Hawk 250 first start problems

[Audihuff]

Hello fellow riders! i was wondering if someone could give me some tips on getting this puppy to start up and idle. As of now it has fressh oil, brand new ngk spark plug, and stock carb. I have gotten it to sputter a few times with choke full on and giving some gas, but it dies very very quickly. i have the upgraded mikuni carb on the shelf. What jets should i put in it for 20-30 degrees and 1000 ft elevation? Was also wondering if i should first mess with the stock carb just to get it started and warmed up so i can properly set valve lash.. then swap carb and retune?

p.s. this is brand new hawk and i dont want to mess annything up lol

[JerryHawk250]

Remove the cap that covers the idle mixture screw and set the idle mixture at 1 1/2 turns out from lightly seated. That will be the best starting point. You can also shim the needle with two thin washers. You will still need to change the 98 main out to at least a 110 but not necessary at this point as that only for 3/4 to full throttle.

[Douglass]

Have you tried to raise the idle with idle set screw. You could try to screw it in quite a bit to see if it will run, then lower it so it will idle.

Have you messed with the with the choke lever after it has fired?

[Audihuff]

Originally Posted by Douglass

Have you tried to raise the idle with idle set screw. You could try to screw it in quite a bit to see if it will run, then lower it so it will idle.

Have you messed with the with the choke lever after it has fired?

thank you everybody for your time and tips! I went home on my lunch break and re jetted the new mikuni carb with a 110 main jet, left the needle alone, and turned mix screw 1-1/2 times from bottom.. still no luck. unfortunately i had to come back to work. when i get home im going to mess with the idle set screw. its probably something silly as im new to bikes

[E-Rock]

it probably wont run very long on full choke anyway. try it with the choke off or half choked at most.

[Audihuff]

ALAS WE HAVE IDLE! thankyou everyone! it was the idle set screw! Next question is can i take a short mile ride before setting valve lash? im getting very excited but still not getting ahead of myself haha. Im also coming across many different specs for intake and exhaust valves.. What works for you guys?

[Ariel Red Hunter]

Originally Posted by Audihuff

ALAS WE HAVE IDLE! thankyou everyone! it was the idle set screw! Next question is can i take a short mile ride before setting valve lash? im getting very excited but still not getting ahead of myself haha. Im also coming across many different specs for intake and exhaust valves.. What works for you guys?

I like .003 INCHES on intake, and .004 INCHES on exhaust. Inches, not millimeters. Somebody else can tell you the metric settings if you don't have inch feeler guages...ARH

[NzBrakelathes]

Originally Posted by Ariel Red Hunter

I like .003 INCHES on intake, and .004 INCHES on exhaust. Inches, not millimeters. Somebody else can tell you the metric settings if you don't have inch feeler guages...ARH

I prefer mm so I can check what I did etc
Let me explain.
0.003 inch is 0.08mm soooooo close its not funny

So you "set" to that as you think it is correct( 3 thou), now what you do to check your self is as follows:

use the 0.07mm and that should fall thru so it is bigger then that, then use a 0.09mm and that should be a really firm one to get thru the gap (it shows it is slightly smaller) and THEN you get the 0.10 and that shouldn't pass thru the gap as the gap should be smaller, if not you did it wrong.
0.10 is a little under 0.004 inch but close enough to call it 4 thou.

See what I mean? you can see if the initial feel of the blade passing is in fact correct as I suspect ( I might be wrong) that many guys with little or no experience are in fact setting their valves incorrectly with the "feel" aspect and this way you can test if you have it right or not.

All valve clearances give you a small range so lets sya 0.0025 tho to 0.0035 tho and you use 3 thou.
In mm that would be something like 0.07mm to 0.09mm and that is close enough to the favoured 3 thou setting.
My "Go no Go" method will show that you are in fact in that range - 0.07 was too loose 0.09 was too tight and 0.10 shouldn't pass when forced or pass but so hard to do so that it is clear it is smaller than 0.10mm.

So that is a method I suggest people use so they actually know it is set to the size they use and confirmed with the "test Go no Go" rather then " only thinking it is" but might be wrong or too big etc.

That is why in my tool kit on eBay it has mm feeler gauges.
Most guys say 3 thou in and ex so 0.08mm (0.07mm to 0.09mm range)

I prefer 0.06mm in and 0.08mm ex but I won't argue the size but I know my Go n Go method will help folk to check if in fact they set it correctly.

I prefer tank off so it is easier to get to everything and I ONLY ever use the proper tool to adj the valve bolt and square head adjuster which is available in my eBay store in the tool set if folk need it.

[roundhouse]

Originally Posted by Audihuff

ALAS WE HAVE IDLE! thankyou everyone! it was the idle set screw! Next question is can i take a short mile ride before setting valve lash?

I rode mine a several months without adjusting them. I could tell a nice diff when I did though. I think you are good to go for some break in rides.

[Megadan]

Originally Posted by roundhouse

I rode mine a several months without adjusting them. I could tell a nice diff when I did though. I think you are good to go for some break in rides.

I disagree with this entirely.

Why:
1. As valves "break in" with the engine the valves settle into the seat some, essentially making the valve clearances tighter.
2. Tight cold valve clearances lead to valves not sealing once hot. Intake valves not seating = potential backfires through the carb. Exhaust valve not seating = burned exhaust valves. Neither seating = lost compression = lost power and efficiency. It can also lead to improper carb tuning.

