Suzuki DS80, no CDI or points?

[heliboy89]

Hi Everyone,

New to the forum here I hope I'm in the right place!

I've got an old DS80 I'm trying to get running nicely for my younger brother, I'm running into trouble at 1/3 - 1/2 throttle position where it dies. I've ran it on the verge of this throttle position then plug chopped, it doesn't appear lean or rich and shows no other symptoms of either.. I've tested crank seals, holds 10psi for ages. I've cleaned carb a few times now and am pretty sure it's not leaking. Had top end apart rings and cylinder look good. At the moment I'm looking at the electronics, it sparks well and idles nicely, I wondered if the coil was playing up under load. One thing that caught my attention immediately was there is no CDI unit or points...? How does this design work?
I've got 2 coils under the fly wheel one for lighting one for ignition as the parts diagram here suggests;
1987 Suzuki DS80 MAGNETO | Babbitts Suzuki Parts House

And the ignition coil (transformer) under the fuel tank which I assume is just for ramping up the voltage. What controls timing advancing/retarding? The mark doesn't seem to move with RPM, but.. surely..? One thing maybe worth mentioning - I'm getting nearly 18k ohms between earth and spark plug terminal, but NO continuity between that other terminal(primary coil?) and earth. I've had my multimeter up to 20M ohms and I did get a reading at 3million ohms or something ridiculous once, but I can't get any continuity at all, testing it right now. I've also had that tested on the bench in town - they said its fine...




I was playing with a timing light and noticed some strange things too, I was seeing TDC at its mark most of the time then seeing it appear to go completely blank, I drew a 0,3,6,9 on the flywheel as you'd see on a clock face i.e 0 O'clock TDC, 6 O'clock BDC, and at certain throttle positions I had the light flashing with 0 and 6 right next to each other at the crank case mark, which would imply a spark at TDC AND one at BDC, whether on the same stroke or not I don't know. Is this likely to be a timing light fault?

Another question I thought I better ask and I would love this to be the problem... Is choke ON, up or down haha... I think it's a Mikuni VM22 - here's a photo. Its not really a traditional looking choke - seems to be an enrichment mechanism.


I'm pretty beaten, turned me into a bad man this bike has lol... I may be completely off track here so any other thoughts, please chime in! I've been known for tunnel vision problem solving haha. Any thoughts will be much appreciated and thanks in advance!
Josh

 

[my67xr]

first up, welcome to Miniriders

i have a DS80 too, as well as a couple of other members.
there is a link to my DS thread below this post in my signature, click on it to view my thread.

with the choke lever in the up position the choke is off.

i will see what info i have and post it up soon


cheers, craig

 

[my67xr]

i am guessing that there is a blockage in the main jet, or the needle jet tube that the main jet screws into.
i will get some pics to help explain what to look for.


also have you tried running the bike without the expansion chamber connected to the head ?
it may be blocked up with oil/carbon like mine was.
mine would idle ok, but would just die out as you open up the throttle.

 

[my67xr]

your coil looks the same as my '86 model

the ignition coil on the 1981 DS80 and onwards also contains the CDI unit.
so unless you have an early model bike then you have the correct parts fitted.

 

[my67xr]

ok, here is my spare carby, Mikuni VM22,
see the brass piece in the centre of the pic, this is what you see when the main jet is removed.
if you take the top off the carby and remove the slide, the needle jet/tube can carefully be pushed up and through the middle of the carby.
it comes out the same place the slide came out.



here it is out of the carb.
see the 3x tiny holes in the side of it (and another 3x on the opposite side too, these must be clear of dirt/debris/gum etc





poke some wire though the holes, (a strand from a wire brush) and then check it up to a light or the sun to make sure it is clear.
there is a small port facing the pilot jet inside the carby body, where the needle jet sits,
this must be clear too.
make sure you blow through all of the ports in the carby while it is apart with compressed air
don't forget to fit the washer ( part number 3 in pic below) between the needle jet tube and the main jet too, once you go to put it together.

once it is all clean and reassembled refit it to the manifold.


are you running the standard airbox and filter still ?



http://www.cmsnl.com/suzuki-ds80-1985-1995-usa_model15977/partslist/89995.html#results

 

[GooseMan]

Welcome to miniriders helliboy, and if you hadn't realised yet, but my67xr^ is a legend.
I also own a ds80, what year is yours? also has it been sitting around for a while?
I had a pilot jet which was so blocked up that not even wire could poke it through, I had to soak it in caustic soda over night. remember, you should be able to see staight through the jets.

 

[motorman]

Man I love DS80's. Scarred myself up big time after a few beers and an over enthusiastic wheelie in the back yard on one. haha

+ Reps for Craig the tech guru. Awesome posts mate.

Hope you get it all sorted.

 

[heliboy89]

Hey fellers,

Nice to see such a welcome response!
Craig, a bunch of Google searches put me onto your thread weeks back - I have read through your restoration a couple of times already looking for clues - your famous huh . So, I'll answer questions from start to finish...

