Starter Issues

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KevariMan
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My Motorcycle: 2001 Sherco HRD 125cc

Starter Issues

#1 Unread post by KevariMan »

Hey guys !

I own a Sherco HRD 125cc (old, carburetor, air cooled, Basic bike like anything else, no computers)
I have a slight issue with starter maybe and i would like somebody to suggest to try something and give tips
So, i have 2 engines for the bike (original and Skyteam 125cc) and it has been used with the Skyteam engine the time that i have been riding with it, and now that i have assembled the original engine back together i have run into problems.Firstly the original engine has lower cylinder done by the last owner to increase hp or torque which ever it does increase(off topic)
I have put the engine on the bike and i have tried connecting battery straight to the starter this was done approx. 1,5 years ago, it ''ran'' fine meaning the engine kept rolling not turned on since i had no gas going to it. But now when i go and try to start it using the same method since it has a bad solenoid(only clicks) it doesnt spin anymore, only thing that happens is that the wires start to melt which in my opinion sounds like it shorted somewhere(?) I have tried connecting the battery to the bike and shorting the terminal on the solenoid but still it just smokes and melts the wires, i dont know what could be the issue, the bike doesnt have a kickstarter so i cant try using that and i dont have chains for it since i dont know if the engine will run and the axle of the sprocket is slightly larger (like 0,1mm) so i cant use the Skyteam engines sprocket on it or gear whatever its called. I have tried looking it with multimeter, and here are something i've found out that could help you guys giving me tips or instructions what to inspect closer: Battery connected, Wire from starter disconnected --> solenoid terminals 3-4v. Wire connected to starter ---> Solenoid 12v, without pressing starting button. So does this mean its really badly shorted somewhere? Battery is fully charged to 12.9 v... Hmmm, could my battery be too weak to give enough power? its just a battery that i found that actually charged still, but the text on it has gone ages ago so cant read any numbers on it. But regardless still is just a 125cc we are talking here so it shouldnt need THAT much power on starter right ? advices anyone?

KevariMan
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Re: Starter Issues

#2 Unread post by KevariMan »

I got the starter working, it was rust and corroded but cleaned it and gave it few smacks and it works fine again. Another issue, might aswell put it here now that i've started this, i dont get the thing running, it doesn't seem to suck gas out of the carb, i have cleaned the whole carburetor just to make sure that isn't the cause. I tried squirting carburetor cleaner, i dont know if that helps at all with running. The carb is full of gas like it should be but its not getting anywhere seems like. So the question now is, does the engine need exhaust for pressure ? or should it start without the exhaust pipe on the cylinder ? and further most what could cause it to not suck gas, i did have a spark but again its a utility plug to say so, i don't know if its the right plug for the engine.What sort of test should i go thru here ? and i was wondering, i have a small ''tube'' coming out of the head of the cylinder and its blowing air out of that aswell, does anyone know what it could be ? its brass colored pipe about 3 cm long sticking straight up from the left side of the cylinder head.

EDIT: Someone tell me am i running the engine backwards or is it normal when i put my hand against the hole where the carb sucks air, its blowing out (?) and i noticed it was also squirting gas out of the hole on the carb, even thought it does blow air from the exhaust side aswell, its like, its pushing air out of every hole put not sucking in (?) do i have the timing backwards on it ?

GS_in_CO
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Re: Starter Issues

#3 Unread post by GS_in_CO »

KevariMan wrote: is it normal when i put my hand against the hole where the carb sucks air

For a 4 stroke engine it is not normal for that to happen.

THat's about as far as I'm willing to go on advice for this.

Is this bike a refugee from the junkpile?
Ron

Current: 1988 BMW R100GS (the 'numberplate' model)

Past: 1987 Yamaha XT350
1983 Honda CB900F
1980 Honda XL185S
1979 Suzuki GS425E

KevariMan
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Re: Starter Issues

#4 Unread post by KevariMan »

GS_in_CO wrote:
KevariMan wrote: is it normal when i put my hand against the hole where the carb sucks air

For a 4 stroke engine it is not normal for that to happen.

