GothicJB Posted June 17, 2011 Share #1 Posted June 17, 2011 I put in new spark plugs ... NGK double checked the gap at .035 ... and now that they are in i have a slight backfire when coming off the throttle ... anyone have any ideas? I can take them all out and check them again but I was very CAREFUL when putting them in so as not to bump them and ruin the gap. Link to comment Share on other sites More sharing options...
muaymendez1 Posted June 17, 2011 Share #2 Posted June 17, 2011 If they are direct replacements there should be no reason the plugs arethe culprit. Why did you change the plugs? How did the old ones look? Was it just a change of plugs or what other service di you preform.Sticky slides, stuck floats,bad gas! Just some ideas. Mine has a slight backfire on decel but so do 2 of my buds ventures of later years. I deal with it. How bad is the backfire. And is it backfiring through the carb or afterburning through the pipes? Link to comment Share on other sites More sharing options...
GothicJB Posted June 17, 2011 Author Share #3 Posted June 17, 2011 ... it's afterburn through the exhaust. I changed the plugs because i just got the bike and didn't know when it was last done. I did add half a can of seafoam to the tank as well (halfway through that tank when I changed the plugs. Two of the old plugs were a little dirty, nothing that would give me much concern though... can't think of anything else i've changed (except the rear brake reservoir lol). Link to comment Share on other sites More sharing options...
Squidley Posted June 17, 2011 Share #4 Posted June 17, 2011 Check your vacuum lines and the caps on the intake manifolds, also do a carb sync on it. I have carbtuned a few bikes that had backfire issues and the sync took it away. Thats what I would start with and let us know how it worked out, we'll get you rolling. Link to comment Share on other sites More sharing options...
GothicJB Posted June 17, 2011 Author Share #5 Posted June 17, 2011 oh yeah ... and it's a subtle backfire ... (almost sounds like a quiet missfire) my fiancee couldn't really notice it when i was trying to get her to hear it ... i guess i just notice it because i know what it was like before lol Link to comment Share on other sites More sharing options...
GothicJB Posted June 17, 2011 Author Share #6 Posted June 17, 2011 @squidley - appreciate it! ... what is the easiest way to do a carbsync on these? do you gotta tear it down? is there a thread somewhere on it? i searched and got a bunch of threads ... looking through them i didn't find what i was looking for though lol Link to comment Share on other sites More sharing options...
oldgoat Posted June 17, 2011 Share #7 Posted June 17, 2011 skydoc_17 had a great write up on doing this along with pics but i cant figure out how to post the link here? Link to comment Share on other sites More sharing options...
dingy Posted June 17, 2011 Share #8 Posted June 17, 2011 skydoc_17 had a great write up on doing this along with pics but i cant figure out how to post the link here? You open the post that you want to link to, highlight it in the browser address bar, (right click and hold right button down in address bar and drag cursor till all text is highlighted) then press ctrl-c (or right click in address bar press ctrl-a, this will highlight every thing, then press ctrl-v) Open a new post in another thread, click in message area and press ctrl-v Otherwise known as copy & paste This is windows way, not sure about the Mac-Nuts guys. Gary Link to comment Share on other sites More sharing options...
