|
Post by islandscrub on Mar 4, 2019 1:55:57 GMT -5
Okay, I’m at a total loss now. Bike starts perfect, Idles perfectly, and drives without issue but it still tops out at 30-31mph. Got a new “stock clutch” it opens more smoothly that the one that came with it. I have tuned the Variator with 4g, 6g, & 8g rollers. I have even alternated combinations of each. The 4g rollers are actually getting the best result. Acceleration & highest top end speed. BBK Engine (Good Compression) New intake & Carb (100 main jet) Air Filter Adjustable CDI box engine is showing just over 7000rpms on the stock rpm gauge. New Coil & Stock Coil seem identical in performance. Stock belt 1 mph faster than the slightly narrower Gate Kevlar belt. I have three different Variators & two different drive bosses. I shortened one of the drive bosses and ruined it because I made it too short. No Change in swapping the different (3) Variators. How to +add 10mph more to this setup baffles me. I am running out of ideas. Average speed is between 26-29mph touching 30-31mph tops. Help, Ideas??? -Adjusting the timing? -Changing fuel pump? If the engine starts up and runs smoothly through the throttle range, just ignore it for now. The golden rule of tuning this stuff is change only one thing at once. From your previous pictures it looks like your belt isn't traveling all the way up in the front. We asked if the rear moveable faces open and close smoothly and to the full extent. If you cant force them open with the big center spring in the middle, just leave it out, put the clutch pack back on and just hand tighten the nut. With it full open, put in the stock belt and see if it can go all the way to the center or very near it. If it does, good. Put the softer stock spring in there and check it again. If that's good, go ride it. If your belt isn't traveling up far in the front you are missing out on 'high gear' which may be hampering your top speed. Also, just go with the 6s for this experiment.
|
|
|
Post by Happypancake! on Mar 4, 2019 7:20:39 GMT -5
100MJ for 50cc is overkill. Your A/F may be off. Google how to tune a motorcycle/scoot. There is plenty of info out there. I'd start walking down MJ size if it idles OK. I'm running an 80MJ 38SJ on my 58cc's.
|
|
|
Post by dexameth on Mar 4, 2019 12:21:08 GMT -5
Do this: Put the bike on the center stand so the rear wheel spins freely. Using a piece of tap, mark the edge of the rim. Now, do the same to your clutch bell. Then, spinning the clutch bell, see how many times it has to spin for one complete revolution of the back wheel... then let us know that number.
|
|
coachm
Scoot Member
All my friends have life goals, I just want to go faster
Posts: 24
Location: USA
|
Post by coachm on Mar 4, 2019 12:29:05 GMT -5
Do this: Put the bike on the center stand so the rear wheel spins freely. Using a piece of tap, mark the edge of the rim. Now, do the same to your clutch bell. Then, spinning the clutch bell, see how many times it has to spin for one complete revolution of the back wheel... then let us know that number. I'll do that after work today. Bike only has a kickstand no center stand but that's easy enough to make a stand.
Dexameth, Some other things I was considering trying today.
- rechecking the valve clearance to see if they have moved and to make sure I am getting sufficient vacuum to fuel pump. - I plan on marking the variator again just to see the belt travel. Someone suggested going to 6g rollers. - Also was considering advancing the timing slightly - Someone else also mentioned lowering the main jet I have an 87, 90, 95, 100 I can test. - I also have a new fuel pump, I could install.
|
|
coachm
Scoot Member
All my friends have life goals, I just want to go faster
Posts: 24
Location: USA
|
Post by coachm on Mar 5, 2019 7:40:07 GMT -5
Update
Rotation of clutch to wheel is 13:1, Compression is 180
Opened her up and checked the valves again. Both valves are set at .004. Here’s the thing, since I had the bike up on stands. I put the 6g rollers back in the Variator and remarked the Variator to track belt travel. I also went back to 90 main jet in the carb. Completely stock clutch and springs open smoothly. I figured I could use this tune as my new baseline.
With this baseline tune I fired up the bike and opened the throttle with it up on blocks and hit 8600-8800 rpms. I thought the issue was fixed! Checked the markings on the Variator and the belt traveled all the way to the top. It sounded good and really felt good running on the stand.
Took the bike down and went for a ride, couldn’t make it to 6800rpms and topped out at 30mph. Just couldn't get the bike to respond as it did on the stands in the garage. The belt is not making it to the top of the variator while on the road.
That’s where I ended for tonight, ready to tackle it again tomorrow.
Hoping for suggestions on what to do next.
|
|
|
Post by dexameth on Mar 5, 2019 9:00:57 GMT -5
Hmm... very strange. Are you a big guy? How much air is in the back tire? Something is definitely restricting, maybe a blown bearing in the gearbox?
|
|
coachm
Scoot Member
All my friends have life goals, I just want to go faster
Posts: 24
Location: USA
|
Post by coachm on Mar 5, 2019 10:10:07 GMT -5
I'm 175lbs. I could check the pressure in the tire but it looks fine... I dunno about a bearing issue, no strange sounds or whine when riding>
|
|
|
Post by tyfumatt on Jun 21, 2019 18:51:51 GMT -5
Umm... Possibly being really dumb here, but here in the UK we have a limiter that cuts power to the cdi, governed by a sensor in the transmission case that reads the revolutions of the clutch, making it impossible to exceed much more than 30mph, even downhill. (legislation to stop 16 year olds going much faster than a pushbike, etc.) you have disconnected this, I take it? Or cut the pink wire leading to the cdi? Otherwise, even with the perpetual advance of the racing cdi, it still won't exceed 30ish. I had this trouble too, and on discovering this from the wiring diagram in the manual, I now run a db50qt-a as stock and get 39-41 at near wot. I'm no lightweight, at 235lbs, but can get 45 at wot on the flat, given enough road! (don't usually though, that's way too scary for the frame...)
|
|