NC35 starts, runs, stutters to halt and then repeats...

[0.S]

I'm a new owner of a 94 NC35 that I brought to Sweden some months ago.
During the past few weeks I have changed a few items like discs, pads etc and decided yesterday I would take it for a test ride.

While I wouldn't say it started easy, it did start and after leaving it run for about 10 mins I set off but... it runs for about 5 miles, bike stutters to a halt and then starts again a few mins later when the symptoms are repeated..
This happned 3 times and last time it would not start and it was a van job home!

(Tank was full and on res positon)

Advice, suggestions and tips are most welcome

[Man_Named_Dave]

Check the electrical system?

[skinnydog0_0]

I would start with the battery, and work back. Reg/rec and genny.
It could be you have a bad earth discharging the battery when the bike is running, but i reckon it's reg/rec related.
any other issues or have you made any carb changes?
Was the bike running when you bought it?
Diolch

[Cammo]

Check the fuel tap vacuum line also.

When it gets hot it can collapse, stopping fuel flow to the carbs.

[alexwitham]

Squashed fuel tank breather?

[skinnydog0_0]

Yes good point Cammo/Alex - i dont have one on my bike so i always forget about it

[0.S]

Thanks for the replies and…

Bike was running when I bought it and rode it briefly between Cardiff / Brecon

I haven’t made any changes to the carbs or anything else that involves the engine running.

I will charge the battery, check physically anything that appears loose etc, check fuels lines and as I was given a new rectifier, I can change that too but I will try one at a time or I'm not going to be any wiser if it suddenly runs…

Bike has been sitting for nearly year but I did put new fuel in the tank as it was drained prior to me bringing it to Sweden

[Cammo]

I will charge the battery, check physically anything that appears loose etc, check fuels lines and as I was given a new rectifier, I can change that too but I will try one at a time or I'm not going to be any wiser if it suddenly runs…

Good idea only changing one thing at a time.

Don't change the reg/rec unless the electrical checks are out of spec. There's a good guide to the electrical/charging system checks at the link below.

http://www.400greybike.com/docs.htm

With the other stuff suggested above (breather & vacuum line etc), just replace them if in doubt. Numerous posts on this forum indicate that the above can be troublesome on these bikes. It's easier to replace these low cost parts to eliminate them as a cause than spend money elsewhere and keep looking for the problem.

I'm sure you'll find the problem in the end with the help of this forum.

[0.S]

Don't change the reg/rec unless the electrical checks are out of spec. There's a good guide to the electrical/charging system checks at the link below.

http://www.400greybike.com/docs.htm

With the other stuff suggested above (breather & vacuum line etc), just replace them if in doubt. Numerous posts on this forum indicate that the above can be troublesome on these bikes. It's easier to replace these low cost parts to eliminate them as a cause than spend money elsewhere and keep looking for the problem.

Thanks for the link and a short update is;

I left the battery on charge overnight and that appears all ok.

I changed the fuel line from the tank to the ‘splitter’ and this was very worn/soft/pliable indeed.
I then changed the fuel tank breather & drain hoses as both of these were worse for wear with cracks visible.
Took the fuel tap off and checked/cleaned the filters but they weren’t that dirty to be honest.

So, after putting the bike back together and adding fuel, it started up and moved onto the electrical tests

Time for multi-meter fun and got a reading between high 13 and low 14 volts.
I did the resistance checks too and all was fine there but as I had the fairing off, I checked the block connector going into the rectifier and there are burn signs but it doesn’t smell or appear fresh.

So, it’s running ok and I'm planning a road test tmw as I don’t fancy doing it alone in case I'm stranded once more.

[Cammo]

I changed the fuel line from the tank to the ‘splitter’ and this was very worn/soft/pliable indeed.
I then changed the fuel tank breather & drain hoses as both of these were worse for wear with cracks visible.

Don't forget to check the fuel tap vacuum line.

Good chance this is your problem if the hoses above were worn.