running lean? - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 15 (permalink) Old 07-28-2011, 05:40 PM Thread Starter
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running lean?

recently purchased an 02 rc51, no engine mods i am aware of. engine runs strong under throttle all the way up to rev limiter. my problem is cruising speed. it wants to buck like hell from @ 2000 up to @ 3500 rpm's. it has a complete akropovic exhaust system but no power commander. i asked the previouse owner about it. he said he didn't have a problem with it untill he changed the gearing. he went down 1 on the front sprocket and up 3 on the rear. but if you run the throttle up (sitting still , in neutral) from idle to @ 3500 it doesnt want to take the gas, doesnt miss fire, it just seems to surge.
makes it very hard to drive in town not to mention it sounds like it gonna rip the trans to shreds or bust the sprocket or chain. also it seems to run exceedingly hot in town, usually @ 220 degrees.
any ideas?
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post #2 of 15 (permalink) Old 07-28-2011, 06:43 PM
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Try a PCIII and a map to suit the full exhaust.

RCs don't like low rpm the way it is, let alone a map that doesn't fuel/air mix the bike properly.

These are hot engines....they will run hot even if tuned correctly, just the nature of the beast.

I remedied this some what by using engine ice.



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post #3 of 15 (permalink) Old 07-28-2011, 07:10 PM
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Originally Posted by madbuyer View Post
Try a PCIII and a map to suit the full exhaust.

RCs don't like low rpm the way it is, let alone a map that doesn't fuel/air mix the bike properly.

These are hot engines....they will run hot even if tuned correctly, just the nature of the beast.

I remedied this some what by using engine ice.
I agree. Get a power commander and have it dyno'd to create a proper air/fuel map for the engine.

Simply put, if you want a bike that putts at 2000 RPM, get a Harley.
These bikes do not like to be lugged below 3500 RPM. They show their displeasure exactly like your description.

Just one RC51 throttle body is bigger than what feeds both cylinders of a Harley, and you have two of them.
It's actually more of a complement it runs as well it does at those low RPMs.
Keep it around 4000 RPM and you should have no problem.

My bike in stop and go traffic can get up to 221 deg F.
My fans start at 218 and cool it down to 205, but it cycles up and down until I can get into moving traffic.
The critical temperature is 251 deg F where the temp indicator starts blinking on the instrument panel. Pull it over and cool it down, or kill the engine.
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post #4 of 15 (permalink) Old 07-29-2011, 09:01 AM
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Or get a manual fan switch by grounding the black wire at the relay, reverse fans or get spals with reverse pitch, to keep the temperature a little lower to help your comfort. The engine is not bothered at 220, but wiring, plastics, and rider suffer from the heat.
VTR-f and VFRs suffer from similar heat.

Avoid revving the engine while in neutral, not good for any engine, bad for twins, terrible for singles, murder for diesels.
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post #5 of 15 (permalink) Old 07-29-2011, 11:41 AM
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You may want to check the boots where the throttle bodies attach to the intake.....if those are loose leaking, it can cause issues too.



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post #6 of 15 (permalink) Old 07-29-2011, 01:38 PM Thread Starter
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Quote:
Originally Posted by madbuyer View Post
Try a PCIII and a map to suit the full exhaust.

RCs don't like low rpm the way it is, let alone a map that doesn't fuel/air mix the bike properly.

These are hot engines....they will run hot even if tuned correctly, just the nature of the beast.

I remedied this some what by using engine ice.
ok, so running my engine at these revs sounds abnormal but i gotta take your word on that as i have never owned an rc 51, what about longevity of my poor overreved twin at this pace? any routine maintenance i should be aware of that would help keep her running a little longer, besides the obvious?
PC III , is that a tune i can download or a hard part i need to buy? sorry but im new to these bikes. is engine ice similar to water wetter?
anything else you can point out initially or maybe direct me to a post?
i appreciate the rather "quick" responses. feels like a very nice forum to be attached to! thanks again.
Allen
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post #7 of 15 (permalink) Old 07-29-2011, 07:08 PM
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How many miles??

PCIII is a power commander, it is programmable and will smooth out your fuel curve to the bike. The preferred method is to take it to a tuning center and have a custom map done. Google dynojet or powercommander,

Pending on the miles, valve train needs the clearances checked around 16,000.

Engine ice is a replacement type coolant. The engines run warm in these bikes, so any improvement helps. It is similar to watter wetter. The major difference is, Engine ice also protects during winter weather to -26 deg. I believe. Water wetter offers no winter protection against freezing.

Just search, there are several posts on anything you need to know here.



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post #8 of 15 (permalink) Old 08-01-2011, 11:05 AM
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Originally Posted by madbuyer View Post
You may want to check the boots where the throttle bodies attach to the intake.....if those are loose leaking, it can cause issues too.
I agree. I found all four loose on my vfr. Unmetered and uncontrolled air going into the cyllinders. Yesterday when accessing my fuel pressure regulator on my RC, I checked those to make sure they were snug.

John, 2000 RC51 #000100

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post #9 of 15 (permalink) Old 08-01-2011, 04:51 PM Thread Starter
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i just pulld the tank this aftrnoon. the boots are tight.
i pulld the plugs, not much of a spark plug reader so if ny 1 can see the pic i downloaded ur welcome to give some feedback on them. looks lean 2 me.
i need to search some posts n see what kind of mods i need to do while i have it apart. nything worth doing or mostly just minor gains?

bike plugs.zip
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post #10 of 15 (permalink) Old 08-01-2011, 04:54 PM Thread Starter
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the one on the bottom is out of the front cylinder
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