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Intermittent low rpm issues

Old 10-22-2014, 05:46 PM
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Intermittent low rpm issues

Ok, so some issues I'm hoping for advice on, and the actual fixes vs. temporary ones. One small one: sometimes the speedometer will jump up to 80ish mph from a steady cruise at 40-50. A speedo healer came with the bike, but I've never used one before, wondering what's up with that...

When idling (cold more-so than warmed up, but still an issue with both) I am having what sound like hiccups and feeling a small jolt. I hear a mechanical sound, almost like it jumped a tooth or something. These hiccups can lead to the bike dieing while idling, it happened to me about 4 times today after coming to a stop. Three times at a light or when pulling into a parking spot, once in stop-n-go traffic (not good as I still haven't bypassed the neutral switch yet...).

Also, the bike has been sitting for a few weeks since its last 3 week straight daily driver run ending in a 25 minute ride through a TORRENTIAL downpour. Bike ran fine and still does (pulls like crazy above 5k), but when trying to maintain slow speed and steady throttle (school zone, slow freeway traffic) less than 45-50 mph, I get a lot of surging and still feel the above mentioned hiccuping/jolting.

I'm also getting a LOT of backfire pops when decelerating with no throttle input. It's VERY annoying and I'd like to to stop.

I haven't done any kinds of tests yet, and I think the bike is due for a sync (driving in CO with TX jetting led to some very strained acceleration uphills with lots of small hiccups). Bike is a 2001 with lightened flywheel, stick coils, PAIR removal, manual CCT's, adjusted TPS and has been previously (before my ownership) jetted to the Danmoto pipes (have baffles now).

Any thoughts as to what's going on?? I'm not really in a carb tuning mood lately (my truck is getting a lot of attention), so I'm hoping it's a relatively easy fix. I still have the new stacks to install, but I'm likely going to take the bike to a local dyno shop to get everything dialed in just right. I really don't have a lot of free time to mess with the tuning lately... (I sure hate not doing this kind of stuff)
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Old 10-22-2014, 07:28 PM
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Sounds like a clogged idle jet.
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Old 10-22-2014, 08:24 PM
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Originally Posted by NZSpokes
Sounds like a clogged idle jet.

are you serious?? Im having the same issues in the same order after the bike sat for a couple months.. It was running great before and I still have the PAIR system.... It didnt pop before.. I changed the sparks, fixed an exhaust leak, change R/R for a 03 R1 and cleanned the filter and I still have the same issue.. Can some one point us in the right way to cleaning the idle jets.. Thanks and good luck..

JON
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Old 10-23-2014, 01:33 AM
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Carb farts are quite normal - try upping the idle to avoid low speed stalling.

As for wet weather riding - make sure the front cylinder drain hole is clear as water can get into the spark plug recess and fill with water. Dry it all out and waterproof it.

And for backfire pops make sure you've got no airleaks in the exhaust system - esp check the graphite seals that link the headers to the link pipes.
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Old 10-23-2014, 09:09 AM
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Ok. I thought air might somehow be getting into the exhaust (common for backfires), so I'll check out all that.

Good call on the drain hole, I wasn't even aware there was one! If there was any water in there, it's long evaporated, so I don't have to worry about drying anything out. I'll check the plugs though.

I have about an 1800 rpm idle now as I upped it awhile back to avoid the low speed stalls, I guess I'll go up to about 2k. I really don't want to have too high of an idle. I thought I read somewhere that with the carbs tuned really well, the farting would be all but eliminated. (At least it's normal)


As for cleaning the idle jets, follow the common rules of cleaning any carbs: carb cleaner, compressed air and if necessary, VERY fine drill bits to scrape off the crud. This has never let me down. The only problem, is you have to take the carbs off, haha. I might try to find the time to do that, but it will be a more "last" resort. I'll up the idle, check the plugs and sync the carbs, should help some. Then when I get some extra cash, I'll take it to get dyno tuned with the new stacks.
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Old 10-23-2014, 11:06 AM
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If it is stalling at 1800 then something else is amiss as standard idle should be 1100–1300.

As suggested and as your doing a thorough going over of your carbs will hopefully sort it.
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Old 10-23-2014, 11:51 AM
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Ok. I figured 1800 was too high to be stalling. Sometimes it'll die very smoothly as I come to a stop, almost like the spark was cut very quickly.

Other times it'll die after one of the hiccups where I can feel a jolt. I have an upgraded R/R from a Yamaha, installed with an eastern beaver connector... Strange
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Old 10-23-2014, 03:51 PM
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Cleaning Idle Jets

Quick and dirty way to clean out jets. No guarantees but sometime this works. Pull tank up and take off airbox cover. Start bike and rev engine to 6k or so, using a rag or heavy glove block off one carb and close the throttle. Remove glove or rag before it stalls and repeat. Do both carbs.


The high vacuum created when you block off carb with force a lot of fuel through the idle jets when you close the throttle. Sometimes this will get a bike to run better. Not as good as pulling the carbs and cleaning but may buy you some time until you can do it properly. Same thing goes for the main jets only don't close the throttle when you block the carb, move it to full throttle and back down to idle several times.


Good Luck
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Old 10-23-2014, 04:46 PM
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Nice info, but I think I'll start by running some fuel system cleaner through the tank to start. Might help a wee bit, certainly can't hurt.

Damn thing died during a left hand u-turn on the way home from work. Looks like this will be moving up on the priority list this weekend. Most of the stalling is when the clutch is pulled in and it's idling. But the hiccups while riding at lower speeds almost feel like the ignition circuit is getting interrupted...

Last edited by wannabridin; 10-23-2014 at 04:52 PM.
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Old 10-25-2014, 10:51 AM
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Originally Posted by wannabridin
Nice info, but I think I'll start by running some fuel system cleaner through the tank to start. Might help a wee bit, certainly can't hurt.

Damn thing died during a left hand u-turn on the way home from work. Looks like this will be moving up on the priority list this weekend. Most of the stalling is when the clutch is pulled in and it's idling. But the hiccups while riding at lower speeds almost feel like the ignition circuit is getting interrupted...
Edit: nevermind

Last edited by CruxGNZ; 10-25-2014 at 10:55 AM.
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