Need help with jetting

[magnang]

Ok, I'm having a few issues with jetting.

Basically I have a CB175K5 that I'm building. It was stock last year and ran OK. Not great, but OK. I could get to 70-72 MPH on a good day. Top speed is supposed to be 85 or so. I had a hard time maintaining 60MPH with a slight headwind or slight incline. The bike was peaky, it had decent power from about 7000RPM to redline (10500) but little torque before that.

I wrote this off as an exhaust issue since I had holes in my stock mufflers. Over the winter I have adjusted the valves, ignition timing, added pod filters and EMGO shorty mufflers. The stock Jets for my bike are #98. I also have a set of #105, 110 and 115.

w/ #115, I had great torque and midrange, but it bogs down at full throttle. I have no power past about 6500 RPMs. It misses and bogs HARD at that point.

w/ #110, I have good power untill 7000, and good power up to about 3/4 throttle and 8500RPM. Then it starts to miss again

w/ #105, I have less power untill 7000 than I did with the bigger jets, but a bit more top end. It still misses and bogs at WOT and around 9000rpms

Am I to conclude that I am still running too rich? I messed with the clip position a bunch and can't really find the sweetspot where I have #115 like midrange and a good top end. I figured with 105 and a lower needle it would lean out a bit a higher rpms but it doesn't make a big difference. All signs are pointing towards going back to the stock size, but this goes against everything I have read about pod filters and aftermarket exhausts.

Is there something else I can try?

Before you guys ask: I seem to have good spark and the float height is dead on. Bike starts on the first kick and idles well. This is definitely a jet / needle issue

 

[supercafe]

hey whats up.
i just built a cd 175, and went to the honda harley dealer in kingston, ont. they told me that the mains should be 90
the book says 95. when i took my carb apart i found that they it was 100, and with exh, and intake upgrades i have no
problems. i have extra jets like these ones, if you want one you can have it, just pay mailing..
it sounds like this might work, right in the middle of your stock and other...my work.
any way talk to ya later..

 

[magnang]

hey whats up.
i just built a cd 175, and went to the honda harley dealer in kingston, ont. they told me that the mains should be 90
the book says 95. when i took my carb apart i found that they it was 100, and with exh, and intake upgrades i have no
problems. i have extra jets like these ones, if you want one you can have it, just pay mailing..
it sounds like this might work, right in the middle of your stock and other...my work.
any way talk to ya later..

Thanks for the help man. I just ordered a set of 100s from the Northcityhonda. It says right on their site that 100 is the stock size for a CB360, which is a twin like my bike that has over twice the cc and 50% more power. If 100 flows enough gas for that bike it should be at the upper end of what will work for me.

Which position did you set your clip at?

 

[magnang]

Weird... I went for a ride with the #98s on and still have the same issues. The bike ran awesome for 15 minutues or so, pulled cleanly to redline. Then it start missing again and approx 9000RPMs at WOT. I seemed to hit a wall at 60MPH...

Could it be a spark issue? Coil not keeping up a high revs?

 

[supercafe]

whats up.
i had a simailar prob with mine, found out the batt was no good. was'nt allowing the coil to keep its spark.
the alt was trying to charge a bad batt all the time and run the bike, when i would turn lights on it would miss
or when i hamered on the throttle it would miss.
check the resistance in the coil on both side of it primary and secondary, see if the readings are the same as specs in the
manual..
i run the 100 jets and it runs awesome with a single carb, and can get 85 mph out of it no problem...
i would check the charging curcuit and see what you get...
let me know!!!
later.

 

[magnang]

That sounds like me, but I have a brand new battery and it seems to hold a charge fine. I was messing around with some lights and stuff and forgot them turned off overnight 2 days ago. It still had 11.5V yesterday, so I think it's okay.

I'm not sure my Coil is any good or that it's getting the full 12v though. If you trace the power form the battery to the coil there is a lot that can go wrong. It goes through the wiring harness, a couple of old bullet connectors and the ignition switch. Odds are some or all of theses have degraded over time and are robbing the coil of power. And even if it was getting full power, I still have the original plug wires which have probably degraded a lot over the years. I think I will be doing the coil power mod that's in the 50$ mod thread. Basically you run a new line from the battey to the coil and have a relay hooked up to the ignition switch, so the coil gets more direct power and from fresh components.

I also ordered a new coil and plug ends, it's for a CB750 but should do.

Now I just have to bite the bullet and take the tank off. Sucks cause I have a full tank of gas and it's going to be messy!!!!

 

[supercafe]

sounds like your heading in the right direction. i have been there, and for alittle bike it can get mind numming.
any way let me know how it turns out, i might want to do the upgrade on mine if it works for you..
later.