70cc S6 Street Race from scratch

[kevin55950]

Those are, as I see, high temperature bearings, that are meant to be used in industrial equipment, not in a engine for continuous high revolution and load caused by the piston coming down, they have really tight tolerances. They will not last in a engine and they will seize fast. Sealed bearing behind a crankshaft or primary gear shart seal will make the seal pop out.
I've seen those bearings on crankshafts when people were rebuilding an engine with what they found.

[oldgeek]

Feb 1, 2013 1:07:20 GMT -5 90GTVert said:

Sounds about right on the jetting. I like to start in the middle position with the needle clip if I don't have any past experience with the setup.

Never seen a partially sealed bearing used on one of these.

I didn't think that bearing looked right LoL! Someone really screwed that engine up at some point.

Thats what I thought about the jetting based on your past tutorials. Thanks for the confirmation.

It looks like I will have to go with a stock exhaust for now since I am broke with no end in sight for a while. I REALLY want to find a GP at some point.

[oldgeek]

Feb 1, 2013 2:20:42 GMT -5 kevin55950 said:

Those are, as I see, high temperature bearings, that are meant to be used in industrial equipment, not in a engine for continuous high revolution and load caused by the piston coming down, they have really tight tolerances. They will not last in a engine and they will seize fast. Sealed bearing behind a crankshaft or primary gear shart seal will make the seal pop out.
I've seen those bearings on crankshafts when people were rebuilding an engine with what they found.

I am thinking I would of at least popped the shield out so the thing could get some oil.

[kevin55950]

Are they siver seal or black seal?
Black seal is a good bearing, only brought at a bearing supplier ( C4 clearance bearings generally come sealed) and not in a scooter parts supplier.
If the seal is silver it is an high temperature bearing, I wasn't able to see well on the picture lol.
I found some gp-style exhaust but it's kinda overpriced... it's a copy of the gp.
www.pro-scoot.net/systemedechappementhor.htm first on top.
Idk if we can get a true Leovince GP, I'll look with the suppliers if you're interested. ZX-R is a great exhaust, doesn't look like the GP, but it's a good, really silent performer. Stage6 Pro Replica exhaust are popular and they are cheap, the best performing exhaust for a stage6 Streetrace is a Yasuni C16 , it give around 11hp, but they aren't cheap but I can find some used but in a really good condition.

[oldgeek]

Feb 1, 2013 10:05:44 GMT -5 kevin55950 said:

Are they siver seal or black seal?
Black seal is a good bearing, only brought at a bearing supplier ( C4 clearance bearings generally come sealed) and not in a scooter parts supplier.
If the seal is silver it is an high temperature bearing, I wasn't able to see well on the picture lol.
I found some gp-style exhaust but it's kinda overpriced... it's a copy of the gp.
www.pro-scoot.net/systemedechappementhor.htm first on top.
Idk if we can get a true Leovince GP, I'll look with the suppliers if you're interested. ZX-R is a great exhaust, doesn't look like the GP, but it's a good, really silent performer. Stage6 Pro Replica exhaust are popular and they are cheap, the best performing exhaust for a stage6 Streetrace is a Yasuni C16 , it give around 11hp, but they aren't cheap but I can find some used but in a really good condition.

The seal on that bearing is silver, the one on the other side is totally open.

As far as the pipes go, I want more low end torque than speed So I plan to save up for a GP until I can afford it. The ZX-R and the C16 can be hard to tune I hear, and me being 6' 300lbs I don't really want to go that far on this build, but eventually I definitely want to do a tuned pipe.

[kevin55950]

Take a look here, they tested a lot of exhausts on the Stage6 Street Race engine. They didn't get good results with the GP...
www.tuningmatters.com/2012/05/17/review-the-ultimate-scooter-tuning-exhaust-comparison-test/
The Street race internals are the same for AC and LC version as I know.

ZX-R exhaust were not hard to tune for me, the jetting was pretty close to the stock exhaust one, only have to lower the rollers weight and upjet a little.

Do not just take a look at the performance list, look at the power curve of each exhaust, that has to be considered because the "wider" the power curve is ( the top of it), the easiest it will be to tune it well, you'll have more acceptable range where you'll get full power. I think it's a really good article about finding the best exhaust for the street race that suits the way you use the scooter. It's also useful to set the transmission , they give the RPM that the power was the highest for each exhaust.

[oldgeek]

Feb 1, 2013 20:59:36 GMT -5 kevin55950 said:

Take a look here, they tested a lot of exhausts on the Stage6 Street Race engine. They didn't get good results with the GP...
www.tuningmatters.com/2012/05/17/review-the-ultimate-scooter-tuning-exhaust-comparison-test/
The Street race internals are the same for AC and LC version as I know.

