Another Hawk Tuning Question

[TxJasper]

I'm new to the forum and also have a tuning question. I bought a Hawk 1 week ago. Stock 15/50 gears and stock settings I was getting 62-63MPH in 5th gear. I have about 245 miles on it. I changed the front sprocket to 17 and rear to 45 and replaced chain. I rejetted my main carb to 110 and shimmed the needle with two 3mm washers, with stock exhaust. Fuel adjustment screw backed out 2 turns (also tried 2.25 and 1.75) Now, I'm only getting 57-58 MPH but then 5th gear starts loosing speed back down to 52-53MPH. Shift back into 4th and MPH climbs back up to 55, shift into 5th climbs to 58 and looses speed back down to 52-53MPH. Popping sounds when decelerating. The idle acts like it hanging (idling high) when coming to a stop and settles down when I let out the clutch a little. I also smell a sharp burning smell when I stop. It seems to me that it's running lean/hot. Any suggestions???

[Ariel Red Hunter]

Originally Posted by TxJasper

I'm new to the forum and also have a tuning question. I bought a Hawk 1 week ago. Stock 15/50 gears and stock settings I was getting 62-63MPH in 5th gear. I have about 245 miles on it. I changed the front sprocket to 17 and rear to 45 and replaced chain. I rejetted my main carb to 110 and shimmed the needle with two 3mm washers, with stock exhaust. Fuel adjustment screw backed out 2 turns (also tried 2.25 and 1.75) Now, I'm only getting 57-58 MPH but then 5th gear starts loosing speed back down to 52-53MPH. Shift back into 4th and MPH climbs back up to 55, shift into 5th climbs to 58 and looses speed back down to 52-53MPH. Popping sounds when decelerating. The idle acts like it hanging (idling high) when coming to a stop and settles down when I let out the clutch a little. I also smell a sharp burning smell when I stop. It seems to me that it's running lean/hot. Any suggestions???

Sounds too lean to me, unless the motor is tightening up from over heating. Changing to a 17-45 puts a real load on an engine that is not really run in yet. Takes at least 500 miles to get the engine limbered up....ARH

[BlackBike]

Originally Posted by TxJasper

I'm new to the forum and also have a tuning question. I bought a Hawk 1 week ago. Stock 15/50 gears and stock settings I was getting 62-63MPH in 5th gear. I have about 245 miles on it. I changed the front sprocket to 17 and rear to 45 and replaced chain. I rejetted my main carb to 110 and shimmed the needle with two 3mm washers, with stock exhaust. Fuel adjustment screw backed out 2 turns (also tried 2.25 and 1.75) Now, I'm only getting 57-58 MPH but then 5th gear starts loosing speed back down to 52-53MPH. Shift back into 4th and MPH climbs back up to 55, shift into 5th climbs to 58 and looses speed back down to 52-53MPH. Popping sounds when decelerating. The idle acts like it hanging (idling high) when coming to a stop and settles down when I let out the clutch a little. I also smell a sharp burning smell when I stop. It seems to me that it's running lean/hot. Any suggestions???

Valve status?

[TxJasper]

Originally Posted by BlackBike

Valve status?

I haven't checked them but could they be that far off after couple hundred miles? And what would the symptoms be? The bike idle seems to hang when I come to a stop and until I let out the clutch, then idle settles down. The loss of power and speed in 5th (I know when re-gearing up, there is a potential to loose power), doesn't seem like the norm after re jetting main jet from 98 to 110 reading others posts. I was wondering about a vacuum leak but didn't know how common they were in new bikes. I'm not a mechanic, but extremely handy and can usually take apart and fix anything. Also, I'm new to working on motorcycles. Please let me know your thoughts...

[BlackBike]

Originally Posted by TxJasper

I haven't checked them but could they be that far off after couple hundred miles? And what would the symptoms be? The bike idle seems to hang when I come to a stop and until I let out the clutch, then idle settles down. The loss of power and speed in 5th (I know when re-gearing up, there is a potential to loose power), doesn't seem like the norm after re jetting main jet from 98 to 110 reading others posts. I was wondering about a vacuum leak but didn't know how common they were in new bikes. I'm not a mechanic, but extremely handy and can usually take apart and fix anything. Also, I'm new to working on motorcycles. Please let me know your thoughts...

