2003 Suzuki JR 80 questions and help please!

[gagallagher04401]

Hey everyone

George here from the cold state of Maine. I am upgrading my nephew from a mini bike to a Suzuki 2003 JR80. He is very excited and so am I. I want a riding buddy. Lol
Here is a little background. Bike is all stock. In good condition. New rear tire and tube. Everything seems to work the way it should. I put in a new spark plug. Cleaned and oiled the air filter. Cleaned and chain lubed it. ( gonna need a new chain before long) Lubed all cables. New tranny oil. Filled up injection bottle. Cleaned all the gunk out of the exhaust end. Cleaned the carb. ( I have a new needle & seat on the way) air acrew at stock setting. Everything in the carb is at stock settings. I compression tested the engine. I am getting 110-115. So before taking the carb off to change the needle & seat the bike started good, idled good, ran ok. Curious to see how the new needle and seat helps her out.

What else should I do for reliability prep?
Any way to lower one of these little bikes? My nephew is a little to short.
Tips on carb tuning?
When I am ready for a top end rebuild do any other bikes have the same top end? I seem to have a hard time finding engine parts for this bike that don't cost a ton.

I know I will have more questions after I get her back together.

Thanks in advance for all the help.
George

 

[gottagetacheaperhobby]

Ds 80 engines are the same, should help you find parts at a reasonable price. Craig ( my67xr ) knows plenty about these, im sure he will be along shortly to answer the rest of your questions

Sent from my SM-T110 using Tapatalk

 

[my67xr]

Welcome to Minirider's

Post up a couple of pic's if you can.
This thread help's explain how to do it if you have trouble.
http://www.miniriders.com/general-c...ers-old-new-few-helpful-tips-hints-ideas.html



Yeah as Stu mentioned the DS80 and the pre 80's RM80 share a few part's, JR took over from the DS
If you have a look in my DS80 build thread (click on the link in my signature) you'll see i modified my suspension to raise it a bit, i made up a new one with longer link's iirc, so some shorter one's will drop the rear end.
You also might be able to find a shorter rear shock, but spring rate's will come into play as well (may need a stiffer spring)
A 5mm to 10mm shorter shock will drop the rear by about 1/2" to 1 3/4".
It might pay to make up a temporary (solid) shock from a piece of wood or similar with say the 5mm shorter eye to eye length and bolt it in to try to try out the ride height it'll give you with that length.
It would be handy if you have a motorcycle wrecker close by.

Top end rebuild i would be fitting a decent piston kit to it if you can afford to, something like a Wossner or even a Pro X.
Have it checked to see if it can be honed, or if it'll need a rebore.
Also if you want a bit more performance you can slightly lower the bottom edge of the exhaust port 1mm or so to help it clean out the gas's when it's running while it's apart.
The DS80 were known for the piston sitting between 1mm and 2mm further down the bore at bottom dead centre.

Jetting wise they should be good for the bike, but tune it to suit (adjust mixture screw), make sure the hole's through the jet's are all open and clean, pilot, main and also the emulsion tube.
And the hole through the bottom of the thread's where the pilot jet screw's into in the base of the carby.
Blow it out well with compressed air, and through the port's on the air filter side of the carby, have the mixture screw and spring out while doing this to clean any debris.


The expansion chamber's seem to build up a bit of oil/carbon too.
You are best off taking the expansion chamber off and burning the oil etc out, this will give the bike the best performance, like a new one.
There are a few good video's on youtube etc showing how to do it on 2 stroke's

Buy a spare brake lever too, they are thin at the pivot point and can break easy if it get's dropped at all.
Even look into an aftermarket generic brake lever and clamp.

Cheer's, Craig

 

[gagallagher04401]

Craig, thanks a ton! I will look into all that and check out build. I am sure I will have more questions in the near future. �� pics to come soon.

Thanks!

 

[gagallagher04401]

Hey guys
Bikes altogether. My nephew is doing well riding it. Still cold here. I am having a little issue with the idle hanging. Kind of chasing it.
I did screw up and put the air screw at 2 turns out. It should be 1-1/4. I will reset and check again. Maybe that was my whole issue. Not sure yet.
I did spray carb cleaner around the intake manifold and all around. Nothing appeared to happen. So I think I am good there.

Thoughts? Maybe just need to be ridden some before friggin with it much more? Seems to run pretty good for a little bike.

Things I did to the bike:
Cleaned whole bike
Cleaned the carb
New needle and seat
Checked float lvl
Lubed all cables
Cleaned air filter
New spark plug
Took the expansion chamber off the end of the exhaust and cleaned it.
Compression test 110-115

 

[my67xr]

With the mixture screw the base setting is 1.25 turn's out.
But you will need to adjust it to suit the bike due to wear and tear etc

Start and warm the bike up, raise the idle speed slightly by turning in the idle speed screw.
Now adjust the mixture screw in or out 1/4 turn at a time while listening to the way the engine is running
After each adjustment wait for it to settle for approx 10 second's.
You need to adjust the mixture screw till you find the highest/ smoothest rev's from the engine
Once you are close adjust it 1/8 turn or less each time.
When you are happy with it, turn the idle speed screw back out till the rev's drop back to a normal speed
Blip the throttle and listen for a hesitation etc, then take the bike for a ride to try it out

If you need to adjust the mixture screw from there, it will only need a touch either way

When you get back from the ride, turn the bike off and grab your screwdriver again.
Now turn in the mixture screw and count how many turn's it was out from being seated.
If it end's up at 1 3/4 turn's then that is pretty good, anything between 1.5 turn's and 2 turn's out is spot on.
Higher or lower that that you need to replace the pilot jet with 1 bigger/smaller depending on where the mixture screw was at.
Now turn the mixture screw back out to where it was when you just rode it and it's ready to go.
If you ever need to adjust it again you have a close base setting for it.

