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Discussion Starter #1
Is there any effect on the performance or gas mileage due to the presence/absence of the exhaust air injection? I just bought my 97 500R last august and have put considerable time into researching the forums regarding my situation. The previous owner put a 2-1 Jardine RT-1 exhaust on it said he had it re-jetted (however upon taking apart the top of the carbs the needles are not adjustable, making me believe that he might have lied about having it re-jetted). Considerable popping was occurring from the exhaust and so i read about this blockoff procedure from this website [http://factorypro.com/magazine/Install_a_jet_kit_ex250,ex500,Rocky.html] and gave it a try. Now the popping seems to be reduced, but it's still there, especially with engine braking or letting off of the throttle. I bought a jet kit and haven't installed it, but before going through process I want to make sure blocking this off will only help and not hurt. I would go back to the stock exhaust but the previous owner only included the pipes and cans, but not the mounting hardware to attach them to the cylinders.

I know the research only shows that re-jetting and a performance exhaust doesn't really help performance of this time-tested engine, but since i own the jet kit and have the exhaust mounted...I'd like to give it a try. (Who knows...maybe this RT-1 exhaust that's not designed for this engine will actually improve performance once it's tuned correctly.

Right now the bike has a flat spot between 4-7K rpms that gets worse as the bike warms up (indicative of it running rich) Possibly a new needle with the height lowered to lean out that rpm range (maybe he meant they just put in new main jets without addding adjustable needles). It pulls great beyond 7K making me believe the main jet is correct, but maybe a smaller one would even help lean out the top end a bit to help with the flat spot...anyone have any ideas? Also has anyone seen improved performance with a jet kit? With gas prices so high i don't just want to be throwing unburned gas out the pipes...

P.S.I have also installed a performance air filter and did FOG's air-box mod.
P.S.S. Does anyone have the brackets to mount the stock exhaust that they wouldn't mind selling? Or have any idea on how to make or have some brakets made? ???

Thanks in advance! :)
-Ken
 

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Is there any effect on the performance or gas mileage due to the presence/absence of the exhaust air injection?
none what so ever. there has to be some 02 being left in the exhaust that stems from the Jet kit. it's putting too much fuel in and the O2 can't completely burn with the gasoline in the combustion chamber so it's burning in the pipe. go back to 100% stock jets and tune the pilots on the carbs. if the PAIR is 100% sealed, you should have very little 'Popping'.
 

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Re: Exhaust air injection and performance- Help with my new 500R, please give ad

from what i have read on this forum... the stock jets are the way to go, i hear of a lot of people with the exhaustandajetkit mod switching back to stock jets
 

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Re: Exhaust air injection and performance- Help with my new 500R, please give ad

but yeah, rejet the s#*@ out of the carbs
 

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Re: Exhaust air injection and performance- Help with my new 500R, please give ad

ok, so i have the carbs apart right now. It looks like stock (130) main jets and stock (35) piolets. Can anyone confirm these to be truely stock? So i'm at a loss for the reasoning behind my flat spot around 5-7K and the popping upon decel or reving up. Also, i noticed there no washers or "shims" on the needles (needles are marked N36N..stock?)...is that they way they come from stock? there is just the white plastic spacer and the needle.

I had already tuned in the piolets for best idle and steady state cruise at 4K and i still had the problems so i'm wondering if maybe my case is rare and the needle height might have to be adjusted as well as the piolets? Could me larger exhaust be an exception? I dunno.. i'm at a loss right now... i have the dynojet jet kit and i'll try it out if anyone thinks it might help. I just didn't want to waste the time and i could always sell it on ebay for more if i don't open any of the packages... also if i drill the slide holes bigger by using the jet kit can i go back to stock or once the holes are drilled do i have to use those needles...

a quick reply would be appreciated as the bike is apart right now...

thanks
Ken
 

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Your problem might not be carburetion but something else. Look at and clean the insides of the plug caps and change plugs if you haven't already. Check the condition of the wires and the connections if the screw ends are loose replace the wire with a copper core piece. renew the ground connections and particularly the battery ground strap. Check for false air and inspect the slide diaphragms.

FOG
 

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Re: Exhaust air injection and performance- Help with my new 500R, please give ad

I cleaned the carbs and put everything back together the way it was before. The carbs weren't even dirty and all of the jets appeared visibly clean. I still made sure to take each jet out and blast it with carb cleaner. It was a rather humbling experience to have to put it back together with no changes and expecting to still have my problems, but much to my surprise there no longer is a flat spot in the powerband! It pulls hard all the way up with no stuttering! I really have no idea what exactly it was that fixed it, but oh well...it's fixed. Maybe it's a lesson in making sure the carbs are totally clean and taking care in putting things back together perfectly.

Thanks for all the advice. I'll be sure to be around.

-Ken
 
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