THat's about as far as I'm willing to go on advice for this.

Is this bike a refugee from the junkpile?

I don't know what youre referring with that question ? you mean like i found it from junkyard or its a ''barn'' find ? no :lol: the bike was my loyal ride when i got my license and it had another motor in it, this motor that im now trying to fix is the original one and came with the bike, it was in ''pieces'' meaning the cylinder head was lowered by the last owner and both ''cheeks'' were open, so the block was intact when i got it. So i guess you could say this is lottery game will the original engine work, since there aren't that many instructions even on the internet regarding it.

EDIT: its not 180 degree what i seemed to learn but you get the idea i hope, i meant that the cam timing gear is ''upside down''

P.S. Could it be that the timing is 180 degree off causing all this hassle ? since the gear on the camshaft has markings opposite sides to each other and if i remember correctly there wasnt any other markings for which side should be inline with the marking on the flywheel and i couldnt find any pictures regarding this engine :lol: that's what i get from buying ''unique'' bike

GS_in_CO
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Re: Starter Issues

#5 Unread post by GS_in_CO »

In your wall-of-text posting I didn't see you were referring to assembling a motor from pieces - which matters a very great deal. It also wasn't clear to me how many different problems you were working on. I'm old enough to require sentences and paragraphs in my text. Otherwise it's unreadable.

Many posters here simply omit stating whether the bike used to work or not. So we are left to guess whether the bike was completely fine yesterday and now won't start, or whether they pulled the bike up from a muddy swamp where it's been stored for 20 years and the first symptom mentioned in their post is that the bike won't start.
(This is why I made a new year's resolution to not participate here in Troubleshooting. But of course I've broken that resolution now......)

Cam timing determines what happens as the crankshaft is rotated. I am uncertain if mistiming could cause outflow from the intake port. This seems more likely to be turning the engine the wrong way. But if you are unsure you've assembled it right - this is a good place to start checking.

Crude testing would be to see if the valves are operating at the right time - meaning that in 1 of the 2 upstrokes of the piston of the 4 stroke cycle, both valves are closed and the ignition system should be on the verge of triggering a spark.

You can use a length of clean wooden dowel down the spark plug hole to see what the piston is doing (if you can't use a flashlight effectively )as you watch the cam operate the valves while you turn the engine over manually. (soft wood won't hurt anything)

Most engines have marks on the crankshaft and on the camshaft so that you can properly position them. Normal to me is to have both marks straight up at the same time or marks aligned to something on the crankcase and head but a service manual would be required to be absolutely sure. Another configuration might be that the marks are close to each other when positioned right.
Ron

Current: 1988 BMW R100GS (the 'numberplate' model)

Past: 1987 Yamaha XT350
1983 Honda CB900F
1980 Honda XL185S
1979 Suzuki GS425E

KevariMan
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Re: Starter Issues

#6 Unread post by KevariMan »

Yes, i understand what you mean by saying that my wall of text is hard to read. Even though i was the best of my class at english i still have problem with...phasing(?) my sentences correctly, so it can look like a mess from time to time, i apologize for this.

So yes, the engine was built basically from scratch, i have never heard it running and i can only trust what the last owner said about it working.

I was thinking about dismantling the engine once again and really try to look for where i might have messed up, since i did build the engine with close to 0 experience on motors. My dad luckily helped me with trying to set the timing correctly but if i remember right there were some issues on determining the timing correctly.

I heard that open intake valve could cause the ''backfire'' of air from cylinder, which can also be a cause since this engine did sit outside the whole winter and even the starter was rusted.

I guess i need to cross my fingers and hope dismantling will shine some light onto this matter

EDIT: I checked the timing and the intake valve opened before the piston was at tdc, could this cause the air to come thru the carburetor ? and how do i find out which direction the engine spins, should i just crank it with the starter and figure that way ?