The bike is 1987 for a start, that seems relevant sorry I missed it. Choke off - lever up, plunger down, is how I've been running it - wished it were that simple but never mind.

I've had the carburettor apart more than once and emptied a whole can of carb cleaner through it with compressed air - I knocked that emulsifying jet that the main jet screws into and made sure I could see daylight through the 3 holes as well as carb cleaner flowing through the port in the side of that shaft housing. Pulled the pilot jet and cleared that, basically blew carb cleaner through every little hole I could find, removed choke plunger and blew all of that out etc... I'm not too experienced but I'm fairly sure it isn't the carburettor. Passed half throttle it sounds just like you're riding with the throttle open and the kill switch held down - you know that groaning WOT dead sound lol... Just before it gets to that point it sounds like it's leaning, gets all weak and wurry, maybe I could make a vid of it for you? Symptoms are not consistent with leaning though, the plug comes out black, piston was covered in carbon when I saw it, it doesn't get cooking hot - I would expect the manifold to glow if you ran it on the verge of starving for 5 minutes...?

I've tried with the expansion pipe off too, didn't ride it like that but cracking the throttle open produces the same results. If it dies when the throttle is cracked open would you usually say this was lean or rich?

Any particular height I should have the float at? And what clip is your needle on? I should have mentioned this ran fine when I was a kid, I used to thrash it and climb banks and all sorts of abusive stuff I can't exactly remember why I stopped riding it, I think we figured it had developed a crank leak with the leaning symptoms I said before, and yeah it sat for a long time after that. I'm 24 now and I would have stopped riding it when I was 11-12.

How exactly does the CDI unit work? How many ohms have you got between that small terminal and earth craig? When it's unplugged?

Thanks a bunch for your help, feels like I'm in good hands I've got high hopes haha .

I will have a go at cleaning carb again, and run it with the pipe off, will let you know what happens.
Cheers,
Josh

 

[heliboy89]

Haha amazes me how many guys our age I see posting about DS80s... As in all ages > 13... Don't tell me you own them for your kids I see right through that... hahahaha.

I've had my fair share of DS80 induced bruises over the years too. And friends of mine... No matter how many times you tell kid who's new to bikes "No matter what happens, let the clutch out slowly"... You can still bet they'll wheel stand into the hedge 75% of the time...

Good days heh

 

[zwebx]

sometimes just spraying carby cleaner up in the jets will not do nothing when there is actual dirt in there and not dried up fuel.. i use an old clutch cable strand to go through everything

 

[my67xr]

it might pay to check the hole where the Pilot jet screws in to as well.
when the pilot jet is out,
you should be able to see right down into the hole, and at the end, you should see a .6 - .7mm or so? hole that goes through to the bore of the carby
that hole needs to be clear as well.

have you tried checking for vacuum leaks?
start the bike and let it idle, spray degreaser or carby cleaner on all the joins,
fuel bowl to carby base, carby to manifold, manifold to head.
if the idle changes in any way then there is your vacuum leak.

i found that both of my intake manifolds were slightly warped on the barrel mounting face
so i wrapped some sandpaper around a flat block of wood, and faced them as flat as i could get them.
i could only get one flat enough to use.
i also made a thick gasket and fitted that between the manifold and barrel too to help it seal

i dont have the DS80 here with me atm to check which needle slot etc
but i think i ended up using an #90 or #95 main jet in it.

i think i had a spare coil around somewhere, i will try and find it to measure the resistance
from memory it should be approx 1 Ohm across the terminal, and the earth point.
(the frame needs to be clean bare metal where the coil mounts up to )
and about 5 Ohms? from the terminal to the end of the spark plug lead.
make sure you unscrew the spark plug cap off the end of the lead first.
if you haven't replaced the spark plug cap yet, it might help too buy an LB05F from your local motorbike shop, cost round $5
the spark plug leads cant unscrew from the coil end either, it will break the coil.

 

[heliboy89]

I have checked the pilot circuitry as well, I thought it was the carb too believe me I have put a lot of effort into it, it has been disassembled to it's smallest possible components (including pilot jet out) more than one time and I haven't just doused it in carb cleaner I've made sure it is squirting out the other end of each hole I'm spraying into, and individually checked it sprays through each hole while blocking others if passages branch off into multiple ports. It's all unblocked...
The only way it will be the carb is if crap has immediately gotten lodged inside it straight after cleaning - but since it's producing the same symptoms before and after, that theory doesn't really sit right with me. It did need a clean though that main jet and emulsifying jet were both blocked.

I've tried the vacuum test, with WD40, I can't really detect any change in idle although it's not idling perfectly smoothly on it's own so it's very hard to tell. Will it change significantly or do you have to know what you're looking for? Maybe a gasket between the intake pipe is an idea... Are you thinking this is a mixture issue rather than ignition?

