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I'm running a Mikuni 30mm VM series. It's not a pumper so I just layed the extra bit of cable up under the tank. That did not solve the backfire issue so many of us have. I am running the stock jets. I have also replaced the CDI, coil, and plug with "hi performance" units. That did not help either. Just for the heck of it, I'm desiginig a signal conditioner for the line from the pulse coil to the CDI.
I was not aware of a back fire problem that "so many of us have". I do not have a back fire problem on my 2012 DF.Quote:
Originally Posted by Roadkill
Please describe this back fire problem.
Miss, backfire through carb, rough idle. Also at roll on and steady speed. Hot or cold. Load or no load. Since it came out of the case. 2012 Installed new fuel filter at PDI and changed at 50 mi. Bike has less than 100mi. I've seen several posts concerning carb problems. I did rejet the stock carb (110). Plug is tan like it should be. Not a mech so I'm guessing maybe valves - haven't checked them but will when I get a few more miles on her. Emmisions crap is gone and hole plugged. Did leave the crankcase breather on but it is exposed to the air as I installed a new air filter of about the same surface area.
Neither of my two DFs had/have this problem you are describing. The stock DF should not be backfiring through the carb. Yep, there are a lot of posts considering carb problems, probably most caused by the owners.:lol8:Quote:
Originally Posted by Roadkill
I just fixed one I caused.
What model DF? How about adding it to your signature line?
Maybe an air leak causing the backfiring. Do you have good o rings on the carb manifold? Your DF should not need a 110 main jet. A 105 should be plenty big.
What was wrong with the stock carb and CDI,coil,etc? Don't just start changing parts out. I'd put it all back stock and start over.
This issue was there with the stock parts also. The CDI did seem to help power at mid to high range because of the 4 degree advance, I would say. I always install new ignition parts on new Chinese bikes and scooters. Probably a head trip, but I feel like the aftermarket parts are a little more reilable and they don't cost that much. I did reinstall the factory carb and main jet, CDI, and coil and nothing changed so I changed them back. As for the stock carb, I like the simplicity and quality of the Mikuni. Nothing got worse with the changes - power a little better. My next step is to squirt starter fluid at the manifold and carb connections. Just not sure what the stuff will do to the paint. I've heard some use WD40 for that test. It's a 2012 "B". Rear sprocket is 35T. Took out links to keep the fender clear of the tire. My back ground is electronic design and all the electronics stuffed into that little can with no sheilded wires bother me a little. Probably won't do much good but I still may look at cleaning up the line to the CDI input. Heck, it's a hobby.
All I can say is that my 2012 DF is all stock except for the rear sprocket change and air injection system removal and does not do the backfiring that you are describing.
I'll play with it awhile and post when I figure it out. Thanks for the input.
ya sounds like u need to adjust your valves - baring a airleak
2010 dong 250 cha chopper 15-33 spockets car rear tire , 110 main jet - 90% highway use Austin tx
77 gs 750 susuki
so u did get another 1 Barnone ? awesome
Just found out that I blew out the plug I put in the emissions outlet that comes off the block. Repaired that and re tuned the carb. It's much improved but I still have the miss so I'll do the valves this weekend. .002 amd .004 if I remember correctly. I had a truck cut the corner and put me down so I'm also gonna change the oil just in case I had fuel leak into the oil sump while she was on her side. She was down for a min til they picked up the bike off of me. Some drivers forget what they're doing whe they see the bobber. Live in the DFW area so dumb drivers are the rule here. Loved Austin when I was there. Should have stayed.
I do mine the same as my 74 Beetle air cooled pushrod engine, 6 and .008Quote:
Originally Posted by Roadkill
and U do know the air injection itself is meant to "pop off" unspent fuel for cleaner emissions , - could that be the "miss" your hearing ?
many of us remove it and block it with homemade plate
[QUOTE=DanDaMan;69744
so u did get another 1 Barnone ? awesome[/QUOTE]
Yep, bought a 2012 last year.
I do thank you for your response. Several owners have removed that system and capped the plate. I removed the system but just plugged the fitting and replaced the air filter. That plug came loose. This is a miss that is present idle to max. Motor responds great to the throttle and pulls well, it just has a miss at whatever RPM I hold her at. Seemed like a spark issue , but I've replaced CDI, coil and and sparkplug. Plug is gapped to .003.
Recapping that emissions and retuning the carb fixed every issue but the miss. I did the leak test for the carb manifold area and checked the header bolts at the exhaust also. I'm gonna set the valves today.
Valves are adjusted with no change to the miss. They were very tight. She is very rideable and I've read the plug and adjusted the carb so I'm sorta confident that I'm not doing any damage by riding her, so ride I will til I'm ready to send her to a shop.
So you have a cap on the port on the intake manifold and a plate on the port on the cylinder?Quote:
Originally Posted by Roadkill
This miss that you have is constant over the RPM range?