My thoughts are that everyone who has completed there first valve job (out of box) from this forum has mentioned that their valve Clarence has been 0. Just saying.

[TxJasper]

Thank you for your replies! I installed 115 main this morning. Also shimmed the needle with four 3mm washers. Adjusted fuel mix screw 1.75 turns out. Awesome difference in idle and 5th gear has power!
Stock speedo cable broke. I pulled it out and welded it back together. Now works great!
Also, it seemed to be having problems shifting. The dip stick was bent and twisted when I changed oil. It felt like it was hanging up, so I just cut it off. Shifts good now.
It's running good now, but will check the valves after it cools overnight. Anyway, just wanted to come back and give an update to the thread.

[TxJasper]

BlackBike, you were right. No valve clearance. The Chinese manual says adjust .005, Motocheez initial video said .005 exhaust, .004 intake, but later suggest .003 for both. Well, I adjusted .005 exhaust &.004 intake but it was too much. Ticking pretty bad. Going to wait until engine cools off and try .003 for exhaust and .0025 intake...we'll see.
Thanks for the suggestion!

[Megadan]

That clattering sound is normal for a mechanical valvetrain. Even perfectly adjusted, every engine with mechanical tappet style valvetrain is going to be a bit "ticky" My goldwing uses the same .004 intake and .005 exhaust and you hear it tick away. My old isuzu 4 banger, the Toyota 22R, and numerous other engines are/were the same way. Adjusting them in further to get rid of clatter can run the risk of being too tight once the engine is warmed up, and it will cause other issues - including burnt valves and damaged valve seats in the worst case scenario and at best the valves not sealing properly causing vacuum and compression issues that will make the engine run poorly. In extreme cases the extra pressure on the cam lobe can cause premature wear. It shouldn't be obnoxiously loud, but it will be audible.

Edit: It should be noted that valve lash should always be adjusted on a stone cold engine, and that means it sat many hours. Any one part of the engine is even a bit warmer than the rest and it can cause the clearances to be off. Even on a warm engine - IE, not hot enough to burn you, but not cold/ambient temp - and the lash adjustment can often end up wider than factory specs.

Also, you need to 100% ensure that you are exactly at TDC. Even a tiny bit off in either direction can sometimes cause your setting to actually be incorrect, because it takes up some slack in the valvetrain and result in an even wider gap than what you intended to set it at.

[BlackBike]

Originally Posted by Megadan

That clattering sound is normal for a mechanical valvetrain. Even perfectly adjusted, every engine with mechanical tappet style valvetrain is going to be a bit "ticky" My goldwing uses the same .004 intake and .005 exhaust and you hear it tick away. My old isuzu 4 banger, the Toyota 22R, and numerous other engines are/were the same way. Adjusting them in further to get rid of clatter can run the risk of being too tight once the engine is warmed up, and it will cause other issues - including burnt valves and damaged valve seats in the worst case scenario and at best the valves not sealing properly causing vacuum and compression issues that will make the engine run poorly. In extreme cases the extra pressure on the cam lobe can cause premature wear. It shouldn't be obnoxiously loud, but it will be audible.

Edit: It should be noted that valve lash should always be adjusted on a stone cold engine, and that means it sat many hours. Any one part of the engine is even a bit warmer than the rest and it can cause the clearances to be off. Even on a warm engine - IE, not hot enough to burn you, but not cold/ambient temp - and the lash adjustment can often end up wider than factory specs.


Also, you need to 100% ensure that you are exactly at TDC. Even a tiny bit off in either direction can sometimes cause your setting to actually be incorrect, because it takes up some slack in the valvetrain and result in an even wider gap than what you intended to set it at.

Was think the same about little 4 cylinder engines, click click click .

2lz likes to set his at 5 and 8 on the exhaust. He has had experience with these hondoids and knows. Mine are set to this and yes they do click. If you can maintain at 5 this will be a perfect setting since most of the manufacturers call for this gap for both sides.(being lazy on setting #s but you get the drift)

Also, you will notice the more open exhaust gap will give the engine a lower pitch sound upon acceleration.

