Go Go Sundiro! 70cc Stage6 Sport Pro MKII build

[morbidmetal]

Apr 6, 2017 7:42:49 GMT -5 lordverminaard said:

Time to drag this thread back up with an update now that spring is almost here. (even though it is supposed to snow tonight, and it was 72 yesterday, WTF Ohio???)

I put my Ducati up for sale, I love the bike but I am not "in love" with it, that will free up some funds too.

Finally bought a carb for my Sundiro, one of the Dell clones on ebay, a 21mm variant:


I tore it down to see what's inside, the needle wasn't marked but from measurements it looks like it is a W16, so I will probably order a W7 since that is what everyone recommends. Floats were set correctly, it had the correct 2-stroke 262AU Atomizer and 9655 bushing, yay! 90 Main jet, 60 start\choke jet, unknown pilot jet. Slide is also unmarked but it has a cutaway bigger than any that I have seen pics of on the internet so I will probably need a new one of those as well, seems that the 40 is the one to have and if I need to I can file it down to a "45".  Need a 90 degree throttle cable top and some sort of remote choke lever so I can mount it on the plastics under the seat.  Managed to find a piece of 1" rubber dishwasher drain hose that fits the outlet of the carb perfectly and allows the boot on the fancy intake manifold I have to fit snugly too. The manifold came from ebay but it looks like a clone of the popular NCY manifold with two vac\boost nipples on it. The inlet side of the carb has a nice plastic screw-on velocity stack and it fits the hose from the airbox no problem. I like it with stuff comes together.

After a lot of research I will probably go with the Stage 6 Sport Pro 70cc kit and more than likely a Stage 6 Pro Rep pipe. Lots of people run that setup, and some of the tuners out there have gotten a ton of power with them with additional tweaks. Also at the price point for them, I am not sure there is anything else close in the aluminum cylinder class.

Got my tires too, Kenda K413 in a 3.5-10. Also got the front shocks installed after fabbing up a quick spacer.

I also have just about everything torn off the engine so that I can clean it. No surprises, everything came off without issue. I was even able to get the flywheel off without a special puller, used my jaw type puller and it popped off easily. I will modify the stator to get adjustable timing "while I'm in there".

Sorry there aren't more pictures, the last few times I have worked on it, I didn't have my phone with me. Once I free up some funds the work will really start.

Until next time!
Brendan

Did the 3.5-10 tires fit? I was given a '98 Akita with the 1e40fm engine. It has the same size stock tires as yours. 

[lordverminaard]

Well, they will physically fit the wheels but I have not mounted them yet so I don't know for sure if they will rub anywhere on the scooter. Preliminary "eyeball measurements" look like they will fit without issues but I won't know until I mount them. I plan on re-painting the wheels so it will be a little while before I get to that point but I will be sure to post a pic of them installed.

Brendan

[lordverminaard]

Ok, stuff is happening!  I have in my hands a new 70cc kit and a tuned pipe!  I am waiting on some additional items from Treatland.tv to arrive so I will keep the cylinder a secret until then, but I am really impressed with how it looks and I really think it is going to be awesome!  The pipe is one of the Scrappydog units which I think is the same one that you can find on Ebay for $100.  I snagged it from a forum member for $25 plus my old pipe.  I know it is not the best pipe out there but it is better than stock.  I didn't see it listed in our pipe "database" but if I can figure out how to measure it properly maybe I will add it and those who are smarter than me can tell me in what areas it is lacking.  Money is tight so I will maybe get a better pipe later.

So some things I did do last night was rig up a remote manual choke cable for my PHBG clone carb, which is manual choke only and already had the provision for a cable choke.  I didn't want to spend $30+ on one of the fancy remote choke kits so I poked around the "help" section of my local Autozone and found this for $9.00:



It came with some mounting hardware, some other junk to replace the automatic choke on old cars, and a cable end barrel secured with a machine screw.  I'll take pics of what I had to do to make that work later.  I think there was about 5 feet of cable in the kit and I ended up trimming about 5 or 6 inches from it.

I found a spot to mount it:


 


I might find a grommet to put around the hole if it bothers me too much.  Also I am probably going to paint that bracket black, I hate chrome.  The plastic of the scooter dash looks like crap too so I will probably paint that as well sometime but not right now.

Running the cable was easy, this scooter even has a little access panel for ease of cable routing:




I did end up modifying and attaching the cable barrel to test but I made it too long and cut it off to do it again later.  The choke mechanism has a heavy spring and upon testing I realized that the choke won't stay open with that spring in there.  My thought is to remove the spring and assume that the cable will hold the choke plunger in the down position.  Anyone have thoughts about that?

That's all for now, I only get about an hour at night after the kid goes to bed to work on it but my motivation is high right now.

