Fuel vacuum issues, please help

[super50zx]

hi all, been reading forums getting some info, decided to sign up as I am having issues any advice would be appreciated. 2002 kymco super fever 50 2 stroke. just got this scooter about a year ago and I really like it alot was running great . Running along and it just quit, at one point it was getting fuel to carb so took that off and cleaned completely as I thought it would be a carb issue, now it wont start and does not get fuel to the carb via the vacuum line from intake manifold. I confirmed that fuel lines are good n clean, sucked ever so softly on the line that operates the petcock from the manifold and fuel flows excellent, took carb apart again and confirmed correct reassembly etc. took intake manifold off and inspected reeds no issues, new gaskets as well, took cylinder head off, piston and sleeve look great and not alot of carbon either, cleaned and new gasket also. I also confirmed spark is there. I have filled the fuel bowl manually and it still wont turn over. I am at a loss, seems I certainly have a vacuum issue somewhere, i checked for any cracks in the motor case also and that all looked good, any help would be great and if I left anything out please let me know, thanks. I am hoping I just need a new carb but the  fuel not getting to it has me worried.....thanks all

[BettinANDlosing]

If you have a "vacuum" issue sound like you have a compression issue. Try with the air box off crank the engine with your hand over the mouth of the carb, does it suck pretty hard? If you manually put gas in the bowl and it didn't work maybe the cylinder is worn. I have had no-run before because of plugged up exhaust but you said there wasn't much carbon on the piston so doubtful.

[super50zx]

I did that and there is not much suction at all....I am not the most mechanical so if the cylinder is worn what would need to be done, ball park on dollars to fix if I attempt and where would I get parts as I have had no luck finding any online. I will buy a compression gauge and check it at the cylinder first and that would confirm it right? thanks for the reply

[zombie]

Compression test is mandatory. It needs to be at least 120 psi with the throttle wide open.
Just a guess would be a case leak. Perhaps the seals on the crank.

If the compression test shows good I would buy a set of crank seals from Stadium Yamaha. 15% off for forum members but the parts are like 6 bucks anyway. They are easy to install, and the old ones can be left in place. Only the variator, and flywheel need to be removed to install them.

[BettinANDlosing]

If your not mechanically inclined you may end up damaging something and paying more in the end.

[super50zx]

hey all, just did a compression test, held the throttle wide open and cranked starter........did about five times and reset the guage each one.....150psi.......so now where should i start to trouble shoot. i have spark, could not find any cracks in the casing will look better again today, just not getting any suction through carb and not getting any vacuum on the fuel line to feed carb, thanks

[BettinANDlosing]

There's a brown spacer between the carb and intake, make sure the o-rings are good and in the right direction. They should face the intake and there is an up and down to it. Possibly an issue with reeds but you said they looked good.

[zombie]

The next step is to remove, and block off the exhaust, and remove the Carb.

You have to rig up a system where you can pressurize the engine to 6-7PSI.



I have one of Josh's leak down test kits if you need to borrow it. Maybe 20.00 to ship it back/forth.
Otherwise they are around 200.00

Another option... http://www.boatersland.com/cdi551-34pv.html?gclid=CO6Wxqeu1L4CFWgF7AodpycAhA

You still have to remove the variator/flywheel to gain access to the crank seals so I would just replace them. BUT the leak could be anywhere. Soapy water will find the leak.

[super50zx]

Thanks for the info guys, yeah the o-rings are good and the spacer is put in properly, zombie thank you very much on the offer of borrowing the leak down tester, a friend of mine here in MD may have one I can use, if not I will let you know. great info and thanks so much, I am not stopping until I get this thing running again!!! will keep you posted.

[zombie]

They are easy to fix. It is NEVER the case 1/2's that leak so it will show up, and be a cheap part.

The tester is always here if you need it. I live 4 doors down from the post so it's a non issue to send it.

[super50zx]

thanks zombie, i will keep you posted. i will be away from it for a few weeks due to work trips but will certainly hit you up if i need that tool and thanks again....hopefully it will be something simple, quick questions could a faulty exhaust gasket make the lack of vacuum and a non start? pulled the exhaust earlier today and the metal gasket was kind of crumpled up and did not appear to be in good shape, but have never seen one like that before. almost like a slinky, thanks

[zombie]

Non issue. It will run with no exhaust.
I think you may have something after market on the bike. Those accordion type exhaust gaskets are the best ones to use, and are NOT oem.

Can you post up a Pict of the cylinder, pipe, carb? It might help.

[super50zx]

trying to figure out how to post the pics, resized, moved, converted etc, keeps saying error.....I am about as good on this as I am repairing my scooter... I would be happy to forward an email to you with the pics, let me know if that would work for you, thanks.

[super50zx]

test

[super50zx]

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