** It's ALIVE **

classic Classic list List threaded Threaded
4 messages Options
Reply | Threaded
Open this post in threaded view
|

** It's ALIVE **

Ericcb750
Hey Guys,  I finally got the bike running as of this past weekend!!! I had the carbs apart and I removed all the jets, floats , etc and cleaned like crazy. When I put the floats in I noticed they looked a little off and the symptoms of my bike fell right in line with not getting the gas needed to keep idling. so I adjusted the floats and when I hooked up the carbs, VROOM VROOM, it ran. It idled and everything. I was extremely happy to get it running. I do have to do some work to get it tuned up correctly as far as the fuel screws / idle adjustment and stuff.  When I twist the throttle it jumps up to about 2700 - 3000rpm and hangs there for a few seconds, Does anyone know why this might happen??  here's my setup so far. I have the PD42 Keyhole carbs, 35 pilot, 110 main, needle with a tiny washer underneath (non-adjustable) and I have the fuel screws out 1.5 turns on each, stock airbox- brand new filter and stock 4-4 pipes. Also how high should the bike idle with the choke all the way out? Does the problem I'm experiencing have to do with the fast idle cam?  Thank you all for your help, I really appreciate it.
Eric - CT - 1978 CB750 K
Reply | Threaded
Open this post in threaded view
|

Re: ** It's ALIVE **

Re-run
Administrator
OK, lets start with the filter. Is it a stock filter, or is it some after market filter? The honda filter is best for paper filters. The cheaper paper filters are hit and miss.

Ok, so if you have the choke pulled out and the idle cam engages, your idle will be around 2500 rpm till you start to push the choke in. It might be a bit higher or lower. You also can't go too much by the stock tach, for fine readings. So to recap, choke out engages fast idle cam and the rpm will be around 2500 or so.

If you have a slow idle return when the choke is off, that usually means the bike is a bit lean. Easiest way to check is to pull the plugs and look at the insulator tip base. If it is really white, it is lean. Try to turn the fuel screws on the corresponding carbs out 1/4 turn and see how it is. Once idle improves some, then sync the carbs and do the final tune then using a more accurate tach.
The ride IS the adventure. The destination is just to get gas!
Reply | Threaded
Open this post in threaded view
|

Re: ** It's ALIVE **

Ericcb750
Hey Re-Run, Thank you very much man. I appreciate it. I have been basing this on the tach on the bike. Also the filter is in the stock airbox but it is an EMGO one? Is that junk? Thanks for the info on the fast idle cam as well as the bike running a bit lean. I will test these out tonight and pull a plug or two to see how they look. I'll keep you posted as to how things go. Thanks again.
Eric - CT - 1978 CB750 K
Reply | Threaded
Open this post in threaded view
|

Re: ** It's ALIVE **

Ericcb750
Hey Guys,  So I checked a few things and I found that my exhaust pipes 3 out of 4 were a bit loose at the head. After positioning them better and tightening them down the bike sounds and seems to idle better. I still have to get a set of the sync gauges or try and borrow one so I can get them all dialed in. Anyone know if for a bench sync if my slides are supposed to be open at all ? Also, are the only adjustments for the PD carbs the fuel screws and the slide heights?? I didn't think there are air screws on the PD42 type carbs but i'm new to this so I'm not positive. Thanks for your help.
Eric - CT - 1978 CB750 K