Budget Bike: Roketa Resurrection

[criggs]

Ok, so good news: the clutch now works beautifully. After 10-15 minutes of riding it seemed to loosen up and now works like brand new. Grabs quite hard, actually, feels like one of my big bikes =P.

Unfortunately the bike only ran for about half of the trip. While it ran, it ran beautifully. About halfway through the second day, though, it stalled and took forever to restart, and after that would only run for about 10 minutes before stalling again. After a few re-starts and stall-outs it eventually would no longer start up again. I haven't had a chance to tear into it yet and see what's going on, but the only thing I can think of is maybe there was something in the tank that re-clogged the carb or something? I'll pull the carb again and check the plug to see what's going on, any suggestions would be great though if there's anything that's common with these bikes that could cause this. I personally really prefer this Roketa over my SSR due to its higher ride height, so I'd like to get it going again asap.

 

[my67xr]

Could be spark or fuel.

Check the ignition coil reading's with a multimeter, and swap over the cdi from your other bike see it that help's

 

[criggs]

So I checked out the bike yesterday, and it has lost spark again. I didn't have my meter at the time, so I'm going to get it from work and re-check everything this Thursday, but the CDI and ignition coil/spark plug lead are both brand new. The only thing that I didn't replace was the stator and wiring loom. I'll check everything out when I go back over there, really hoping it's something simple this time. Is it possible that the stator is bad and fried the CDI and/or Coil? Or is it more likely just cheap chinese parts?

 

[my67xr]

I would go over all the connection from stator to main harness, and harness to cdi, cdi to coil and check they are all good.
Use you multimeter on it,
Set it to 200 Ohm's and put one lead on the black w/red wire on the main harness, and the other lead to the black w/red wire where it connect's at the cdi.
It should have very low resistance between the 2x end's of the wire
Then check the green wire same as above, and the blue w/white stripe
Same thing again from the cdi plug, check the black w/yellow stripe and the green at the ignition coil
And try unplugging the kill switch too, if it start's then the kill switch might be faulty or corroded inside

If you replace the Stator, then i would spend an extra $10 or so and replace the main harness too.
The terminal's in the main harness's plug's and socket's can bend easily and can cause intermittent contact's,
making it seem like there isn't a problem.
Then when you go riding over bump's etc, the connection's go open circuit and it will not let the power get through to the next component.
You might be able to use a small flat head jeweller's screwdriver in the female terminal's and move the tab's to help make a better contact

 

[criggs]

I checked the resistances of the wiring harness today, and all of the wires from the main connector (stator connector) to the CDI had 0 ohms of resistance. The two wires from the CDI connector to the coil also had 0 ohms each. The coil has 3 ohms of resistance on the primary side, which is what it had when it arrived in the box originally.
After all this I decided to check the resistances of the stator again. I checked at the CDI connector to make sure that the wiring was ok.

The pulse coil (between green wire and blue wire) still gave 130 ohms, as it did before.
Trigger coil (between green wire and Black/red wire) now showed only 160 ohms, significantly lower than it did before, which is strange because the reading I got before was too high. I double checked at the stator connector to be sure, and both readings were the same.

Something is wonky with this stator, and it's making diagnosing this bike very annoying. Also there is still no voltage pulse at the coil while plugged in, which is what it was doing before when the CDI was bad. I'm wondering if the stator could be causing a fault in the CDI somehow? I'm thinking of replacing the stator and throwing another CDI at it to be sure.

 

[my67xr]

The high primary reading on the ignition coil doesn't sound right to me.
A cdi coil should have about .7 Ohm's primary resistance, and between 3000 Ohm's and 5000 Ohm's resistance on the secondary side.
That ignition coil may have damaged the stator, and has caused the low reading's from the source coil on the stator now (black w/red, and green)

 

[criggs]

Alright, so I finally got a new stator installed on the Roketa, along with a new CDI and Ignition coil that came together as a set (the other coil I got fit very loose on the plug, and I wanted a set that "matched" as closely as possible). I also went over the whole wiring loom (I couldn't find one that wouldn't require a lot of cutting/refitting), making sure all wires ohmed out fine and were all properly insulated. Once I got everything back together, bike started on the first kick. Rode it around for around an hour, parked it for dinner, then rode it around for another half hour or so, and it runs beautifully. I hope it stays that way, this time. I really like this bike, by far my favorite out of any mini I've ever ridden, so I hope with all the new ignition parts and properly secured wiring that it is ready for the long haul, this trip.

One thing I noticed while working on it is the rear sprocket seemed extremely loose, so I pulled the wheel off, removed the outer hub that the sprocket mounts to, and found this:

Bad picture, I know, but what you're seeing is the holes that the bolts fit through are cracked/breaking apart for some reason. There are nuts on the other side, so I was able to tighten them down and secure it for now, but is this something that I should be worried about? Can that outer hub be replaced separately from the wheel? Really curious how it got that way...

