popping and banging

[(RIP) pastyman]

Well I took the new 80 m0n0 out to get her boots muddy last weekend, It was peeing down but after hiding for a while in the local bikers cafe ( with all the guys who had come in their cars) I went out to play. got nice and muddy and just managed to keep it shiny side up. wrong tyres fitted. Anyway the engine never missed a beat. got home and is my wont, a quick spray with flash and a good hosing down( not a pressure wash) put her away and sat5 down to a nice bit of roast beef....
Now the real reason for writing this.. couple of days later started her up (the g/s) as usual running sweet until she warmed up a bit and I closed the choke. Pop ...Bang ....rough as an old boot then stopped and refused to start. checked all the usual, spark and fuel. No sign of water in either the tank or the bowels. Left alone till next day, tried again and exactly the same. started off the button, sweet then popping and banging. left alonhe with battery charger on and try again next day. still the same. more bits checked again including air filter. Today I started her again and would you believe it, perfect and stayed that way...... I did however notice that the little cap on the top of the right hand carb is missing. there is a rubber bit in there but I dont know if the cap goes over that or whether someone has stuffed this in instead. I suspect that water has got into the vacum chamber then cocked up the running on that carb.........Now then can anyone answer the above and also can the little metal cap be obtained or is it a new carb top.

 

[Daithi]

I suspect that water has got into the vacum chamber then cocked up the running on that carb.........Now then can anyone answer the above and also can the little metal cap be obtained or is it a new carb top.

I'm really only bumping this, and have no idea and don't pretend to. But if water got into the carb
via the vacuum tube wouldn't the bike be spluttering from the moment you started it ?
I would have been thinking cracked ignition coils getting warm and breaking down or something.

This is only a BUMP, please refer to my first sentence !

 

[DrFarkoff]

Would put me in mind of a cracked coil or leads that have dried out!

Next time it fecks about try checking it out in the dark you may see the spark jumping on the lead or coil or something (but don't get your nose too close) or maybe you've got water in the ignition amplifier jobbie and it's sendin the signals out when it feels like

BEfore you take it out or get it wet spray all your block connectors (Inside and out) with ACF50 or WD40 or summat like that

 

[(RIP) pastyman]

Thanks for that. I was thinking along the same lines but could find no fault with the electrics. everything seemed nice and dry and no shocks even when touching coils, leads etc. She always seemed to start off the button, cold though I did notice the exhaust was a bit steamy. Yesterday though she started and continued to run fine with no problem so I can only put it down to the carb and the most likely area is the missing cap on the top of the left hand carb. I dont know where water would go down this hole. I suppose it could get into the vacume chamber on top of the slide then get drawn into the carb proper, I dont know. Anyway I need either a new top or as my original question, can the little metal caps be got seperately?

 

[MickDB1]

Have you got Mikuni carbs on it or are they the standard Bing jobbies
You discribe a hole in the top of carb, I dont think there is one on the Bings
My mate had some posh Mikuni's on his 80
Some crap went down the cable adjustment to the throttle slides and stoped them sliding shut as they should
HTHY

 

[(RIP) pastyman]

They are the standard bing carbs. The top of the carb is an alloy cover with a pressed in steel cap. Thats whats missing.

 

[Daithi]

Well, they all seem to have their own part numbers, kinda implies they can be bought seperately.

Daithi

 

[Shep]

No Idea really, but if you do choose to wash the bike after riding it, its best to wait till the bike cools down, as the steam created if the engine is hot, can permeate almost any normal auto electrical connector, creating issues.

Shep

 

[nud1e]

They are the standard bing carbs. The top of the carb is an alloy cover with a pressed in steel cap. Thats whats missing.

The alloy cover with a pressed in steel cap is an integral working part of the carb, and the rubber that you can see through the hole is the diaphragm.
Without the steel cap, there is no vacuum created for the diaphragm and so the needle won't rise.
I've never encountered this failure before. Remove the damage cover and see if the steel cap has dropped through. If it has, you might be able to solder is in place again as a temporary repair.
In any case, you need a replacement cover.

 

[(RIP) pastyman]

The alloy cover with a pressed in steel cap is an integral working part of the carb, and the rubber that you can see through the hole is the diaphragm.
Without the steel cap, there is no vacuum created for the diaphragm and so the needle won't rise.
I've never encountered this failure before. Remove the damage cover and see if the steel cap has dropped through. If it has, you might be able to solder is in place again as a temporary repair.
In any case, you need a replacement cover.

Yep, I decided that I would have to strip the top off the carb(Bugger, I'll have to balance everything again) I found that the pressed in steel cap is missing and someone has replaced it with a rubber plug ,liberally applied with silicone. There were signs of water in there too. Ive been on to motorworks who are sending me a second hand cover and some other bits so it would seem the problem is over.
Thanks for all the replies.