Trying to get 5 pit bikes running, one at a time.

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edwards30

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I am working on this pit bike I purchased the other day for $120 and it has me stumped, I am getting spark, using starting fluid for initial start up with no fuel hooked up to the carb, I adjusted the valves, and when I plug the spark plug whole with my finger it feels to have good compression. Another thing that is weird about it is that when I go to kick it sometimes the kicker feels like it is stripping and won't turn the crank. Which I guess is a secondary issue if I can just get it started.

I will include several pictures below as I do not know what frame/motor this is or even the size of it.

Thanks guy!
http://i1335.photobucket.com/albums...6EE950-11586-000003EDD9A52C04_zps0a5dbefd.jpg
http://i1335.photobucket.com/albums...D63F1B-11586-000003EDDF6FCC8A_zps77aebc1a.jpg
http://i1335.photobucket.com/albums...1A6040-11586-000003EDE3F25BB3_zps04bd6d47.jpg
http://i1335.photobucket.com/albums...B8F31E-11586-000003EDE7BCEBDF_zpsa8ec8229.jpg
http://i1335.photobucket.com/albums...BD64F6-11586-000003EDEB112542_zps5016da9a.jpg
http://i1335.photobucket.com/albums...F5E54C-11586-000003EE0022D227_zpsda53743f.jpg
http://i1335.photobucket.com/albums/w672/bryceedwards30/null_zps01a036ae.jpg
http://i1335.photobucket.com/albums/w672/bryceedwards30/null_zps03ea0ea1.jpg
http://i1335.photobucket.com/albums/w672/bryceedwards30/null_zpse9cce8ef.jpg
 
should prolly roll start it mate, could have done a kicker gear or its just warn...
ive seen some really low comp engines run (extreamly low) so maybe thats not your issue
 
straight away, its a start in neutral type clutch, meaning its a 125 or smaller. should say on the cylinder.


the kickstart feeling like its not turning the crank would most likely be a slippy clutch. pretty easy to adjust, and if you get stumped by one screw and locknut, theres plenty of threads on clutch adjustments ;)


so, youve done most of the normal things...shove some flammable fluid down the hole and give it a good kick. that will usually result in at least a pop or kickback type affair... apparently not in this case.

strip carb, give it a good clean and blow out. then try it with the fuel. works on my 140 that will not pop with fuel down its hole! weird that... fuel is fuel, isnt it? regardless of how it gets there? maybe not...

get a bran nue plug :) they can work out in the open but under compression the spark can travel over the insulator, etc...meaning you get a sore leg from kicking, cus it has spark, right? right!

um... kickback arrestor. pop off the top cylinder cover, yes the one thats held on with the cylinder studs. take a peek inside. if you only see cams and rockers, close her up quick and look elsewhere! if you see some type of thin sheet steel and springs that obviously are NOT the valve springs, you have a kickback arrestor. they pivot on the rocker pins from memory...

theyre a horrible invention and i always pull them off. this involves pulling cam, rocker pins and horrible device out, then replacing just cam and rocker pins, leaving scrap steel in the bin where it belongs...

when mucking around with valves on an engine that wont start at first, set the clearances to somewhere around a millimeter! yes, it will click and rattle if it starts, but it really ensures the valves are seating completely. it wont hurt it if you only run it for a few minutes. adjust them to correct clearance after you get the thing running :D


other than that....um. um. um. stator plate could be 180 out, meaning its sparking at BDC? i dont even know if its possible to get the stator on upside down... ive never tried!


thats my head emptied for now :)
 
Thank you for the quick replies. I have cleaned the carb thoroughly twice just to be sure, my spark plug is new but I am not sure if it is gapped properly? Also sometimes when spraying it with starting fluid I will get a lot of fluid blowing back on my leg. When I do kick it over without a spark plug in it I never have it do the slipping sensation. Also when I engage the clutch it will not kick over the motor at all, is that normal? No kick back arrestor since I did take apart that part of the engine today while doing the clearances on valves. Any ideas on if the compression tester I showed before would work?
 
im guessing it's got a big vacuum leak ?
there should be a plastic spacer/insulator inbetween the carby and manifold.
do you have one you can fit there?

if not, get some 1.6mm thick gasket paper and make a gasket for it, it may help it to seal properly.

 
check that timing. undo cam sprocket cover. thats the big round thing on the head, near your left leg. nut for it is on the other side of the head.

sprocket has a lil dot on it. it should point to the top of the head, or 9oclock. there should be a lil notch normally.

take the cover off the crank end. shifter side. big slotted nut thing. underneath theres a 14 or 17mm nut. use it to turn the crank.

above that cover therell be a smaller one. remove it, and peek through hole. turn crank with socket, and you will see the flywheel turning.

turn until you see a mark T.

at this point, that mark on the cam sprocket should be lining up with notch. if it isnt, fix it! a few degrees is normal, whereas an obvious link or two out of line is bad!