Metal does strange things on a molecular level when subjected to temperature cycles. Ask cheesy about changes in Rail lengths due to temperature.

[Ariel Red Hunter]

Originally Posted by Megadan

That clattering sound is normal for a mechanical valvetrain. Even perfectly adjusted, every engine with mechanical tappet style valvetrain is going to be a bit "ticky" My goldwing uses the same .004 intake and .005 exhaust and you hear it tick away. My old isuzu 4 banger, the Toyota 22R, and numerous other engines are/were the same way. Adjusting them in further to get rid of clatter can run the risk of being too tight once the engine is warmed up, and it will cause other issues - including burnt valves and damaged valve seats in the worst case scenario and at best the valves not sealing properly causing vacuum and compression issues that will make the engine run poorly. In extreme cases the extra pressure on the cam lobe can cause premature wear. It shouldn't be obnoxiously loud, but it will be audible.

Edit: It should be noted that valve lash should always be adjusted on a stone cold engine, and that means it sat many hours. Any one part of the engine is even a bit warmer than the rest and it can cause the clearances to be off. Even on a warm engine - IE, not hot enough to burn you, but not cold/ambient temp - and the lash adjustment can often end up wider than factory specs.

Also, you need to 100% ensure that you are exactly at TDC. Even a tiny bit off in either direction can sometimes cause your setting to actually be incorrect because it takes up some slack in the valvetrain and result in an even wider gap than what you intended to set it at.

I don't agree 100% with this. The valves are closed during the last quarter of the compression stroke (and the lifters are off of the cam ramps), and they stay closed through at least the first half of the power stroke. So, anywhere at or just past TDC on the compression/power strokes will be fine. A lot of people on here have had good results at .002 intake, .003 exhaust, this is in inches. Others have reported success at .003 and .004. Too much valve clearance reduces valve timing and adds impact loads on the cam and lifters. But yes, the engine must be overnight-cold....ARH

[Megadan]

Originally Posted by Ariel Red Hunter

I don't agree 100% with this. The valves are closed during the last quarter of the compression stroke (and the lifters are off of the cam ramps), and they stay closed through at least the first half of the power stroke. So, anywhere at or just past TDC on the compression/power strokes will be fine. A lot of people on here have had good results at .002 intake, .003 exhaust, this is in inches. Others have reported success at .003 and .004. Too much valve clearance reduces valve timing and adds impact loads on the cam and lifters. But yes, the engine must be overnight-cold....ARH

So you disagree with specs that I never stated. Makes sense.

Or was it my tdc remark? In which case, i disagree with you disagreement. We are dealing with thousandths of an inch at the rocker arm and valve, usually at a ratio greater than 1 to 1. So even the smallest difference at the cam is even more so at the valve end. Ensuring that you are at tdc is a 100% guarantee that you will have eliminated this potential variable. That is why all engine manudacturers state to set it at tdc.

[JeremyC]

I set mine both to .003". Runs great!

[Ariel Red Hunter]

Originally Posted by Megadan

So you disagree with specs that I never stated. Makes sense.

Or was it my tdc remark? In which case, i disagree with you disagreement. We are dealing with thousandths of an inch at the rocker arm and valve, usually at a ratio greater than 1 to 1. So even the smallest difference at the cam is even more so at the valve end. Ensuring that you are at tdc is a 100% guarantee that you will have eliminated this potential variable. That is why all engine manudacturers state to set it at tdc.

You may never have intended to state a spec, but someone on here will take your .004 valve lash setting as one. Yes, I know that was for a different make of motor cycle, but you'd be surprised...ARH

[pistolclass]

Originally Posted by Ariel Red Hunter

You may never have intended to state a spec, but someone on here will take your .004 valve lash setting as one. Yes, I know that was for a different make of motor cycle, but you'd be surprised...ARH

So what you're saying is I should adjust my Corvettes engine to .004?

[Ariel Red Hunter]

Originally Posted by pistolclass

So what you're saying is I should adjust my Corvettes engine to .004?

I always like a guy who makes me smile...ARH