2020 rps hawk fuel problem

[Nab]

Hi. New to getting help this way so sorry for whatever. I recently bought a hawk and it was running okay but was running lean so I tried adjusting the fuel are mixture to no avail. Now all it does is run on cold then when hot it stumbles on acceleration and runs Rich no matter how I adjust the fuel-air mixture and I've tried changing the Jets. It's a nibbi 30mm that has the stock jets. Any help will be appreciated.

[BuffaloChinaRider]

Originally Posted by Nab

Hi. New to getting help this way so sorry for whatever. I recently bought a hawk and it was running okay but was running lean so I tried adjusting the fuel are mixture to no avail. Now all it does is run on cold then when hot it stumbles on acceleration and runs Rich no matter how I adjust the fuel-air mixture and I've tried changing the Jets. It's a nibbi 30mm that has the stock jets. Any help will be appreciated.

What are the jet numbers? Is it stock exhaust?. Your jetting could be off or there could be a vacuum leak somewhere as well. Carb should be taken off and cleaned well too.

[Nab]

Originally Posted by BuffaloChinaRider

What are the jet numbers? Is it stock exhaust?. Your jetting could be off or there could be a vacuum leak somewhere as well. Carb should be taken off and cleaned well too.

I'll have to check the jet numbers forgot to write it down. Stock exhaust with cat delete. New fuel lines, filter and fuel cut off switch. Vacuum leaks? Like in the intake Manifold? How would I find out if I do have a vacuum leak? I'm used to working on small engines and trucks so would I do the same thing as a car and spray brake cleaner around the area to find a leak if there is one?

[Deckard_Cain]

Originally Posted by Nab

I'll have to check the jet numbers forgot to write it down. Stock exhaust with cat delete. New fuel lines, filter and fuel cut off switch. Vacuum leaks? Like in the intake Manifold? How would I find out if I do have a vacuum leak? I'm used to working on small engines and trucks so would I do the same thing as a car and spray brake cleaner around the area to find a leak if there is one?

Yes, the brake cleaner spray trick works. That's now I found out I put the plastic thermal spacer on my carburetor in backwards on my Vader..causing a vac leak.

Definitely get those jet numbers... and it matters what your elevation is as well.

[JerryHawk250]

Good starting point on jets are a 40 pilot and 110 main. Get the idle mixture resolved first then work on main jet tuning after you have the pilot jets and mixture adjusted.

[Nab]

Originally Posted by BuffaloChinaRider

What are the jet numbers? Is it stock exhaust?. Your jetting could be off or there could be a vacuum leak somewhere as well. Carb should be taken off and cleaned well too.

The jets are, main 128 and pilot 40. Like I previously stated it was running great but cut out on full throttle in fifth gear at 8 thou rpms with 15 front and 50 back sprocket. Sooo I bought a 17 front and ran with that but cut out at 6 thou rpms instead. I currently have black soot on sparkplug and coming out exhaust. All I did was adjust the fuel air screw and now it cuts/stalls on acceleration and I tried readjusting the screw to no avail putting it back to the way it was to no avail.

P.s, if she running good enough then don't fix or improve itdoh:

[Nab]

Originally Posted by JerryHawk250

Good starting point on jets are a 40 pilot and 110 main. Get the idle mixture resolved first then work on main jet tuning after you have the pilot jets and mixture adjusted.

Do you know what I should put the screw at? I currently have it set to 1 3/4 turn.

[JerryHawk250]

Originally Posted by Nab

Do you know what I should put the screw at? I currently have it set to 1 3/4 turn.

1 1/2 turns out is good starting point. If it still running rich at idle then try dropping to a 39 or 38 pilot. 128 main will be too big. You're running way too rich.

[Megadan]

I think doing a bit of research on how the jets affect different aspects of throttle position would go a long way here. You are adjusting the idle mixture because the engine is blowing black smoke and cutting out at what I can only assume is near wide open throttle conditions.

So, right off the bat, you are in for a bad time. You have little carb tuning experience and you are trying to tune a too big carb on a nearly stock bike.

