dla88 Posted July 2, 2008 Share Posted July 2, 2008 I recently got this bike running, I have rewired it, changed the battery, plugs, cleaned the carbs and air filters, just to get it to this stage, now I am having another issue.... While I am in gear if I snap on the throttle a little bit (more than 1/4 of the throttle) the bike bogs down...but while in neutral or with the clutch pulled in I can snap the throttle all the way through and the bike responds with the roar it should have, i have ONLY had this problem in gear while riding it, I'm not sure where to look to diagnose this issue....plugs are good, wiring is good, charging system is in check, filters are in check, and the battery is good... Anyone have any ideas or suggestions? Link to comment Share on other sites More sharing options...
desertxr Posted July 2, 2008 Share Posted July 2, 2008 I recently got this bike running, I have rewired it, changed the battery, plugs, cleaned the carbs and air filters, just to get it to this stage, now I am having another issue.... While I am in gear if I snap on the throttle a little bit (more than 1/4 of the throttle) the bike bogs down...but while in neutral or with the clutch pulled in I can snap the throttle all the way through and the bike responds with the roar it should have, i have ONLY had this problem in gear while riding it, I'm not sure where to look to diagnose this issue....plugs are good, wiring is good, charging system is in check, filters are in check, and the battery is good... Anyone have any ideas or suggestions? does this happen in every gear? you may have to shift down to do any hard acceleration. you may also want to check rear wheel /chain alignment. Link to comment Share on other sites More sharing options...
dla88 Posted July 2, 2008 Author Share Posted July 2, 2008 does this happen in every gear? you may have to shift down to do any hard acceleration. you may also want to check rear wheel /chain alignment. it does happen in every gear, its not too bad in 1st but becomes very noticeable in 2nd gear and up, the chain and wheel alignment is good... Link to comment Share on other sites More sharing options...
Cy Welch Posted July 3, 2008 Share Posted July 3, 2008 it does happen in every gear, its not too bad in 1st but becomes very noticeable in 2nd gear and up, the chain and wheel alignment is good... Assuming good compression and spark, make sure that the carbs are clean (sounds like dirty main jets to me) and that the float levels are correct. If those things are right, it should run good in all gears. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted July 3, 2008 Moderator Share Posted July 3, 2008 Assuming good compression and spark, make sure that the carbs are clean (sounds like dirty main jets to me) and that the float levels are correct. If those things are right, it should run good in all gears. just had an idea check your brakes arn't dragging, when i had mine powder coated, they partially seized and it felt like evry time i changed gear the bike slowed noticably. I just gave the caliper a kick and a bit of shaking to free up the seizure. it took a while to keep doing ( ijust rebuilt them so i knew i had no seal issues) and now no problems Link to comment Share on other sites More sharing options...
dla88 Posted July 3, 2008 Author Share Posted July 3, 2008 Assuming good compression and spark, make sure that the carbs are clean (sounds like dirty main jets to me) and that the float levels are correct. If those things are right, it should run good in all gears. there is good compression and spark, them two things are in check, and i have pulled the carbs off and cleaned them already...that was my initial thought on it, but maybe i will take them off again and give it another go....just to double check Link to comment Share on other sites More sharing options...
dla88 Posted July 3, 2008 Author Share Posted July 3, 2008 just had an idea check your brakes arn't dragging, when i had mine powder coated, they partially seized and it felt like evry time i changed gear the bike slowed noticably. I just gave the caliper a kick and a bit of shaking to free up the seizure. it took a while to keep doing ( ijust rebuilt them so i knew i had no seal issues) and now no problems Brakes are all in check, i actually had to adjust them to get them working properly....so im pretty sure its not that...also the symptom isnt a general slow down of the bike, its an engine issue and once again im leaning towards the carbs....i will at least give it a double check to make sure.....its just odd because of the fact it revs fine in neutral, and with the clutch pulled in....just not while youre riding it.... i think i may pull off the chain and put it in gear and rev it then too.....maybe that will narrow down some more options..... thank you and everyone else for the ideas and if more come in i would like to hear them, i will post again after these two more things are done to it Link to comment Share on other sites More sharing options...