Brendan

[ryan_ott]

You may need to modify the spring for the choke to stay open. You also need it strong enough to close and seal. It's a compromise. I had to trim one shorter on a PWK, I'm just using the plunger on my phbg.

[lordverminaard]

Thanks Ryan, I cut down a spring and adjusted the length and it still doesn't feel right so maybe I will try again before I try to start it for the first time.


Did a lot of work on the scoot again over the past few days.  First, being a cheapass, I didn't want to spend the extra money on a 90-degree throttle cable entry for the carb, especially if a new throttle cable is also needed.  I decided to try and make one with the 90-degree that came on the stock carb.  

First, I used a punch to tap out the pressed-in bendy in my stock Mikuni carb:





Then I broke out the M6x0.75 die which matched the threads in the PHBG cap and threaded the end that was pressed in to the Mikuni carb top:
 




Then used a little threadlock and it fit nicely:





Test fit on the carb to check for throttle throw and it looks like it will work perfectly.

Also, here is a pic of the pipe I will be using for now:





Getting in to the exciting bit here in a minute.  I decided to tackle something that I really didn't want to do, clean the engine cases up.  I don't have a parts washer (yet) and I was dreading doing it with a degreaser and wire brush, so I used some gasoline in a ventilated area with a cheap paintbrush.  It worked really well but man did I stink afterwards.  I later touched up some spots that I missed with some spare coleman camp fuel I had in the garage, much less stinky and seemed to work just as well.  I wasn't going with show-quality clean but just "good enough".  I think it came out great:





Now, on to the reveal of the cylinder......





Yep, it's a Stage6!




Sport Pro MKII to be exact.
 










I was originally going to go with the "Street race" iron kit from Stage6 but DynoScooter.com had this for only $7 higher than the lowest priced StreetRace kit, so I figured what the hell.

Everything went together pretty easily, the squish is slightly higher (numerically) than Stage6 specification, (spec is .6 mm and I think I am at about .8mm) but using no gasket did not allow the piston to come all the way up and I didn't feel like trying to make a thinner gasket.  Used a new bearing and all that jazz.  Engine looked good too!




I also managed to get the carb cleaned and the new jets, needle, and slide installed.  Also got all of the shrouds and stuff re-installed so the engine is ready to go back in the scooter now.  I tried to unmount the rear tire but it started to bend the rim flange when I was trying to pry the bead off.  I got frustrated and decided to skip it for now, I'll try again later.

Hopefully tonight I can get it all put back together. I need to stop and get some fresh 75-90 for the final drive tonight after work too.  Should be running very soon!  I am getting excited.


Until next time,
Brendan

[lordverminaard]

Started it up on Monday night, had issues with the choke so I fixed that on Tuesday and was able to tune it pretty good, it starts first kick, and throttle response is pretty good too. Couldn't get around to road testing it, as I mounted the new tires to the wheels but couldn't get the bead to seat.

Still have a handful of things to do, like clamp up and tidy the fuel lines, make spacers for the airbox mounting, and fix an exhaust leak. Once that is done and the tires are installed, I can go on a road test and finish tuning.

So far tuning the PHBG seems pretty easy, at least as far as getting it to start and idle nice. I have a 42 pilot jet and 90 main in it right now, with a 40 slide and W7 needle. It does seem a little sluggish in the lower RPM's but I did rev it out a couple of times and it is very snappy at high RPM's. I have little experience with a piped 2-stroke so maybe that is normal. We will see how the road test goes.

I'll have some pics soon.
Brendan

[lordverminaard]

After calling every tire shop in a 10 mile radius, finally found one that would assist with seating the tire bead on the wheels. I guess that means I need a compressor. Anyway, got the wheels mounted and went to take it for it's first ride around the block. I didn't make it. It didn't have enough power to make it up a very small hill. Initial throttle response is good, but it seems like right after the clutch grabs completely, it just runs out of steam and won't accelerate at all and bogs really bad. I pulled the plug and it looked a little lean to me, and I was already running the higher 42 pilot jet. So I took the unknown pilot jet I had and made a makeshift drill from a piece of .030" welding wire, which would be something like a 76 pilot jet, lol. I just wanted to see if it made a difference. Well, I had to basically raise the idle as far as it would go, and lean out the mixture screw almost all the way to get it to idle. the bog was still there but not as bad, and at least it had enough power to get me around the block but I couldn't go more than 3/4 throttle still. The plug was pretty black after doing this, so I still think it was rich at idle\idle circuit area but leaning out still in the transition. So I put the 95 main jet I had in, put the 42 idle jet back in, and lowered the needle to the richest position, and it still bogged pretty bad at about 1/2 to 3/4 throttle at low rpm's. I could richen up the mixture screw almost as far as it would go and it made it slightly better but not really. 1/8 to 1/4 throttle blips seem pretty good if I keep the mixture screw at a reasonable place. (2 1/2 turns out or so)