Jet suggestions from the guy who first installed a PE30 on a Hawk? 35 or 38 pilot jet.

Needle, for now leave it in the 3rd slot, but once you sort out the pilot, idle mixture, and main we can revisit as it may need to go up one slot to the 2nd one.

Main jet. 128 is too big. A 115 is likely going to be the ticket, but you will have to do the work to determine where it should be. The PE30 is a tricky carb to get the tune dialed in with, especially on a bike with no head porting. It's like putting an 850cfm Holley on a 289 chevy small block.

[tknj99]

Originally Posted by Megadan

I think doing a bit of research on how the jets affect different aspects of throttle position would go a long way here. You are adjusting the idle mixture because the engine is blowing black smoke and cutting out at what I can only assume is near wide open throttle conditions.

So, right off the bat, you are in for a bad time. You have little carb tuning experience and you are trying to tune a too big carb on a nearly stock bike.

Jet suggestions from the guy who first installed a PE30 on a Hawk? 35 or 38 pilot jet.

Needle, for now leave it in the 3rd slot, but once you sort out the pilot, idle mixture, and main we can revisit as it may need to go up one slot to the 2nd one.

Main jet. 128 is too big. A 115 is likely going to be the ticket, but you will have to do the work to determine where it should be. The PE30 is a tricky carb to get the tune dialed in with, especially on a bike with no head porting. It's like putting an 850cfm Holley on a 289 chevy small block.

Sorry to threadjack.. but a question for @Megadan re: jetting which may also help the OP..
My Brozz with the PE30 is running great with my jetting listed in my sig.. the only hiccup i notice is if i go wide open and pin it for a bit and then let off abruptly the bike will feel like the engine is pausing for lack of a better way to explain and will pop once or twice.. could this be too rich on the main with the 140? It builds up to full speed with no issues, its just the letting off abruptly that causes this symptom.. thanks

[Megadan]

Originally Posted by tknj99

Sorry to threadjack.. but a question for @Megadan re: jetting which may also help the OP..
My Brozz with the PE30 is running great with my jetting listed in my sig.. the only hiccup i notice is if i go wide open and pin it for a bit and then let off abruptly the bike will feel like the engine is pausing for lack of a better way to explain and will pop once or twice.. could this be too rich on the main with the 140? It builds up to full speed with no issues, its just the letting off abruptly that causes this symptom.. thanks

Very possible the 140 is just a hair on the rich side. Drop to a 138 main and see how the behavior changes. One of my favorite things about the pe30 is being able to swap mains relatively easily.

[Nab]

Originally Posted by Deckard_Cain

Yes, the brake cleaner spray trick works. That's now I found out I put the plastic thermal spacer on my carburetor in backwards on my Vader..causing a vac leak.

Definitely get those jet numbers... and it matters what your elevation is as well.

My current elevation is 600-663ft. I've never had to factor in my elevation so any help understanding what I need to do will be mu h appreciated.

[Nab]

Originally Posted by Megadan

I think doing a bit of research on how the jets affect different aspects of throttle position would go a long way here. You are adjusting the idle mixture because the engine is blowing black smoke and cutting out at what I can only assume is near wide open throttle conditions.

So, right off the bat, you are in for a bad time. You have little carb tuning experience and you are trying to tune a too big carb on a nearly stock bike.

Jet suggestions from the guy who first installed a PE30 on a Hawk? 35 or 38 pilot jet.

Needle, for now leave it in the 3rd slot, but once you sort out the pilot, idle mixture, and main we can revisit as it may need to go up one slot to the 2nd one.

Main jet. 128 is too big. A 115 is likely going to be the ticket, but you will have to do the work to determine where it should be. The PE30 is a tricky carb to get the tune dialed in with, especially on a bike with no head porting. It's like putting an 850cfm Holley on a 289 chevy small block.