I read on the net it should be 1 ohm across terminal and earth point, and in the thousands for the ignition lead, which would make sense, that is the higher voltage circuit it will have more turns. Is that an issue then, that I'm getting no continuity at all on that primary terminal? I get nothing no matter where I earth it, I'm certain it's earthed because I can earth at two different points and get 0 ohms. (or bugger all anyway..) I figured - since it must have the CDI unit in it that it isn't just a straight coil and perhaps won't have the same resistance as the generic coil would...

Shall I make a video of what it's doing, I'll put it back together tomorrow and take it for a blast you guys might pick up something I'm missing...

Thanks for everything so far.

The filter is one I have made I didn't want to buy any more parts from the shop I got a throttle assembly from they sort of screwed me over lol. It should be tuneable with no filter at all though right? It behaves the same way with no air box attached or air box or airbox + filter, and did the same thing with old filter before replacing it.

 

[Chronic]

also check to see that the carby manifold isnt warpped or cracked! mine was warped and running like crap!

 

[zwebx]

Dont rule out bad crank seals its an old bike and they do happen.. (to test block exhaust header and blow if you can into the intake side.. it should hold pressure)

 

[my67xr]

i tuned mine without a filter, then fitted a foam pitbike one
the air/fuel mixtures didn't need touching.


ok,
so when you have fitted the carby back on the bike, how many turns out is the air screw set at?

what i do, is turn in the idle speed screw, so it idles at about 1500-1800 rpm
then adjust the air screw in or out until the idle speed is the highest/smoothest.
then turn the idle speed back down and take it for a test ride.
it can be tweeked a little ore if needed still.

 

[my67xr]

when you test the coil reading
test the primary side, terminal and earth with your meter set to 200 Ohms.

then when checking the secondary side, earth and end of spark plug lead, set the multimeter to 20,000 Ohms

 

[heliboy89]

Chronic I have cleaned up that manifold it is in bad shape admittedly, I gave it a good clean with some petrol and got it as good as I can get it, it is flat and I'm pretty sure it is making a good seal but I could try making a gasket for it - I will try that tomorrow before I take it for a ride.

Zwebx.. I have done the crank seal test I took it right up to something like 16psi and it only lost about .7psi over 6 minutes - I got sick of watching it and deemed that well within limits.

And craig as far as the air screw goes... I've tried it all the way in, 3-4-5 turns out, I can get the tune to respond to the screw but nothing gets it right. I found if I lifted the needle on the slide to the lowest clip (i.e. full rich). Put the air screw all the way in closed - i.e. full rich, road the bike down hill, if I was careful and the wind was blowing the right direction (^^) I could carefully float the throttle through this dead zone, then I could get it WOT, on the throttle stop, and it would scream nicely, top end would perform well. So for ages I was convinced it was leaning in the mid range because, full rich at bottom and top end would compensate for it. Except like I said the symptoms don't align, plug doesn't get white, engine doesn't get hot...

So anyway.. I'm ranting. To answer your question, it idles happiest with the air screw about 1.5 turns out I suppose, but this isn't the problem I'm fairly sure, I've tried all sorts of positions.

And your method you described to test coil is what I've been doing. There is infinite resistance between primary terminal and earth, (i.e. no continuity). Doesn't matter if the multimeter is set to 200ohm or 20M ohm, it gets -1, like the probes are when they're apart.
You'd think that'd stop it running though right...?

One thing I discovered tonight... I forgot to put that copper ring back in between the exhaust manifold and pipe... Could that be the reason it's playing up this bad...? I will get it back together tomorrow properly and get back to you guys. Too dark to ride tonight haha.

Thanks again you guys are awesome!
Josh

 

[my67xr]

i am wondering if the reed valves aren't sealing properly ?
maybe gummed up, cracked or something stuck in there holding them open?

if they don't shut properly it gives less vacuum signal to the carby, and wont supply enough fuel.
but at higher rpms the pressure can help them close a little more.
it will also make the bike a bit harder to start too.

might be worth pulling the barrel to check them?

the copper seal on the exhaust may be causing a little problem with the full reverse pulse not returning to the cylinder,
another question, are you running the baffle in the muffler still ?

 

[heliboy89]

I have pulled the barrel already I didn't think to look specifically at the reeds but from what I remember they looked pretty clean. I can start the bike with my hand it has no trouble.

Still running the baffle yup, I've checked it for carbon I used to get the little nuggets building up in the sections of that last bit but it is clear. Runs the same with the baffle on or off. The expansion pipe seems clear to I can blow into it and I can't feel any resistance. Sealed an air gun in there with a rag and it has a good flow of air out the other end...

 

[heliboy89]

I wonder if it might be the intake pipe have a look at these photos, it is a little out of shape. I would have thought if this were the case that the WD40 vacuum test would produce a result. I will get it as flat as I can get it and put a gasket in there, see how we go. It's going back together now standby for a video if I have no luck! .




I can only find the thinner paper gasket stuff in the drawer, the auto store doesn't seem to have the thicker stuff by the roll, still worth a shot you reckon?

Thanks again