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525EXC Jetting/ Carb help please!

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Hi All,

 

I need a bit of help setting the carb up on a euro spec '05 525EXC. The problem is, when you crack the throttle from low revs it just bogs down which is really annoying! You can wack it open if the revs are built up a bit or if you have no traction and the bike runs really well apart from this.

 

The bike is stock and had been sitting for many years, valves are in spec, clean air filter, brand new NGK plug, I have striped the carb and cleaned then air lined the jets ( brand new main jet).

At the minute it has the 6 days needle, OBDTR clip 5 and jets, 178 main, 2 turns out on the fuel screw.

 

I have tried a JD Blue on the 3rd clip and then 5th clip and a JD red needle and neither helps, the bike ran a lot worse actually,which I was not expecting.

 

I have done the o-ring accelerator pump mod, and even tried a Yamaha diaphragm (Same a Honda I believe, noticeably longer) but it made it bog more!

 

 The carb does not have a leak jet but I could try the bottom of a Yamaha carb with one?

 

Any other ideas?

 

I know the preferred needle is a OCEMR, I haven't got around to ordering one yet - Will the needle have anything to do with the bog? Shall I try different clip positions etc?

 

Thanks all and sorry for my long winded boring post!

 

Trev 

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check the AP pump squirt...the nozzle in the throat can easily plug up when the bike sits with gas in the carb. Or the squirt timing can be off and hit the slide.

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Mike, you are 100% correct. I dealt with the same thing on my 08 excr and the nozzle was clogged. Same symptoms. Amazing how quickly the nozzle can get clogged

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Hi

 

Many thanks for your replies and you were correct, the AP is not working!

 

I still cant get it to work though even though I can spray carb cleaner through the lower half of the carb and it comes out of the brass nozzle - It took ages to clean this!

The pump just doesn't seem to be pumping any fuel to it - the diaphragm looks perfect and O-rings appear fine ??

 

Any ideas? I really don't know what else to try, If you push the diagram down with an Allen key with the float bowl off the carb and filled with fuel it doesn't squirt any fuel up - the check valve is not stuck but you have to push it down - is this normal?

 

Many thanks!!

 

Trev

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there are a few passages to clean in the bowl and parts, one passage has a check valve, two O-rings, a spring and diaphragm. There is a passage that goes from the bowl to the carb body as well-this is to get the squirt up to the nozzle. The check valve sometimes sticks. I push it with a tool and spray in there at  the same time. On the outside of the carb there is the linkage and levers. Make sure they are working right as well-these are adjustable. I can do all this, but it is hard to explain. I would look for a thread that has photos. There are some here and on KTMTALK. Look at the parts diagrams to see if you have all the little parts to if you are not sure.

 

I clean the nozzle with a single fine wire from a small, stainless steel brush. I put it in a vise grip to hold it and then stab the hole in the throat of the carb. Then spray it out with cleaner and do it again. Then put gas in carb and manually twist throttle linkage and check the squirt.  It should squirt 8 ft or so.

Edited by Mike in Fresno

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