I've already ruled fuel line out by opening it up and it flows great. If I open the fuel bowl screw and see how the fuel is flowing through the carb I should be able to verify this correct? Maybe my fuel is frothing due to vibration as I agree it does seem like it's starving for fuel at the top end. I'll try rerouting the fuel line line and remounting the fuel tank with thicker rubber under it.
micargi puma gts newbie build
- Thread starter Motakitty
- Start date
So I noticed that while I'm accelerating if I go to wot while going from 8mph to 20 it runs great but it's just when there isn't a load on the motor that the issue shows itself.
I have not flushed the tank but I'm not running the in tank filter and replaced the filter after my first gallon. I'm approaching 200 miles now
I'm still running the stock jet so I'm thinking it's getting too much fuel from that because the top of the piston was black. Before I had the sbp pipe I tried leaning out the jet but I only went three sizes smaller and it didn't help the issue then I got the pipe and went back to stock. My stock jet was a #70 drill bit size and I had gone done to a #73 so now I just resoldered it to a #75 and I'll try that. I've been reading about 4 stroking and how if the motor runs good with load on and then stutters off load then it's too rich. That's why I'm thinking it's the main jet that is just too fat.
So dropping the jet made it run way worse. I had to ease the throttle and it bogged allot more at wot. So I think I'll go fatter than the stock jet one size at a time. My motor didn't over heat though cause I went easy on it and kept it under 3/4 throttle and didn't get hot to the touch. Experimenting with the jet isn't fun but at least getting to it is easy.
So I opened up the jet to a 68 drill bit size and although it started very quickly even though it was very cold outside it had a very distinct 4 stroking at wot. It had torque down low but as soon the motor had no load it 4 strokes and list power so I'll drop one jet size and see how it runs. I still kinda think my gas tank is vibrating too much but I don't know.
I'm swapping out my jet to a 69 cause it'll be just slightly leaner than stock and in going to remount my gas tank to minimize vibrations to the tank. Swapping out the jets didn't help my issue of bogging at wot but I did notice the fuel in my filter was vibrating like crazy. Does anyone have any ideas to isolate the fuel line from the frame as I like to keep the line attached to the frame. I'm going to cut up an old tire and place that under the tank and line the straps with some kind of rubber maybe a bike tube. When I'm holding the throttle open my tank is vibrating like crazy so that's why I'm thinking it's vibrations. Any suggestions please let me know.
So today I went to remove my jet and I always just take the whole tube out. When I went to unscrew the tube the top part broke off inside the carb so I removed the carb and got the piece out(it just unscrewed very easily, lucky me.) I had an extra one from my stock carb so that went easy.I also cut a piece of an old tire to place under my gas tank instead of the mouse pad I had before and lined the tank straps with the mouse pad to try to isolate the tank from vibrations. I also moved my fuel line away from the frame. Now the tank wiggled slightly where as before the tank was rigid. I'll see if that helps at all. I also had to re-tention the motor chain, no big deal.
lol daily problems 
if something is not going wrong for a couple days i think there is a major problem lol
if something is not going wrong for a couple days i think there is a major problem lolTrue. But I've been having this same issue for awhile now and I just want it solved. I really don't mind working on my bike but at some point I want it where I just need to do maintenance on it.
I rode today and still sane problem but I saw some bubbles from my spark plug gasket so I'm losing compression there so I'll replace it but before I do I'll check the compression. I have a tester at home.
I'm getting good compression, between 120-130psi. I cleaned the spark plug seat cause it had some paint spots on it and installed a new plug. I remember my motor running great with a port matched exhaust but then after I matched the intake is when the issue started of it bogging at wot. I didn't smooth the intake I just left it alone after opening it up. Maybe if I rough it up more it'll help as I've ruled out fuel delivery, compression, jetting, vibrations, air leaks, spark. Or maybe I'll just get a stock intake and leave it as is.
Replaced the plug and that wasn't the issue. I'm going to rough up the intake manifold more where I port matched it since I did notice the issue after doing the mod. I'm getting top speed of 24mph which isn't bad but I know there's more in it and is like to cruise at 25 with a top speed of 30 so I'm not far off.
I would think you would want to polish it smooth, so there is no hangup for the gas to catch on.
Don't know why more people don't use the diaphragm carbs with adjustable jets. So easy to maintain the fuel flow, and if you measure your mixture every time you mix should never have adjust much at all. Like what FFV8 did http://motorbicycling.com/showthread.php?p=577691#post577691 ................Curt
Don't know why more people don't use the diaphragm carbs with adjustable jets. So easy to maintain the fuel flow, and if you measure your mixture every time you mix should never have adjust much at all. Like what FFV8 did http://motorbicycling.com/showthread.php?p=577691#post577691 ................Curt