Tach reading 4K rpm at idle

[MtnBoy]

Been working on an '07 VFR that had done only 300 miles when I acquired it, so I had been ignoring my NC30 for a couple of weeks. Decided to take it for a spin through the mountains. Pulled up the choke, fired up normally and died after about a minute. I had turned off the fuel. Fuel back on, fired up and I proceeded down the driveway. Stalled at the street but fired right up. As I accelerated , I noticed the tach was reading about 4K rpm high. Just running through the gears, the tach would max out. Idles, and not very well, tach indicating about 4K but engine turning, I would estimate, 1000 rpm Have the battery on charge at present. Any ideas? It has always run perfectly, up until now, anyway. Any ideas? Thanks and Cheers, Robert

[MtnBoy]

Actually, the bike runs perfectly except for the tach being off by 4K rpm. I had left the choke on, hence the poor idle. The bike is a '92, by the way. Any help would be greatly appreciated. Cheers, Robert

[Devon462]

I'm not amazing at mechanics so I'm going for the easy guess! If the engine is sounding ok maybe the needle has been knocked or the previous owner has played around with the dials. Might need the needle removing and replacing? I replaced the dials on my super four and the resting position is just under the needle rest.

[Trinirides]

Hi,

Hope I have this correct? the bike is idleing fine but the Tach is showing 4k?.. This seems to be the next step in the NC30 puzzle re keeping these bikes on the road, just a few months ago my Tach did the same thing and it was simply a buggered rev counter. There are a few reports online re the same situation with this model, the NC that I had the issue with was a 93, I got a good condition used unit and all is well now, for future reference my bike is near mint qith 20'000 klm on the clock dry stored.

Also for reference this is my WTD post, I did have a more detailed post regarding this problem but I cant seem to find it?
viewtopic.php?f=79&t=49741

Good thing is once the upper fairing is off its a really quick job to replace.

On a side note if it is not the Rev counter then most likely it would be the carb rubbers and a quick spray of WD40 around the rubbers once the bike is warm should see the spilt or hole filled for a moment and the bike should idle ok. This is if the bike is actually running with a high RPM rather than the first explanation of the bike running perfect and just the Tach over reading..

Hope that helps

[MtnBoy]

Thanks for the reply, Trinirides. My '92 is also mint. I have owned it for about 8 months and store it in a climate controlled garage. The last time I rode it, about 2 weeks ago, all was as it should be. When I started it yesterday, all was good, until I looked at the tach. The bike idles and runs superbly. I normally ride it a couple of times a week, Went about two weeks this time. Must me the rev counter. Just fired it up now reading 5K at idle. I also have an NC29 of the same year. Wonder if the tachs are close enough to exchange them for a test? Also have access to an MC28 tach. What do you think? Is there a pick up or sender for the rev counter that could be going bad? Cheers, Robert.

[Trinirides]

I tried cleaning everything and nothing worked, the Tach is a sealed unit also so the only option was to get another to try. I have no idea re other possible exchanges with other models sadly.

This is the forth Tach i have known this to happen to this year on a 92-93 bike i have a feeling more people will be posting up with the same problem in the near future

[MtnBoy]

Trinirides, Just checked the charging system. Battery is at 12.7V with ignition off, 14.3-14.4 at idle. Battery is 7 months old. Is this about right? Getting ready to remove front fairing to check things out. Did some research on the forum. CBR tach is not compatible. Cheers

[MtnBoy]

Removed the tach/speedo assembly and cleaned all the connectors. Did it with the front fairing in place. What a pain. Anyway, the tach still reads 4K at idle. Looks like I'll need a replacement. Any recommendations? Thanks, Robert

[richyrd5]

Put a post in the wanted section.i have one but its up a freinds garage and i cant get it for at least 2 weeks!!

[MtnBoy]

Done!