Looing for some help.

Jberkhoudt84 · Post by **Jberkhoudt84** » Tue May 19, 2020 2:50 pm

Hello, I was hoping to get some insight on tuning my 49cc Genuine Buddy. Over the last few months I turned it into my quarantine project and overhauled most of the bike. The only problem is I cant seem to get my air mixture and idel set correctly, when I stop the bike it dies unless I keep it revved a little. There is a white smoke coming from the exhaust - smells very rich it also doesn't start on the dime with the auto start button like it used to, I have to give it a little gas. Any advice on tuning or recommendations on kit would be helpful. I did a compression test and its between 1 and 1.5 PSI. I also want to kind of get some input to make sure I did everything correctly. Here is what I am running:

- Polini Big Bore 70 CC Kit with Polini Hi-Speed Variator, Polini 16x13 rollers, Polini Torque Spring, Polini clutch springs
- Yasuni z Exhaust (removed the restrictor)
- 6mm Replay fuel filter
- 21 mm Delorto PHGB carb (Inside of the Carb is a 35 Pilot Slow Jet and a 105 Main jet. Stock was a 50 Pilot Jet and 85 Main Jet. )
- 32mm NCY Intake manifold
- Stage 6 manual choke
- Style pro Racing Carbon reedvalve

Thanks!

buzzvert · Post by **buzzvert** » Tue May 19, 2020 4:55 pm

Any reason you dropped in size on the slow jet? That may be the issue...

Jberkhoudt84 · Post by **Jberkhoudt84** » Tue May 19, 2020 5:39 pm

At first the engine was bogging down at about 1/4 throttle, I was reading this may be because the jet was to big so I changed it at the same time I also discovered a welded restrictor in the Yasuni. Since the bike was running, I never thought to put the old slow jet back in. Do you think that would be a good idea?

buzzvert · Post by **buzzvert** » Tue May 19, 2020 6:03 pm

Jberkhoudt84 wrote:At first the engine was bogging down at about 1/4 throttle, I was reading this may be because the jet was to big so I changed it at the same time I also discovered a welded restrictor in the Yasuni. Since the bike was running, I never thought to put the old slow jet back in. Do you think that would be a good idea?

I would give it a shot- the problems you describe are consistent with a fuel flow issue at low RPM. I see this a lot with clogged slow jets. A too-small slow jet could be the issue... I know it's a pain to pull the carb but if it's accessible with the bike apart, may be worth it. But, this could be a rich/lean situation as well. A plug chop may tell you more.

Jberkhoudt84 · Post by **Jberkhoudt84** » Tue May 19, 2020 6:42 pm

Thanks a lot, Ill give it a shot. A few other things id like to run past you if you don't mind.

After the build I put a new spark plug in and shortly after maybe 5 miles - just doing testing the spark plug had a gunky oily build up which was making the spark low. I cleaned it and have checked back periodically which doing tune ups and its not so bad of a build up now but still looks like I'm running rich - what is the best way to fix this?

There is oil that drips from the exhaust silencer - is this normal?

Is a 21 mm Carb to big for the 70 CC build?

Is there a way to gauge tempreture with out getting a temp gauge?

Thanks alot with helping me on these finishing questions.

buzzvert · Post by **buzzvert** » Tue May 19, 2020 10:37 pm

Jberkhoudt84 wrote:Thanks a lot, Ill give it a shot. A few other things id like to run past you if you don't mind.

After the build I put a new spark plug in and shortly after maybe 5 miles - just doing testing the spark plug had a gunky oily build up which was making the spark low. I cleaned it and have checked back periodically which doing tune ups and its not so bad of a build up now but still looks like I'm running rich - what is the best way to fix this?

There is oil that drips from the exhaust silencer - is this normal?

Is a 21 mm Carb to big for the 70 CC build?

Is there a way to gauge tempreture with out getting a temp gauge?

Thanks alot with helping me on these finishing questions.

The gunky buildup and exhaust oil may be the same condition - oil overfill. Check to see how much it's up the dipstick.

If it's not overfilled, yeah, sounds like you're running rich which could cause a lot of your woes. I will admit that's the limit of what I can help on the 50cc scoot... the rich condition may well be the issue too with the cold performance. I'll leave it to those more familiar with the smaller Buddies to see if they have any input.