Finally got the Mack Mag built!

[FurryOnTheInside]

When you say there is a delay or lag in the rpm can you elaborate? Like when I pull the throttle it takes longer to reach the rpm?

I mean you vary the throttle and.. then the engine begins to pick up or slow down, that is lean.
If the engine responds instantly to any varying of the throttle then it isn't lean.
Not about how quickly the RPM climbs. Just the time it takes to react to your input.

 

[Street Ryderz]

No no no don’t get me wrong I know you have much more knowledge on all this than I do and I really appreciate the help and advice! Shoot, without these forums I’d be in deep trouble lol. So I did some further testing when I got home from work. Pulled and cleaned the whole carb just so be safe and left the air filter off just to find the sweet spot for jetting there.Got the engine warmed up and started with a 70 jet in the RT. Wasn’t getting me very far running very rich so went down to a 69, better but not there yet. Jumped to a 68 then to 67. At 67 I felt like it was right about where I wanted it to be as far as all my rpm ranges feeling good and some slight four stroking at WOT. Pulled back into the shop and put the uni filter on and it was running rich. Ended up finding a similar sweet spot that I felt like keeps me on the safe side of not running too lean with a 64 jet. The reversion is still there but I believe I can manage it currently. Does a 64 jet seem too low? Without a spark plug digital temp readout I can’t really tell what is too hot for my engine and since it’s shiny aluminum my laser therm may not be reading it correctly, but what is a safe temp range for these to be running at? And what’s a p/p engine lol?

I dont like to run them with a constant temp above 300f and I use an ir type temp reader it works great,I check it's calibration all the time with body temp LOL it's accurate if you aim between the head and cylinder like your aiming at the gasket it's self and between the plug and exhaust port.The 64 jet sounds better you should still probably do another plug reading after it's run a bit, I'm really suprised that the uni filter is being that restrictive you may want to try different fillters to see witch will allow the same jet or as close to it as without the filter.

 

[Kpi890]

I dont like to run them with a constant temp above 300f and I use an ir type temp reader it works great,I check it's calibration all the time with body temp LOL it's accurate if you aim between the head and cylinder like your aiming at the gasket it's self and between the plug and exhaust port.The 64 jet sounds better you should still probably do another plug reading after it's run a bit, I'm really suprised that the uni filter is being that restrictive you may want to try different fillters to see witch will allow the same jet or as close to it as without the filter.

I will do that and thanks for all the help I appreciate it!

 

[Kpi890]

For all those that may be following this thread I figured I’d give an update. As of right now the bike is running pretty darn well! Picked up a snorkel extension for the air filter which killed two birds, it got my air filter up behind and beneath my seat and improved the fuel reversion issues I’ve been having a little bit. I did see some oil gathered underneath the lowest part of the crankcase yesterday but wiped it up and haven’t seen any back since and I’m not sure how long it’s been there. I bought some 1” ID flexible exhaust tubing on amazon that slid perfectly over my expansion chamber so I can route that wherever I would like, which is nice I’m not getting 2 smoke up my shorts anymore! Also got some new Kenda City Slick tires which made a nice improvement and added some smoothness to the ride. Most everything you see on this bike is still slightly temporary (hence all the cable ties and exposed wiring with wire nuts lol) but I haven’t settled on a final routing procedure for all my brake cables, exhaust, and wiring yet. Also, because I feel like I’m just waiting for another “issue” I’ll have to troubleshoot and don’t want to have to unbolt everything. But for now I’m pretty happy, it starts smooth idles as low as I want and is getting decent top speed although it four strokes at the highest rpms on flat ground or downhill it evens out when I hit the uphills. Should be nice riding at the lake this weekend! If anyone has any suggestions on things I can do to tidy and clean up this mess I have created as far as the looks I would appreciate it! Or any other general criticisms are always welcome. Thanks!

EDIT: Also need suggestions on an absorption style muffler if anyone know where I can attain one at a cheap price otherwise I’ll just research and make one once the weather cools down in a bit. This thing screams just like a dirt bike and needs to be dampened a little bit!

 

[FurryOnTheInside]

For all those that may be following this thread I figured I’d give an update. As of right now the bike is running pretty darn well! Picked up a snorkel extension for the air filter which killed two birds, it got my air filter up behind and beneath my seat and improved the fuel reversion issues I’ve been having a little bit. I did see some oil gathered underneath the lowest part of the crankcase yesterday but wiped it up and haven’t seen any back since and I’m not sure how long it’s been there. I bought some 1” ID flexible exhaust tubing on amazon that slid perfectly over my expansion chamber so I can route that wherever I would like, which is nice I’m not getting 2 smoke up my shorts anymore! Also got some new Kenda City Slick tires which made a nice improvement and added some smoothness to the ride. Most everything you see on this bike is still slightly temporary (hence all the cable ties and exposed wiring with wire nuts lol) but I haven’t settled on a final routing procedure for all my brake cables, exhaust, and wiring yet. Also, because I feel like I’m just waiting for another “issue” I’ll have to troubleshoot and don’t want to have to unbolt everything. But for now I’m pretty happy, it starts smooth idles as low as I want and is getting decent top speed although it four strokes at the highest rpms on flat ground or downhill it evens out when I hit the uphills. Should be nice riding at the lake this weekend! If anyone has any suggestions on things I can do to tidy and clean up this mess I have created as far as the looks I would appreciate it! Or any other general criticisms are always welcome. Thanks!

