won't accelerate with air cleaner on By kajin911 (Read 989 times)

[kajin911]

I have a mc-54-250b and it acts as if it’s starving for gas. It won’t accelerrate very well at all. however when I take the air cleaner off it runs fine back to 70MPH. as soon as I put the air cleaner back on it idles fine but sputters if I hit the gas. It does it when I put the housing on even without a filter in it. There is no blockage in the rubber boot that leads to the filter housing. I am at a loss not sure where to go from here?

It only has 400 miles I bought it new in 08.

Any help is appreciated


K

[Alleyoop]

The problem is your running RICH as HECK it is NOT starving for gas. Did you change any jets in it or Raise the Needle in the Diaphgram?
Alleyoop

[sunlproblems]

put a uni filter on it check the sparkplug see if its running to rich for a change because its usally the othewr way around set the af screw out 2 and a half turns and go from there

[kajin911]

I haven't changed anything yet, but thank you for the info! I am new to these scooters. I will try your suggestions is there a "default" setting for the sir flow screw? it is the one nearly imposible to get to on the bottom of the carb right?

thanks again

[mike6736]

Yes that is the screw to adjust turn it in than out 2 1/2 turns than adjust from there. It nay have a cap on the screw just pop it off

Mike

[kajin911]

Well no luck, I removed the carb it all looks brand new and everything seems to function fine. I adjusted the A/R screw 2.5 turns then played with it ¼ turn at a time in and out but it makes no difference at all that I can tell. Not sure what to try next, I did try new gas but no luck there either…
Thanks for the help so far!

[bhinch]

Sounds like the time to adjust the valves situation...not sure why everyone thinks the carb has a problem....and they start messing with it...I have never touched the carb adjustments for 5800 miles....3yrs.....the valves fixed everything.... .004 intake.... .006 exhaust.... then reset the idle.....1700-2000....try it...you will like it....the low mileage is the give away...the boys across the pond can not adjust the valves properly at the factory or where ever they put these scooters together....every scooter has to have the adjustment done...period...I installed the manual choke mod....allowing me to adjust the idle with the choke...

[kajin911]

!
This site is the best support forum I’ve come across in a long time thank you all!

I adjusted the valves as suggested the exhaust valve was right on, the intake valve was touching so I can’t tell how far off it was. All is adjusted fine now. It was an easy job because I already had all the plastics off.

Unfortunately all that did was increase my idle so I re adjusted it back down to just under 2k. At this point I was bummed it still was drowning as soon as I juiced it.

I decided to take the carb apart one more time. I checked the float before to be sure it was working as it should and it seemed too but it wasn't closing the valve until it was almost all the way to the top. I bent the tab up so it would close a little faster and presto we are back in business its running like a champ. I am assuming it was the valve adjustment but it is way more responsive than before it always had a hesitation but not bed enough for me to worry about I just figured it was a cheap Chinese scooter but man it runs like a jap bike now for sure.

Thanks again for your help