GS_in_CO
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Re: Starter Issues

#7 Unread post by GS_in_CO »

Thanks for better formatting. Much more readable. If English isn't your native language you are doing very well with vocabulary and spelling. The formatting is easily fixed.

The usual cause for backfire is triggering the spark while the cylinder is still filling with fuel/air on the intake stroke. Without spark there's no fire in the backfire. (long ago I hooked up the spark plug wires wrong on a V8 engine so igniting the spark in the wrong place resulted in backfire -FLAMES!- thru the carb. oops!)


I think it IS possible to have reverse flow thru the intake port if the cam timing is off.

If you are unsure of the direction of rotation then, yes, the starter should tell you what you need to know quickly. Kick starter (if any) would also.

Sitting outside wouldn't cause backfire unless it caused enough rust that the intake valve is sticking and not closing properly. But most (many?) engines are such that you can watch valve operation and see if this is the case. It's very unlikely to be the case though since sticking valves is usually not caused by simple rust.

I expect that if you disassemble the motor to be able to see timing chain/gears/sprockets and their relationship that you will find some kind of marks and reference marks now that you know to look for them. I've seen them on the gears inside lawnmower engines and marks on the ends of camshafts in single overhead cam engines and marks on the double overhead cam ends on a more complex engine. For car engines the crankshaft pulley usually has a "timing mark" on it for knowing TDC as well as setting ignition timing. When set to 0 the cam ends should align to something.

Note that the crankshaft turns 2 revolutions for each revolution of the camshaft. So one tooth mismatch is a fairly large error in cam timing. (4 stroke engine - I'm assuming this is a 4 stroke. Is it?)
Ron

Current: 1988 BMW R100GS (the 'numberplate' model)

Past: 1987 Yamaha XT350
1983 Honda CB900F
1980 Honda XL185S
1979 Suzuki GS425E

KevariMan
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Re: Starter Issues

#8 Unread post by KevariMan »

Thank you for your kind words, and also for trying to help me here. (I'm from Finland btw)

So i took the flywheel cover off and there really isn't any markings for the tdc (except on the cover itself), only marking for tdc i had was a little spot on the crankshaft bolt holding the flywheel, and on the flywheel theres a small ~2cm long rectangle shape rise on the flywheel, possibly the signal for the spark, thats what i assumed atleast.

I made my own timing on the camshaft, which usually isn't good idea but i really had no other way for it.

The timing is now ALOT better, it's sucking from the carb now and making those ''bubbly'' sounds from the exhaust port.
it can be wrong few tooth still but its much better than what it was. It was hitting exhaust valve after first adjust and luckily i turned the engine with my hands instead of using the starter.

But it still wont fire, this could be cause of bad spark plug (it's really hard to see the actual spark when i ground it to the cylinder)
So i will try tomorrow another spark plug if that would make difference

Now a question, could the timing be so wrong that its pushing all the stuff out of the motor straight away and missing the whole compression stroke ?
The spark does occur everytime the piston is tdc and i can't really affect the spark in anyway.

Yes this is indeed 4T engine.

Oh, before i forget, what i meant with the ''backfire'' was, the carb was pushing air/gas out of it and not sucking in at any point, but that problem has been solved with the new timing.

GS_in_CO
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Re: Starter Issues

#9 Unread post by GS_in_CO »

This feels like we're communicating now. Good job!

The marking on the flywheel for these purposes does not have to be large. The rectangle you describe might actually be it.
Can you compare its position with actual piston TDC?

You mention TDC marking on the flywheel cover? Could there be a viewport in the cover that can be removed to look thru the cover at the flywheel? This would be a typical way of checking spark timing using a timing light. (and is how several of my motorcycles presented marks for timing.)

