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AP mod problems!!.. runs horrible.. stock 05 450

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Hey guys,

While my engine was being rebuilt in the shop (snapped connecting rod, blew hole the cases... not fun, shouldnt have happened.. anyway) I though I would try out the AP mod.

While my bike ran great anyway, I figured I might as well try out the mod to see if there would be an improvement in throttle responce.

So I shaved down the AP diaphram rivit so there was no gap at WOT and put an O-ring to keep the levers together. SO I give the bike a little test run down the street (it was dark out so i couldnt try it anywhere else) and it ran fine, I didnt chop the throttle hard because I didnt want to wake up the neighbors.

Anyway, so I go into the garage today and noticed a puddle of gas on the floor. The leak was comming from the AP diaphram cover. I though maybe I didnt tighten the bolts enough, so I tightened them a bit more and take it for a little ride. This time I chopped the throttle and the thing bog/ coughed and almost put me over the bars. I thought.. maybe the bike is cold. Nope.. its good to go... when I open the gap fast on idle it dies too, check the spray from the carb and I cant see a stream comming out.

So I go back to the garage.. tear the bike apart and the leak was caused by the AP diaphram. Why? because the rivit is too short and instead of creating a seal, it just sits there and gas leaks out. SO regardless if the mod would have worked or not.. it would have been leaking gas out of the ap cover.

Maybe this isnt an issue with the quick shot... but with the stock AP cover and a shaved rivit.. gas leaks out and the bike coughts/bogs horribly... both on the stand and while riding. So.. it wasnt the outcome of the mod I was looking for and I would not recomend the mod to anyone with a stock bike without the quick shot ap cover.

Any ideas guys?? Because I cant think of any (mind you this is only my 2nd bike ever). Im ordering a new diaphram in the morning and putting it back to how it was stock.. because that would be a 100% improvement to how it is right now. Hopefully the part will be in by friday so I can actually ride on the weekend! (after my engine being in the shop since june 5th and just getting it back yesturday on july 4th.. yeah it sucked and I'm itching to ride... so this AP mod problems isnt very pleasing).

Dave.

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I'm not being rude im just stating that it seems you performed the mod wrong so there isn't really anything with the mod it's self.

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I'm not being rude im just stating that it seems you performed the mod wrong so there isn't really anything with the mod it's self.

agreed, because ive done the mod my self and it didnt do anything worse or any damage to my bike other than the fact that i need a bigger leak jet ( after pumping the throttle a few fast times theres no more fuel in the AP bowl and the bike hesitates) othere htan that i think it might have improved throttle response.

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agreed, because ive done the mod my self and it didnt do anything worse or any damage to my bike other than the fact that i need a bigger leak jet ( after pumping the throttle a few fast times theres no more fuel in the AP bowl and the bike hesitates) othere htan that i think it might have improved throttle response.

Hmmm how did I do the mod wrong? I shaved the rivit down (as per the mod)so there was no gap at WOT and wired them up. Pretty simple procedure no?

However, I didnt try a larger leak jet, but regardless, the shorter rivit length is causing a fuel leak from the stock ap cover and even with a larger leak jet it wouldnt solve the leak.

For the people with the mod done, when your bike is sitting there at idle, or not even running for that matter. When you twsit the throttle can you see a stream of gas squirt out? I cannot see anything, while I could before the mod was done. The leak could be the problem because it maybe it cant provide enough pressure to squirt the gas, Im not sure.

But with a shaved rivit as per the mod, I got a leak with the stock cover. SO maybe if the mod was done without shaving the rivit down and wiring them up it would work fine. But I would not touch the rivit if you're runnning the stock cover. Either way, Im not buying a quick shot when the bike performed great stock, much better than this anyway.

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Hmmm how did I do the mod wrong? I shaved the rivit down (as per the mod)so there was no gap at WOT and wired them up. Pretty simple procedure no?

However, I didnt try a larger leak jet, but regardless, the shorter rivit length is causing a fuel leak from the stock ap cover and even with a larger leak jet it wouldnt solve the leak.

For the people with the mod done, when your bike is sitting there at idle, or not even running for that matter. When you twsit the throttle can you see a stream of gas squirt out? I cannot see anything, while I could before the mod was done. The leak could be the problem because it maybe it cant provide enough pressure to squirt the gas, Im not sure.

But with a shaved rivit as per the mod, I got a leak with the stock cover. SO maybe if the mod was done without shaving the rivit down and wiring them up it would work fine. But I would not touch the rivit if you're runnning the stock cover. Either way, Im not buying a quick shot when the bike performed great stock, much better than this anyway.

I did this mod to a 450 and a 250 recently and havent noticed any leaks. My 450 had a bog and this mod fixed it. Maybe when you shaved the rivet you cut the diaphragm or bent the metal washer to where the diapraghm doesnt seal. I have helped a couple of friends do this mod and we have found no ill effects. Our bikes all had the stock AP cover. My 450 Im running a 55 leak jet and it seems to run great. A larger leak jet will cut the gas in the AP by draining the excess faster so Im lost on your logic there. It hits off the bottom like a 2 stroke.

