22 year old coax, its no wonder you can’t transmit very well, you’re swr’s are probably off the charts, I’d start with a new coax make sure all the connections are clean and corrosion free.
Most swr meters are set up to use PL-259 connectors with a jumper coax between your radio and the antenna coax, I have no idea what Honda used for coax some of these weird automotive am/fm/cb radios used Motorola type jacks, this could complicate maters for you.
Walcott radio in Walcott Ia. Might be able to help
www.walcottradio.com 42-year ham radio operator (30 year Extra, with a formal RF/EE background) checking in here.
Unless that short of a coax run is physically damaged somehow, it will add nothing in the way of an impedance mismatch to the system. I'd check with a different antenna (the loading coils in these are known to go open-circuit). Depending on what sort of equipment is available I'd start with an SWR bridge at the radio-to-antenna connection and a 50-ohm dummy load in place of the antenna. That will absolutely rule out the feedline as being the problem.
FWIW, every Hondaline coax assembly I've ever messed with (and this numbers in the high dozens, if not hundreds) is pretty decent quality and won't degrade. This includes fitment on GL1100, 1200, 1500 and the Valkyrie models.
If the original poster happens to make it to a place where I can test his radio installation I'll be glad to. There's also one other "gotcha" with the Hondaline CB radios. Put simply: The RF final section will not allow 100% modulation at rated (4w carrier) power without distortion due to the use of an RF transistor whose gain and dissipation figures are marginal at this power level - it's a 5w device. A few well-known shops tune these radios for maximum carrier (not optimum modulation envelope) and the result is that your buddies can't hear you due to distortion. There's simply not enough headroom in the power amplifier chain to allow the RF envelope to reach full modulation without flat-topping.
There are two ways to fix: Reduce the carrier level and increase the modulation level (via internal adjustment on the main board) or swap the power amplifier transistor for a device with higher dissipation ratings. I've done the former with every Hondaline/Clarion CB I've owned - and with 2w unmodulated carrier, the radio can be heard at a considerable distance using the stock antenna. (Blondie and I once did a base-to-bike test and got in excess of 10mi range on flat terrain.)
Connectors used in this system are the old RCA automotive radio type. Adapters to insert SO-239/PL-259 equipped gear can be found at any amateur radio or scanner supply shop. I don't see a lot of CB-exclusive outfits carrying them, however.
