I'm having horsepower issues with my Maddog

[jayb]

Thank you. I bought the valve head as part of the kit. It says they are 69mm so I should have bought the correct rocker arms as it stated for 69mm valves. I think I'm good now and have all the correct parts ordered, at least I hope so!

It's just odd that it wasn't part of the kit. If I didn't start watching the videos you recommended I would have started building this to find out I'm missing the rocker arms..lol

I'm still learning 😋

[sinfull]

We all learn. When maddog 1st came out I threw part after part at it and failed. Took me a long time to actually figure it out and a whole lot of going backwards. What makes a normal tire scooter faster doesn't work on a maddog. That rear tire is just really difficult to overcome with 50cc

[GrumpyUnk]

When you put it back together, make sure all shrouds are installed and that they fit properly. The gasket around the cylinder head keeps the air flowing past the hot spots rather than blowing out and cooling nothing. Be sure to stuff some paper towels/rags around the connecting rod to prevent parts/dirt/tools from jumping into the crankcase. The circlips holding the wrist pin(gudgeon in UK) will jump out and hide with little encouragement. You may want to insure they have no place to hide behind or under, or use a large enough plastic bag over the piston to catch them as you remove them from the groove. Some say(I agree) to put the circlip opening at the top or bottom so it cannot squeeze closed when the piston reaches TDC or BDC and comes to a quick stop before reversing direction. It does make sense, but I would like to see someone do a high-speed camera recording to actually see if the circlips flex then. Check ring end gap, a calculator on site in the tools/tech section, before installing, and pre-set the gaps 120 degrees apart. I drench the rings and cylinder with oil to make installation easier and pre-lube before first start. Some do, some do not. Be CLEAN. No goozie on the paper cylinder base gasket so you don't block the oil passage by mistake. Hold the cam chain from disappearing into the gloom with a coat hanger or length of string/rope with a weight. Not fun to fish out. And, have fun.
tom

[jayb]

It's been fun putting this together. My torque wrench wasn't working correctly when I was tightening the 4 nuts on the rocker assembly and it snapped so I had to order another one..lol

It's all put together now and my variator tool came today so I was able to install that as well. I just have to put the plastics over the engine back on then I can start it up and see.

One question came to mind while I was putting the valve cover back on. I was wondering if I needed a different one since I went from 64mm valves to 69mm valves. It fit perfectly fine when I put it on.

I checked online and there seems to be no difference in fit. The only difference is the kit removes the egr assembly so you can buy a new valve cover to remove the unnecessary parts. I'm not worried about that at this point. Just a looks thing. I should be good using the same valve cover. If I'm wrong on this let me know.

I should have waited till next week to do all of this though as I took the week off work. I'm running myself a bit thin doing all of this during the work week. I can't help myself though as I'm excited to feel the change...lol

[90GTVert]

The valve cover should be fine.

I'm a bit concerned that it dropped 10MPH from original speed and that was never resolved, so just be attentive when tuning the new setup in case there's still some underlying issue. Not trying to worry you, but it's good to stay on your toes.

Jul 9, 2024 10:31:19 GMT -5 GrumpyUnk said:

Some say(I agree) to put the circlip opening at the top or bottom so it cannot squeeze closed when the piston reaches TDC or BDC and comes to a quick stop before reversing direction. It does make sense, but I would like to see someone do a high-speed camera recording to actually see if the circlips flex then.

I have no idea if there's actual evidence of this out there, but piston manufacturers and engine builders recommend it. Maybe message one of the folks that has made a clear cylinder on social media and offer the idea to test. It's probably hard to capture and I'm not sure if they'd also need to be on a dyno for heat/load to test all conditions or if it can even be accurately tested with those clear cylinders, but that's likely our best hope of seeing it. I do know that it can be devastating when a circlip comes out, so even if it's a slim chance that it causes an issue it's worth it to minimize any risk that you can. Other tip is always check that it's in and doesn't spin easily once it's in. Here's my two-stroke from this past Saturday. Expensive garbage now from a tiny little circlip.







Again, sorry. This isn't intended to induce anxiety. Just good to know why the issue gets attention.

[jayb]

Okay, everything is installed and put back together. I started it with making no changes to the carburetor. Took a bit but it started.

Then I increased the main jet from a 98 to 100 and started it again. Sounded way better.

I have a question about the rockers and noise. Are you supposed to hear them chattering all the time? I put the gaps both at 0.04 and made sure the 0.05 wouldn't go in.

I didn't hear the tapping much at all with the stock motor so I'm wondering if my gap is to big? I was going off mini me on YouTube as he has the same bike.

It's not super loud but you definitely know what it is when you walk up to the bike.

The manual says to gap between 0.04 up to 0.07 so I thought 0.04 would be ok but it's a bit annoying. I haven't took it for a test ride yet to see if it's noticeable while driving because I don't want to screw up the bike if I'm wrong.

[jayb]

I'm wondering if I should give it time to see if it gets better as I believe I saw something about having to break it in for the valves to expand right or something... or another

[sinfull]

Dumb question, did you put oil in the bike ??

