1 Millionth Hawk Carb Jetting question

[nij_tp]

(Need to pull the carb off to check sizes that I am at, but this is a general(ish) question) So I had the stock Exhaust on and had fitted a PZ30 and jetted it and it ran well. Have fitted the ebay special exhaust and now it runs like a dog (always thought this was a strange expression as my dog run like the wind!) I can get to 25 ok in 2nd if i baby the throttle but if I change into 3rd, zero acceleration and just gets slower and stalls if I don't change back down. Do I need even bigger jets (off hand I think I'm at 115 and 40 or 45, middle notch) I'm (pretty much) at sea level. Also she needs to have a twit of the idle screw as she wont idle.

As always thanx in advance.

[JerryHawk250]

Jetting sounds about right. I've accidentally had mine on half chock one time and that's the exact symptoms. lol

[nij_tp]

Ok so this may be a me issue, but with the lever up it stalled out with it down it stalled out in the middle just about idled.

[Wild Dog]

That sounds that you are a bit rich, try to raise the needle clip a notch.

[nij_tp]

Wild dog, dumb question when you say raise it you literally mean pull it up higher and move the circlip down (towards the point end).

So I checked and it's running 115 and 42 so I was in the correct ball park.

The air fuel was 2 turns out and I've read that 1 1/2 is possibly better. Thoughts?

[nij_tp]

Other dumb question on choke.

Lever down plate fully open
Lever up plate fully closed

So down is choke full off
Up choke is on

Correct?

[Wild Dog]

Originally Posted by nij_tp

Wild dog, dumb question when you say raise it you literally mean pull it up higher and move the circlip down (towards the point end).

So I checked and it's running 115 and 42 so I was in the correct ball park.

The air fuel was 2 turns out and I've read that 1 1/2 is possibly better. Thoughts?

No what i mean is put the clip on the second notch counting from top of the needle.
I think you may be a bit rich


Indeed if the lever is down, there no choke, when the lever is up, you are on full choke.

[nij_tp]

Wild dog, thank you I will have a go at that when I eventually get up, later today :-)

[nij_tp]

So I moved it up (down (towards the not pointy end)) and what a difference. Sorry to be a newb but my question is how does one notch makes such a difference (what is it doing (I am sure I can youtube this but life is way to short especially without knowing what I am asking)). It still seems i little rich so does air/fuel also come into play or just smaller jets?

again and as always thanks in advance.

[Goob]

Originally Posted by nij_tp

So I moved it up (down (towards the not pointy end)) and what a difference. Sorry to be a newb but my question is how does one notch makes such a difference (what is it doing (I am sure I can youtube this but life is way to short especially without knowing what I am asking)). It still seems i little rich so does air/fuel also come into play or just smaller jets?

again and as always thanks in advance.

The center being the typical starting point. Down=richer because it holds the needle up higher out of the main jet, up=leaner because it drops the needle down further. This will effect 1/4 to 3/4 throttle. 3/4-1 is main jet.

Here are a couple of good tuning guides...same principles apply to most all carbs.

http://www.vintagebikebuilder.com/mi...ing-guide.html

http://www.iwt.com.au/mikunicarb.htm

[nij_tp]

Thanks Goob

[nij_tp]

Just for completeness I came to the 115 and 42 (didnt have a 45) based on a conversation with MegaDan.

I am at sea level and he said to try 115/30 for Mikuni and 45 for Khein looking at the chart (below) a 115 Mikuni is a 130 Khein but who knows with the knock offs.

https://www.jetsrus.com/FAQs/FAQ_mik...ihin_sizes.htm

[Goob]

Originally Posted by nij_tp

Just for completeness I came to the 115 and 42 (didnt have a 45) based on a conversation with MegaDan.

I am at sea level and he said to try 115/30 for Mikuni and 45 for Khein looking at the chart (below) a 115 Mikuni is a 130 Khein but who knows with the knock offs.

https://www.jetsrus.com/FAQs/FAQ_mik...ihin_sizes.htm

Send a photo and measurements to Jetsrus. Mike will help you figure it out if they are Mikuni or Keihin.

If it is Mikuni (VM26 Flange Mount) then the parts will be Main: N100.604 (Jetsrus #M21) and Pilot: VM28/486 (Jetsrus #M24). That is what I had for my RXB150

[Goob]

Originally Posted by nij_tp

Thanks Goob

I thought about putting the Subaru engine in the 914 2.0 I had. It had a non-original blown engine when I bought it. If they had the conversion kits they do now I would have done it. Also considered putting in a 4-carb 140 hp Corvair engine (Crown did have the kit back then), but ended up with a high compression 1.7 L Type 4 with hydraulic lifters and single barrel dual DelOrtos . I was trying to get 100 HP and fuel economy, but in the end only got the HP...so later wished I had done 2 liters with 40mm dual Webers.

Sold for $4500 in 1996, about what I had in it. Since it was rust free...I am figuring it would be worth about double that now. Wish I had kept it, but it would likely have been destroyed in one of Denver's many hail storms since then.