Engine problems on new bike...Spark Plug?

only1soe

New Member
Jun 19, 2008
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Had some problems with my bike recently. Once again here is the video of the bike:

YouTube - Motorized Bicycle

I bought the bike basically brand new 4 months ago off a guy here in LA. The guy I bought it off just assembled this bike (it was his first one) and bought the engine off Thatsdax.com. Let me first mention I am not engine guy and know very little about them.

When I bought it the engine was in the break in process.

I was told the next gallon of gas to stay at a 18.1 ratio (7.1 ounces per gallon) until the engine was broken in and to try to stay away from WOT which I did.

I am on my 2nd gallon of gas and was instructed to then go to a 30.1 ratio (4.25 ounces per gallon).

This more recent gallon of gas I have rode the bike a little harder and faster. but recently the engine started to spudder. The engine was getting gas so I am not sure what it could be.

I checked the spark plug and there was black sluge at the bottom which I cleaned off.

The engine kind of goes then gets weak goes then gets weak until it finally just died out.

After cleaning the spark plug the engine still ran rough for about a half mile until dying out.

I spoke to duane and he told me to post here. I ordered 2 of the same spark plugs from thatsdax to test that out first.

I also cleaned out the little carberator as there seemed to be a little dirt on it. In addition I also emptied out all the gas.

Duane asked me if the engine idles which I didnt even know it was supposed to. I guess the knob near the primer when twisted in could help with that. Typically when i ride it I need to get near 12mph and give the throddle some gas. Once I let go of the clutch it kicks in but i have never stepped off the bike and just heard it idle on its own.

Can you guys help me trouble shoot with this problem? Do you think the spark plugs will help or maybe the oil to gas ratio is wrong. Let me know if you can help.

Mark
 

misteright1_99

New Member
Mar 21, 2008
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Treasure Coast, Florida
First I would upgrade the plug, plug wire, and cap... What is your plug gap? What are you using for oil? What position is the clip in on the needle inside the carb. Do you have an inline gas filter? Where are you located? Near sea level? Need more info tho help....
 

only1soe

New Member
Jun 19, 2008
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I bought two more LDZ spark plugs and Duane said these work fine. Maybe its not too late to switch the order.

Plug Gap? I dont know what that is as I mentioned I dont know motors well. Not sure what an inline gas filter is. On my video above if its what I think it is you can see the gas filter if I am not mistaken. I dont know what position the needle inside the carb is either.

Break in process used Maxima oil
After that and on the most recent take of gas I ran out and went to Castrol 2 stroke engine oil that I got from pep boy

Located a quater mile from the beach and maybe 100 feet above sea level tops. The bike is stored in an open air garage port but in a locked storage area.
 

thatsdax

Member
Feb 22, 2008
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www.thatsdax.com
Try.....

Try pulling your gas line off your carb and let it run into a can. See if the fuel keeps running out into the can or if it eventually stops. If it stops, then you have a vacuum in your tank and you will need to drill a tiny hole in your gas cap off to the side behind the rubber washer. Hope this helps..
 

misteright1_99

New Member
Mar 21, 2008
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Treasure Coast, Florida
I bought two more LDZ spark plugs and Duane said these work fine. Maybe its not too late to switch the order.

Plug Gap? I dont know what that is as I mentioned I dont know motors well. Not sure what an inline gas filter is. On my video above if its what I think it is you can see the gas filter if I am not mistaken. I dont know what position the needle inside the carb is either.

Break in process used Maxima oil
After that and on the most recent take of gas I ran out and went to Castrol 2 stroke engine oil that I got from pep boy

Located a quater mile from the beach and maybe 100 feet above sea level tops. The bike is stored in an open air garage port but in a locked storage area.

