Bonneville America Forums Forums Technical Forums General Tech running rough

I have an 04 speedmaster 15k.on it. The last 2 weeks it has started to back fire in the left carb and run rough. I changed out the plugs they looked all right. Not lean or wet. Ran ok for a few days now back to the rough idle and starts to die then burps and runs. Ai removed had a dyno last year did not change any jets. Has TORs on .... I am at a lose here.

stock besides no AI and TORS? maybe the mix screws need a tweek.Maybe balance too.

That is all the shop said they had to do on the dyno. I have the snorkel out also.If i tweek the screw which way and how much? Or should I take it to a shop? I have no way of balancing the carbs.

Turn them all the way in but dont crank down on them. Then turn out about 3 turns on each side....maybe 3 1/2.

Good luck. There are some threads i remember seeing about removing one plug wire and turning air screws out on one carb at a time...I think.....someone else may chime in on this method

turn your idle up some and disconnect one spark plug so you can adjust the other side. With it running on 1 cyl. turn the screw in until it runs rough then out until it runs rough counting turns then set it half way between the 2. Repeat for the other side. Number of turns will vary from bike to bike and even from 1 carb to the other so don't worry if 1 carb is 2 1/2 turns and the other is 2 3/4 turns more or less. If you are much over 3 turns increase your pilot jet 1 size and try again. Once all is done adjust your idle with both cyl. firing. There is a simple carb balancer you can make from clear tubing and a yard stick with 2 cycle oil in it, costs about $5 more or less to make.

Thanks a saturday projet...I will give it a shot dealer is 300 miles round trip.

Here is a link to the homemade carb sync tool but be careful, you can suck oil in the engine, I use the 2 stroke for that reason it won't hurt anything if you suck the oil in. Another member here had the idea to put a small ball valve at the bottom of the yardstick so after hooked up you can slowly open the valve and if it looks like you are going to suck fluid in the engine close it again and adjust the balance some then try and reopen again. Once you can fully open the ball valve adjust until the oil is even on both sides.

Before you go nuts adjusting be sure and check those vacuum plugs, they can dry rot without showing symptoms and cause this exact behavior.

Oldroadie before I went and turned any thing, I looked at the vacuum plugs for dry rot, was a easy fix left carbs was cracked replaced and runs great. I will leave the crab adjusment for a later date. Thanks for everyones in put.

Glad to hear you solved the problem.

You might want to rejet those carbs anyway. If the jets are stock and you are running TORs with the snorkels removed, you have to richen things up. I'm running 130 mains, TBS needles with 1 shim and I am still a bit lean (same setup as you with no snorkels and TORs). Pull the plugs and note the colour.

That is what I have been hearing here. I asked the shop to do that and when they dynoed the bike they said it did not need to be rejeted?? I ran that jet tool Dog sent to me and with the elavation I live at 6000 it also told me to rejet. Shop showed me the graph and it did not look way out. running about 53 hp. So I will pull a plug and see ... If it is way gray running lean right, or black rich. I know rich from running KDX and high oil mix for the desert. It erks me to go to a shop and they try to tell you what "you" want!!! Trust you guys here more than them.. Let me know

I would think you are lean if you still have the stock jets and no snorkel and TORs. White is lean gray or brown are OK black is rich, ideally you want a light brown.

EDIT: corrected it as per Unclecharlie.

I think Ian meant: black is rich, not right.

LOL, yep black is rich.

William, you're spot on when saying you trust these guys more than those at your shop. I've been the same for ages now and it has been confirmed several times since as well.

If you are serious, you'll learn enough here to even do your own mechanical work. That way you'll know it's been done right, you'll save some serious coin and you'll gain a huge sense of satisfaction.

Even if you don't initially, at least you'll be able to know whether the dealer is ripping you off or not.

William, you stated that you were shown the dyno run chart. Do you have a copy with the fuel/air ratio you can scan and post for us?

You also stated that you are at 6000ft elevation? That will allow you to run a couple of points leaner on your jets and take some power away. Might be part of the reason your horsepower seems a bit low.

I will dig it up this week and scan it .. Went on a long ride today was in the 80's and it did not want to idle and was a hard start. I have something going on. I noticed at higher elavation idle was fine and started all right. Ride was at 5000 stop for gas at about 9500 when it did better ,was also cooler up there.

As you go higher there is less air so if it ran better there you are probably lean at lower altitudes, fix that and you should have easier starts.

One more thing to go over with you guys. I have one carb left with a plug that is the one I replaced . Rt carb still has a hose on it.. Is this right? Both I am talking about is right on top and closer to engine. I do not have a clue here. Fell like a bloomin idot. Ready to buy a HD NOT..

That hose runs to the remains of the AI, you should replace it with another vacuum plug to completely eliminate the AI system. With the AI removed the silver AI attachments in the heads next to the spark plugs ought to be replaced by bolts and you should find four identical vacuum plugs on top, two on the carbs next to the manifold boot clamps and two on the manifolds again by the manifold boot clamps. Ideally the shop pulled the AI valve system from under the tank and removed all of the associated hoses and gave you all that stuff in a box.

All the shop had removed was the 1 vac. hose on manifold of L carb. I have now removed all 4 hoses and pluged the carbs and manifolds. The AI by the plugs have been removed and pluged. My next question is the vac hoses that have been removed go to 2 canisters under swing arm. Can I remove those? LG line from LG canister goes back to a tee under tank. 2 vac lines go to a sm. canister with a vent on the bottom mounted just above LG canister. The way they had screwed this removal up I am thinking They have only removed about 1/3 of AI. I would like to remove all vac hose's and canisters that I can. When this is done right I am betting that I will have to rejet. Time to learn to do my own work. I would like to get a shop manual to help out. Any links? I heard a flush sound on the $$ I spent on this work. Do my own work and will find a new shop for any thing else I need to have done.

Don't overlook the obvious. I have had rough running cycles 2 times. Rought idles and backfires. One was a ignition coil, the other was a plug wire. Don't jump to the fuel system until you are sure the ignition is up to snuff.

You will need to plug the air box and under the tank is the AI pump itself to remove. In addition to what was stated above. There used to be a large hose (may still be if the shop didn't remove it) going to the air boa that should be removed and plugged. The air pump under the tank is held on by 2 bolts.

Air pump is out. I have a dumb question here. I can remove the canisters? They were part of the AI. I think I understand they are part of the AI as evaperators and such.You guys are in for some dumb question with me doing this work for awhile.... May be when I am no longer a "newbie" I can help HUH...

I pulled battery and holder to get to air box to plug it and the shop had plugged the end of 2 lines they seemed to be over flow lines or was the easyest way for them to plug them. Are these the right lines to plug at the box. Plus here is the scary part for me one had about 3 table spoons of water Right one and back a little. The left one had the line full and ran out of air box all oil. I put my finger inside Left carb hole and finger came back with oil on it... To much oil for me not knowing what is up. I do not see how oil could get there. Air intake.. Blow back from the engine seems to me that that much oil, bike would be more noticable running like s*#@ than rough idle.

AI is all removed all lines pluged that needs pluged.Air box pluged. I looked and figured oil came from vent hose to clutch housing. Just have not figured out why yet.Oil level is fine. 19 year old son tipped it over on one of his rides ??

Thanks for the help here all you guys. Dog, Oldroadie you helped a bunch. Will order some jets from eddie.