165fmm and nibbi PE28FL tuning questions.

[NathanTC]

Originally Posted by Megadan

I think you are forgetting the Primary Drive ratio. That is the ratio between the crank gear and clutch basket gear.

i knew there was something im missing somewhere. My bike is not in any of the list on any of these things.

I assumed that the crankshaft to drive sprocket would be .98 in 5th gear. Didn't think there was another reduction somewhere in between. Engine is a 165FMM other than that, i cannot find the info on the ratio you just mentioned.

Also i hope to get the bike apart again soon to check that float level. I see a couple things i did incorrectly when setting the float that may have it a bit high.

[toneloc6530]

My jetting ended up similar but 40 pilot with 115 main. Mine does the same thing if I go zero to wot as fast as possible. I think it’s just too much carb for the engine imo but I am far from an expert. I did exactly what megadan described as far as tuning pilot at idle. I wonder if some of these tuning differences are variances in Chinese jets

[Megadan]

Originally Posted by toneloc6530

My jetting ended up similar but 40 pilot with 115 main. Mine does the same thing if I go zero to wot as fast as possible. I think it’s just too much carb for the engine imo but I am far from an expert. I did exactly what megadan described as far as tuning pilot at idle. I wonder if some of these tuning differences are variances in Chinese jets

I use genuine keihin jets for that reason.

As far as the throttle bog. Setting my float height to 18mm and moving my needle to the second notch solved that issue for me. My issue was just too much fuel on that transition.

[Megadan]

Originally Posted by NathanTC

i knew there was something im missing somewhere. My bike is not in any of the list on any of these things.

I assumed that the crankshaft to drive sprocket would be .98 in 5th gear. Didn't think there was another reduction somewhere in between. Engine is a 165FMM other than that, i cannot find the info on the ratio you just mentioned.

Also i hope to get the bike apart again soon to check that float level. I see a couple things i did incorrectly when setting the float that may have it a bit high.

The primary drive for your engine is likely the same 3.333 ratio as the CG engines since they basically use the same clutch setups and baskets. Your 5th gear ratio is also close to the same as the CG250. You could just use the rps Hawk in gearingcommander and alter values as needed like tire size and 5th gear to get the desired result.

[NathanTC]

Originally Posted by Megadan

I use genuine keihin jets for that reason.

i used these

https://www.amazon.com/dp/B082F7Y6ZK...roduct_details

[Megadan]

Originally Posted by NathanTC

i used these

https://www.amazon.com/dp/B082F7Y6ZK...roduct_details

My biggest issue with jet kits like that is that the labeling and actual sizing tend to be inconsistent. They do work, but you can't always trust that the number stamped on it is actually the number it represents.

[NathanTC]

well, looks like the person who said "float was incorrect" is spot on. Went for a ride today and when i put the bike in the garage i could smell gas. I always turn off the fuel and let it idol until it dies. Looking it over the fuel filter smelled like gas and there was just a little gas on the over flow hose and swing arm. Damn it. I get to take this thing apart and get the float correct. I bet this is going to mean re jetting again.

On a side note, i now have confirmed that i have a 13t-42t sprocket set and i believe a 520 chain. Gotta mike it to be sure.

On a much more fun note, my M35A2 and home made crane are going to work flawless for taking 4 bikes and some gear out for a good time.

[grhanka]

Are you just seeing a hesitation on rapid twist of the throttle? This is a classic problem with carbureted engines, and the reason for an accelerator pump (present on most cars and some bikes) to give a quick squirt of fuel.

[grhanka]

Be advised that pod filter will probably strangle your engine if it gets wet. Paper filters look cool and filter fine particles, but they swell when wet and stop passing air. This is such a huge flaw, I don't understand why they are popular.

[NathanTC]

Originally Posted by grhanka

Be advised that pod filter will probably strangle your engine if it gets wet. Paper filters look cool and filter fine particles, but they swell when wet and stop passing air. This is such a huge flaw, I don't understand why they are popular.

I'm absolutely not new to motorcycles. The rapid twisting of the throttle should not cause a bog even without an accelerator pump. I've had many bikes that did not have this issue, and I am sure I will figure out how to tune it out of this one. As for the pod filter, there isn't any other option on this bike, with the carburetor I chose. The carburetor inlet is much larger than the old air intake on the bike, and the carburetor itself is physically longer. So using the factory setup is not an option. And the factory style carburetor is an inferior one. So it has absolutely nothing to do with the pod filter being popular, and everything to do with it being better than no filter at all. Got to use what fits. As for the argument about the filter getting wet, I have zero interest in riding in the rain or water.

[Megadan]

Originally Posted by NathanTC

I get to take this thing apart and get the float correct. I bet this is going to mean re jetting again.

Might not need to do a full re-jet. At least not on the main. The pilot maybe, and idle mixture for sure will need a bit of tweaking.

