SOHC.co.uk Forums > CB500/550
Trouble with bike
K2-K6:
--- Quote from: beardylondon on February 23, 2025, 10:23:36 AM ---Thanks Julie, I'll buy some if I need them!
Another question, Valvoline carburetor cleaner is only available from Opie it seems and is quite expensive when you add delivery.
OB41 has good reviews and is half the price, anyone used it?
https://www.screwfix.com/p/ob41-carburettor-cleaner-400ml/859fe
--- Quote from: Nurse Julie on February 23, 2025, 10:11:39 AM ---I sell the OEM TEC condensers as they are the best.
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Those two carb cleaner look quite different in constitution, no experience to offer in comparison and effects that can help.
I do use STP cleaner though, which is much closer to Valvoline in product content, possibly more economic to buy that in general market.
Don't know which stabiliser you've used ? But if you've any spare small amount then some of that administered via syringe into "airscrew" port (remove screw to access) may give direct cleaning of the idle circuit etc. Or the same for carb cleaner via the little tube that comes with them.
beardylondon:
Thanks. Have used Stabil storage fuel stabilizer
K2-K6:
--- Quote from: beardylondon on February 23, 2025, 12:52:47 PM ---Thanks. Have used Stabil storage fuel stabilizer
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Looking at it before in forum thread, it appears to contain plausible chemical concoction to mitigate and dissolve gummy residue. A small amount in concentration of idle circuits may help here.
The Valvoline & STP show content of various % in amongst them, toluene, acetone, naphtha solvent to attempt removal of varnish/gumming etc. Both would be suitable I think.
andy120t:
Carb cleaner - I used Valvoline because it's instructions ( which I found online somewhere) specifically said it worked without needing to dismantle the carbs (ie) spray it into a running engine .. and as I was getting tired of dismantling carbs I thought it was worth a try.
deltarider:
--- Quote from: K2-K6 on February 23, 2025, 12:49:13 PM ---[...] But if you've any spare small amount then some of that administered via syringe into "airscrew" port (remove screw to access) may give direct cleaning of the idle circuit etc. [...]
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I have had good results with that ^. Spray some carbcleaner from a can with a straw in the orifices. Before removing airscrews, first turn them in fully - GENTLY! - so you can take notes of the position they were sat at and can reposition them again afterwards.
I still don't know what made you replace the coils. Which coils do you have now? Are you sure the primary feed to them is connected firmly? We welcome pics.
I myself haven't used fuel stabilizers so far. When my bike is in hibernation, I leave the carbs in their natural state, which is wet. But... every two months I drain the bowls. Then - with the carbbowls empty - I crank the engine a couple of times, so the downgoing pistons can suck air through the jets. After that I open the petcock to have the bowls refilled again. This has always worked for me. You could 'perfect' this method somewhat: when you drain the bowls, why not remove the drainscrews completely, so you can spray some carbcleaner in there from a can with a straw, refit the drainscrews and then crank the engine a couple of times. Won't hurt and maybe it helps to have the jets getting sucked clean.
If you have the engine running and you suspect one (or more) idle circuits, here's a method for diagnosis.
Turn the airscrew of carb #1 fully in and wait some 30 seconds and then open the airscrew 3 turns out and wait another 30 seconds. If you notice within that minute some change in rpm - this does not have to be much! - the idle circuit still works. Repostion that airscrew to where it was before. Then repeat this for carb #2, then carb #3 and finally carb #4. The difference in rpm is often not much, but... if there's no difference at all, it indicates the idle of that particular carb is disfunctional and needs to be inspected. When all 4 carbs show a change in rpm, there's a good chance all idle circuits are OK. When in doubt, add a liberal amount of a socalled fuel system cleaner additive to the tank and go for a ride. There's no risk of an overdose. These additives are also hydrocarbons and will happily combust.
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