oldgoat Posted June 17, 2011 Share #9 Posted June 17, 2011 First Gen. Carb. Sync. With Carbtune Including Pics! There have been so many people asking about Syncing. the Carbs on their First Gens. that I thought I would take a few pics of the way I do it so that other members would have a general Idea how to go about it. (Disclaimer: My way is not the "do all, be all", just the way I do it. Take what you need and leave the rest.) I start by removing the screw in the false tank cover and unhooking the front of the cover, It does not need to come off. I then remove both side covers. I then remove both of the Radiator side panels to expose the 2 screws that will allow the lower fairing legs to be pulled away from the Carb. Bodies. (NOTE: if your lower fairing legs are in bad shape, you may want to remove the lower cowling which will expose the screws that will allow you to completely remove the lower fairing legs, Mine are still pretty flexible so I don't take them completely off. (Do what you feel "warm and fuzzy" about.) With the plastic off, I start the bike and let it run up to "operating temperature". Pic #1 shows the temp. gage about 1/3 the way up. Depending how "hot blooded" you bike is, this may take a minute or two. While the bike is warming up, Pic #2 shows how I suspend my Carbtune from the ceiling in my shop with a long shoe string and center it right above the gas cap. This allows the Carbtune to remain vertical and also allows me to work both sides of the bike with out moving the Carbtune . At this time, I shut the bike off. Pic #3 shows the location of the Vacuum ports on the right side of the bike, I remove them and plug in the Carbtune on that side. Pic #4 shows the lines installed on the right side. I then move to the left side of the bike, Pic #5 shows the one Vacuum port Cap and the "Boost Sensor" Vacuum line that is connected to Cylinder #2. (NOTE: These pics were taken of an 1987 VR MKII, I don't know if the MKI is the same because I don't own one!) I remove the Vacuum port cap from the #1 cylinder and the Boost Sensor line from the #2 cylinder and Pic #6 shows the two lines from the Carbtune connected. I am now ready to restart the bike. Pic #7 shows how I position a fan at the front of the bike to keep the engine temp. from going too high. I like to take my time when I'm adjusting the Carbs. on a bike and this gives me the extra time. With the bike running and at temp. Pic #8 shows the location of the Idle adjustment screw. (NOTE: I moved the #2 cylinder Carb. Bowl Drain Tube out of the way for the pic. This screw is hard to find unless you are squatting down... and use a flashlight!) Pic #9 shows the Tachometer at 1000 RPMS (By the book 950-1050 RPMS) Pic #10 shows the Carbs. are in fact out of adjustment. I have the left two channels of the Carbtune connected to the left side of the bike, (cylinders #1 and #2.) and the right two channels of the Carbtune connected to the right side of the bike, (Cylinders #3 and #4). Starting on the left side of the bike Pic #11 shows the location of Carb. Sync. screw "A". (NOTE: This is another screw that is hard to see at first, and it is at a downward angle so it will be hard to get a screwdriver on it properly, be patient!) The object here is to rotate "Screw A" until you get the left two channels balanced. Make an adjustment, then "Blip" the throttle and let the bike return to Idle. If needed, adjust again. With the left bank of Carbs. adjusted, I move to the right side of the bike for the rest of the adjustments. Pic #12 shows the location of the "B" and "C" screws. Screw "B" is used to adjust the right two channels of the Carbtune, and Screw "C" is used to adjust the left bank of two Carbs. (Cylinders #1 and #2) to the right bank of Carbs. (Cylinders #3 and #4) Using screw "B" I adjust the right two channels, "blip" the throttle and readjust if necessary. Then I use screw "C" to adjust the left bank to the right, "Blip" the throttle and readjust. Pic #13 shows all four Carbs. on the Carbtune adjusted pretty darn close. Basically, you are done at this point. I wanted to add a few personal suggestions that I use to "enhance" the Carb. Sync. experience to make the bike run even better for me. After I am done with the Carb. Sync. at Idle, I Rev the bike to the 1800 to 2000 RPM range and hold it there, if all four of the Carbs. aren't holding the same vacuum at 2000 RPMS I make slight adjustments (split the difference) between Idle and 2000 RPMS. The reason I do this is because when I am stopped, and start to take off, I increase the RPMS of the bike into the 1800 to 2000 RPMS range as I am slipping the clutch to engagement. I don't want one or more Cylinders "cutting out" or "cutting on" as I am trying to look cool pulling away from a light, especially with Jean on the back! The next issue I would like to address is the "Reliability" of the Carbtune Manometer. Here is a list of Items I purchased to build a simple "Manometer Tester" Manifold. Pic #14 shows the "Manifold" and Pic #15 shows how I test my Carbtune BEFORE I use it. I got these Items from NAPA Auto Supply: Part# 2-616 (2 needed) Vacuum Connector $1.49 each $2.98 Part# H-459 (1 foot needed) 5/32 Vacuum Tubing $.99 1 qty. 1/4-20 screw Free from toolbox 6% Tax (Pa.) $.24 -------- $4.21 Total I hooked all 4 Carbtune lines to the manifold and hooked the Manifold line to one of the carbs. on my 87'VR. My Carbtune checked out OK. If you have any questions, PLEASE feel free to ask. Earl Attached Thumbnails __________________ Link to comment Share on other sites More sharing options...