 

[my67xr]

Does it run a cush drive, like the older PW80 etc ?
eg rubber bush's between the sprocket mount and the actual hub to soften it a bit ?

The bolt's/nut's may have been overtightened at some stage and crack the hub where the bolt's nut's sit.
This is the rubber's

And the sprocket hub

 

[criggs]

Yeah, that's exactly what it is. I'd never actually taken one apart before, so I was fairly dumbfounded when I first pulled it apart. The rubber is in good condition, and once I tightened it down it seemed to be fine, just want to make sure that it's cool to ride it like this for now. If it's not too pricey and I can find one I'll probably end up replacing it.

 

[my67xr]

Make sure you loctite the bolt's/nut's to prevent it happening with the new hub if you get one

 

[criggs]

The Roketa got some new plastics over the weekend. Here's a few (crappy phone) pics:

During the last trip, someone crashed the bike and destroyed the left side gas tank shroud. That, plus all the sun/weather damage and awful graphics, made me decide to get a new set for each of the pit bikes. I wanted black with white number plates for the SSR, and red for the Roketa, but none of the black ones I found offered anything else other than all black. So, I decided to swap the black number plates to the roketa, and the white ones from the Red set to the SSR. I personally think the red and black looks awesome. Just needs a new seat to go with it, now =P.

 

[criggs]

Also, a question I've been meaning to ask but keep forgetting:

This bike is missing the little "oil filter" screen behind the right side engine case. Will that little thing really make a difference? Can I run it like this no problem, or is it something I should invest in replacing?

 

[my67xr]

You are better off running an oil filter screen just as a bit of insurance, they cost under $5.
If you chip a gear or something like a bit of gasket inside the engine come's loose it'll stop it from going through your oil pump or blocking the oil feed gallery to the head etc.
It might save you having to rebuild your engine in the long run.
These guy's sell them and have a warehouse in Vancouver, they're the same as Honda CRF50 filter's, part number 6 here-
Save 20% on OEM Honda Dirt Bike Parts | MotoSport

 

[criggs]

Ok, good to know. I should be ok to ride it like this for now until I can get a new screen though, right? As long as I change the oil often until then will it be alright?

 

[my67xr]

Yeah, should be ok for a while i guess.

 

[criggs]

So a few months back the Roketa quit in the middle of a ride. Again. One of my baby sisters finally got brave enough to ride it (she's just a bit short for it), and about 10 minutes after her confidence allowed her to shift gears and get comfy, the bike stalled and she was forced to push it back. I felt terrible. Checked everything out a few days later and found the solder that attatched the ground wire (green) to the stator had broken. Re-soldered it and it's been fine since. Seems like this bike just loves to lose spark randomly =P.

Anyway, I also finally decided to get a new seat for it since the current one looked terrible and fell apart a little more every time we rode it. I think it looks pretty nice:

Now the frame and engine need a new coat of paint, and I think it'll look like a brand new bike.

 

[criggs]

I know it's been forever, but I finally decided to tear down the Roketa and give it a bit more of a restoration:

When I got down to the steering, the bearings (unsurprisingly) fell apart completely. It's hard to tell for sure, but it looks like they might be PW50 style bearings?

If anyone has any idea how to replace these I'd appreciate the info, haven't ever run into this style of bearing before.

Oh also, stator went out again last riding trip. 4th time this bike has lost spark while out on a ride =P.

 

[criggs]

So I got started stripping paint a week ago or so. I started with the swing arm as the paint on it was the worst shape out of every other area of the bike, and it was so thick I was worried I'd have trouble getting it all off. I used "Aircraft" paint stripper that I picked up from my local O'Reilly auto parts store, and some 120 grit sand paper to finish it off. I think it came out okay:

Before

First coat of stripper

After the 3rd coat of stripper

After about 30 minutes of clean up sanding

There was a good bit of rust on the inner sprocket side arm where it looks like the chain had worn some grooves down into the metal. Other than that it went fairly easily. Already started on the frame itself, but ran out of the paint stripper about halfway through. I'll have some pics up of that once it's done.

 

[Cordogs]

Looks good mate! :coolthumb:

Keep the updates coming.

 

[criggs]

Alright, a few more updates. Got the frame, swing arm, and handlebars stripped, cleaned, and primed. Unfortunately I got ahead of myself and forgot to take before pics of the frame and bars (they were terrible, about half of the paint already chipped off/rusted through), but hopefully these will do.

Here is a small section of the frame just to show how well the paint stripper worked (I switched to DupliColor paint stripper, worked a lot better than the Aircraft stuff for me):

Here are the parts stripped, cleaned, and ready for primer:

And here they are after 2 light and 1 thick coat of primer (sorry for poor lighting):

Next comes paint, hopefully I'll have that all done within the next few weeks. Still trying to decide how I want to do the engine. I'm either painting just the head and cylinder black, or the whole thing. I feel like paint won't stick to the case well, but it is really ugly looking (scratched like crazy, and stained from oil) as is. It's coming along, though. Slowly but surely.