Cy Welch Posted July 6, 2008 Share Posted July 6, 2008 Brakes are all in check, i actually had to adjust them to get them working properly....so im pretty sure its not that...also the symptom isnt a general slow down of the bike, its an engine issue and once again im leaning towards the carbs....i will at least give it a double check to make sure.....its just odd because of the fact it revs fine in neutral, and with the clutch pulled in....just not while youre riding it.... i think i may pull off the chain and put it in gear and rev it then too.....maybe that will narrow down some more options..... thank you and everyone else for the ideas and if more come in i would like to hear them, i will post again after these two more things are done to it The main circuits don't really fully kick in when out of gear. I would still guess either the main jets are having trouble, or the vaccum slides are not working properly. Link to comment Share on other sites More sharing options...
dla88 Posted July 7, 2008 Author Share Posted July 7, 2008 The main circuits don't really fully kick in when out of gear. I would still guess either the main jets are having trouble, or the vaccum slides are not working properly. Well it is definatly a carb issue slides and jets should be good now but the floats may be off? runs great on half choke but dies out without it so......now i have to figure out how to fine tune them....by any chance do you know how to go through these particular carbs and fine tune them? I have not worked on carbs like these so I am pretty unfamiliar where exactly everything is on them and I have not found much info on them on the net so any info you could provide would be much appreciated By the way, the jets did get some more stuff in them, and they were partially clogged Link to comment Share on other sites More sharing options...
Cy Welch Posted July 7, 2008 Share Posted July 7, 2008 Well it is definatly a carb issue slides and jets should be good now but the floats may be off? runs great on half choke but dies out without it so......now i have to figure out how to fine tune them....by any chance do you know how to go through these particular carbs and fine tune them? I have not worked on carbs like these so I am pretty unfamiliar where exactly everything is on them and I have not found much info on them on the net so any info you could provide would be much appreciated By the way, the jets did get some more stuff in them, and they were partially clogged First, put an inline filter between the tank and the carbs. Second make sure it's really clean, needing part choke to keep running means it's not really clean yet. Remember to clean the main jets you need to remove the vaccum slides and diaphrams and then loosen and remove the jets through the top. Also make sure you clean the idle jets which are under the rubber plugs in the bowl. If you get it all clean it should run good, although you MIGHT need to drill out the mixture screw plugs and replace the o-rings on the idle mixture screws (they get eaten up by modern gas) if their bad as it won't idle well without good o-rings. Then start at about 2 1/2 turns out on the idle screws and then (I feel this is REALLY important) adjust the mixture with the engine running, and adjust them out for highest idle and then back in just slightly. You may find a world of difference after doing that, I sure did. The BS34 III's like you have (yamaha seems to have used them on almost EVERYTHING for a few years starting with 1980) have very little adjustment so cleaning is very important as it float level. Link to comment Share on other sites More sharing options...
dla88 Posted July 8, 2008 Author Share Posted July 8, 2008 First, put an inline filter between the tank and the carbs. Second make sure it's really clean, needing part choke to keep running means it's not really clean yet. Remember to clean the main jets you need to remove the vaccum slides and diaphrams and then loosen and remove the jets through the top. Also make sure you clean the idle jets which are under the rubber plugs in the bowl. If you get it all clean it should run good, although you MIGHT need to drill out the mixture screw plugs and replace the o-rings on the idle mixture screws (they get eaten up by modern gas) if their bad as it won't idle well without good o-rings. Then start at about 2 1/2 turns out on the idle screws and then (I feel this is REALLY important) adjust the mixture with the engine running, and adjust them out for highest idle and then back in just slightly. You may find a world of difference after doing that, I sure did. The BS34 III's like you have (yamaha seems to have used them on almost EVERYTHING for a few years starting with 1980) have very little adjustment so cleaning is very important as it float level. Alright thank you, I will give all that another try on the next nice day we have and I will post back up with the results Link to comment Share on other sites More sharing options...
joecool85 Posted July 8, 2008 Share Posted July 8, 2008 Definetly sounds like it's leaning out. Are your carb boots in good condition? Link to comment Share on other sites More sharing options...