ZX-R exhaust were not hard to tune for me, the jetting was pretty close to the stock exhaust one, only have to lower the rollers weight and upjet a little.

Do not just take a look at the performance list, look at the power curve of each exhaust, that has to be considered because the "wider" the power curve is ( the top of it), the easiest it will be to tune it well, you'll have more acceptable range where you'll get full power. I think it's a really good article about finding the best exhaust for the street race that suits the way you use the scooter. It's also useful to set the transmission , they give the RPM that the power was the highest for each exhaust.

Thanks for the link, a good comparison of pipes as far as I can tell. I found a technigas next-r for cheap, I wonder how well it would work for me. According to the list, it seems to have a fairly wide powerband.

I got the engine mounted today, and as usual I had some issues. I slid the hangar rod into place, and noticed the shock was not lined up, and the back wheel was not centered I put the hangar tube on the same way it was on the original motor that was on the scooter, but I guess whoever did the work for the PO had installed it wrong, which explains why the snap ring was loose on one side so they could shift the motor over instead of pulling the motor and flipping the tube around. It was no big deal to remove it and install it correctly, just stupid of me.

I checked on the gas tank that has been sitting full of vinegar for several days. It looks much better, so I topped it off with vinegar and tomorrow I plan to dump the vinegar out, and immediately immerse the tank in a tub of water & baking soda. I think neutralizing the vinegar is the key to keeping it from flash rusting as that always seems to be the issue people have with cleaning out a MC tank. We will see how it goes.

I am getting close to firing this thing up. If the weather holds up, I may get it running tomorrow.

[oldgeek]

I finished up the gas tank cleaning job I described earlier, and I have to say it worked VERY well. The inside of the tank looks new. Its hard to believe that tank had so much rust in it. I wish I took before and after pictures. Hats off to whoever came up with that process.

The stock exhaust pipe is mounted now. It sticks out to the side a good bit, so I guess the 70cc S6 street race cylinder I am using has different angles on the exhaust port than the original cylinder. I left all mounting bolts loose and tried to shift everything best I could, but this is how it looks.


I also found this, guess I should replace the brake cable ASAP.

[oldgeek]

Amazingly I got all of the loose ends tied up this evening that were preventing me from starting this scooter up. So I turned the key, and pressed the starter button and it turned over, and over, and over. No start, I checked for spark and found nothing! I swapped a couple stator wires, checked the coil, and still nothing.

The stator I used on this build did not come from the engine that was on this scooter. All plugs mated up fine, but all of the colors were different. I decided to pull the flywheel to check the stator wiring. I compared the stator that originally came with this scooter to the one I put on it, and noticed right off that the pickup had only one wire going to it but the one on the scooter had 2 wires going to the pickup. I decided to make things easy for myself, and just swapped out the stators.

I put it all back together, and this time it started up immediately. It was quite dark by then, but I did manage to set the air screw, and idle ok. I decided to do a couple passes on my street, which is really a long common driveway with speed bumps. I did not have plastics installed on the scoot, so I did not have a headlight. I got it warmed up a bit, so I could re-torque the head tomorrow, or whenever I can work on it again.

Here is what the plug looked like.



It seemed to be sputtering just a bit, I never went past half throttle.

[ottootto]

leovince and tecnigas are low level system

for sure
got what you pay for (no idea of the price down there...)

[aznatama]

FWIW, I have the sme BBK kit, and my stock exhaust also hangs out to the side by a fair amount. I went with the Stage6 pro replica, since it's rather cheap and has good performance. I figure it would match with the stage6 street race bbk better than any other pipe.

[kevin55950]

Stage6 Pro Replica are good exhausts for those engine, and they're cheap.
Also better quality that technigas one's, spray some WD40 around 30 min. after a ride when you leave the scooter for the night, and you'll never see rust on your exhaust. Chrome version is more expensive, but you have a better rust protection. On the non-chrome version, you can paint it black or if you want to keep the unpainted finish, spray some layers of VHT high temp clear coat.

With technigas, I got some pain installing them because of the brackets (I'm talking about Technigas exhausts in general, not only a particular model), and rust was always a problem, no matter if I protected them or not. I never owned one but I installed some on my friend's scooters.

[oldgeek]

I just had my very first soft seize! kind of scary.

I took the scooter out for some break in runs and when I was exactly as far away from the house as possible on the loop I ride it happened at WOT. I let it cool for a while, and to my relief it started right back up. I eased it back home at 1/4 throttle cause it seemed to be happy there. I had an 80 main jet installed, so I guess its time for an 85?

[Corrosion]

I do 5 tanks of fuel. Before you WOT on a S/R. At least thats what I have found. And I found out the Same way you did.

[90GTVert]

I'd add a larger jet now even if you are going to go easy on it.