is causing a problem when you start to put things back together again and you could end up causing damage to new parts............
You could have a stuck float or it could have developed a hole . you need to remove and check or sometimes a tap on the bowl, (gently), will get it unstuck.
You need to slow down and start from the beginning.............. Do one thing at a time and don't get confused with tying to sort all of your problems at once.............. You had the bike running with the carbs , so you should get the carbs fixed first and then get the motor running as good as you can . .............I say this because if you jump from problem to problem before fixing them as you go then you will not know what is causing a problem when you start to put things back together again and you could end up causing damage to new parts............
rustynail99
XS650 Addict
ok guys, i redid the compression test holding the slides open and the keeping the butterflys wide open as well. and i got the same readings as before. now does this tell me that im a complete idiot (very possible) or does it tell me that something inside the motor is definitly wrong. if so will i know what i need to replace once i take it apart or will i need to know what to do going into the topend rebuild. also does anyone have a link to a topend rebuild thread, i searched on this site and google and couldnt seem to come up with anything. im trying to see what im getting myself into before i start takin the motor apart. thanks again guys for you extreme patience.
Rusty
Rusty
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http://www.bikerworld.co.uk/tech/XS650engine/index.html
You won't know what needs replaced until you open the engine.
You won't know what needs replaced until you open the engine.
Pyrobooster
XS650 Enthusiast
Did you ever get it running right? I have a similar problem, but my bike only has 3500 miles. Its a 1980 special 650.
