New Motor Issues??

Mac

Mac

New Member
Well I've just completed 2 Schwinn Riverside/Zoom "80cc" Slant Builds. My first was a Silver Jet for ME and the second(after allot of help from you folks and trial and error) a Black Jet for my son. Well I am familiar with 2 strokes, started the silver on 15:1, no issues, ran a tank thru it, it's a good thing. Today, I started my son's...
Real pain to get going, only runs somewhat with choke on a bit AND no smoke! Shut it off. I've checked for air leaks(thinking lean??) head bolts, carb tight(manifold too), moved C clip on carb needle Down 1 slot(and added more oil just to be sure), checked for obstructions in jetting/float level etc. Ran a bit better but nothing I'd take anywhere.
I know it's a green(new) engine, but it is SO MUCH different from my silver? Any suggestions would be helpful. I don't want MY bike disappearing at X-mas! LOL.
Thanks!

Mac
 
whoa... 15:1 is waaay too rich. the directions specify that because the chinese broke their motors in with 30 weight, not the super oils we have today. i'd suggest going to 24:1, and putting the clip back up a notch.

all these motors are gonna run different, but sounds like you're just dumping oil into the motor and it can't swallow it.
 
Thanks guys, I'll adjust the ratio, use the 16:1 in the weed eater... Odd how the Silver jet ran well... what am I thinking, applying the "rational" theory LOL

Black jet runs like poop. 1/2 throttle max, it's only cooperation is simply Staying running. At WOT, just the sound changes(only did this to troubleshoot) If I let the rpm's increase at 1/2, it 2 strokes on SLOW acceleration, when it does the 2 stroke rattle(when it should be comming into power band) that's it. deadsville. I will re-adjust mix and go and get a couple of NGK B5SH plugs. Last question, why no smoke if the mix was that fat?
2 stroke mix was Amsoil synthetic. (don't shoot me for breaking in with synthetic :-)

Thanks again!

Mac
 
"These things are pretty much all the same, inconsistent"
BikeguyJoe

Just always thought that was funny.
 
Mac said:
Thanks guys, I'll adjust the ratio, use the 16:1 in the weed eater... Odd how the Silver jet ran well... what am I thinking, applying the "rational" theory LOL

Black jet runs like poop. 1/2 throttle max, it's only cooperation is simply Staying running. At WOT, just the sound changes(only did this to troubleshoot) If I let the rpm's increase at 1/2, it 2 strokes on SLOW acceleration, when it does the 2 stroke rattle(when it should be comming into power band) that's it. deadsville. I will re-adjust mix and go and get a couple of NGK B5SH plugs. Last question, why no smoke if the mix was that fat?
2 stroke mix was Amsoil synthetic. (don't shoot me for breaking in with synthetic :-)

Thanks again!

Mac
Click to expand...

Nothing wrong with breaking it in with synthetic..
 
Check your fuel system. I recently had two different problems that affected performance on new kits. First was a petcock. It had a piece of the rubber gasket partially occluding the fuel passage way. This caused starvation issues. The second issue I encountered was a loose main jet. Both these problems caused similar performance to what you are experiencing. Also, the stock plugs are crap. Throw them away and replace with an NGK plug from napa. Best advice I can offer is to take some time and disassemble and check everything on a new kit prior to attempting to utilize it.
 
I agree with Gareth (his two posts so far are rock solid!)

