Hi All, newbie here. This is my mild restored/modded 78 Pinto RR. I'm hitting 35Mph on my top end. Does that make sense with my setup?
Now my take off it is scary slow for where I live... Any advice?
Setup:
Engine and Cylinder totally stock from the 7O's . ( just fresh oil)
15mm Bing, w Grandpa 15 intake and mesh filter.
Proma Circuit Exhaust.
Main 68, Neddle 9,17 ( I can swear is a 9) 3rd top notch.
plug reads seems on the spot with a nice uniform sun tan color.
Gearing is stock 14/45
You will want to tune your clutch. You can try kickstart springs, maybe flush at first since you have a stock cylinder and work your way in if needed, no more than 3 turns from flush.
Also, if you haven't yet, you will want to service your ignition components and set your points and timing, as they may have gone out of spec after many miles/years.
Most use a 2.17 atomizer with a 15 bing. Are you sure it reads 9.17?
Also, just a tip, when you wrap an exhaust you should wrap from the back to the front so that wind and road debris don't get caught in the folds and cause it to become loose and come off. (edited)
When you say “sun tan color” what shade we talking? Cause my sun tanned skin would be lean as hell.
14x45 gearing and that pipe should have plenty of low end grunt off the line.
35 is pretty fast for stock so you are good there. Clutch tuning is what will help most now. There are also springs just a little less firm than the kickstart ones. They are ESB brand I think and are black. They made a huge difference in my takeoff and I am a big guy and riding a magnum which is almost twice the weight of that pinto.
Thank you Chris. That is what I thought with the clutch.
Weird think with the needle but it does say 9,17. Maybe my eyes are fooling me.
Yes a little on the lean side for a two strokes I guess.
Agree. Jay I've been looking also the blue springs. But I think the black as you said are better. Now that I'll have to remove the clutch, should I also add new shoes and a brace? Can't seem to find a good one.
Thank you all for your answers.
Post pics of the clutch shoes when you get the clutch out and we can let you know if they need to be replaced or not. Also you won't need a brace as long as you do not lighten the shoes or remove the stop pins.
Also post a pic of the # on the atomizer
If you have a 2 shoe leave it alone aside from maybe adding a brace. I bet it will still be pretty good since it has stayed stock until now. If you have a three shoe, definitely brace it and consider finding a OEM 2 shoe.
O.k. sounds like a plan I'll be back in a couple of weeks with the pictures of the clutch.
wait!!!. Jay that means that the 2 shoes are sturdier that the 3???
Generally 2-shoes are better than the 3-shoe clutches yes. And while you're in there get rid of the atf fluid and run straight 10w30 synthetic motor oil in your gearbox.
Thank you Thomas.
Now I'm wondering ... What are the pros of Synthetic oil? And also is 10W30 good for a very a very hot weather like South Florida?
Yes 10w30 is better with heat than the ATF is. You can try going a little lighter in Weight, like a 0w30 but it probably wont make much difference. I run full synthetic 10w30
And the 2 shoe is better than the 3 shoe for a few reasons. Mostly that it is easier to get the 2 arms to grab at the same time than to get 3 arms. If the 3 arms are off by too much you can cause stress on the arms that grab first and they can break or at the very least cause very uneven wearing on the pads and then it wont function at all.
The jammer clutches uses a 3 shoe setup but the way those grab the clutch bell is different and they have a lot more surface to grab than the stock 3 shoes. The KTM clutches are only 2 shoe and are the most used in Euro moped racing.
Once you start getting into clutch tuning the shit starts getting real. Real annoying. Ha!
> Jay Rivett Wrote:
> -------------------------------------------------------
> Once you start getting into clutch tuning the shit starts getting real.
> Real annoying. Ha!
LOL ... Shit. I'm also overwhelmed reading about mild porting the stock cylinder.
I wish I could get maybe 40-45 Mph top and a decent take off with the stock cylinder. That's it, I don't need more...
You are gonna need to do some really serious port work to get there with any kind of quickness on a stock 50cc cyl. If you get a 70cc tccd from treats or 70cc dmp from dos cycles you would be at 45 just bolting it on and tuning it so it doesnt seize.
True. Let me keep my expectations low and see how much gain I'm able to get with a mild porting. That experience will for sure help if I add a kit in the future.
Yes I always think you should learn as much as possible about a stock running bike before attempting a kit.
Took apart my top engine to discover that it was seized!
I thought my plug color was healthy but not...Somebody said once "good lessons cost money right"?
My plan was to do some mild porting and tune the clutch but now I'm stuck in here and not sure what to do next. It seems that the piston seized and some material melted on the the cylinder. Can that be fixed with the Dremel tool.??? I really don't want to put a kit and FK...iU. =(
Also can somebody tell looking at the pictures if that hole that create a bridge to ignition should be there?
Thank you.
Forgot to attached the images. Here they are!
