Sir Puma Posted October 12, 2012 Posted October 12, 2012 Ok, so most everything seems to be working well. I'm sure I have my headlight issue fixed (loose wires under the seat) and I've changed a LOT of parts. My current issues is a lack of power or hesitation when the engine is cold. So, from a cold start, no matter what the daily temps are, I need to use the "fuel enrichment" lever to get it to start. But I have to let it run for some time to fully heat up otherwise when I try and go it hesitates and will sometimes die. Even once it's warmed up a little and I don't need the choke anymore for it to run at idle, when I give it a little throttle the engine acts like I cut fuel and it hesitates and wants to die. It's not until after I've driven for at least 20 minutes before it will run fine at low idle and low exceleration. Had a guy at a gas station (petrol service station?) tell me it might be the idle jets sticking. Not sure what that means exactly. Any ideas, gents? I have a new fuel cock but haven't replaced the fuel or vacuum lines. The bike also likes to "run out of gas" when there's still a couple gallons in the tank and shouldn't need to go to reserve. Not sure if it's related or not.
Moderator Cynic Posted October 12, 2012 Moderator Posted October 12, 2012 Its no idle jets stocking. Dont take the bike there for work...... In the carb you have 4 systems that work to put fuel into the engine. 1 the choke or enrichment circuit. This richens the mixture in the engine. Several ways. Some block the carb somehow to increace the draw. Some just squirt more fuel in. 2 the idle circuit. These are really small jets that give the squirt of fuel that is just right for the bike to run on a closed throttle. 3 the jet needle. This lives within something called an emulsion tube an does most of the work. Unsurprisingly its a calibrated needle that restricts the flow from the main jet to the level the engine requires. 4 the main jet. This is for those flat out times when you have wound it back to the stops. Right that is a carb in basic terms. I have left float heights out as they will confuse things. What you probably have is one of the pilot jets blocked. Then one cyl will be dragging the whole motor down. No easy way to tell which one bar pulling and checking all 4.
dt502001 Posted October 12, 2012 Posted October 12, 2012 Ok, so most everything seems to be working well. I'm sure I have my headlight issue fixed (loose wires under the seat) and I've changed a LOT of parts. My current issues is a lack of power or hesitation when the engine is cold. So, from a cold start, no matter what the daily temps are, I need to use the "fuel enrichment" lever to get it to start. But I have to let it run for some time to fully heat up otherwise when I try and go it hesitates and will sometimes die. Even once it's warmed up a little and I don't need the choke anymore for it to run at idle, when I give it a little throttle the engine acts like I cut fuel and it hesitates and wants to die. It's not until after I've driven for at least 20 minutes before it will run fine at low idle and low exceleration. Had a guy at a gas station (petrol service station?) tell me it might be the idle jets sticking. Not sure what that means exactly. Any ideas, gents? I have a new fuel cock but haven't replaced the fuel or vacuum lines. The bike also likes to "run out of gas" when there's still a couple gallons in the tank and shouldn't need to go to reserve. Not sure if it's related or not. Jets dont stick they get pluged up Reserve is determined by how tall the main feed pipe is in the petcock,some bike have a large resv. As cynic suggested onlly removing the carbs and giving them a good cleaning will you know if they are the root of the problem. If the bike sat for a while before you bought it they probably need cleaning.Fule dries up and leaves nasty crud in the circuts. Getting them out may prove difficult as the air box rubbers will have gone hard by now ,warming them up with a heat gun will help and removing the bolts holding the air box in place will help give you a bit more room to work the carbs out. The other possibitly is that the valves need adjusting
Sir Puma Posted October 13, 2012 Author Posted October 13, 2012 I've fully disassembled and cleaned the carbs twice already. I'll probably do it again in a while but for now the weather is getting rather cold and wet and makes riding no fun. The thing about the "your tank is empty" situation is that it is random as to when it starts to cut out, anwhere from full tank to 1 gallon left. I've also put the fuel valve on prime and let it sit for a few minutes. After that the bike will run fine for a long time. It's been getting better and I'm just wondering if the vacuum valve in the tap just needs to be broke in. The tank is a 3.5 gallon tank and the reserve is supposed to be 1 gallon. The last few times that I've filled the tank after having to put it on reserve I've put in 2.25 gallons.
Moderator Cynic Posted October 13, 2012 Moderator Posted October 13, 2012 Ah. Now we get the telling info. Replace the vac line. When they split they slow the fuel flow and spoil the idle. Due to the air leak. Its ok at higher rpm because the vacume has increaced enough to either seal the gap or make up the losses.
trumpetdude Posted October 13, 2012 Posted October 13, 2012 I don't intend on highjacking this post but are the many differences between the xj650 and the XJ600n/s engine? It doesn't sound a million miles away from the problem I'm having. (See post in this section)
Moderator Airhead Posted October 13, 2012 Moderator Posted October 13, 2012 check your air filter isnt ripped or has holes in in puma
Sir Puma Posted October 14, 2012 Author Posted October 14, 2012 check your air filter isnt ripped or has holes in in puma Air filter is brand new. One of those spendy K&N types that have the metal mesh screen that don't need repacing.
Moderator Airhead Posted October 14, 2012 Moderator Posted October 14, 2012 Hmmm so perhaps it affected the mixture this change in filter 1: did you oil the filter? 2: Did you reset the carb mixture screws? Try turning all the mixture screws anti-clockwise about 1/4 turn (90 degrees)
trumpetdude Posted October 14, 2012 Posted October 14, 2012 First of all guys, I think some of the replies to this thread have helped sort out the problem with my divvy so cheers! Re the XJ650 - can you check that the bike is definitely pumping fuel? i.e. a visible fuel filter with fuel in it? Also, faither told me about cranking the engine (without spark) to see if the end of each of the plugs is wet with fuel - an oldie but a goodie?