What DOES your plug look like now?
 
i am retired and make a good side living installing these china girls into a costomers bike. i'e done over 30 of them so far.
many of the retail sellers DEMAND 2-stroke synthetic at 16 or 18 to 1 for the first 200 miles. bikeberry will void your warranty if they open it up and synshetic was not used.
jim (the manic mechanic) uses mobil 2-stroke at 6 or 7 ounces per gallon for breakin and reccomends 20 0r 25 to 1 thereafter.
i have had 3 motors come back within 3 weeks siezed up and they all admitted runnung 32/1 from the start.
yes, during breakin they do not run as well due to too much oil for good performance, live with it.
when you drop to 5 ounces per gallon (25/1) horespower, milage and performance improve greatly.

stay dry

gubba
 
Hi Mac,

We just finished a Grubee angle plug kit install and we had very similar results as you. I went ahead and sealed up the carb intake and the cap of the carburetor with an o-ring. I think that helped. It still doesn't run like my first Grubee but, it's not broken in yet and we're still running 16:1. I'll be very interested to see how this engine reacts once it gets broken in properly. We've got about the first gallon of gas through it and, it SEEMS to be getting better. We'll see.
 
hey mac
where in maine you at, there are a bunch of guys on the blue hill peninsula, gotta be at least 10 now
 
Hey folks,
Just an update. New NGK's and ign. wire's, chased jet (taking Norm's advice .7mm) re-did mix 24:1, (amsoil synt.)covered all fuel delivery basics... also took the dremmel and cleaned out intake manifold and opened intake gasket to size of manifold with a slight radius to facilitate good flow to cyl. Silver runs REAL good... Black runs better but still way less than Silver. Plugs read nicely after WOT run(.020 gap) Ordered better air filter, "O" rings for carb and a pipe/chamber(Sick)(for the silver after break in :-))
In AM I plan on taking the head/Cyl off and taking a look/see. I have allot of 2 stroke experience both bigger and smaller(Motorcycles and Radio control aircraft etc) I really feel something is a-miss with Black sheep... oh I meant Black Jet LOL.
Thanks for all the help and suggestions!! It'll come together.

Happy new year to all!!
Mac
 
Thebeak,
I live in Durham, Basically mid-coast Maine in between Lewiston/Freeport/Brunswick.
 
Good to hear that you're catching up with it MAC. We've got ours to where it will 4-stroke at light throttle, up to about 2/3-3/4 throttle. Then it still has a slight ping. I'm thinking of opening up the jet a little bit to get more fuel at WOT. Then it should be good. BTW: I found a rubber o-ring at AutoZone that is intended for oil pan drain plugs. It has a shoulder on the inside of the o-ring with a hole that is just large enough for the return spring to fit into. I've installed two so far, one in this bike and one in mine, to see if it would make a difference. It helped the lean runner and, when I installed it in my bike, I actually needed to screw in the idle setting screw to keep it running. My line of thinking is that it was leaking air through the cap and when I replaced the old o-ring with this one, it cut off all the un-metered air that was bleeding through so I needed to open up the idle setting a little bit more. Not a bad thing in my opinion! I wish I had gotten a photo of the o-ring before I installed them both but it's an Oil-tite! black o-ring (PN66451) and you can get them in the area where they have the oil plugs and such. I hope this helps someone else out!
 
'Hello again.
Well I took the top end off of Black jet this morning. I don't see anything jumping out at me except an abnormal (to me) amount of wear front and back of bottom cyl/piston skirt area. I say abnormal because there is only a bit over a tank of gas thru it. It is from the piston skirts, not the rings. No foreign objects in crank case or looseness, rings on pins too. I've ruled out carb (swapped with silver jet for Trouble shooting)
If anyone has any Ideas... please give me a shout. Next step is to contact vendor for replacement.