Put a few miles on it and then recheck valves. Also try to see where the noise is coming from. Take the Valve cover off and does it look oiled or not getting oil.

[jayb]

Yes the oil is full. These are tapper valves so they are supposed to make some noise. I do know that is the noise I'm hearing.

I will work on breaking it in since it's all new and then do an oil change. Then I'll double check the spacing in the rockers.

I've spent more man hours on the bike than I have in riding hours. I think it's time to step back and hit the roads for awhile 🤣

I can hear and feel the power now so I'm excited to get on the road and see the difference.

[sinfull]

That is what it is about. Have fun 👍 😊

[jayb]

I am all set now. I took it out for a test drive last night. I changed the carb from a 98 main jet to a 100 main jet and adjusted the mixture screw.

Took it to a friend's house and pulled the sparkplug. It was completely black so we cleaned it up and changed the needle hight fom the 5th notch to the 4th notch. Adjusted the mixture screw again to where she was sounding awesome.

We went for a ride and I am so happy with the bbk. I am finally able to keep up with traffic. I was able to hit 45mph which is where I wanted to be.

Do you think it would be worth it to change the torque and clutch springs? I thought about ordering the blue 1,000RPM ones to install but I'm not sure if it is necessary or not. What are your thoughts?

I also want to replace the rear shocks as the ones on the bike are really stiff and hurts my back. The streets around me are horrible to ride on. Every bump, crack and pothole I can feel it in my back. I'll have to find ones that actually move with the road conditions.

[sinfull]

Clutch springs are going to be personal preference and how the bike responds. Some people like the stock engagement Some want it to grab quicker. Personal choice and how you want it to feel.

Rear shock is again going to be all about you. Every ncy shock I have ever had has always been softer than stock, some bikes it works out to be a good thing others it turned out to be all bad. No body work on the maddog to bottom out and crack plenty of room to go softer. I don't remember if the 1st gens were adjustable with a collar on the body or not, changed mine right away with generic Chinese that were softer. Getting a good tire with more of a actual bike tire helped mine out, got rid of the flat hard as a rock tire. Wide flat tire looks cool not much give to it. Take the back tire and hold it arm length chest high and drop it, tire should bounce, mine had no bounce

Only problem with scooter shock are they usually don't have a lot of posted information like spring and travel so it's a dice throw, sometimes it is good sometimes it's bad. Ordered a rear shock before and was able to flex it by hand. Like hold it like you were going to break a stick and hear it clicking as you bend up and down. Not supposed to flex like that.

[jayb]

Thanks Sinfull. You know, I was wondering what was up with the back tire on this thing as it looks more plastic than rubber. That makes sense though. I'll definitely look into this more.

You are correct about it being a crapshoot on the shocks. I have been noticing that there isn't a lot of info listed about the specs on most of the shocks online. It seems like it would be better to pay the higher cost for the nyc shocks having a peice of mind knowing that's the best way to go.

It was a lot of fun though being able to take a ride around the city with the extra power. Well worth the research and questioning to get to this point. I might try the clutch springs later on to see if I like it or possibly even look into upgrading the gears. But for now I think I'll take a step back and enjoy the fruits of the labor and ride.

[GrumpyUnk]

Check the tire pressure. Could be over-inflated which would cause a harsher ride.
I think that you can close the valve clearance a bit more if you want to. When cold, you might find the clearance is at a minimum, and it opens further when hot. The expansion rates of Fe and Al are different, with the Al expanding more per degree change in temperature.
My observation, anecdotal, is that valve noise is louder when the engine heats up. That happens when clearance increases. If the taps are too loud, close down the clearance if it is bothersome. I do not think it will adversely affect anything. I think the valve clearance is adjusted to almost zero from the factory, and when we poke around and adjust to the 'suggested' clearance, we get some noise. I like a little noise, but it can be louder than expected.
I do suggest a few good hard pulls with the engine in 'top gear', and then backing off the throttle completely. That will help the rings seat as the pressure will get behind the rings and push them against the cylinder tightly. Or so I have read from a set of rings decades ago. You want to keep the rpms down if you can(ha!) and almost floor it. Hard to to on a CVT machine. The instrux said to do 10 accelerations and slow downs.
tom

[kevino]

Jul 11, 2024 12:05:32 GMT -5 jayb said:

Yes the oil is full. These are tapper valves so they are supposed to make some noise. I do know that is the noise I'm hearing.

I will work on breaking it in since it's all new and then do an oil change. Then I'll double check the spacing in the rockers.

I've spent more man hours on the bike than I have in riding hours. I think it's time to step back and hit the roads for awhile 🤣

I can hear and feel the power now so I'm excited to get on the road and see the difference.

I'm relatively new to 50cc scooters.  But I have 30 years experience rebuilding old VWs.   Valve lash is supposed to be 0.4 but over time the #3 cylinder overheats and burns the bearing.    0.4 is okay for the other cylinders but #3 needs 0.8.  Because of the oil cooler there's less cooling reaching the cylinder.    Experts tell me if you can hear the valve clicking it's safe.  If you can't the engine will fail eventually.