I dont know what a LDZ plug is. If that is the stock chinese plug forget it there junk, I would go out and buy a NGK or Champion plug. The plug gap is the distance between the electrode and gound strap on the spark plug and should be adjusted to .020 to .025 of and inch useing a feeler gauge. I would do a search and read up on needle adjustment inside the carb. here, there is a lot of good infromation. Castrol is a good oil and if mixed properly should be fine.
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
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north carolina
First of all my engine starts at about four miles an hour. I can't even pedal it to twelve I have a bad heart and would surely meet that great biker in the sky.

Did the guy you bought it from explain what the choke is and what it does. If not we can take you step by step through how your bike works.

If you set your choke about half way and pedal it about a quarter block you should be able to drop the clutch and keep pedaling and have it start. If that isn't happening then first thing to do is figure out why. If it was his first build, he quite possibly has left some air leaks. That is the most common problem with these engines.

By all means buy a good plug. Take the extra one with you to an auto parts store. Tell the man you want a champion or other top brand to replace it. Then have HIM gap the plug for you to the above suggested gap. You should replace the wire as well.

I did have to remove my in tank fuel filter after about five tanks of gas, that happens now and then I think. A good inline see through fuel filter is a good idea. It will tell you if there is gas going to the carb as well as trapping dirt. While you are at it get a piece of good black rubber gas line and dump the fish tank line.

Try to be systematic in your trouble shooting. Rule out one thing then move on to the next most logical problem.

Idle: when you stop at a stop sign can you release the throttle. If you can it is idling if it dies then it is not.
 

only1soe

New Member
Jun 19, 2008
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You know I have read on other sites, heard it here, heard it from the guy who made my bike that the LDZ plug is a piece of junk and cheap. I mentioned that to duane over at Dax today and he said his has been working fine for a while.

I think I have a lot to go on and try for now. I will try these thing and check in after I do so. Thanks for the help.
 

only1soe

New Member
Jun 19, 2008
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After I have been riding the bike for a decent distance and put in the clutch it will idle for a few seconds when the throddle is turned all the way off then just turns off. I thought that was a normal part of it.

I have to say I am very much a beginner on this stuff. I have never riden a motorcycle or dealt with a clutch so even something simple like that was something new for me.

Engine work even minor is new too but the way you guys explain it doesnt seem difficult.

When I went to pep boys with the LDZ spark plug they had no idea what it was then again the guy may not of known what he was talking about.
 

misteright1_99

New Member
Mar 21, 2008
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Treasure Coast, Florida
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Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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up north now
When you get it running, or until it quits again, have another look at the plug. It should be chocolate colored, not black and oily, not black with a white or light grey center, uniform chocolate.

What proceedure do you use to start it? When did it's start running crappy? You can run it harder, just vary the throttle amount and the engine rpm. Running it too slow is harmful too.
 

MarkTur

New Member
May 23, 2008
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What is the gap for it?

I seem to be losing power at WOT, especially when running at top speed (26-27mph) on a 40t, and I'm 6' 215lbs. At 3/4 it's beautiful, just won't accelerate past that, no matter how much further the carb opens. Feels like it's losing power.

NGK B5HS plug.
Carb set with e-clip on the last notch at the END of the needle (lean setting). Plug looks good in color. I was black at the second notch down from the end, went back. It was chocolate brown at that setting previously. I have a rubber o-ring between carb and manifold - don't think I'm leaking air.

Anyway, I think it's electrical, so I want to set the gap. I just put the plug in without checking and have been running it like that. :)
 

MarkTur

New Member
May 23, 2008
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PS. Can someone describe exactly how to change the plug wire? I know this sounds silly, but I've never done it before... thanks.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
237
63
up north now
Set your plug at .020"
To change the wire, unscrew it from the CDI, and replace it with a 7mm wire from an auto parts store. Make sure you match up the plug cap to the type of plug you use (look at the tip).
 

misteright1_99

New Member
Mar 21, 2008
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Treasure Coast, Florida
If your going to use the NGK plug you can get either cap because the top unscrews off. Just go to auto parts store and ask them for a distributor coil wire. NAPA took me back and let me pick the length I wanted. Only thing is they didnt have any with copper.
 