So my thought right now is that I need a bigger main jet still. I am a little concerned because what I see most people running a 21mm PHBG with a 70cc sport kit running is a 95 main. But I don't know the details or elevation or anything like that so I suppose my setup can be different. I thought also maybe the needle is not quite right but I am not sure if I have seen anyone run anything but a W7 needle in these, other than racers that sometimes use a W6. I will see if I have an appropriate sized drill bit to open up the 90 jet the carb came with to maybe a 105 or so and see if that helps. If anyone has any thoughts to share, I would appreciate it very much!

Thanks,
Brendan

[190mech]

Stock airbox,snorkel removed,good air filter element???

[lordverminaard]

Jul 10, 2017 18:26:43 GMT -5 190mech said:

Stock airbox,snorkel removed,good air filter element???

Yep, stock airbox, snorkel removed, also a couple of holes drilled in the backside (filter-side) for extra flow.  Filter element is..... old, but fairly clean.  I was able to mate the stock intake hose to the PHBG velocity stack.

Thanks,
Brendan

[lordverminaard]

Also pictures of what it looks like at the moment with the new tires.





Brendan

[lordverminaard]

Soooo.... I have been playing the carb tuning game for the past few days, which also means instead of buying a ton of jets I have been using makeshift drill bits to enlarge the jets I have. Right now I am up to a 56 pilot jet, (up from 42 that I started with) and a 126 main jet, (up from the 90 that I started with). I am still not able to give it full throttle without it bogging under load, but it is at the last 3/4 of the throttle now instead of 1/2 throttle like when I started. When riding, it seems pretty "normal" at 1/4 throttle, but it is still lacking power at 1/2 throttle and beyond. I still don't think I got over 25 mph with it.

I am kind of thinking that the CVT is shifting so early, that the bike is nowhere high enough in the powerband to pull after the CVT shifts. But also, this is a 70cc sport kit, I would think it would have enough power to pull a stock CVT setup when the stock 50cc cylinder could do it.

I am also thinking, I have no idea what the gas is in the tank. I know the bike sat at least a year or maybe two before I bought it, then it has sat a year after that basically, and who knows what was in the tank. I also guesstimated some oil addition to the tank after the first start. (Stage6 recommends 60:1 pre-mix along with stock oil injection) So I think my gas is bad\too much oil. I have seen very few people running jets this big on a 70cc sport kit with 21mm PHBG. So before I go bigger I will drain the tank and put in some fresh gas and see what happens.

If anyone has any thoughts, it would be appreciated. I'm still not very confident tuning carburetors.

Thanks,
Brendan

[90GTVert]

I think it's a good idea to drain the tank, go over the fuel system, and make sure the carb is clean.

[190mech]

Agreed Brent!Dump that crap gas,flush the whole system and start fresh,,,Yep,you'll need to go thru the CVT,clean and grease the Torque Driver,stiffer clutch springs,around 4,5 Gr vari weights,,etc..

[lordverminaard]

So I drained the fuel, filled with fresh, and cleaned the carb out again.  It's better, but not quite what I think it should be, however I do feel I am making progress.  I took a video which hopefully shows what it is doing.  Hopefully I don't sound like too much of a dork, haha.



At the end, I was originally going to stop the video there but I decided to take another video of it with the mixture screw turned in to a normal level.  (about 2 turns out)  The idle hanging tells me that it's lean now with the screw, however it revved out better and cleaner than it has since I started doing this.  I'm thinking, I should lean out the needle some, (right now it is in richest position) which should let me richen up the screw a tad for the low rpm, then the leaner needle should clear up that half to 3/4 throttle choppiness evident in the first video.

I have gone through the CVT and cleaned everything, belt is still well within wear limits, but I do feel it is shifting VERY early.  I will probably experiment with weights and see if I can make it rev out a little more before shifting so I can purchase the correct weight sliders.

Also, immediately after that video, I pulled the plug to have a look and took a pic of that too.  Remember this was after a couple rides around the block at 1/2 throttle, then the revs in the video.






Thanks for the help, I feel like it is close now.

Brendan

[90GTVert]

I don't think I'd worry about the CVT right now with it sounding like that on the stand. It should power through the range of the CVT when not under load like that, even if it's quite a bit out of tune.

You made sure there was not restriction in the header? Don't know that that style of pipe comes with them, but it will make them really weak no matter how you tune them. I did that on a 90cc once and it wouldn't top 35MPH with maybe stock 49cc acceleration and I could not figure out what it wanted for the tune. Everything I did was wrong till I removed the restriction in the header.