I do indeed. Both the block and intake manifold are capped. Throttles up smoothly and good power. Just has that miss at all RPM. Gets a little better at the top end. I have also changed the air filter to one of about the same size but without the emissions input. I have tried:
CDI, coil, plug, carb tune, starter fluid air leak test, valve adjust, fuel filter, pull the gas cap to make sure it's not a vent issue. Plug is tan and gapped to .0030. Bike starts easily with choke when cold and except for the miss runs well after 5 min warm-up. I think that with carb not running lean, and the valves adjusted, I've checked things which cause damage to the engine so I'll just put a few miles on her and see what happens?
My background is not mechanical, so I think I've exhausted all of my limited skills. I have ordered a in-line spark tester and a compression guage mostly because any job worth doing is worth buying a new tool.
Is this an actual miss, or is it more of a pop? On a single, if you have a miss, it's major, since you don't have any more cylinders to keep the engine spinning. Sometimes an engine that's slightly rich or lean, can have a minor pop. But you say your plug is tan, or brownish? A richness can cause some raw gas to collect in the exhaust pipe, and then can ignite, maybe causing a pop. Suzuki Savage/S40's tend to produce a loud backfire when they are shut off due to a lean mixture. But, yet, they run fine. This is an interesting one.
Not much left to fix the miss.
Could you do an audio and video of the miss at different RPM? Maybe somebody here can help if they hear the miss.
I do thank all for the input! I'm sure that a good mach could figure it out quickly with the bike in front of him. It can be very hard to solve the unusual problems long distance - especially when working with a layman. I will try to get a video this week-end.
Hang in there. At least, it sounds like you are able to ride it.
Thank-you birdmove. It is a miss, not a backfire. Had both but all of the things I've done have cleaned her up a great deal so all that's left is the miss. Wish I had a scope so I could look at the trigger pulse coming off the stator. I'm trying hard to find my "tar pit" in the next 3 months or so and retire. I'll have lots of time to play and learn then.
1 thing to note , the engine is a CG 125 , turned into a 250 but it still has the THROAT of a 125 ,
a better "air cleaner" can actually be acting as if its always part choked
replace air cleaner with stock and go for another ride
It's the same surface area and shape. Only difference is that the new one does not have the fitting for the crankcase breather
believe me from exp with this blog , upgrading the air filter has caused multiple people issues , leave jets stock and upgrade the filter makes the mix richer
upgrade jets then filter makes ya way to rich
as quotedQuote:
Originally Posted by Bobthebobber
My thanks, Dan. I have no doubts about the accuracy of that statement. I did a mod on the intake of my trike that taught me that lesson well.
I have the same issue with stock carb, stock jetting, 110 jetting, stock air cleaner, no air cleaner, aftermarket air cleaner - Also, Mikuni carb with the jet needle at the bottom, middle, or top clip. Same air cleaner options. Every carb option I've tried has the same miss. I've had that miss since the first time I fired her up after PDI. New plug and I've tried new CDI and new coil also. I have a new fuel filter but I haven't replaced the fuel lines yet. Maybe I should try that option also. Probably not that because she goes from idle to full throttle without a hitch and holds RPM steady. It's just that the only time the miss goes away is when she's reving up. As soon as I hold her at any fixed RPM, she starts missing again. She's much better at 3/4 and above though. I do want to run a compression test when the gauge comes in next week. .
It might not be relevant, but I noticed that when I adjusted the valves, the base of the adjustment screw on the exhaust valve does not sit flat on the top of the valve stem. That's why the compression test. Valves were very tight! The guy who held his thumb over the spark plug hole while I was trying to locate the compression stroke said he saw metal flakes. Maybe a chipped valve? I don't even want to think about that till I've tried all other options. If you, know long should compression hold on a leak-down test? Also, I'm tbinking maybe 60-90 pounds?
I still suggest pull air cleaner off and go up the block
valve float and air starvation are this bikes limiting factors
but metal flakes blowing out sparkplug hole pretty serious mmkay
all I know about its compression is 9.2:1
Update.
Still cannot get her to turn over.
starter works.But.. When I remove the timing mark cover I can notice that while I engage the starter, it is NOT turning the flywheels gear. I have it at TDC mark, and it just does not move.removing all covers including the flywheel cover I see that there are only three gears that link from the starter to the flywheel gear. all gears are free from bind. In order to have the sytem function, it all must be together,so putting it together and checking once again, the starter does NOT move the flywheel gear.it does move the reduction gears, and when i turn the flywheel by wrench all gears move back to the starter.
I am lost here. Why will the starter NOT turn the flywheel?
Attachment 15482Attachment 15483Attachment 15484here are pics of the gears
Attachment 15480Attachment 15481
wish I could help u have the most miles of us all , all I can suggest is ordering a Honda CG125 starter
There is a clutch on the back side of the charge rotor that is made up of 3 rollers with pins and springs pushing them out.It will only allow the engine to spin one way.The other way should engage the starter drive train.If something in there is slipping,the starter drive train will never engage the rotor and spin the engine over.This happen to me on my GS500.I ended up buying a rebuild kit.I don't know what's available for the DF.It kind of works like the old ball bearing pull starters on lawn mowers.
http://www.mychinamoto.com/forums/at...0&d=1402952073