Sir Puma Posted October 15, 2012 Author Posted October 15, 2012 Hmmm so perhaps it affected the mixture this change in filter 1: did you oil the filter? 2: Did you reset the carb mixture screws? Try turning all the mixture screws anti-clockwise about 1/4 turn (90 degrees) Yes, I oiled the air filter. I didn't touch the mixture screws, only the idle screw. When I first got it running well it would idle at around 2500. Manual says around 1100 for the idle so I tuned it down. Soon as I can get some vacuum line I'm going to try changing that. Trumpetdude, there really isn't enough room to put in an inline, but I do want to do that just as an added filter process as the tank is old and a bit rusty inside. I wish there was a source for new tanks. I would love an aftermarket tank that would hold more fuel, but no one makes any that I've seen.
dt502001 Posted October 15, 2012 Posted October 15, 2012 Might need the carbs syncrozied you could have a lazy carb,not sure why it would work better hot ,other than a we bit more vac from a hot eng vs a cold eng. Just a thought are u sure the carbs a fully sealed after having them out 2x the old intake rubbers might not be sealing fully untill hot. Try spraying some wd-40 around the intake rubbers when cold.And see if the idle changes. Iwould def start with a new vac line first. You can get a sealer kit for the rust in the tank about 40 bucks.
Moderator Cynic Posted October 15, 2012 Moderator Posted October 15, 2012 Might need the carbs syncrozied you could have a lazy carb,not sure why it would work better hot ,other than a we bit more vac from a hot eng vs a cold eng. Just a thought are u sure the carbs a fully sealed after having them out 2x the old intake rubbers might not be sealing fully untill hot. Try spraying some wd-40 around the intake rubbers when cold.And see if the idle changes. Iwould def start with a new vac line first. You can get a sealer kit for the rust in the tank about 40 bucks. Make sure its etanol resistant, the cheaper ones turn to sludge and then you have 2 problems....
Sir Puma Posted October 15, 2012 Author Posted October 15, 2012 As I pulled my vacuum line for inspection I got to thinking on a couple things. First I pressurized my hose with about 80-100 PSI and found a couple small pin holes. Then I got to thinking that the original valve is connected only to the cylinder 3 intake for vacuum. I'm wondering if the spring in the aftermarket valve is simply too strong for the vacuum generated at low idle. Since each intake has a vacuum connection I'm going to tie both cylinder 3 and 4 to increase the vacuum and replace the hose with some new hose. I'll test that and see how the low RPM engine control is. This is a major issue for me because as I'm training to be a safety instructor I have to ace the test on my own bike. It's about a total of 8 miles of driving in 1st and 2nd gear at 2-15 mph. So I need to be able to really control that low RPM engine. The course and test are really designed for bikes under 500cc and with my 650 I can't have it hesitating or stalling when I try to put on a tiny bit of throttle at low RPM. I have heard about the various tank treatments and will probably have to settle for one. But they aren't cheap and I'll need to wait for warmer weather. The carb rubbers on the intake side are fine though cyl 1 and 4 rubbers on the airbox side are a little funky. I doubt they would effect the engine. The engine did run fine and smoothly with the old fuel cock in there but then again it was so messed up it was constantly dumping fuel into the carbs. I'll let you all know how things change with new vacuum line and combining two cylinders.
trumpetdude Posted October 16, 2012 Posted October 16, 2012 You're way ahead of me on bike knowledge and it sounds as though you know what needs to be done. A wee question Thouh regarding combining the two cylinders, won't the vacuum be sporadic?
dt502001 Posted October 16, 2012 Posted October 16, 2012 Absoutly no need to join 2 cylinders for vac it won't help. And if your going to do it ...use pair cylinder's... not oposing. Ie: 1-4..-23 not 34-12 unlees your firing order is 34-12 But Ihave never seen a yam with that firing order.
Sir Puma Posted October 17, 2012 Author Posted October 17, 2012 Well, pairing 34 seemed to help a little, but I still have the issue. Currently, after letting the engine warm up with the choke (it's been getting cold out now) until the idle will purr without it. Then as I gradually ease on the throttle a few RPM at a time (sitting with engine in N) when it gets to about 4K suddenly the engine bogs down, RPM tanks and the engine dies. After I've driven it around for a while, say an hour, I can gradually increase the throttle to over 7k without any hiccups. Before combining the vacuum lines the RPM would tank at about 2-2.5k. In the next few days I'll pull the carbs and clean them out again, but I want to get new needles and such. They may need tuning but I'm really not equipped to deal with that and I certainly don't have the money to take it to the shop and have them work on it.
dt502001 Posted October 17, 2012 Posted October 17, 2012 Does the bike run any different if you try running on prime?
Sir Puma Posted October 18, 2012 Author Posted October 18, 2012 Does the bike run any different if you try running on prime? I'll test that out and get back to ya.
dt502001 Posted October 18, 2012 Posted October 18, 2012 Hope this transfer over1st time trying to move a old post,but here is a home made carb sync tool video I've been using my 2 pot differential manometer for a while now and it's proved way more accurate than any other setup. Whereas yours works by each pot sucking against air pressure or a closed pipe, the differential setup has the carbs sucking against each other so no danger of the fluid being sucked out, plus there's an element of self-damping built in. Here, have a video: For a 4-pot system (eg the lad's Bandit 600) I balance 1&2 then 3&4 then 2&3, you generally find they're linked in pairs like that anyway, so no great problems. I'd be interested to see your setup in action, gonna do a vid for us? Ok it worked so have a look at some of the other videos after lots to watch and see how easy it is to make a tool for under 20 bucks
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