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Hard Starting When Cold


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2 hours ago, Grum said:

But............ you can shove the cam gear whine up.....wherever! 🤣.

 

Sacrilege!   

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My 99 had this problem. Below around say 75°F, it would pant and die on the first attempt and start on the second attempt. This was after a valve check, replacement of all intake rubber, vacuum synch, and fuel injector maintenance. I used Sea Foam at the rate it prescribes for "cleaning." That helped the engine start and shoot up instantaneously, like a dart, to a high idle of 3200+. I cannot help but wonder where the problem was. Gunk built up in the fuel rail?

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with EFI systems, the ECU can only function properly if its inputs are proper. Most important of input sensors is air-temp and coolant-temp sensors. This is how ECU knows you're in winter and it needs to add additional petrol for cold-start enrichment. It can inject +10 to +33% more petrol depending upon temperatures.

 

obviously if your temp-sensors aren't reading properly, ECU won't add additional petrol. Nice thing about carbs is organic computer starting bike knows when it's cold and can manually activate choke.

 

So... test your IAT and ECT sensors. Procedure's in manual. They have you measure it at ECU connector after disconnecting ECU. That's to make sure wiring in between is good as well.

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IAT and what?? You guys are way too smart. I was excited this summer when I replaced my brake pads! I wish i had the knowledge and confidence to tackle a job like that or do the valve adjustment. Maybe some day....

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IAT = inlet air temp sensor

ECT = engine coolant temp sensor

 

Biggest clue is that bike only runs badly when cold. If you had issue with clogged injectors or bad ignition, bike would run badly all the time. Since it only does it when cold, sure sign ECU isn't detecting cold-start conditions properly.

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1 hour ago, interceptor69 said:

IAT and what?? You guys are way too smart. I was excited this summer when I replaced my brake pads! I wish i had the knowledge and confidence to tackle a job like that or do the valve adjustment. Maybe some day....

Sent from my SM-G975U using Tapatalk
 

 

Valve adjustments on 5th gen aren't too bad - you can do it.  If you get hung up lots of help on the site to get you un-stuck.   As long as you keep the cams in time you'll be fine.  I finally got to painting a tiny dab of white paint on each gear prior to dis-assembly - made it much easier to get them back perfectly.  Cleaned the paint off when finished.  Doing more complex jobs is just a matter of diving in, but doing so with the needed tools and a shop manual.  Knowing people here have your back will make it easier.   The satisfaction from doing that is high when you complete a job you were unsure of at the start.  :fing02:

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8 hours ago, Cogswell said:

 

Valve adjustments on 5th gen aren't too bad - you can do it.  If you get hung up lots of help on the site to get you un-stuck.   As long as you keep the cams in time you'll be fine.  I finally got to painting a tiny dab of white paint on each gear prior to dis-assembly - made it much easier to get them back perfectly.  Cleaned the paint off when finished.  Doing more complex jobs is just a matter of diving in, but doing so with the needed tools and a shop manual.  Knowing people here have your back will make it easier.   The satisfaction from doing that is high when you complete a job you were unsure of at the start.  :fing02:

That's interesting. I may have to give it a try. That job is so hard on my CBR600 that I've just about convinced myself that shops never do it. They just take the money and tell you it's good-to-go.

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On 12/11/2020 at 1:48 AM, JimMoore said:

That's interesting. I may have to give it a try. That job is so hard on my CBR600 that I've just about convinced myself that shops never do it. They just take the money and tell you it's good-to-go.

The VFR is an easy starter bike to learn on when it comes to the valves. The rear cylinder head is easy to get to so you can easily see what you are doing. The picture below shows a marked gear tooth sitting next to a reference point on the cam saddle. The only slightly offputting thing is the split gears are sprung apart and don't look to be exactly right until you tighten the cam saddles down and pull the teeth into alignment. I usually only work on one cam at a time and don't touch the crank so as not to mess up. I bought a Hotcams shim kit a few years ago, so I don't need to wait on any parts from a dealer once I start. A small 1/4" torque wrench is a good investment for peace of mind and avoidance of breaking things! 

image.thumb.png.e464685ce24e5e9cd6e4924861a681a9.png

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1 hour ago, JimMoore said:

Cool. Thanks. Why are the gears split like that? Any idea? 

From what i can remember. The split spring loaded gears create a constant positive mesh so there is never any buildup of backlash or gear wear as the years go by.

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Just read this thread.

 

To the OP, I rode a 5th Gen for 130k miles and managed virtually all the servicing myself (with a little help) including the 16k valve check and if I can do it, anyone can! Once the plastics and tank are out of the way, it's simply do A, then B, then C and as long as you follow the manual, it really is easy.

 

Likewise the starter valve check/adjust - it is imperative that it is regularly done. I did it every 4k miles which seemed to work fine for me. Again, it is simple enough.

 

As to the 5th vs 6th vs 8th debate, there will never be a consensus, there are those that love the whine, the lack of VTEC and the seamless torque, there are those that love the better fuel economy, brakes and handling of the 6th and those that have ridden the 8th and realise that with everything else that has been improved, it is the best combination (actually, the best is the 8th Gen with an upright seating position.....I think they call it the VFR800X 😜).

 

JMHO :beer:

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7 hours ago, JimMoore said:

Cool. Thanks. Why are the gears split like that? Any idea? 

also reduces noise.

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7 hours ago, JimMoore said:

Cool. Thanks. Why are the gears split like that? Any idea? 

 

It's common - my 4 cyl Camry's intake cam drives the exhaust cam (tho with a spiral cut gear)  and has the same split gear setup on the driven gear. 

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