Fueling problem

[cakey]

I have a p200e engine fitted which has a Malossi 210 top end, ported casings and a flowed crank. The carb is a standard si24/24e dellorto fitted with the recommended 130 main jet. I have altered ignition timing to 18 degrees TDC as required. The problem I'm having is a lot of fuel blowing out the top of the carb so much so it runs down the crankcase ! I've put a122 jet in which has made it a little better but it still does it, I've checked the choke and it isn't stuck on ! I've even tried a brand new spaco but it still does it...... any advice would be appreciated

[doulsy]

spitting out the carb? im told blow back is pretty normal, had it myself with my standard p200e, runs ok, had lots of issues with my carb, run it with a spaco carb now, pretty sure i started a thread about it on here before.

[pxguru]

A little blow back is normal but running down the casings is too much. By ported casings I assume you mean barrel transfers matched to the casings. If someone has been in the rotary inlet and gone too far that could be your issue. Assuming that yours is like a normal 210 and runs generally fine, then it is just not properly set up.

Timing at 18 degrees BTDC is where I would put it, any less and you start to lose the bottom end for pulling 4th gear (even with a T5 cog).

Even though you have tried two carbs, first you need to check the carb doesn't leak. The best but not safest test is to leave the fuel tap on for a few days and first see that it hasn't wet itself and then see if it still needs choke to start cold.

Jetting is next. You will blow up the engine on the 122 so put the 130 main jet back in immediately. If you are running with no air filter. Make sure it is drilled out and put it back on.
Check the other jets in the carb too. They should be all standard at this point, pilot 55/160, Air corrector 160 and Atomiser BE3.
Adjust the mixture screw at tickover (all the way out and slowly in until about 1.5 to 2 turns out where the revs pick up).

Get this checked and see how it goes.

[cakey]

I shall leave the fuel tap on overnight but I'm confident there's no leaks, the inlet hasn't been touched it's still standard. The engine was fitted in the scooter when I bought it and I was under the impression it was a standard lump it wasn't until I removed the top end I noticed the transfers and the polished con rod. I dropped the gearbox oil out this morning and that looked perfect black but no fuel or bits so it seems like seals are ok. Thanks for your help

[pxguru]

The blowback won't be seals and sounds like it isn't the inlet then. The air filter is on the carb? The rest is jetting. What was in the carb?

[cakey]

The carb is a new one and the jets are standard and exactly the same as you said in previous post, apart from the main jet which I put the 130 back in.
It probably needs to get to normal running temperature and see if it does it when hot

[cakey]

Problem sorted folks I ended up taking the scooter to Readspeed for a dyno fuel air set up. Bearing in mind it's a p200e with mallossi 210 kit, flowed crank, ported casings, stock carb with a drilled filter and 130 main jet. Plus a sip road 2 exhaust.
It's ended up with a 122 main jet and a new air filter NOT drilled. Its power output is 15.5 hp and rides great with the extra 50% on the stock p200 lump.
Food for thought on all the comments on drilled filters guys. There opinions were drilling out the filters makes the engine run a lot leaner so you cannot get a main jet big enough to balance it out as a 135 is bigger than the 24/24 carb body it's self. The carb tubes? effectively becomes the main jet, hope that makes sense!

[mijapxman]

I've heard that a lot of times about Max jet sizes on standard 24mm type carbs.I do know standard carbs, with the air hose connected to the frame are a nightmare to jet, if the plastic drip tray? under the standard petrol is missing, believe it makes the frame act as a carb airbox.
Glad your all sorted now 😀.