Gunson colour tune or similar
Discussion
I’ve got a 1978 Honda CX500 that I bought as a project. I’m having some trouble getting it running well. It starts easily enough but tends to stumble a bit when revved and smells like it’s running rich.
Is something like the colour tune enough to give me an idea of the mixture?
I’m already quite far off normal base settings to get the bike to a rideable point. I cleaned rather than replacing the jets, would I be best buying new jets?
I’ve no idea how many miles are on it, the odometer ties in with recent mots but it may have been changed at some point.
Is something like the colour tune enough to give me an idea of the mixture?
I’m already quite far off normal base settings to get the bike to a rideable point. I cleaned rather than replacing the jets, would I be best buying new jets?
I’ve no idea how many miles are on it, the odometer ties in with recent mots but it may have been changed at some point.
Does the bike still have the original airbox, filter and lid on it. If not and you are trying to get it to run correctly then this will be problematic. If you look into the mouth of the carburettor you will see that the low speed or air correction are in a separate chamber at the bottom of the inlet circle at the rear of the carbs.
Pods don't have that partition and air enters everywhere at the same speed and pressure. This is really difficult to get it to a point where the flat spot is acceptable.
Also you mention cleaning the jets, if you had a build up and used the wrong cleaning method, then it is possible that the jets size or shape has been changed internally.
For me I would start by checking the mounting rubbers for perishing and leaks at where the carb balancer goes on. The by purchasing genuine Honda jets if you can find them, or jets from David Silver. Look at getting new needles too and check the diaphragms for pin holes or tears. Once the carbs are fitted with new hardware then move on to the airbox and filter.
A Honda CV Carb really needs an airbox and filter/lid.
Most of this info has had to be dredged up from my memory banks from 1978-81 when these old girls were new, so thats 45 years ago when I were but 21 yr od. So some of it may be hazy to say the least
Good luck in getting it running nicely.
Pods don't have that partition and air enters everywhere at the same speed and pressure. This is really difficult to get it to a point where the flat spot is acceptable.
Also you mention cleaning the jets, if you had a build up and used the wrong cleaning method, then it is possible that the jets size or shape has been changed internally.
For me I would start by checking the mounting rubbers for perishing and leaks at where the carb balancer goes on. The by purchasing genuine Honda jets if you can find them, or jets from David Silver. Look at getting new needles too and check the diaphragms for pin holes or tears. Once the carbs are fitted with new hardware then move on to the airbox and filter.
A Honda CV Carb really needs an airbox and filter/lid.
Most of this info has had to be dredged up from my memory banks from 1978-81 when these old girls were new, so thats 45 years ago when I were but 21 yr od. So some of it may be hazy to say the least
Good luck in getting it running nicely.
It’s about as standard as you can get when buying bikes that were cheap workhorses 47 years ago!
I’ve got bikes I’ve modified but this was bought to do things like the DGR and slow trundles so I wanted comfort.
I cleaned everything by soaking the parts in carb cleaner for a couple of days then flushing them through with more carb cleaner, no wires were used.
Looks like David silvers have full carb kits for sensible money so that’ll be my next job. Hopefully it solves the issues!
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