I'm not understanding the delay on this website lol. I didn't see all the replies until I made another comment.
Didn't realize I bought a carburetor that was to much to start with.
I will have to order the jets. any suggestions on what brand will be good? Or does it matter? Head porting? Aftermarket exhaust? CDI and coil suggestions would be great if it will help my hawk have a better life. I'm doing research but unsure who to listen to lol. Like I said I'm new to bikes but have experience with small engines like chainsaws and the like , trucks and cars. The Holley reference was great by the way. I understand that talk great lol. Side note, should I adjust the valves? A couple people said they always come to tight.

[Megadan]

Originally Posted by Nab

I'm not understanding the delay on this website lol. I didn't see all the replies until I made another comment.
Didn't realize I bought a carburetor that was to much to start with.
I will have to order the jets. any suggestions on what brand will be good? Or does it matter? Head porting? Aftermarket exhaust? CDI and coil suggestions would be great if it will help my hawk have a better life. I'm doing research but unsure who to listen to lol. Like I said I'm new to bikes but have experience with small engines like chainsaws and the like , trucks and cars. The Holley reference was great by the way. I understand that talk great lol. Side note, should I adjust the valves? A couple people said they always come to tight.

I get that weird delay thing too sometimes. I couldn't begin to tell you why it does that either.

I think the issue with the Nibbi PE30 is that, after I installed it and then made videos about it, people ignored all of the other elements about my bike and just heard me say "Yeah, more power!!!" and "Nibbi PE30" and just assumed it was a good upgrade lol. Then others saw them do it, and so on, and eventually it just spiraled into a "Just get this carb" thing. It can work on a mostly stock bike, but it can be a challenge to get it dialed in, so be prepared for a bit of a struggle.

As far as jets, I am always a fan of quality jets, either OEM or OEM equivalents from jetsrus.com 99101-393 and N424-21 for main and slow jets. However, one can always use one of the many jet kits out there on Amazon. This is one that I have used and have been satisfied with their performance. https://www.amazon.com/Supermotorpar...484744&sr=8-11

As far as CDI and coil. At this point I wouldn't worry about it too much. Focus on getting it running.

Head porting and exhaust mods are going to be the best bang for the buck if you are chasing some extra power, and with a ported head the PE30 is going to be better utilized.

Also, yes, adjust the valves. They do come tight from the factory. For break in I recommend setting the valves to .07-.08mm aka .003". Then after that you can set them a bit tighter at .05mm/.002in for little less noise.

[Nab]

Originally Posted by Megadan

I get that weird delay thing too sometimes. I couldn't begin to tell you why it does that either.

I think the issue with the Nibbi PE30 is that, after I installed it and then made videos about it, people ignored all of the other elements about my bike and just heard me say "Yeah, more power!!!" and "Nibbi PE30" and just assumed it was a good upgrade lol. Then others saw them do it, and so on, and eventually it just spiraled into a "Just get this carb" thing. It can work on a mostly stock bike, but it can be a challenge to get it dialed in, so be prepared for a bit of a struggle.

As far as jets, I am always a fan of quality jets, either OEM or OEM equivalents from jetsrus.com 99101-393 and N424-21 for main and slow jets. However, one can always use one of the many jet kits out there on Amazon. This is one that I have used and have been satisfied with their performance. https://www.amazon.com/Supermotorpar...484744&sr=8-11

As far as CDI and coil. At this point I wouldn't worry about it too much. Focus on getting it running.

Head porting and exhaust mods are going to be the best bang for the buck if you are chasing some extra power, and with a ported head the PE30 is going to be better utilized.

Also, yes, adjust the valves. They do come tight from the factory. For break in I recommend setting the valves to .07-.08mm aka .003". Then after that you can set them a bit tighter at .05mm/.002in for little less noise.

I really appreciate your advice. It was a big help you letting me know that the carburetor was not a good first upgrade because it was to big. I figured it out. 2nd notch on throttle needle with 110 main on hot days and 105 on cold with 35 pilot. 115 main it wanted to stumble on acceleration until it warmed up to running temperature with strong exhaust smell. Still runs weak on top speed but it runs with full throttle and that's all I need. And with the port/polish I Can't find anyone to polish/port the head so probably won't ever be done.