Weird hole in carb

[lutorm]

So I'm taking my carbs apart for cleaning and I noticed that the number 4 carb has a hole in the lid where the throttle axis goes:

That's not normal, is it??

That hole area was covered with gunk which I now suspect was epoxy or something meant to cover that hole, as if someone accidentally punched a hole in it and then tried to fix it up. It doesn't look like that part comes off, either.

While I'm at it, I noticed that the choke linkage is mismatched so the front and rear cylinders are not getting the same amount (it engages the fronts first and but there's slack in the linkage to the rears so they don't engage for a while). Is that adjustable somehow? I see how the left vs right ones are adjustable by moving the tap on the long bar, but there's no obvious way to adjust the front vs rears.

Thanks a bunch guys,

/Patrik

[JC120]

Just checked mine and there's definitely not supposed to be a hole there. I'm not sure what to do about that or why it's there. You could just get another set of carbs or epoxy it.

Not sure about the choke linkage either. From what I see there's no way to adjust it. Maybe if you bent a part to take up the slack.

[Cammo]

Best to block that hole back up, it shouldn't be there and will affect how the bike runs.

Many sets of carbs that i see don't uniformly open the front and rear choke plungers the same amount. As long as the choke plunger is being moved by some amount (don't have a set in front of me at mo to give estimated measurement) then the choke function usually works fine and I wouldn't be too concerned - they don't need to move far to be fully open.

Not sure if you've seen the V4 carb jetting/cleaning guide here, it might be worth a read if you haven't seen it: http://www.400greybike.com/docs.htm

[lutorm]

Best to block that hole back up, it shouldn't be there and will affect how the bike runs.

Many sets of carbs that i see don't uniformly open the front and rear choke plungers the same amount. As long as the choke plunger is being moved by some amount (don't have a set in front of me at mo to give estimated measurement) then the choke function usually works fine and I wouldn't be too concerned - they don't need to move far to be fully open.

Not sure if you've seen the V4 carb jetting/cleaning guide here, it might be worth a read if you haven't seen it: http://www.400greybike.com/docs.htm

Oh yeah, I remember looking at the cleaning guide way back, thanks for pointing that out again. I noticed something else funny: the one carb I've dismantled (#2) has a #110 main jet, but this is a 'N' model so both that guide and the Haynes says it should have a #120... I guess I'll see what the other ones are before guessing what's up here.

[Cammo]

I noticed something else funny: the one carb I've dismantled (#2) has a #110 main jet, but this is a 'N' model so both that guide and the Haynes says it should have a #120... I guess I'll see what the other ones are before guessing what's up here.

Yeah happens all the time from past owners fiddling with things, the only way to tell what's inside the carbs is to open them up!

[Neosophist]

You may well find that the carbs were left for a long time with stale fuel in them, gumming them up real bad.

Sometimes unless you have good cleaning equipement and decent ultrasonic bath it is really difficult to unblock the small pilot circuit passageways so it never idles properly.

Often in this case it is cheaper to buy a decent condition set of second-hand carbs.

My guess is that somebody brought a new set of carbs, didn't know the early model had different jettings and just bolted them on.

Or, your bike is actually a K model, if it has the brass adjuster screw in the middle of the front forks, remote resevoir rear-shock and grey/black calipers then its most likely the later model.

[lutorm]

You may well find that the carbs were left for a long time with stale fuel in them, gumming them up real bad.

Sometimes unless you have good cleaning equipement and decent ultrasonic bath it is really difficult to unblock the small pilot circuit passageways so it never idles properly.

Often in this case it is cheaper to buy a decent condition set of second-hand carbs.

My guess is that somebody brought a new set of carbs, didn't know the early model had different jettings and just bolted them on.

Or, your bike is actually a K model, if it has the brass adjuster screw in the middle of the front forks, remote resevoir rear-shock and grey/black calipers then its most likely the later model.

Yeah, strangely enough, the insides of the carbs don't look bad at all. The whole exterior engine is filthy (i think due to a combination of bad fork seals that threw oil everywhere when it got on the tire and a leaking front valve cover) but the insides aren't bad. And it's definitely an N-model, the equipment, the engine number, and the sticker under the seat all agree on that.

I guess we'll see what I find when I open up the others...

[Cammo]

And it's definitely an N-model, the equipment, the engine number, and the sticker under the seat all agree on that.

You can also check from the carb ID whether they're early or late model carbs: http://www.400greybike.com/files/models.htm

[lutorm]

You can also check from the carb ID whether they're early or late model carbs: http://www.400greybike.com/files/models.htm

Yeah, they are K-model carbs, so I guess that makes sense. Someone must've done a carb swap at some point.

[Neosophist]

You can also check from the carb ID whether they're early or late model carbs: http://www.400greybike.com/files/models.htm

Yeah, they are K-model carbs, so I guess that makes sense. Someone must've done a carb swap at some point.

Yep, often when they are messed about with / badly shitted up its sometimes cheaper to buy a set from a working bike than have them professionally cleaned, especially if you dont have the equipment to do it yourself.

Soem peopel dont realise different models will have different jetting.