Norman

LORD VADER Moderator
Jan 16, 2008
2,605
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pampa texas
the o-ring thing can work loose and go through the engine(not good) and block the intake behind the carb, cause poor performance. I use RTV to seal the carb to the intake. Look at my post on the carb tear down for instructions. I run a plug gap from 0.017 to 0.025 use what works best closer gap easier for spark to jump the gap but will fowl( haven't had it happen) easier. Larger gap will not fowl as easy but cause cutting out if ignition is a little weak. experiment with it there is no set rule.
The stock plug wire will work great if it installed properly as in tightly screwed into the cdi you can check the wire out of the cdi with an ohm meter there should be little to no resistance from one end of the wire to the other end of the wire. I'm running the china plug in all the engines except one and I'm running a champion plug # L78C and a high grade silicone plug wire with copper wire core and a G-man plug boot I did this chasing a stock china plug that had finally given up the ghost.
Norman
 
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Skyliner70cc

Member
Mar 8, 2008
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Maxima Oil should not be used at a ratio greater than 5 oz per gallon. In fact, 4 oz would probably be best. At high oil ratios, the castor is gunking up the plug big time and putting deposits on cylinder.

4 oz/gallon when new is just fine with a roller bearing engine using Maxima oil and you need to run your engine at WOT when new once warmed up, not just continuosly but in spurts. YOur new engine needs to see its full range of engine load and engine rpm or it won't break in properly.
 

MarkTur

New Member
May 23, 2008
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Well, last night for kicks, I pulled the plug and found the gap to be .022. I left it alone, and reinstalled it. I did however find that I was able to turn the plug wire in almost an entire turn. So now that's tight...I took it for my first night ride last night, and I think it was a little better, but I'm going to go for a good 10 mile ride this afternoon so I'll have a better idea by then. If it's still acting the same, I'll go pick up a new wire and boot at Discount AP.

I'll re-pull the plug and make sure it's a nice chocolate color when I get back and let the motor cool first. I'll post again if there's still an issue.

Thanks all! :)
 

only1soe

New Member
Jun 19, 2008
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Ok here is an update. I got the LDZ spark plugs from DAX over the weekend but just put them in last night. I did as you guys suggested and screwed in that little spring nob near the primer. The engine started off a little rought but once it kicked in I flew around the block easily and the engine stayed ON THE ENTIRE TIME.

I have never seen that before. Now I am curious if I ran the spark plug dry by not having that little nob screwed in. Everytime I woud ride the bike for about 3 or 4 months and wanted to get the engine running i would have to get it around 10 miles per hour , give it some gas and then let the clutch go. If I stopped the engine stopped and then we started over. If I turned the throddle down or off even during bike pedaling it turned off. I wonder if starting it and then restarting it wore that spark plug down?

Or maybe it was something else.
 

misteright1_99

New Member
Mar 21, 2008
716
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Treasure Coast, Florida
Ok here is an update. I got the LDZ spark plugs from DAX over the weekend but just put them in last night. I did as you guys suggested and screwed in that little spring nob near the primer. The engine started off a little rought but once it kicked in I flew around the block easily and the engine stayed ON THE ENTIRE TIME.

I have never seen that before. Now I am curious if I ran the spark plug dry by not having that little nob screwed in. Everytime I woud ride the bike for about 3 or 4 months and wanted to get the engine running i would have to get it around 10 miles per hour , give it some gas and then let the clutch go. If I stopped the engine stopped and then we started over. If I turned the throddle down or off even during bike pedaling it turned off. I wonder if starting it and then restarting it wore that spark plug down?

Or maybe it was something else.
The little spring nob (idle screw) just sets the lower limit of the engine, to keep it from stalling. Once set after breakin you shouldnt have to adjust it again. What did your old plug look like when you took it out?