That hole you see on the inside of the engine is supposed to be there it is an oiler port that only leads from the back of the crank to the transfers. Totally engineered to be there. Sorry you seized your cyl. Such is the cost of pushing the limits of your engine. You could try salvaging your cyl but unless you use a honing tool it will not allow the piston to reat correctly. You will also need to get a larger bore piston for the now larger cyl bore.
It’s gonna take more time, and probably money, to fix that top end than to get another.
I know there are piles of stock cylinders, with their resident pistons, sitting on shelves in garages of almost person on this forum. I bet you could get a set for dirt cheap from the B/S.
Get you up and running again and then play with fixing this thing as an experiment. Maybe it could be a backup or you can sacrifice it for porting trials.
Yes to what Papa said for sure. I actually have a stock cyl/piston/head for you but didn't offer it cuz it is a magnum style with the angle exhaust port which means you would also need to buy a new pipe for it. But if you want to go that route. A good pipe would be that angle port circuit that MLM makes.
100% agree with you all Papa and Jay. I want to keep messing with cheap stock cylinder before stepping up. So I'll ask on the B/S
Jay thank you for you kind offer. I just got a new Proma Circuit and I love the Chainsaw sound so I would rather stick with it.
What I need to understand is why it seized. I remember driving to do some plugs readings at WOT and the bike stopped like..."when It seized" But then ran again so I though maybe wat the new petcock or fuel starvation etc. That was a cool day for Florida standards like 64°.
The plugs read seems fine to me. So I'm wondering if maybe mopeds are not intended to run at WOT? and how to avoid this to happen again. I'm afraid this thing is going to fry like an egg on summer.
I have to wonder what caused the deterioration of that one single spot of the piston crown edge .
The rest looks pretty normal .
You might think about just cleaning the cylinder with a quick hone and then free that upper ring . Making sure the landing is clear .
It might not last as long as a fresh piston , but ...
Or just find another piston to match and run it .
Make sure there's no air leaks , anywhere .
You can't tell from the pictures but it was in several spots... 4 or 5. =)
I feel like you would benefit from a temp gauge to see if you are spiking in temos.
My best guess tho is either a recently developed airleak or an overlooked one. Bing carbs like many clamp on carbs have troubles sealing up at the intake. A head air leak is super easy to get if you have taken the head off a few times and reused the head gasket.
Reusing any gasket can be asking for trouble honestly. If you see any gasket stuck behind on a mating surface, you would be best advised to remove the material left and replace the gasket with a new one. I realize this is not always possible or cost effective, but best practice I would say.
Mopeds like any vehicle can be run at WOT for a while, but temps will always start becoming an issue. Air cooled engines especially in high temp areas, are going to have a harder time keeping cool. Race built things are designed to run at WOT or close to it for extended periods of time and not blow up, but they still can and they will almost always get rebuilt before the next time they hit a track.
The only thing you can do is keep the engine free of air leaks and keep it lubed on the top and bottom ends, and hope for the best.
Probably not a big thing in FL, but I would avoid WOT on large downhills. That's a good place to blow up your engine.
I want to redirect that last comment a bit.
My experience has been that a modded stock E50 (pipe, carb, mild porting) can happily run WOT all day and bomb hills without any danger.
My first maxi ran 35 on flat ground and mid to upper 40’s bombing hills. I had a Boss pipe too, which theoretically would let me rev into more dangerous territory than that circuit should.
I read posts, Jennings, asked some questions. Ride, listen, feel, then spend some time thinking about it. Eventually, you will have a more organic understanding of what is going on. You don’t have to be a scientist or engineer to go a little faster and not blow up.
Taking your top end off a lot is good too when you’re getting it all figured out. See where the heat is going. Maybe catch that ring blow-by early and correct it before something gets hot and stuck.
Like PD said, make sure there are no air leaks anywhere. No other tuning makes sense unless you are 100% positive the engine isn’t breathing through a hole it shouldn’t.
A tiny leak that barely causes a problem at idle may get more action when running full speed and pressure changes in the system are max. So, maybe you think the bing carb and intake are sealed well enough. Best to overkill and put an o-ring in there. Press them together tight and lock down the carb clamp. After that, only pull the carb via the intake nuts and leave those two clamped together while changing jets and needle settings. New intake gasket after that.
All good points thank you. Air leaks are a pain to get rid off indeed so I'm getting a temp gauge to be safe.
The firs thing I did was to put a O-ring and clamp the intake to the carb with some pressure. But still got some air leaks on the intake connection to the intake head port. I did not know by then that the gasket had to be soaked in oil (Now I do it it that way).
I also was running without the head cylinder gasket to raise compression, but getting a good seal that way it's hard. I also notice when I removed the exhaust that despite the crush gasket it was not tight enough.
Can you guys tell me what torque specs you use for the Intake and exhausts bolts to get a good seal and not get the studs stripped ?
Carlos.
Want to post in this forum? We'd love to have you join the discussion, but first: