2 Brand new engines Seize?

[brawleyerict]

I recently bought a 70cc 2 stroke kit from ebay. I got everything installed and when I went to start it for the first time, the engine cycled a few times then seized up. So that my back tire would not turn, even with the clutch all the way pressed. The person I got the engine from exchanged it for me and when I got the next engine, something similar happen. But the second time the engine tried to turn over twice before seizing again.

I do have experience with 2 stroke engines, so the obvious should be known. Like I did mix the oil with the gas properly. Had the fuel valve switched on and primed the carb, with the choke up.

I have yet to get two of these engines to even turn over for me once. Am I missing something obvious or do I just have bad luck. As far as buying junk off
ebay.

Eric T

 

[Andyinchville1]

Hmmmm.....Could the chain have bunched up under the cover because of it running too loose or having a tight link?....That can cause the rear wheel not to turn with the clutch pulled in also...

Unusual that the engine would seize up so quickly....I mean within just a few cycles (maybe something like a rod or something broke?)I would guess running straight gas (no oil mix) the engine should last longer than a few strokes (I know because a helper of mine once ran straight gas in a 2 stroke Lawn Boy mower.....actually lasted quite awhile considering no oil....) BUT since you said you did put 2 stroke oil in the fuel I would think it has to be something mechanical....

Andrew

 

[brawleyerict]

Hmmmm.....Could the chain have bunched up under the cover because of it running too loose or having a tight link?....That can cause the rear wheel not to turn with the clutch pulled in also...

Unusual that the engine would seize up so quickly....I mean within just a few cycles (maybe something like a rod or something broke?)I would guess running straight gas (no oil mix) the engine should last longer than a few strokes (I know because a helper of mine once ran straight gas in a 2 stroke Lawn Boy mower.....actually lasted quite awhile considering no oil....) BUT since you said you did put 2 stroke oil in the fuel I would think it has to be something mechanical....

Andrew

I will take a good look to see if a chain is bunching up. If this is the problem would not changing the angle that the chain enters the motor relive this tangleing? So that the bunching of the chain would be freed up and then continue normal function of the engine. I would love for that to be the problem, but I doubt it.

Thank you for your prompt response,

ET

 

[cdoug50]

angle of chain should not cause chain to bunch or hangup. What can do it is if the "c" clip on the master link is on backwards. The rounded end of the "c" clip should be first to ride over the engine sprocket, followed by open end.

 

[misteright1_99]

Another thing that could cause the chain to bunch up would be the drive sprocket needs to have the sharp edges ground off. The instructions with my kit suggested this to keep the chain from "sticking" to the sprocket...

 

[Bikeguy Joe]

Don't forget to get the chain aligned properly and don't over tension it- 1/2"-3/4" play.

 

[Bikeguy Joe]

A locked up engine will not prevent the sprocket from turning.

 

[brawleyerict]

A locked up engine will not prevent the sprocket from turning.

When you get these kits out of the box, is there anything you need to do to the clutch or the engine before you start it? Could this be a clutch issue. I did not adjust the engine in any way out of the box. Just installed, gas/oil and go.

Thank for your help,



ET

 

[Bikeguy Joe]

Yes, there are several things you can do to help have a nice, reliable bike....
http://motorbicycling.com/f30/bicycle-motor-preperation-care-354.html

Sometimes the sprockets are tight right out of the box, you should turn the sprocket first, or push the bike slowly and let the clutch out until you know it's free.

 

[BlueCollarBike]

A locked up engine will not prevent the sprocket from turning.

Agreed..

Pulling in the Clutch will eliminate any motor strain.

It seems your having a problem with the Drive chain and sprocket.

You need to make sure the drive chain and front sprocket are not jammed..

cheers

Bob

 

[NickDK]

If you say that you cannot move the drive wheel even when you engage the clutch that tells you that the problem is NOT in the engine. When you pull the clutch handle you disengage the gearbox from the engine. If the engine itself was seized and you pulled the clutch, the back wheel would be able to move (unless you had clutch problems as well). So, we know your problem is somewhere before the clutch. Your problem can be any of these things (assuming your clutch is working): chain kinking under the sprocket (most likely) or a gear before the clutch may be sticking. It is easy to check if your chain is getting caught, just remove those 3 screws to take off the cover plate over the engine drive sprocket. Hope this helps!

 

[brawleyerict]

I finally got the third engine in. This time the clutch would not engage. I am not good with engines, but started to take this thing apart. With help from another thread on clutch adjustment, I was able to get the clutch working. Seems that the center of the assembly was stuck somehow. I disassembled and turned a few times to release it.

After looking at all your replies (which has been so much help, thanks), I believe that several factors where a problem for me. I installed the engines right out of the box and did not take any links out of the chain. I thought that i could just do this later and wanted to hear the engine turn over. This is the fist and biggest mistake that i think i made and appears to be the #1 factor which i think made both of the first two engines fail. There was way too much slack in my chain. I am not sure if this would factor in, but I am 300 pounds. I am wondering if my weight and the looseness of the chain contributed to the same scenario happening twice.


I am taking this one very slow and will definitely take the links out before trying to start for the fist time. I was thinking and will submit this idea to all of you: Because I have been having problems getting these engines started, can't i just take the cover off the magneto and start the engine with a power drill with a socket on it to rotate to start? This way I can cycle the engine to start without peddling and just keep the clutch pressed the hole time. Get the engine started and tuned. Once everything is working, then starting it up as normal.

I will wait for suggestions before trying...


Thanks for your help,

Eric

 

[deacon]

I'd have put my money on a too long chain. It happened to me but after I had the bike running. usually they come a couple of links too long.

 

[Biker Mike]

I agree. Sounds like the chain is binding. I had a bike I built for my dad and rode to the end of the drive and it died and the wheel slid me to a stop. When I pulled the clutch the wheel still would not turn. It scared me to death. I just knew my 1st project just locked up on me. Turned out the chain jammed at the engine sprocket. Good luck.

 

[SgtNorthcutt]

I also had a "seizure" just down the drive. I had accidentally reversed the master link clip. The chain kinked inside the drive sprocket housing. The clip shot off and my bike was down until I got a replacement at a motorcycle shop. The clip I purchased at the motorcycle shop was a better one anyways. Tuff lesson to learn. I wish I could read every post first. I bet I could skip ALOT of unforseen future problems this way.
I will try my best, but no promises. The road beckons!

 

[Bikeguy Joe]

Eric-

300 lbs., and the loose chain WILL combine to a jammed up mess where the chain 'goes in" the engine.

Make sure you have 1/2"-3/4" of freeplay, not more or less.

Take the time to do your bicycle motor kit right, and you will get many hours/miles of service. Whip chop it together, and you will have nothing but trouble.