My advice. With a cold engine (has sat several hours) set your valve lash. It takes 15-20 minutes tops to do.

[Ariel Red Hunter]

Originally Posted by Megadan

I disagree with this entirely.

Why:
1. As valves "break in" with the engine the valves settle into the seat some, essentially making the valve clearances tighter.
2. Tight cold valve clearances lead to valves not sealing once hot. Intake valves not seating = potential backfires through the carb. Exhaust valve not seating = burned exhaust valves. Neither seating = lost compression = lost power and efficiency. It can also lead to improper carb tuning.

My advice. With a cold engine (has sat several hours) set your valve lash. It takes 15-20 minutes tops to do.

Megadan is 100% right on this. There are lots of long term problems with letting adjusting valve lash "go for a while." Besides the obvious ones, which Megadan mentioned, stretched exhaust valves, from over heating (exhaust valves give up about 2/3rds of the heat that they pick up WHEN THE VALVE IS OPEN to the valve seats, rest is dissapated via the ex. valve guide.) This also raises the oil temperature of what is a pretty skimpy oil supply in the first place. Needless to say, the exhaust valve seat suffers from localised over heating as well. In the test house, we've had engines loose their valve seats from running on the dyno at 85% of maximum output running lean, but not lean enough to get out of "The Red Box". In case you haven't heard, the engines that come in these motor cycles come here with very lean main jets, in order to satisfy the boffins at the EPA. Not to mention that steady running at 1300f EGT is a little hard on an aluminum head. AND, this little engine has to run at, or very near wide open throttle to go any distance on the highway...ARH

[Ariel Red Hunter]

Originally Posted by NzBrakelathes

I prefer mm so I can check what I did etc
Let me explain.
0.003 inch is 0.08mm soooooo close its not funny

So you "set" to that as you think it is correct( 3 thou), now what you do to check your self is as follows:

use the 0.07mm and that should fall thru so it is bigger then that, then use a 0.09mm and that should be a really firm one to get thru the gap (it shows it is slightly smaller) and THEN you get the 0.10 and that shouldn't pass thru the gap as the gap should be smaller, if not you did it wrong.
0.10 is a little under 0.004 inch but close enough to call it 4 thou.

See what I mean? you can see if the initial feel of the blade passing is in fact correct as I suspect ( I might be wrong) that many guys with little or no experience are in fact setting their valves incorrectly with the "feel" aspect and this way you can test if you have it right or not.

All valve clearances give you a small range so lets sya 0.0025 tho to 0.0035 tho and you use 3 thou.
In mm that would be something like 0.07mm to 0.09mm and that is close enough to the favoured 3 thou setting.
My "Go no Go" method will show that you are in fact in that range - 0.07 was too loose 0.09 was too tight and 0.10 shouldn't pass when forced or pass but so hard to do so that it is clear it is smaller than 0.10mm.

So that is a method I suggest people use so they actually know it is set to the size they use and confirmed with the "test Go no Go" rather then " only thinking it is" but might be wrong or too big etc.

That is why in my tool kit on eBay it has mm feeler gauges.
Most guys say 3 thou in and ex so 0.08mm (0.07mm to 0.09mm range)

I prefer 0.06mm in and 0.08mm ex but I won't argue the size but I know my Go n Go method will help folk to check if in fact they set it correctly.

I prefer tank off so it is easier to get to everything and I ONLY ever use the proper tool to adj the valve bolt and square head adjuster which is available in my eBay store in the tool set if folk need it.

I like the go-no go idea. Set the intake to .003, which means that an .003 inch guage should pull through this gap with a one or two pound pull. an .004 won't go, an .002 will fall through (means no drag). For the exhaust, the .004 is our go to guage, so set the clearance so that the guage pulls out with a one or two pound effort. The .003 guage wiil pass through with no drag whatsoever, and the .005 guage tells you 'no kinda' way'...ARH

[OneLeggedRider]

Adjust the valves before you even start it the first time. Mine took all of 10 minutes and you don't even have to remove the tank. And mine were screwed down tight with zero lash. I'd even recommend setting them a little loose until after the first few heat cycles. Jmo

[OneLeggedRider]

I'm surprised folks are so wary about doing such a simple screw and locknut valve adjustment on a single cylinder 2 valve head. I think I learned that when I was about 11. Even before I went to MMI I was doing multi valve shim under bucket adjustments on inline 4s where you had to keep going over to the bench grinder because you didn't have all the proper shim sizes and you wanted to get your buddy back on the road.

The important thing is you wanna feel just a slight amount of drag on the feeler gauge as you pull it through and be sure your on the right stroke. And do your adjustment with the engine cold as the manufacturer intended.

[Megadan]

Originally Posted by OneLeggedRider

I'm surprised folks are so wary about doing such a simple screw and locknut valve adjustment on a single cylinder 2 valve head. I think I learned that when I was about 11. Even before I went to MMI I was doing multi valve shim under bucket adjustments on inline 4s where you had to keep going over to the bench grinder because you didn't have all the proper shim sizes and you wanted to get your buddy back on the road.

Welcome to the uni-cam head design of the VFR1200F, with shim under bucket intake valves, and a roller rocker solid tappet exhaust actuation that has two clearances to set, cam side and valve side.


I would gladly do 100 Hawks before doing this valve job again. That is the easy to reach rear cylinder head.