Honda-SOHC

Any ideas where I may find a decompressor cable for the 250RS? Looks Like Dave Silver cannot supply.....

Will any other cable from any other bike fit?

I should have mentioned this is not a Honda- rather a 58 Velocette Viper where drive from the kickstart to the box then via the clutch to the primary drive. I need to be able to tell when I just have clutch slip in order to adjust the clutch. Velos have a unique adjustment technique.

A slack cam is no good at all! ATU weights should move out freely, springs free of any crud. Oil the pivot points perhaps. Also check out all screws holding points for 2 and 3 are tight, and re-check the gap. Clean the points. Check out all electrical connections to 2 and 3 points and check out the condensor -  with ignition on and if it sparks when you open the points gap, then a possible condensor problem. Have you a spark across the points when it turns over? 

Chaps

I am very pleased to report I have just ridden the bike very quickly up my very convenient, quiet test hill just outside the village, and I can report all seems well. In fact far better than before! It pulls like a train. The problem did indeed appear to be condensors, and in all probability, one of them was on the way out creating less than adequate sparking before it finally gave up.

Couple of points - pun intended....

Intially I must have inserted the fork connectors of the condensors to the small bolts incorrectly. I do realize there are insulating washers and that the contact fork terminal sits in there also. Initially the bike would not start after replacing the condensors. I then fiddled about further, and inserted both fork terminals under the washer which sits under the head of the bolt. The insulating washer follows this, which would seem to insulate the bolts/forks from a bracket and thus the contact breaker plate? When it would not start, I feel the fork connector(s) may have been in contact with bracket/contact breaker plate. I am no sparkie so lesson learned perhaps....which is carefully note how things are connected/attached before removing them!

Everything pointed to fuel as the problem. I guess the condensor died when I turned the ignition back on at the petrol station. One for the brain's hard drive -  not to be wiped. Thinking about it, the bike now performs so well that it may be worth replacing condensors on other bikes as a matter of course. I have no idea how these things behave and if condensors degrade over the years, but for £10 from Fleabay, it may be a worthwhile thing to do on the 400/4 and the GS1000.

Very many thanks for all your suggestions and help. I find these forums are a truly beacon of kindness in this increasingly disagreeable world. 


       

Dave

Pretty sure nothing blocking the air intakes - which is indeed under the seat, but I'll check it out. I've known stranger things to happen! Condensors - hopefully that will be the issue. Perhaps after turning the ignition off/on at the petrol station, one condensor just gave up...who knows. If it is not condensors, then I'm stumped  :'(

Dangling the part over a portable gas fire seems to work just fine for curing the Plastikote paint at least. You may be sure I will be dangling from the end of a rope were I to use the oven.

I am open to other suggestions for heating the part to such high temperatures.....

Dave

Yes - I too thought about the ATU not working properly so I sprayed it - behind the contact plate -  with WD40, and also oiled the pivot points - although I must admit I haven't checked it properly as the contact plate fixing screws are a swine to remove!  ATU's don't often go wrong though do they?. I also visually checked the connections around the coils/earth/plus leads - nothing obvious. I did though check the condensors. According to Haynes, if points spark on breaking with the ignition on, then possibly one of the condensors is goosed. One did spark, and reading up, what I am seeing when riding the bike could be symptomatic of a failed condensor.  Condensors now on order.....

I agree that all these things are very odd. One minute it is running fine, very well in fact - the next hopeless, for no obvious reason. Britsh bikes are even worse for this!

Thanks for all the info - all useful stuff. Honda RS progressing - slowly. Bottom end done, barrel back on.       

It's proving not to be an easy fix. That or I'm going dotty! Filled a clear empty brandy bottle with petrol to test presence of water in fuel - so much more sophisticated than a jam jar I feel! - Nothing settled out. Replaced all fuel with fresh from another petrol station - no joy. Removed the in line filter between petcock and carbs - no joy. Rode it with filler cap open - no joy - Fuel tap all clean...Proving to be very irritating! Any more clues would be greatly appreciated......