LCGB Forums

Is a 300 float valve big enough in a 30 phbh running a imola kit. Reason i as is i was out on it yesterday and give it some beans up to about 60 - 65mph and after about 10 seconds it felt like it was running out of fuel. I backed off to around 45-50 and it ran fine again. Come to a stop at lights a short time after and it ticked over ok and after switching it off a while after it started first kick ( as per usual) and once again ran fine although i didnt get up to that speed again due to being in built up area. Wondered if i need to say go up to a 350 valve ?

I would a 300 should be enough, so perhaps it would be an idea to check the other things that could produce the same symptoms, such as the air breather in the handle of the petrol cap.

What fuel tap Have u got fitted have you checked the flow ?

I'm sure that there's plenty out there with the factory fitted 200 still in the carb with no issues. Use a 270 in my PHBH26.

Would there be any possible downside of going too big?

Thanks for replies. I had actually drilled up through one of the small tubes so it exites were the handle goes in to cap as it was blocked by the powder coating id had done. Got a fast flow tap which i at the minute always run on reserve due to tube needing cutting down as it is too long an i had to turn on to reserve at not much under half a tank. I checked flow a couple of hundred miles back an if i recall it was just over a litre a minute. I am using one of the old black coils/cdi (the black plastic square type) ,it was on the scoot when i bought it and a rectifier of unknown quality although i am about to order a ducati items as it cant do no harm to up grade these things (i hope).

300 is plenty big enough, I would as knowledge and Toddy suggested be looking at fuel flow via tap, is fuel pipe snagging or kinking somewhere or fuel tank vacumimg as a result of no breather, you may also want to check there are no puctures to floats and that the float height is set.

Good luck and dont you just love em?

check that at no point the fuel pipe is higher than the lowest point on the tank if so when fuel level drops so does the flow to carb as part of the fuel inthe pipe is working against gravity .
also if using older rubber pipe it may be breaking up inside.
had a so called fast flow tap that when fitted worked and flowed fine after a couple of months the rubber seal in tap broke up and turned cutting fuel flow drasticaly

Fuel pipe is ok no kinks and routed correctly . I will re check the flow rate tomorrow and also check the float as you suggested. Without sounding dumb how would i no if floats at correct height.

I have to say that about 4 years ago I reverted back to using 30mm PHBH carbs from using Mikunis and copy Keihins. I haven't had cause to check the float heights at all since I changed back but this gives you a starter:

http://www.dellorto.co.uk/images/parts/floatlevel.pdf

Just to echo what has already been said, I have the 300 on both a TS1 and a GT186. No problems.

thanks storkfoot.

R e fuel flow,I was experiencing the same symptoms and went through everything.I didn't suspect the tap as it was only a week old and a genuine OMG.It turned out it was only putting out 150 ml per minute