Thanks.
Mac
 
I'm guessing you can't get it to run wide open?? I sort of skimmed through the posts.
You said your not wanting to swap out carbs with the engine that runs good. That is one thing I would do if it then runs good then that would tell me it is the carb causing the problem.
Paublo(from sick bike parts) had a carb that would not let the engine run much over idle. he sent me the carb I put it on my bike and it ran just like his ran horrible.
What I found was his needle was not tapered correctly. I redid the needle and tested it on my bike until it was working good I returned it to him and I don't know or remember if he ever used it.
you can mic the needle and see if its tapered correctly I think that the clip end it should be around 0.080" and at the pointed end around 0.068" not much of a change.(not sure of this as I don't have a carb with me right now so these measurements are more than likely wrong)
You could swap out just the throttle slides needles off of the good engine and try it on the poor running engine see if it helps and while your doing that measure them to compare them.
I guess you checked for all the normal spots for air leaks and also at the cranks main seal for being leak free and in place so they are not being rubbed? you did seal the carb to manifold with silicone and not using an o-ring? you also redrilled the main jet what was its size before you did this?
you checked that the throttle slide will go completely open and closed? spark plug gapped at around 0.025" fuel mixed at around 25 to 1 or more leaner?
I'll relook at these posts and see if I can find any more things to check or look at.
you don't have any black oily stuff leaking around on the engine case? sometimes that is a sign of a case gasket leaking. new engines do run crappy but sounds like yours is dropping a load in the bed right out of the box.aka running very poorly from the start I'm leaning towards it being the carb. with not being there to see it myself its a little hard to pin point the problem.
Norman
 
Last edited:
Hey Norm,
Thanks for the quick reply. I did swap the Carb. from the Silver Jet, Runs same, so that's been checked. Plug gap +/- .020, I did move it around from .016 to .030, little difference. Visual spark is good. Top end looks unremarkable. Top of Piston carbon just blackened except for visual "flow path" out of left side(while sitting on bike looking down)on top of piston. I was thinking about crank seals today but didn't check them yet(will do in AM). No Really noticeable black staining on split lines of engine, but the engine is Black so it would be more difficult to detect. Jet size before .7mm drill chase was Soooooo close to bit size, I was able to twist the bit through with just my fingers. Good throw on the Carb. open to close, after-burner light off out of specs (sorry... flashback!!) Fuel 24:1, Synt. Amsoil.
Let me say this even with the given broad spectrum tolerances of these motors, the Black Jet did not respond to anything I've tried so far, the Silver one does, maybe there is a air leak. As far as operating, even with clutch completely dis-engaged the rev-up is strained and has maybe 2/5ths the power of the Silver good motor.
I'll look at the seals and take some measurements next year. Till then, Thanks everybody and have a Safe New Year.

Mac
 
Mac
This is a new engine right? could be it will get better as you Break it in. I wonder how thick is the base gasket on this engine can you tell if it has only one gasket or a couple? I've seen one engine that I bought had 3 base gaskets I removed them and installed my own home brewed gasket it helped it run much better changed the port timing a little I guess for the better.
Could be the timing is off too they are not adjustable unless you make a key then its a hit or miss thing. When I get the time I'm going to try an adjustable timing set up.
I have one engine that will run like a scalded dog it sounds like a high performance dirt bike engine compared to the rest very fast on throttle response. I need to sit down with this engine and do some serious readings on timing of the ports and ignition etc.
Back to your engine if you match up the gaskets intake and exhaust clean up the weld boogers in the flange part in the exhaust just smooth out the flow for the gases that will help. even the cylinder to the case areas and get the gasket there to match the cases so there is not any gasket hanging out in the flow.
I use poulan syn. 2stroke oil with regular cheap gas the lowest grade 86 octane mixed at 40 to 1 I've found this to work the best for me. Premium gas didn't do a thing for them. Alcohol will get a little boost in performance but to run properly you have to shove a bunch through the engine which isn't practical for street use mileage changes to blocks per gallon plus you have to use an oil that will mix with alcohol which is more expensive. I went to a main jet of about 1/8" and it still didn't run right needed to change the needle to the richest setting and it still was lean so I quit that test. by the way happy new year!!! 2010 is here.
well I need to get off and go to bed
 
Norm,
Single base gasket, green fiber type, guessing .050" thick. Yes new engine, mabye a tank thru it. Funny you mentioned alternate fuel, I do have a gallon of 30% nitro/methanol downstairs.... Naaa not going there especially with a poorly running engine but the nitro would make a decision for me = new engine LOL
the Head gasket is aluminum, way thicker than I expected an easy .100".
More later, have some stuff to do.
Mac
 
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