[SGVRider]

Hello. I recently purchased an 88 EX500 off a racer (I'm planning on racing it). It's in good shape, but the bike won't run without the choke on. Even then, I have to rev it a little to keep it going. Above about 5000 (estimated, someone at my last apartment building stole my tachometer) it begins to bog out, drops down to about 2000 revs, and then dies if I twist the throttle further. It dies completely if the choke is off. I went to clean the carbs, but upon disassembling them they were already extremely clean. The bike had been drained of all fluids when I bought it. The gas flow from the tank appears to be adequate when I apply suction to the vacuum line on the petcock, but I'm of course not sure if it is. I looked at my Clymer's guide, and it says the idle screws are permanently set on US models. I think I may have to place a vacuum cap on the emissions port between the two carburetors, but beyond that, I'm not sure what it could be. Everything seems to point to the carburetors, but beside the emissions port, what else could it be? Any help would be much appreciated. I did see a post addressing this issue from a few months back, but it appears to have a different root cause, and my model is much older..

A few more things: The bike has an aftermarket Muzzy exhaust, and appears to have a jet kit. The needles don't look stock, they have the same sharp point look of the Dynojet kit, not the blunt look of the stock needles. Maybe I need to adjust the height of the needles, but wouldn't that really only come into play at high RPMs?

 

[QKENUF4U]

even though it was drained of fuel it could still have clogged pilot jets (one peice of dirt/one drop of varnished gas)
the pilot is down in the hole beside the main jet. make sure your screwdriver fits it VERY VERY well cause they are easy to crack the tops off (brass, shears easily) pull them out and run a small wire thru them.
as for the jet kit, i would leave all that alone since it was prob. setup by the prev. owner when he raced.
also make sure the battery is FULLY CHARGED , i helped a kid with a bad battery on his and it wouldnt rev with the bad battery in it.
good luck

 

[Commuter]

You should have the vacuum line on one carb going to the petcock, the other vacuum line from the other carb went to the emission stuff. If the emissions equipment has been removed, make certain that the vacuum line is plugged.

Can you get any information from the previous owner as far as was it ready to run when he parked it? Maybe he knows why its doing what its doing...

Good luck.

 

[SGVRider]

Thanks for the replies. Okay, I got it to run without the choke today, but I had to warm it up for about 10 minutes beforehand, also, it refuses to idle for more than about 10 seconds with the choke off. Also, with the choke off, it will rev fully (presumably to the red line), it does make sputtering noises, though. The only changes I made were to mess with the idle screw a little, and to plug the emissions port POS that's between the two carbs. Actually, I'm not sure that IS an emissions port. What is the port that's mounted in the middle of the carbs? The Clymer's Guide didn't give me a very good diagram of carb setup. The idle is also very high, probably at least 2000, but I'm not sure because as I said someone stole my tach... I actually did reclean the jets, and the entire carburetors when I took them apart, I'm fairly positive they're clean. If I disassemble them again to clean, should I worry about needle height or the float bowls while I'm at it?

 

[RomSpaceKnight]

What shape are carb manifold boots in. Cracked and holes maybe. Spray with WD$) does it get better as WD temporarily plugs leaks.

 

[SGVRider]

Haven't check the manifold boots yet, I will tonight. I should've asked this earlier, but here goes. This bike came with K&N pod filters, I've been asking and looking around and most people say it runs much better with the stock airbox. I would presume the guy had it set up correctly before, but maybe I should just find a used stock airbox on the cheap and try it out? The previous owner had bought it from another guy who had it sitting around for about 2 years, and he doesn't know much about it.

 

[wiredgeorge]

SGVRider... you mentioned the emissions system and if I read correctly, it is either partially missing or disconnected? OK, here is how it works. There are vacuum spigots on each carburetor. One is likely hooked to the petcock and the other goes to a vacuum switch which opens the reed valves on your bike. If EITHER of these hoses that should be connected to the vacuum spigots are not connected, the bike will be EXTREMELY hard to start and won't idle or run properly. You can test this theory by purchasing TWO 7/32" vacuum caps at your local autoparts store from the "HELP" section and put the caps on both vacuum spigots. Put your petcock in the PRIME position. Choke your bike and don't twist the throttle and start it. Allow it to idle/warm for a bit and you should be able to put the choke off. See if it responds to throttle as it should. If it does, suggest you look to repairing the line between the vacuum spigot and petcock AND/OR removing the vacuum switch and all associated hoses and plugging/capping the reed valve intakes where the largish hose went (up on valve cover I think). If the fellow you bought this bike from was racing, I would be surprised if the emissions system is intact.

 

[SGVRider]

I plugged the vacuum port that used to be connected to the emissions system, and the other vacuum line is connected to the petcock. I'm wondering about the black plastic port that is between the two carbs, what exactly does it do? I can't find any indication as to what it does. Here is a picture of it: http://cgi.ebay.com/ebaymotors/Kawa...ryZ35597QQrdZ1QQssPageNameZWD1VQQcmdZViewItem It's the black port that's facing downward.

 

[secutright]

Sorry to revive a very old thread, but it sounds like you're describing the vent. Most people just leave the hose off and unplugged.

 

[tomsteere907]

The plastic port that's connected to both carbs is the fuel overflow vent. It should have a hose that just runs under the bike just in case the float gets stuck then the fuel will be directed away from the hot engine.

 

[Kawasakian]

This is a 12 year old thread...................................

 

[WFO-KZ]

While reviving an old thread is discouraged, in this case it may be helpful. The last two members (secutright and tomsteere907) who revived this thread answered the unanswered question posed by SGVrider in post#8 in 2007.

So while SGVrider is likely long since gone, the answers may help a future EX500 owner who does a search for this kind of info.

But in the future all members are reminded to check the date first, before you reply. Take the date into consideration especially if asking for a response from such an old thread.