yes, those motors are start in neutral. they wont start when you pull in the clutch. the kickstarter drives through the clutch, hence having to start in neutral. they will start in gear, they just wont sit still... :p exciting :p

it wont slip when the plugs removed, theres no compression. only slips against compression. if adjusting it fails, youll need new clutch plates.


gap on a plug is something people always ask about. a gap is a gap. slightly important on some fancy german thing with autocompensation on everything and anything possible, pretty irrelevant on a thumpy :) if its about half a mm, good-o :)


dont worry about compression and guages for testing. if the clutch slips,even occasionallllllllllllllllllly, its got enough compression to run.

if you were digging around in "that area" of the head to check valve clearances im scared? :hmmm:
 
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As far as the gasket, there is a round gasket and the end of my carb, no spacer though. I will check the timing here in a few hours. I wasn't aware of the mark in the rear since I have the inner rotor setup I thought I would have to take that off but I guess not. As far as taking off the valve cover when I did my valve spacing I just wanted to make sure there wasn't anything obviously messed up while I was taking stuff apart in that area anyways. I will check back in a few hours about the timing. Also I will check to make sure the gasket between carb and intake is now worn flat.

Thanks
 
you would be extremely lucky if it didn't leak there.
 
extreamly, i cut 3 gaskets for one of my bikes (there was that much gap on it)
 
I added a carb spacer from another bike and still no luck. As far as the timing I can't check the crank timing because I can't see any mark. I assume because of the inner rotor. I dont have any service holes to view crank TDC. Also I saw the access hole get clutch adjustment. Which way would I turn the threads after loosening the lock nut?
 
edwards30 said:
I added a carb spacer from another bike and still no luck. As far as the timing I can't check the crank timing because I can't see any mark. I assume because of the inner rotor. I dont have any service holes to view crank TDC. Also I saw the access hole get clutch adjustment. Which way would I turn the threads after loosening the lock nut?
Click to expand...

right to tighten, left to loosen and then to do them up get a 9 on the locknut and hold the adjustment with pliers
 
anyone else have ideas as to why it won't start? I attempted to adjust the clutch plates but if I turned it just a little either way it completely slipped and I couldn't turn it over. I just ordered a compression tester as well.
 
ah poop! an IRK! this makes life slightly difficult.

youll need to find a longer plug (an E, not H as the last letter) to find TDC. just get an old one from a bike shop. theres other ways but this is the best way. not a new one, its only for finding TDC! or get a standard plug, bust out the ceramic, and insert a rod so it really sticks into the cylinder. you need this position to stay put, its a reference. so just inserting a stick down the hole wont work.

insert the plug or "piston stop" as us profushenals call em... slowly and carefully turn crank until it stops against your long plug thing. smack a mark on the engine casing in a handy location next to the flywheel. scratch/likki paper the flywheel in line with this mark.
now turn crank back the other way until it stops again. mark the flywheel again. the point halfway between your two marks is TDC. make sense? if so, punch the TDC point. now you know where tdc is each and every time.

the plug should spark around about 5-10 degrees BEFORE TDC. cant figure out how to do this mark?

wrap a string round flywheel. measure it. divide by 360. now, times that result by 5...or ten...or 8 is best, somewhere in between 5 and 10.... measure that out on the flywheel from the mark for TDC, in an anti clockwise direction.(same direction as crank rotates when running) now punch that mark as well. give it an F for FIRE if you have funky letter punches or a dremel.

get a timing light, and check spark as you kick. should be flashing as it passes that last mark you made... :D

or you can just check that the magnet on the flywheel passes the smaller pickup coil at this point if timing lights arent handy. a few degrees either way wont hurt for now. this can be tweaked later on.

check and make sure the flywheel is still keyed to the shaft FIRST. it could be all it is. many people have trouble with woodruff keys when assembling these types of things.

jam some rope down the plug hole to lock the crank when you want to undo the crank nut. not the funky long plug thing from earlier! that will damage the piston. with luck you can see if the key is actually there without pulling the flywheel.
 
is there any slack in the clutch lever? should be a few mm of travel at the lever before you feel any pressure on it... loosen the cable off completely before adjusting the clutch itself!


nuts are normally like grinders... to LOOSEN, turn the same way that shaft spins in use. but i dont think theres ANY LH threads in 99% of motors. china, jap or other... so just think all bolts and nuts loosen anticlockwise.

pop the entire cover off the flywheel for easy access.
 
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Okay thank you, I believe I understand the piston stop idea. Would it be possible for me to just buy a bolt with the threads the same as the spark plug? Also do I take out my IRK for all of this? One last thing, approximately how long should my "piston stop" be?

I will loosen my clutch lever completely and then adjust the actual shaft for my clutches.
 
Thank you for the reply once again headsmess I am waiting for my compression checker, which should be here today then I'm going to get right back at it. I will check in once again tonight or tomorrow.
 
Okay another update, I did the compression check and two different times kicking it got a reading around 180 psi. Also I did the timing test by using a screw driver in the spark plug hole, according to my measurements it is dead on.
 
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