 

[gagallagher04401]

Thanks!

Will do it this way see how I make out.

Thanks again.

 

[gagallagher04401]

With the mixture screw the base setting is 1.25 turn's out.
But you will need to adjust it to suit the bike due to wear and tear etc

Start and warm the bike up, raise the idle speed slightly by turning in the idle speed screw.
Now adjust the mixture screw in or out 1/4 turn at a time while listening to the way the engine is running
After each adjustment wait for it to settle for approx 10 second's.
You need to adjust the mixture screw till you find the highest/ smoothest rev's from the engine
Once you are close adjust it 1/8 turn or less each time.
When you are happy with it, turn the idle speed screw back out till the rev's drop back to a normal speed
Blip the throttle and listen for a hesitation etc, then take the bike for a ride to try it out

If you need to adjust the mixture screw from there, it will only need a touch either way

When you get back from the ride, turn the bike off and grab your screwdriver again.
Now turn in the mixture screw and count how many turn's it was out from being seated.
If it end's up at 1 3/4 turn's then that is pretty good, anything between 1.5 turn's and 2 turn's out is spot on.
Higher or lower that that you need to replace the pilot jet with 1 bigger/smaller depending on where the mixture screw was at.
Now turn the mixture screw back out to where it was when you just rode it and it's ready to go.
If you ever need to adjust it again you have a close base setting for it.

Is an out of adjustment air screw the reason for the hanging idle?

I did notice I turned the air screw in yesterday briefly (when thinking the stock setting was 2 turns, it is for my 4-wheeler) and the bike had more snap, but was lagging/not wanting to go kind of, had to work by it, it was not real smooth. towards the top end?

I assume there must be that sweet spot, that happy medium?

Thanks!

 

[my67xr]

Yeah rev hang is due to it being too lean.
If it was too rich then the idle would come right down from rev's and stall.

My DS80 has a blocked pilot circuit hole, take the pilot jet out and look into the base of the carby at the bottom of the thread's where it screw's into
There should be a small hole that lead's into the carby bore, if it's blocked or partly blocled with gum then it will cause problem's being lean
Poke a single strand of copper from some old car wiring through all the jet's hole and the on in the bottom of the thread's for the pilot.
You should also pull the emulsion jet out and check it's all clean through those hole's too.

Might be worth giving the carby a good soak overnight in some Yamaha Carburetor Cleaner dip
Then give it a thorough blow out with compressed air

 

[gagallagher04401]

Yeah rev hang is due to it being too lean.
If it was too rich then the idle would come right down from rev's and stall.

My DS80 has a blocked pilot circuit hole, take the pilot jet out and look into the base of the carby at the bottom of the thread's where it screw's into
There should be a small hole that lead's into the carby bore, if it's blocked or partly blocled with gum then it will cause problem's being lean
Poke a single strand of copper from some old car wiring through all the jet's hole and the on in the bottom of the thread's for the pilot.
You should also pull the emulsion jet out and check it's all clean through those hole's too.

http://s598.photobucket.com/user/xr...y/ds80mikuni20mmmainjetpilotjethole.jpeg.html



Might be worth giving the carby a good soak overnight in some Yamaha Carburetor Cleaner dip
Then give it a thorough blow out with compressed air

Thanks my67xr

When I got home today I reset the air screw to stock and tried the bike. Still not running the best. Well I decided to spray around to check for air leaks. I sprayed around the intake and the motor and the bike would stall. AIR LEAK! So I took it apart and put a bead of high Temp gasket maker on and put it back together. No more air leak. Before I did this it did not matter how I turned the air screw the rpms never changed. Now at least when I turn the air screw the rpms will change. So at stock setting it stutters a lot. Does not want to get up and go. I turned the screw out I am just over 2 turns out from fully closed. Bike goes pretty fast, had good top end it seamed, but if you come onto it to hard down low it hesitates. Once by that hesitation it pulls pretty good and goes ok.

Am I just expecting to much? I know it is not going to be perfect I guess. Just got to let the little guy ride it.

Thoughts?

Thanks all

 

[my67xr]

So you adjusted the carby like i described in post #6 above ?

I would try it with the mixture screw somewhere between 1.75 and 2 turn's out
A hesitation is too lean mixture

 

[gagallagher04401]

So you adjusted the carby like i described in post #6 above ?

I would try it with the mixture screw somewhere between 1.75 and 2 turn's out
A hesitation is too lean mixture

Yes I tried to the best of my ability. I have been fussing with it so much I kinda lost my way on it, second guessing myself etc.

I will adjust it a little more. Seems like I turning the screw all over and never finding the ideal spot. If I get good low end I lose the top end, it hesitates and doesn't want to accelerate. If I get good top end I get a slightly boggy hesitant low end.

I feel like I can't win. Very frustrating because I literally have no help be sides the Internet.
Maybe I just asking to much out of the bike. It inst brand new. Has been used a good amount and is just maybe warn some and not going to perform perfect.

Is there a fuel filter in the tank on the fuel valve? Though about taking the fuel valve out see if it is dirty and clogged up some.