oldgoat Posted June 17, 2011 Share #10 Posted June 17, 2011 thats from skydoc_17 not me credit goes to him okay Link to comment Share on other sites More sharing options...
muaymendez1 Posted June 17, 2011 Share #11 Posted June 17, 2011 I was gonna say a hotter plug but the afterburn is subtle. Carb synch should clear that up. you may also need to go through more tanks of seafoam gas to make sure its clean. Put some morein synch and rideher like shes the hottest thing in your town. Link to comment Share on other sites More sharing options...
Squidley Posted June 17, 2011 Share #12 Posted June 17, 2011 @squidley - appreciate it! ... what is the easiest way to do a carbsync on these? do you gotta tear it down? is there a thread somewhere on it? i searched and got a bunch of threads ... looking through them i didn't find what i was looking for though lol There's some boys up there in Minniesoda and Wisconsin that have carbtunes. It's a relatively quick process. I'm sure you'll get a few that will pop in and post up. If you were closer I would show you how to do them and then you could do them in the future, but it's about 1500 miles for you to get here. If you want to come down we'll leave the light on for you though Link to comment Share on other sites More sharing options...
GothicJB Posted June 18, 2011 Author Share #13 Posted June 18, 2011 definitely would not argue with someone with a carbtune gauge thing whose willing to show me how to do it lol ... Just called the local shop/dealer and they want $115.95 for one lol ... Thanks guys I appreciate all your help ... after i get them sync'd and tuned i'll let you know how it turns out. Probably gonna have to buy one next week after I get paid. Gonna check online for a cheaper one. Link to comment Share on other sites More sharing options...
camos Posted June 18, 2011 Share #14 Posted June 18, 2011 There isn't much point in syncing dirty carbs. Since the bike is new to you and it appears you do not really know what state the carbs are in, I would suggest you do not go ahead with the carb sync until you have run at least a full can of Seafoam through using 1/2 can per tankful and then run a tank of straight gas though it. There is no guarantee Seafoam will completely clean everything in the carbs but it does a very good job within its capabilities. Link to comment Share on other sites More sharing options...
Yammer Dan Posted June 18, 2011 Share #15 Posted June 18, 2011 Don't buy a Carb-Tune til you get info from here as to best buy. Anybody??? Link to comment Share on other sites More sharing options...
dingy Posted June 18, 2011 Share #16 Posted June 18, 2011 Don't buy a Carb-Tune til you get info from here as to best buy. Anybody??? Dan, Are you feeling OK???? You posted in a thread about a carb problem and didn't mention SEAFOAM ???? Did you sell your stock???? Gary Link to comment Share on other sites More sharing options...
Yammer Dan Posted June 18, 2011 Share #17 Posted June 18, 2011 Dan, Are you feeling OK???? You posted in a thread about a carb problem and didn't mention SEAFOAM ???? Did you sell your stock???? Gary Been a rough day Gary! SEA_FOAM it. Then sync them and Sea-Foam them again!! I'm going to buy a Carb-Tune one of these days. Still using my old Mecury Sticks. Link to comment Share on other sites More sharing options...
Freebird Posted June 18, 2011 Share #18 Posted June 18, 2011 Here is a pretty good writeup on synching the first gen carbs. http://www.venturerider.org/forum/showthread.php?t=56723 Link to comment Share on other sites More sharing options...
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