Newbie needs help! - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 5 (permalink) Old 06-11-2017, 03:24 PM Thread Starter
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Newbie needs help!

Hey everyone this is my first post and my 2nd rc. This one I recently picked up is an 03'. The problem I'm having is it runs bad. It idles Ok but severely lacks power and is slow to rev and will randomly stall. No FI light. I noticed the front exhaust pipe isnt nearly as hot as the rear, which would surely indicate my problem. I changed the plugs to iridium(only helped a little) and did a compression test cold and got 130psi front and 128psi rear. When I pulled the front coil off the plug, it came off rather easy as if it wasnt latching properly, but i stuck the plug in and grounded it to metal and i can see a decent spark on both front and rear. I also started it with the airbox off and I saw the injectors spraying fairly evenly between front and rear cylinders so I know the front is getting plenty of fuel. That means I have knocked out the 3 things needed, spark, fuel, and compression. The bike sat outside for a while so things are dirty/corroded here and there. I also took off the ecu plugs and cleaned the contacts because a few of them were slightly corroded and that did seem to make it run a little better, but still nowhere near what it should be. Maybe the spark is fine off the bike but under compression its not strong enough? Corroded grounds? Thanks
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post #2 of 5 (permalink) Old 06-12-2017, 03:04 AM
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Did you check the FPR while you in there?
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post #3 of 5 (permalink) Old 06-12-2017, 06:02 PM
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That compression sounds low. I thought 150 was about the minimum?
Service manual calls for 176. Did you do the test right, with a known good meter?

John, 2000 RC51 #000100

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post #4 of 5 (permalink) Old 06-13-2017, 12:54 AM
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I think it was this board where a guy had similar problems with his bike running like shit. It turned out the throttle bodies were not fully seated in their respective boots. He saw it after checking just about everything else.
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post #5 of 5 (permalink) Old 06-13-2017, 03:44 PM
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low compression?

agree with Jondog.....when Rodger Ditchfield fckd up my bores with 0.005" piston-cylinder clearances, I had 140 psi as WILL run at 120 psi or so but it ain't gonna run well. Did you WOT when cranking it over for your compression test? See if you can get a bore scope or fiber optic and look at the bores down the spark polug's what mine looked like.....see pic-is the bike blowing oil out of the breather hose=loose bore-was happening on mine.
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