dla88 Posted July 9, 2008 Author Share Posted July 9, 2008 Definetly sounds like it's leaning out. Are your carb boots in good condition? If you are talking about the ones that connect them to the engine, no they are cracked....i noticed that when i took the carbs off again today, i will definatly silicone them up. They had some tape on them and at first i thought it was just because they didnt have clamps on them took the tape off and well they are cracked up havent checked the bike yet after once again recleaning the carbs but i will fix the boots and such before hand I didnt think that would cause an issue with the running.....but i suppose it could pull in more air and throw everything off.....thanks for the post and the new idea hopefully its a mix of the both of these issues Link to comment Share on other sites More sharing options...
Cy Welch Posted July 9, 2008 Share Posted July 9, 2008 If you are talking about the ones that connect them to the engine, no they are cracked....i noticed that when i took the carbs off again today, i will definatly silicone them up. They had some tape on them and at first i thought it was just because they didnt have clamps on them took the tape off and well they are cracked up havent checked the bike yet after once again recleaning the carbs but i will fix the boots and such before hand I didnt think that would cause an issue with the running.....but i suppose it could pull in more air and throw everything off.....thanks for the post and the new idea hopefully its a mix of the both of these issues I don't think things will be right without clamps either as you really need an airtight seal which I don't think you can get without the clamps. Link to comment Share on other sites More sharing options...
joecool85 Posted July 9, 2008 Share Posted July 9, 2008 I don't think things will be right without clamps either as you really need an airtight seal which I don't think you can get without the clamps. Agreed. You will need to replace the boots and use clamps before you will be able to get the bike to run properly. The boots you can get for $30-35 on eBay new, the clamps you can just use large radiator hose clamps, $1-2 each at any parts store. It'd be the best $40 you could put into that bike. Link to comment Share on other sites More sharing options...
xtonyx Posted July 9, 2008 Share Posted July 9, 2008 Check your battery, make sure you're getting proper charge.. when my battery starts to die I slowly start to lose power in lower and lower in my power band. Link to comment Share on other sites More sharing options...
joecool85 Posted July 10, 2008 Share Posted July 10, 2008 Check your battery, make sure you're getting proper charge.. when my battery starts to die I slowly start to lose power in lower and lower in my power band. An an XS400? My 82 SOHC XS400 doesn't care about battery voltage. The battery in there is dead (the bike had a really bad short when I got it, drained the battery flat and I haven't replaced it), I just kick start it and it goes fine. Link to comment Share on other sites More sharing options...
bralkan Posted July 10, 2008 Share Posted July 10, 2008 An an XS400? My 82 SOHC XS400 doesn't care about battery voltage. The battery in there is dead (the bike had a really bad short when I got it, drained the battery flat and I haven't replaced it), I just kick start it and it goes fine. On my '80 there needs to be a solid battery - without voltage the charging system won't supply the right amount of voltage. Link to comment Share on other sites More sharing options...
joecool85 Posted July 11, 2008 Share Posted July 11, 2008 On my '80 there needs to be a solid battery - without voltage the charging system won't supply the right amount of voltage. Huh, maybe the 82 is different. That or maybe my bike received more XJ550 parts other than the fork before I got it (doubt it). Link to comment Share on other sites More sharing options...
dla88 Posted July 12, 2008 Author Share Posted July 12, 2008 I don't think things will be right without clamps either as you really need an airtight seal which I don't think you can get without the clamps. Dear everyone im making one reply to everything i got the carbs in good condition, battery is good, i have already gone through and got that in order, my bike is an 81 and it does need a solid battery, which i do have, i used silicone on the boots, i definetly fixed them, i dont need new ones now i will add the clamps on them, but i just tested the bike and the bog is almost gone, a little more tuning, maybe a brand new 20$ battery, and those clamps, should fix the rest of it I thank everyone for all the help and knowledge i am finally on the right track with it and its running pretty good right now and i hope i can get it up to the full potential once again thank you all Link to comment Share on other sites More sharing options...
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