Back to the start of your post, if your bike was running great why tamper with it anyway. Good Luck.

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There is no way that shortening the rivet could cause a leak. It's not possible. Did you put the diaphragm in upside down? Did you lose one of the AP cover o-rings?

Don't bust on the AP mod because you screwed something up. The rivet has absolutely nothing to do with sealing the AP cover. I bet that it will still leak when you put the new diaphragm in. It's not the mod, it's not the rivet, it's you.

The reason there is no AP squirt is because the AP cover and diaphragm are not sealed and not creating enough pressure to push fuel into the carb bore.

Please refrain from trash talking the mod simply because you don't understand it.

Shortening the rivet simply allows the AP rod to push the diaphragm down further into the cover. Did you put the diaphragm in with the rivet facing up? Are you sure that you put the cover back on with both o-rings in place? If you are having problems, just ask, but don't start jumping to conclusions and telling people that the mod won't work with the stock cover or that it screwed your bike up. It didn't.

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I'm guessing he lost an o-ring in the process. One of them is tiny enough to not even notice if it fell out.

ben

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I'm guessing he lost an o-ring in the process. One of them is tiny enough to not even notice if it fell out.

ben

Either that or he has the diaphragm in upside down.

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Hmmm how did I do the mod wrong? I shaved the rivit down (as per the mod)so there was no gap at WOT and wired them up. Pretty simple procedure no?

Yes it is simple, but you still got something mixed up.

However, I didnt try a larger leak jet, but regardless, the shorter rivit length is causing a fuel leak from the stock ap cover and even with a larger leak jet it wouldnt solve the leak.
The rivet has nothing to do with the cover sealing. Nothing whatsoever. The cover is sealed by the outer lip of the diaphragm and the inlet and outlet holes for the AP fuel are sealed with two o-rings.
For the people with the mod done, when your bike is sitting there at idle, or not even running for that matter. When you twsit the throttle can you see a stream of gas squirt out? I cannot see anything, while I could before the mod was done. The leak could be the problem because it maybe it cant provide enough pressure to squirt the gas, Im not sure.
Of course it squirts, that's what the AP does. It's even stronger with the mod performed correctly. You have no squirt because your cover isn't sealed.

But with a shaved rivit as per the mod, I got a leak with the stock cover. SO maybe if the mod was done without shaving the rivit down and wiring them up it would work fine. But I would not touch the rivit if you're runnning the stock cover. Either way, Im not buying a quick shot when the bike performed great stock, much better than this anyway.

The shaved rivet is NOT causing the leak, it can't! If you don't shave the rivet and you still wire it up, get ready for the throttle to stick wide open. :ride: The mod did not cause any of your problems, it was purely operator error, plain and simple.

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Redbeard,

Thanks for the reply. I dont see any orings there, so thats is probably the cause of the mod not working, hopefully I can find those lying around somewhere! I thought with the shorter rivit it was causing it not to seal as well, but I guess the orings are the problem. I did see a small oring on the ground and I wasnt sure where it was from, Im pretty sure I put it on the work bench incase it was for the bike.

I only seen one though, but there is two you say? Are they both the same size? Because if they are I could go to the hardware store and maybe match them up.

I wanted this mod to work and I understand the work you put into showing us all the mod, so thanks for that. If I came across like I was bad mouthing the mod, sorry about that. I was/am mad at the fact that after not having my bike for a month and my first weekend to ride, messing with the ap mod might have screwed me for the weekend, but its my fault.

Again, thanks for the reply... its promising news.. and if I can find those orings I can ride this weekend!

Dave.

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The o-rings are not the same size. There is one for the fuel inlet into the cover and one for the outlet hole. Pull the cover off and see what you have left on there.

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After reading this, I have no doubt that the mod ****ed his bike up.

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After reading this, I have no doubt that the mod ****ed his bike up.

This kind of wit after only 3 posts????...I can't wait to see what he'll offer next. :ride:

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Hey guys....thanks for the help.. it worked!

I opened up the AP cover... and yeah there was a missing o-ring on the cover itself, one of them was still stuck to the carb though. So I installed a new o-ring and bam... it was squirting again!

I havent had the chance to try the bike out yet.. but on idle its not bogging anymore and it squirts so everything should be good. I post a ride report about the mod later on.

Thanks again!

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Hey guys....thanks for the help.. it worked!

I opened up the AP cover... and yeah there was a missing o-ring on the cover itself, one of them was still stuck to the carb though. So I installed a new o-ring and bam... it was squirting again!

I havent had the chance to try the bike out yet.. but on idle its not bogging anymore and it squirts so everything should be good. I post a ride report about the mod later on.

Thanks again!

:ride:

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I am kind of new to this site and I was wonder where you this AP mod is listed and if there is some kind of mod section of this site. Thanks

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i ended up buying the jd kit because i needed the leak jets,and at the same time i got a new diaphram already shortend,i put in the 75 leak jet,and let me tell u, this thing flat out rips! btw, good mod red!

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