[Megadan]

Originally Posted by grhanka

Are you just seeing a hesitation on rapid twist of the throttle? This is a classic problem with carbureted engines, and the reason for an accelerator pump (present on most cars and some bikes) to give a quick squirt of fuel.

You aren't understanding the issue because you aren't familiar with how these carbs behave. The Nibbi PE's have a slightly more aggressive needle taper and diameter, so they tend to be richer much sooner than the PZ or even most PWK carbs. normally this results in a random but fairly light occasional hiccup at 1/4 and 3/4 throttle as it transitions between the jets.

Add in a too high float height causing extra fuel to basically be spit into the intake with rapid throttle application and you get an actual rich spike as it tries to equalize, resulting in the bog he is having. It is an issue I am very familiar with having tuned the PE30 and now this 28mm version.

Originally Posted by grhanka

Be advised that pod filter will probably strangle your engine if it gets wet. Paper filters look cool and filter fine particles, but they swell when wet and stop passing air. This is such a huge flaw, I don't understand why they are popular.

I do fun things to prevent my paper pod filters from getting wet. I actually use an outer foam sleeve pre-filter and a filter sock, but it is also surrounded on most sides with things that prevent it from being splashed or otherwise soaked. I have ridden in literal downpours and never had a wet filter. It's all about precaution and placement.

[NathanTC]

ok so still working out some bugs, have yet to pull the carb again to set the floats at 18mm.

Found this info on the net about the 165fmm engine
Roted Power & Rotating Speed: KW/(r/min): 11.0/(7500± 500)
Max. Torque & Rotating Speed: N. M/(r/min): ≥ 17/(6000± 500)

Just installed a 15t sprocket and now notice the engine seems to be out of its power ban around 6500-7000 rpm. With the original sprockets it would just run right up to 8000 rpm but was gutless getting there.

My question is this, should i be looking into CDI box's or different jetting? Or should i be gearing the bike a bit taller to get a 65mph 6500 rpm cruise speed/rpm? Engine pulls strong up to 6k but noticeably starts to fall off after that. Not sure if that is just what this engine has to offer or if its tuning.

current set up is a 520 chain, 15-42 sprockets and verified 7200 rpm at 65 mph
if i drop it to a 520 chain 15-40 sprocket set i should be 6850 rpm at 64.99 mph
if i drop it to a 520 chain 15-39 sprocket set i should be 6700 rpm at 65.2 mph
if i drop it to a 520 chain 15-38 sprocket set i should be 6500 rpm at 64.92

im sure someone here has been right where im at. Trying to get the bike to a 65 mph cruise speed. I dont need anything faster and i dont want to be at the max to get there. I hate to do it but im almost tempted to buy all 3 rear sprockets and try them all, just feel this will require cutting the chain as i step down. Went from a 13 to a 15 with the oem chain so maybe that give a little wiggle room.

Just not sure if i can tune the engine for more rpm without losing my fun low end power.

[ghostdancing]

Originally Posted by NathanTC

ok so still working out some bugs, have yet to pull the carb again to set the floats at 18mm.

Found this info on the net about the 165fmm engine
Roted Power & Rotating Speed: KW/(r/min): 11.0/(7500± 500)
Max. Torque & Rotating Speed: N. M/(r/min): ≥ 17/(6000± 500)

Just installed a 15t sprocket and now notice the engine seems to be out of its power ban around 6500-7000 rpm. With the original sprockets it would just run right up to 8000 rpm but was gutless getting there.

My question is this, should i be looking into CDI box's or different jetting? Or should i be gearing the bike a bit taller to get a 65mph 6500 rpm cruise speed/rpm? Engine pulls strong up to 6k but noticeably starts to fall off after that. Not sure if that is just what this engine has to offer or if its tuning.

current set up is a 520 chain, 15-42 sprockets and verified 7200 rpm at 65 mph
if i drop it to a 520 chain 15-40 sprocket set i should be 6850 rpm at 64.99 mph
if i drop it to a 520 chain 15-39 sprocket set i should be 6700 rpm at 65.2 mph
if i drop it to a 520 chain 15-38 sprocket set i should be 6500 rpm at 64.92

im sure someone here has been right where im at. Trying to get the bike to a 65 mph cruise speed. I dont need anything faster and i dont want to be at the max to get there. I hate to do it but im almost tempted to buy all 3 rear sprockets and try them all, just feel this will require cutting the chain as i step down. Went from a 13 to a 15 with the oem chain so maybe that give a little wiggle room.

Just not sure if i can tune the engine for more rpm without losing my fun low end power.

did you had to grind a bit the engine case to install the 15T 520 sprocket?

[NathanTC]

Originally Posted by ghostdancing

did you had to grind a bit the engine case to install the 15T 520 sprocket?

yes, and still working out if/where i want to relocate the gear position sensor wiring. Honestly that part is not all that important to me but it may be for some

http://www.chinariders.net/showthread.php?t=30657