Project My Fizzer

All roads seem to lead back to relying on the needles holding or there's a problem.
Maybe we need to replace the needles more frequently to avoid these problems ?
There's a Mikuni dealer down south somewhere that should have specs & parts.
Seems when ever someone does a carby clean or rebuild they go better for a while, haven't read where anyone has replaced the needles because of the cost & probably because of knowing what is the right part number for the 250's.
I can translate from Jap if anyone has a Jap part book ?
I'm not too keen on using 400 or 600 parts as an alternative, factory engineers go to a lot of trouble calculating specific parts for specific models in an effort to keep costs down, not saying nthey don't share parts but you'd think fuel supply requirements would be critical & different enough to warrant slight changes, pump pressure & fuel consumption would have an effect maybe.
Anyway I'm getting a better picture of what we are dealing with & we are going to be better off for it.
Your right they are like women, you have to get to know them & deal with them appropriately
Remember beware the cycles of the moon & keep your distance.

 

Hey Will, fear not we have the info you need - part number is 3gm-14107-10-00 - it is the exact same part used on other models, not a close match or subsitute

Available from partzilla ~$22 US, or other sources if you need alternatives. See if you can split shipping costs with someone in oz that may have an order for parts as shipping adds a bit to the cost.

Alternative is Yamaha Aust - they've got some arriving approx 10th January $60 each though.

BTW my new needles & seat valves arrived yesterday, but I'm waiting on some o-rings to test for Grey, once I've got that done I'll give a complete set of results of the part replacement.

The o-rings that came with the new parts are completely inadequate, I can lift the needle seats out with the floats attached by just lifting the floats - petrol under pressure is going to get past a seal that loose way too easily

peace out

 

My testing today was inconclusive - so watch this space, I think I have made a breakthrough, but don't want to spill the beans too early and end up with egg on my face - this message seems to have a food theme - I must be hungry

 

So I'm guessing the the seat is an insert into the float mounting base piece & the insert has an o ring around it.
I wondered what the talk was about the o ring, I thought it was the big one on the base piece that comes in the kit. The fog is lifting, I never went that far when I rebuilt the carbs, maybe a good thing not to have disturbed them. It'd be nice if it is just the o ring that leaks & not the very expensive needle & seat.
Or have I got it wrong?

 

I replaced the housing o ring as per your instructions with your rebuild kit. So what o ring are you talking about doing a run of? the new one was a very tight fit, relying on the pressure of the bowl fit keeping it in place.

 

Well we're now back to my initial exclamation of the cause - the list is short however, run/stop switch and sidestand switch and tci & relay connections

I need a way to differentiate between the carbs flooding and an electrical gremlin is those switches check out

 

I've got no issues doing SMD rework on circuits so not afraid of the TCI, but not going to run at that first thing

I still have to eliminate flooding and test the other o-rings, more to do just when I thought I had it licked

 

Forgot to mention that with the new needle & seat valves installed my fuel level changed to 9.2mm above the casting line on the carb - which is in accordance with the 3ln1 supplement that Blair posted.

Interestingly it was 10.5mm across the board with the old parts. I measured it very accurately both times.

The viton tip can become hardened and slightly deformed as well as the tiny spring becoming fatigued and weaker.

So for anyone with a bike running rich it's worth the few dollars to replace the float needles at the very least - they're cheap and easily available locally - a link to motorcyclespareswarehouse is somewhere in this thread

peace out