Idling and Carb problems, little help?

hey there! I'm having a few problems with my bike while its running, and i realize its LIKELY that these will be resolved once i sync the carbs. but wanted to check if there was anything else i can do, as my friends dad is the one with all the tools to syhnc, and he is currently on vacation... grrrr

My bike is an '81 XJ750R Seca

So the problems are as follows:
1) When The Bike is Hot and ive been riding for a while and i pull up to a light, ill engine brake and all that. but as soon as i pull the clutch in the idle jumps to 2 grand, even 2.5 sometimes. If I Give the throttle a sharp fast twist, the engine will rev up, and then return to normal idle (1050RPM). But will continue revving at 2.5 next time i come to a stop.

2) If the bike is in neutral at a stop, under the same conditions as above, sometimes there is nothing i can do to make the revs come down short of putting it in gear and blipping the throttle (like above)

3) some times its sputters and even almost backfires... its weird, because it mostly does it when its cold, or revving up like above. And its very intermittent. It occasionally does it while im riding but theres very little rhyme or reason to it.

4) My Exhaust smells Really very potent. It jsut smells like exhaust but, its an overpowering smell. If i shut the bike off, and leave it outside for fivce minutes, and then bring it in the garage, the whole garage smells like exhaust until you air it out good. also sometimes my exhaust has this white haze that mostly seems to come out the left muffler, and it doesnt disperse or dissapear it floats around in the area... is this normal?

if anyone can confirm that these will be solved by a carb sync, or tell me else there is i can do about it, please let me know.

P.S. I have already adjusted the Idle Screw.

 

Woah, pull your plugs and look at your colors. I'll lay odds they are black. You would probably need to clean the carbs really well and do the sync your waiting on but it sounds like there is more than just that. Sounds like an enrichment problem, check the choke cable and circuit. Have at and let us know where you land!

 

haha thanks for the advice rob. its like your the only guy on here the last few days....

ill give them a pull and have a look, see whats going on in there.

if only school was open this week i'd have access to all my tools i could do it now... damn you vacation!!

haha never thought i'd say that.

 

You don't have tools at home or on the bike? You should have a minimum kit on hand with the ride just for emergencies. Hit a wrecking yard for the kit. Come to think of it, a fellow has the set for sale on our forum, check out the for sale folder. What kind of mechanic doesn't have tools at home? Hummm..... Gotta watch out for you whippersnappers. Vacations are rest for the mind, live it up and don't curse too harshly, they will become rarer the longer your around. As for the enrichment issue, I've found stuck cables (improperly routed) cause the issue you discribe. Check to make sure the choke cable is seated in the mounting ferrule at the carbs, it may need to be slacked as well. Don't pull it too tight or it will engage the circuit. Good luck!

 

I live right near my school and usually during vacation i bring them all home... as honestly who can afford TWO sets of snap-on tools. They aint cheap, but there worth it. This time didnt, and completely forgot that iw as going to be working on the bike. O well what'cha gonna do. Ill jsut borrow some from a friend, I just bought the bike and am in the process of stocking the "cubby hole" under the seat. So far i have a rain poncho an adjustable wrench a 10mm and a 12mm box wrench. No spark plug socket on the bike yet. i need a first aid kit aswell.

thanks for the tip off with the choke cable. I'll check the cable routing to the service manual and make sure everything is correct.

thanks again robert, for your quick and knowledgable responses

 

I love Snap On too. However, owing to the cost, I purchase only what cannot be had through other means. I live less than a mile from Harbor Freight in Camarillo CA. Their tools have served well for many years at a fraction of the cost. They have a lifetime warranty as well, but you gotta have the reciept (big pain in the neck a few years on). I purchase Craftsman because there usually is a Sears in just about every town and they are open 'till 9PM in most places. Snap On guy just can't get here in an hour. Need a new wrench, Sears is right there. There was a wonderful comparison article a year or so ago in Hot Rod between Snap-On, Craftsman, Husky and Harbor Freight rachet drivers (3/8" drive). After runnning them all through the proverbial wringer (dirt/mud bath, salt water bath, exposure, impact tests) the cheapee $8 Harbor Freight rachet kept up with all of them with one small disadvantage. It had slightly larger pall teeth and couldn't swing as far in a close space. That was the only down side. I guess I'm trying to say Snap-On is great, but why spend all the money when a less expensive tool will suffice. Here is another side. My buddy had his entire Snap-On box lifted out of his locked truck, $2,500 worth of toys gone plus the damage to the truck. Sound familiar? He replaced everything with about $200 worth of toys from Harbor Freight and no one has bothered him since. How much do you want to loose? How often do people steal Harbor Freight? I'll let you decide. You bought some fine steel, but your going to be constantly looking out for theft, cause they WILL walk off first chance somebody gets. Great shame too. Get a good name and it becomes a target. I hope you don't suffer similarly Brian. Can't go wrong with Snap-On though. Outstanding tools. Have you got a set of their reverse twist drill bits yet? Best toy for broken screws since easyouts. Catch you soon.

 

yea my bike does that too!

its annoying but since its intermitent

i can live with it iguess!

but u could check for air leaks to carbs

like cracks in the boots and stuff!

mine only comes back down after i turn it off :cry:

 

Sounds like we need another poll: what tool brand does everyone here go for? I must admit, Snap On is a bit above my budget...