First ride - needs tuning

[Rusty_S85]

Well I rode the bike today for a whopping 5 minutes before the motor got warm enough for the clutch cable to start sticking on me again. I finally had to push the bike with the engine engaged as fully pulled back on the clutch lever wasn't disengaging the engine think the arm slipped on the clutch cam again.

But I need some advise on tuning a Mikuni VM18 carb. Everything I find online is all scientific and measurement precise I just need to know how to tune it to get it better.

If I try to pedal start it the engine I guess tries to 4 stroke but wont run if you do get it running it stalls out pretty quick with a little throttle and releasing the clutch but that might be normal. Accelerating from a stand still you have to give a good amount of throttle and its fine but it does reach a point that it starts to feel like it lacks power and doesn't have a smooth pull.

I did get the bike up to about 15 mph not sure I want to go much more than that since I am still regaining my balance after not riding a bike in a good 20 years.

 

[6blueoval9]

This guys funny but knows what hes doing..hope some info in here helps familiarize yourself with the vm18.

 

[Street Ryderz]

Well I rode the bike today for a whopping 5 minutes before the motor got warm enough for the clutch cable to start sticking on me again. I finally had to push the bike with the engine engaged as fully pulled back on the clutch lever wasn't disengaging the engine think the arm slipped on the clutch cam again.

But I need some advise on tuning a Mikuni VM18 carb. Everything I find online is all scientific and measurement precise I just need to know how to tune it to get it better.

If I try to pedal start it the engine I guess tries to 4 stroke but wont run if you do get it running it stalls out pretty quick with a little throttle and releasing the clutch but that might be normal. Accelerating from a stand still you have to give a good amount of throttle and its fine but it does reach a point that it starts to feel like it lacks power and doesn't have a smooth pull.

I did get the bike up to about 15 mph not sure I want to go much more than that since I am still regaining my balance after not riding a bike in a good 20 years.

Wow the clutch arm and cam shaft are splined and very hard to seperate I have a prefference in two of the types of arm and have to use my press and a little jig so as not to mess them up and once it's on it's not moving EVER lol.The Mikuni tunes the same way all good carb's do you'll have to dertermine weather the idle(pilot)jet is the right size and the air screw set right for the idle mixture,then move to the transition between the idle and slide/needle and so on thru the main jet.You said it's four stroking at start up and that's a good start the idle jet may be big enough,when you peddal and release the clutch to start it 1. keep peddaling with just a bit of throttle input until it feels like the engine is pulling on it's own.2. pull in (disengage) the clutch and see if it maintains an idle and let it warm up.If it stalls from being to rich turn the air screw out a 1/4turn at atime and wait 30 seconds or so for the changes to take affect when running.You have to ride the bike for the rest to see what it's doing with it's load on and some airflow at normarl operating conditions to get the transition and needle then main is all trail and error.

 

[Rusty_S85]

Well the only thing I ever messed with on the carb was the knurled adjustment I have it set 1 turn out. It was the only way to get the bike to idle on its own when I first started it last week. I played with the air screw I turned it in a full turn to a turn and a half and it wouldn't run. so I turned it back out like it was out of the package. The bike kick starts fairly easy but the choke just doesn't work as it probably is set way too rich right now.

I have to wait till I get my new clutch arm and cam cause I think since the box was beat up I think the motor was dropped and mmight have landed on the arm and damaged the splines on it. I also need to figure out wth, my clutch cable worked great but after the motor got some heat in it, the cable started sticking on me. Not sure if its the plastic housing softening up by getting a little warm from the engine or not.

In any case when ever that stuff comes in I can try again. I am not going to pull the clutch arm off again and try to move it out and get it to work again that didn't last long.

Pedal starting it seemed like it was 4 stroking trying to run crack the throttle it did start one time but second time I just wasn't able to get it to start. I had better luck kick starting it with a little throttle given and it will idle on its own in its current configuration.

 

[FurryOnTheInside]

How long do you have to wait for the new cam and arm? Can the stripped one be drilled and screwed as a temporary fix?

 

[Rusty_S85]

How long do you have to wait for the new cam and arm? Can the stripped one be drilled and screwed as a temporary fix?

The splines is what is stripped out. It looks like it was forced and rounded some splines off. The cable hasn't slipped on me but yet the clutch was working fine then all of a sudden pulling the clutch in wouldn't disengage the engine. Cable hasn't pulled so the arm had to have moved.

As far as when it will come in don't know. I ordered from Bicycle-Engine the replacement parts as they had better pricing wanted to get USPS shipping as its cheaper but only option was fedex, checked tracking number today found out they charged me $17 for fedex shipping but yet shipped it usps 2 day priority which was around $7 to ship it. Its been listed as delayed for 3 days going on 4 days tomorrow. I don't know when I will get it. I am afraid it is going to be just like the seat post I ordered from ebay that got delayed and is still delayed but I am waiting on him to refund my money as I requested a refund on it.

Ideally if I can get it Saturday I will be fine I am out of town Saturday but I can mess with it when I get home and I could go out for a ride sunday to work on breaking the engine in and working on tuning the carb. But as of now I am not going to try a distance ride I only rode up and down my street a couple times up to 15 mph at about 1/4 throttle or so and did put 0.4 on the odometer under engine power.

Also think I might need to tighten my brakes up a bit more they are disc brakes and they do stop but they just feel like they aren't grabbing like I think they should.

 

[FurryOnTheInside]

Yeah I understand it's the splines on the steel cam and arm but I would be tempted to try to get a set screw in there since it's going to get replaced anyway and I would be impatient.. but I guess if it arrives tomorrow it doesn't matter.

That's depressing. So expensive and then the service is soo bad.

 

[Rusty_S85]

Yeah I understand it's the splines on the steel cam and arm but I would be tempted to try to get a set screw in there since it's going to get replaced anyway and I would be impatient.. but I guess if it arrives tomorrow it doesn't matter.

That's depressing. So expensive and then the service is soo bad.

It is especially considering they charged me more money for fedex shipping but then ship it the cheaper usps priority but yet didn't give me a refund on the difference.

I sent them an email about it also asking if they know why its delayed. I tried to find out on the delay on my seat post from usps and they couldn't tell me anything. I finally had to break down and order Amazon prime and get it and now I'm stuck waiting on getting my cash back.

 

[FurryOnTheInside]

So still no saddle on the bike?

Oh and brakes, if the rotors are cleaned (isopropyl alcohol) and the pads too (fine sandpaper), and have not been badly contaminated by oil spills (probably just throw pads away if they soaked), then you just need to bed them in and then they'll be much better. Just like rings and cylinder they need to be worn in a little at first, then any time you move anything around. Adjust so the pads are as close as possible without being too noisy.. a tiny tickle of pad on rotor is okay. You can accelerate the bedding in by just dragging them a bit while you ride, not stopping fully but just giving them a bit of pressure.
I made the mistake of trying to get my rear brake adjusted a little bit more perfectly today. Only made things worse before returning it to exactly how it was before I started.

 

[Rusty_S85]

Nope there is a saddle on the bike, I ordered a sunlite post from amazon prime it came in yesterday.

Was real comfortable for the little riding I did. Hopefully it will be good for longer distance rides. I just need to try what the video showed as I didn't mess with the air valve I know running the engine today seemed to smoke a bit more than last Saturday when I first ran her but it seemed to go away once warmed up. I couldn't even run the bike on the choke flip the choke on and it would stall out from being too rich. It also looks like my air screw is threaded out pretty far so I don't know if I understand right from the video it needs to be turned out for lean and in for rich.