Checking your own timing on the camshaft is annoying but you are learning a lot from having to return to the basic principles of what makes this machine run. Good thing you did it by hand. I was considering describing the possible contact between valves and piston top (known as an "interference engine") but decided you probably didn't have one. Contact would be a positive sign of wrong timing. Too much contact breaks things. (which is why timing belts need to be changed regularly on some models of cars. A rubber belt can break from age and if the engine is running at the time - valves hit pistons and damage occurs.)

I can't think of a way for the camshaft to be set so that exhaust valve opens right after the intake shuts. Pushing air/fuel out the exhaust is just a symptom of not firing the mixture.

Spark is normally ignited a few (say 5 degrees of crankshaft rotation) before TDC. This is because it takes a bit of time (=crankshaft rotation) for the mixture to really fully ignite when the engine is turning at speed. In the Model T days the spark timing could be changed by the driver to optimize for starting and then for running. (spark timing later for good starting, earlier for faster RPM)

Chances are that your spark plug is ok but your wire might not be. Aged/degraded spark plug wire can bleed off some of the spark energy leading to weak spark. Are you using the same plug wire as was on the previous good engine? Or is this reuse of an old wire that spent the winter outside in the rain? (when my cars had spark plug wires I would change them out about every 5 years just to be sure) A hot, fat spark is the goal.

You can sort of get a sense of the camshaft timing of the engine by putting your thumb in the spark plug hole (ground the plug wire so you don't get zapped) and turn the engine over with the throttle open (free air flow thru the intake). You should feel it suck lightly (intake), compress, suck hard (power stroke but no power and valves are closed as the piston goes down), then compress lightly (exhaust). If your thumb comes up wet with gas - that means that it's getting fuel/air during the cycle.

A compression tester device would be helpful but a lot can be done just by feel and knowing the principles. (you are getting lots of practice with the principles!) I learned this stuff nearly the same way when I was a young teenager except my Dad was alongside to help explain things - and we worked on lots of cars together.
Ron

Current: 1988 BMW R100GS (the 'numberplate' model)

Past: 1987 Yamaha XT350
1983 Honda CB900F
1980 Honda XL185S
1979 Suzuki GS425E

KevariMan
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Re: Starter Issues

#10 Unread post by KevariMan »

The rectangle on the flywheel is actually shortly after tdc, so it could basically be the spark indicator, right ?

There is a large screw on the flywheel cover, which i can remove and turn the engine by hand. Its right in the middle of the crank axle(?) holding the flywheel and theres a small groove on the axle pointing the tdc, thats what i figured out atleast.

There was a little bit of rust on the frame where the battery (-) connects, so that could cause some interference.
I did try with another spark plug, and that one had better visible spark on it.
Yes, the wire is the same that was on the other engine, since its connected to the bike itself. So yes, it is the same wire that was also outside thru winter, but bad grounding could be the issue aswell.

I did smell gas from the exhaust port when the engine was cranking, since there is no exhaust pipe at the moment connected to the bike.

Unfortunately i dont have compression tester.

My dad also helped me with building the engine, mostly i did the job and asked whenever i wasn't certain of something.
Unfortunately he's at work for the next week so i have to manage on my own, and rely on the help of the internet.

One more question considering the timing possibilities, there are some markings on the camshaft axle itself pointing up, down, left and right. So 4 markings 90 degree from eachother. There are also 2 marks on the camshaft gear itself opposite from eachother, now i don't know which of these are what markings or if the markings on the camshaft even mean anything since there are 4 of them. Anyone have any idea about these markings ?

What happens if i mix up compression and exhaust stroke ? does the engine suck from exhaust port and blow out from intake ? Right now its sucking from intake port, there isn't that strong of a blow on the exhaust port, but i can still feel it puffing out air that smells like gas.

Also i can't run the starter with the start button since the solenoid has gone bad, so i have to physically hold the positive terminal wire and the starter wire together for the engine to crank.

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