New Engine running - no power
- Thread starter Predator303
- Start date
I had a problem with my bike the other day, where I would try to rev at idle, and for a second it would seem that it was either flooding or getting no gas at all, then it would rev super high. after a few times revving it like that, the bike jumped away from me as the motor shut off. I had just gotten my bike fixed up after sitting for 2 months. I drained the old gas and put new in, and voila! no more funny revving. Old gas, even a month old, can cause an engine to run poorly. If your gas is new, then thats obviously not it. just sharing my experience.
i drained the carb and it was like that for 6 days between the engines. the only thing different now is that i use 5-6 times more oil for breaking in than i ever did
You need to: measure your oil properly. 24:1 should be ok for break-in, though I run 16:1 personally with no issues. 24:1 is about 5 ounces to a gallon, 16:1 is 8 ounces to a gallon. I run 32:1 after break-in, which is 4 ounces to a gallon. I told you this before, no two of these engines are exactly alike, so the way you had your carb tuned for your other engine may not work the same for your new engine. some engines also like the carb tuned a little differently for break-in than for normal operation as well. Since you are an engine builder, you ought to know what tolerances are. At the factory, they either dont have very strict tolerances or they dont pay attention to them. I am betting a little of both. This is why no two engines run exactly the same. You keep comparing your old engine to your new one, thinking the tuning and everything else should be exactly the same. Forget about how your old engine was tuned and how it ran. You're starting from scratch with a new engine. Nothing is wrong with your carb, you just need to re-tune it. Adjust your idle screw and play around with your plug gap a little. If need be, adjust your needle clip position. If you have an inline fuel filter, make sure its clean and not clogged with debris.
The magneto cant have anything to do with that right? Because I didnt use the one of the skyhawk, but the one of my old (1month old) bottom end.
I run it now exactly 25:1 for 2-3 tanks full. I already played around with the idle screw but nothing much change. I will try to move the clip and try to adjust the gab. Can somebody tell me whats the difference between the b7hs and the LD Z4JC plug that was included?
The heat index is the difference. Some spark plugs use numbers to indicate heat index, others use letters. ngk, who makes the b7hs, uses numbers, the higher the number, the cooler the plug. I am not sure if the plugs that come with the kit use letters or numbers (the letters and numbers and their order mean a different thing for almost every brand of spark plug, and I dont know if the kit plug is hotter or cooler than the ngk b7, but I think at least a little hotter). But the number 7 for ngk indicates a slightly cooler plug, which is fine. I run a B6L, which is a little hotter than a 7. If you dropped your spark plug at all or even set it down on a hard surface wrong, that could have messed with the gap. When I gap my plugs, I use the tip of a small flathead screwdriver to set the gap, and it works fine for me. And yes, a weak/damaged magneto can also cause an engine to run poorly.
I have an engine I ordered from boygofast on ebay, and its pretty decent. Faster and pulled a little harder than any of my other engines, right out of the box. Had it for almost a year and a half now, and its running like a champ.
Could you do me a favor and check the seller for me? Oh sorry I just realize you wrote the name already
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Huh, looks like I am mistaken. I just checked my purchase history, and I actually bought my engine from luckyearlybird. Not much of a difference, though. They are husband and wife, and ship out of the same warehouse. When you buy from luckyearlybird, sometimes the shipping label even says boygofast. My engine is 68.5cc though, neither luckyearlybird or boygofast are currently carrying 68.5cc engines.
Yes there is one kit where the 68.5 is included. I will send that POS back to GasBikes and buy somewhere else. I rather wait 2 more weeks without bike then getting more junk from them.
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Tom
Tom
They may have a 68.5cc engine included in a kit, I did not look at the kits. But they do not have any 68.5cc replacement engines. All their "engine only" sales are for 66cc engines.
OK for the fairness for GasBike I have to add this here. I waited for today to get to talk to the Support even even though the guy I talked to was a little unfriendly I got it resolved in a fair way. First he told me I cant get a refund since it was used and I had to ship it back to get it replaced with the same engine and a while later I called back to tell him that due shipping costs and waiting time it would be better if I just order the parts I think cause the problem (Piston, Rings, Cylinder Case). He told me that if I pay for the shipping they would send it to me like that but after checking address and me asking him how I could pay the shipping, he told me that they will just ship it for free and give me the parts for free as well. This way I can keep driving the bike until then even without good compression and dont have to pay anything. Now all whats left is to hope it was that and that the new parts have compression.
Last update here so far. Kept driving that POS engine over the weekend dealing with super low compression (over 3000rpm it would finally push a little), clutch didnt work at all and it would turn off the engine couple times because it was impossible to get the right point, made noises (probably cheap pads and got hot in no time), and then it also started to make metallic sounds from the bottom end which didnt sounded healthy at all. I managed to make it all the way home and when I took the cylinder off for the at least 8th time since I got it, I realized that also the piston rod had way too much movement when I pushed it towards the walls of the case left and right.
So I decided to use the cylinder I had with my old botom and buying a A version of the piston in a local store in a kit.
I just installed that and I realized that the piston now comes all the way up and a little out of the cylinder without touching the head when installed. Obviously thats why the other GT5 engine doesnt have any power if the difference of the way the piston makes all the way up is so extreme... Is that normal?? I always thought the GT5 had a higher compression and more power. It seems like the head of the GT5 have a smaller combustion chamber compared to the other engine heads. I am going to close it tight with nuts now and already know now that I will have a high compression after I finished this.
So I decided to use the cylinder I had with my old botom and buying a A version of the piston in a local store in a kit.
I just installed that and I realized that the piston now comes all the way up and a little out of the cylinder without touching the head when installed. Obviously thats why the other GT5 engine doesnt have any power if the difference of the way the piston makes all the way up is so extreme... Is that normal?? I always thought the GT5 had a higher compression and more power. It seems like the head of the GT5 have a smaller combustion chamber compared to the other engine heads. I am going to close it tight with nuts now and already know now that I will have a high compression after I finished this.
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if its not the same piston it isnt going to work you are going to kill your head or smash it into the plug at least there are 2 or more different pistons for these engines with different wrist pin locations and skirt lengths