New Member

[Davelu88]

Hi all
         New member to this site but i have been a member on the US one for a little while ( didnt know about this one ) anyways im in North Yorks area and i have a 1975 400/4 Varnish Blue with 38k on the clock , pretty much restored apart from the tank as i like the patina of it , having a bit of carb prob so here i come begging for info lol.
Dave

[Nurse Julie]

Welcome Dave. Didn't know about this site?......gosh. Anyway, you are in the right place now. What's the problem with your carbs?

[Davelu88]

Hi Julie
        Im bad not knowing about this site so apologize to all.    Bike was running a bit crappy lacking power and wanting to stutter but idling  ok but with an overflow from one bowl so i stripped the carbs cleaned as best i can and rebuilt with new jets and float needles, its stopped the overflow so no prob there but it was still not right so i took to shop who balanced carbs and adjusted tappets its got a Boyer Ignition. It seem to have a bit better top end as before would struggle to 60 but when riding slow EG: in traffic it stutters and sometimes when slowing down from speed it seems like its gonna cut out and then picks up. any help would be appreciated. its all stock apart from Motad 4-1 exhaust .

[Nurse Julie]

Do you know what setting the mixture screws are set at ?

[Davelu88]

Hi , No i was hoping shop took care of that side of things when they balanced them !! forgot to mention it has new carb boots to airbox as well

[royhall]

Give it a run and as soon as you stop pull the plugs out and have a look at the colour. Will give you an idea if it's running rich or lean, or if one cylinder is different to the others. Post a photo if you can. "O" and welcome by the way.

[Nurse Julie]

So no air leaks that you have found ?. I run standard points on mine and have no experience whatsoever on BB electronic ignition, so I cannot comment on that side of things. It may be a bit of dirt in the idle circuit. Are the revs holding constant at idle or do they go up and down on their own ?. Do the revs come straight back down when you throttle off or 'hang' and then come down?

[Davelu88]

Idles at 1200 but rises to 2000 rev it up and it drops back to 1200 but creeps up again , as far as i know no air leaks i have given it a spray round that area to see if revs changed but no change.

[Nurse Julie]

Looks lovely. What spark plugs have you got in ?

[Davelu88]

Thanks , plugs are NGK D8ES  it did have D8EA in it but when i changed plugs had trouble getting the 8EA

[Nurse Julie]

I could be wrong but I think the ES is just the new version of the EA (someone will tell me if i'm wrong i'm sure !!!). I was just making sure you were not using plugs with R in the title which means resisted, with resisted plug caps as that combination gives the symptoms you are describing with the fluctuating revs. I know this as I fitted the resisted plugs in error one time and had all sorts of problems !!!. As Roy said earlier, whip the plugs out after a run to get a general idea of if she is running lean or rich, my guess would be lean which is no good at all and running long term like this can cause serious damage to the engine(see my engine rebuild thread  ).

[Davelu88]

Many thanks for all the replies , i will do a plug chop in the next couple of days and see whats what.

[royhall]

I could be wrong but I think the ES is just the new version of the EA (someone will tell me if i'm wrong i'm sure !!!). I was just making sure you were not using plugs with R in the title which means resisted, with resisted plug caps as that combination gives the symptoms you are describing with the fluctuating revs. I know this as I fitted the resisted plugs in error one time and had all sorts of problems !!!. As Roy said earlier, whip the plugs out after a run to get a general idea of if she is running lean or rich, my guess would be lean which is no good at all and running long term like this can cause serious damage to the engine(see my engine rebuild thread  ).

Yep probably lean. Sounds like an air leak to me?

[Davelu88]

I couldnt find one and sprayed carb cleaner all over area to change revs but no joy , anywhere else too look for leak ?

[Nurse Julie]

Absolutely anywhere that rubber meets metal or anywhere there is an opening with something in it that isn't fitting tight enough