Topic: what size main jets do you run?

[JAG]

I was just curious to see what size mains you guys run.

With my particular set up, engine stock, pods, needle set one notch up from middle.

I get bogged down at WOT, and it seems like (to me) that the engine is running hotter than what I considered normal operating temps.

I'm running 115's, and I think I need to go up to 120, 125's.

What do you guys run? What size should I go up to?

Thanks

[kpier883]

1976 750K with about 20000 miles on it (according to the speedometer), but who really knows.  I can vouch for the most recent 14,000 miles myself. 

I run a 37.5 pilot and a 105 main.  I am fixing to change to 102.5 mains.  I don't remember which slot my needles are in but I will check when I change the jets.  Stock air box and Honda filter.  Some no-name 4 into 2 chrome pipes.  Dyna S ignition.

[Bill/BentON Racing]

Try the 125s and go from there,883,you have less restrictive pipes and are going to go down? I would think maybe 110 mains.,Bill

[kpier883]

Try the 125s and go from there,883,you have less restrictive pipes and are going to go down? I would think maybe 110 mains.,Bill

PO (or factory) had 110s  in it when I got it.  I was always fouling out plugs, even the D7.  It laid down black smoke on heavy throttle and would not take full throttle.  The motor would bog at WOT, but pick up if I backed off of full throttle some.  I got terrible mileage - high 20's and low 30's.  So I changed to 105s and smaller pilots.  No more fouled plugs, better response on top, and low 40s for mpg. 

The pipes are probably junker JC Whitney or somesuch.  All I know is that it was too rich before and I still think it may be a little rich. 

The only negative is that now I actually have to use the choke when the engine is cold.  Maybe PO used some Keyster parts somewhere in the carbs to make it behave so...

[JAG]

The pipes I have are 2-1 on either side.

I changed the needle position because from the higher temps I felt as it was running lean.

However at WOT it'll start bogging down at around 6K rpms.

I have a set of 135's from some donor carbs, and I tried those in there and it seemed to run like crap, very bogged down and rough at idle. With that said Does the carbs need to be re-sync when changing the mains??

I've heard a lot of people using 135's with pods, and it seems to run fine for them. I think even Carpy runs 135's with his set ups.

[bucky katt]

i run 120's with a kerker exhaust and stock airbox with k+n replacement filter. may go to a 122.5 after a bit.

[Flying J]

Mac exhaust, foam filters, 125s with needle up a notch. Not running right. It was doing better at 125 and stock setting needle.

[HedNut]

Here's a neat carb Jet chart I grabbed from www.hondachoppers.com.  It shows you what jet/needle adjustments affect which throttle range.

It gives you a great idea of what setting/jet you should play with if your getting problems in different areas of throttle range.

Hope this helps.

[JAG]

Here's a neat carb Jet chart I grabbed from www.hondachoppers.com.  It shows you what jet/needle adjustments affect which throttle range.

It gives you a great idea of what setting/jet you should play with if your getting problems in different areas of throttle range.

Hope this helps.

That's pretty sweet bud.

I def think 125's will be the way to go.


I went up on the needle position to help rich it up a bit. So you'd think going to 125's that more gas flow you would want to go back to mid way on the needle position.

Mac exhaust, foam filters, 125s with needle up a notch. Not running right. It was doing better at 125 and stock setting needle.

[Flying J]

somthing is messed up in my carbs again. I lost the 0-1/2 throttle range while riding. Any where in that range and the bike dies. Stay above and it runs. As soon as i get that fixed, and drop the needle back to stock im going to do a plug chop and i will try to post my results.

[BobbyR]

78K with stock air filter and exhaust. I run 120 mains which the PO had put in when the bike was 2 years old. He died so I have no idea why. Runs OK at alll throttle settings. He died so I have no idea what he did. He was a racer so anything is possible. The plugs stay reasonably clean.