EDIT: Also need suggestions on an absorption style muffler if anyone know where I can attain one at a cheap price otherwise I’ll just research and make one once the weather cools down in a bit. This thing screams just like a dirt bike and needs to be dampened a little bit!
View attachment 82639View attachment 82640View attachment 82641

If you check out the media page you'll see @gary55 posted a photo very recently of a bike with the muffler you want.
If that's the stock kit fuel hose I would get some nice soft silicone hose and move the fuel filter closer to the carb to get that bubble inside the filter rather than the hose, and hopefully get the hose further away from the head. The kit hose is PVC anyway, I believe, so it isn't really worth keeping for the price of some much nicer red or black silicone.
Looking pretty great so far though. And that's quite a snorkel!

 

[gary55]

HPS 1 Foot Silicone Tube Coupler Hose Turbo Hot Side Aramid

Motorcycle Modified Muffler Exhaust 150CC Racing Scooter Dirt Bike ATV 2 Stroke 727670536836 | eBay

Use the 7/8" ID hose
View media item 61262

 

[Kpi890]

If you check out the media page you'll see @gary55 posted a photo very recently of a bike with the muffler you want.
If that's the stock kit fuel hose I would get some nice soft silicone hose and move the fuel filter closer to the carb to get that bubble inside the filter rather than the hose, and hopefully get the hose further away from the head. The kit hose is PVC anyway, I believe, so it isn't really worth keeping for the price of some much nicer red or black silicone.
Looking pretty great so far though. And that's quite a snorkel!

Funny you mentioned that I have some red 3/16” nice fuel line ready to go on it right now you just reminded me! Yea this kit hose is rock hard right now and I’ll have to come up with a sneaky way to get the filter close to the carb because the way I have the carb setup it’s really close to the straight bar on the bike. You think I could come off the Pitcock and go over top of the bar and then to the carb? If so that would allow me more options for that setup. Thanks!

 

[Kpi890]

HPS 1 Foot Silicone Tube Coupler Hose Turbo Hot Side Aramid

Motorcycle Modified Muffler Exhaust 150CC Racing Scooter Dirt Bike ATV 2 Stroke 727670536836 | eBay

Use the 7/8" ID hose
View media item 61262

Ooooh that’s the muffler I need! How well does it work for you? Right now I just have the super loud dirt bike sound to the bike coming from the expansion chamber. And Gary have you seen the self fusing high heat silicone tape? It’s extemely easy and cheap to use and is heat resistant to 500F. 10 foot roll is only $5 if I recall correctly, I wrap it tightly around and then secure it with a black cable tie. It doesn’t ever get hot enough through the tape to even affect the nylon cable ties. Just thought I’d mention it! I’ll definitely be looking into this exhaust though thank you!

EDIT: also do you have any pictures on how you adapted that muffler to fit? My expansion chamber tip is 1”OD.

 

[gary55]

Ooooh that’s the muffler I need! How well does it work for you? Right now I just have the super loud dirt bike sound to the bike coming from the expansion chamber. And Gary have you seen the self fusing high heat silicone tape? It’s extemely easy and cheap to use and is heat resistant to 500F. 10 foot roll is only $5 if I recall correctly, I wrap it tightly around and then secure it with a black cable tie. It doesn’t ever get hot enough through the tape to even affect the nylon cable ties. Just thought I’d mention it! I’ll definitely be looking into this exhaust though thank you!

EDIT: also do you have any pictures on how you adapted that muffler to fit? My expansion chamber tip is 1”OD.
View attachment 82642

I saw that tape earlier in the thread. It looks like it could come in handy. I didn't know the zeda66 pipe had a 1" od stinger. I'm using the mz 65 pipe and it has a 7/8 od stinger. You could cut some splits in it to reduce the od at the end to fit it into the flange, or take it to a muffler shop and have the flange on the muffler welded onto your pipe. These mufflers work great. They really tone it down, and have great flow.

 

[Kpi890]

I saw that tape earlier in the thread. It looks like it could come in handy. I didn't know the zeda66 pipe had a 1" od stinger. I'm using the mz 65 pipe and it has a 7/8 od stinger. You could cut some splits in it to reduce the od at the end to fit it into the flange, or take it to a muffler shop and have the flange on the muffler welded onto your pipe. These mufflers work great. They really tone it down, and have great flow.

Awesome that’s just what I needed and man for $15 I’m tempted to buy another to experiment with! Thanks!