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Mechanical Tachometer

Posted By: John Ellis

Mechanical Tachometer - 06/23/19 01:13 PM

Hope I havenít missed a post, but through searching all I could find are digital inductive tachs being installed. Recently saw a picture from a TAT page on FB with an XT225 with factory looking speedometer AND tachometer(believe itís from a DT125/175) but the guy posting didnít get any information or the riders name. Iím just wondering how difficult the install would be to have a gear driven, factory looking tach.


Posted By: Muniac

Re: Mechanical Tachometer - 06/23/19 03:05 PM

If you did find an analog tachometer driven through a cable. Where would you tap into the engine for the cable? And how would this be calibrated? I think an electronic tachometer with an analog dial would be much easier to locate and install. You can derive a signal from the primary of your ignition coil. I'd guess the pulses per second would be a factor of 2 and a time base conversion to get engine RPM. That would all be in the tachometer's internals. Just a thought. Good luck!
Posted By: John Ellis

Re: Mechanical Tachometer - 06/23/19 03:33 PM

Right, I understand all that and that is my question. DTs have a hole right near the oil pump on the front of the engine where the mech drive for the tach comes off. I was hoping to find this person as a member here to fill in the blanks. Iíd post the photo, but Iím not sure how to from my phone.
Posted By: Muniac

Re: Mechanical Tachometer - 06/24/19 02:38 PM

Imgur can provide a free photo hosting service and clean URLs which can be used here to embed photos. You'll upload to Imgur, get a link ending in .jpg or .png and use that to display your photo(s). From the Full Reply Screen, you'll use the 4th icon from the left.

On the XT225, I'm not aware of any holes (or gearing) in the engine case for a tachometer.
Posted By: John Ellis

Re: Mechanical Tachometer - 06/24/19 11:43 PM

[img]https://www.amazon.com/photos/shared/6w33tssSQeaV7ogs1m2-ew.A1axtmC_DazY_0T0KCs6mL[/img]

This is the picture but it doesn't really answer any questions. Maybe someone will recognize the bike🤷🏻‍♂️
Posted By: Rubicon

Re: Mechanical Tachometer - 08/06/19 05:55 PM

Actually the picture answered everything.I was going to tell you that the XT350 has a mechanical tach and to look there for possibilities as the front wheel is easily put on the 225 because it is the same except for a larger brake rotor.The minute I saw the picture it is clear that is a 350.I would still advise you to pursue the possibility of adapting a tachometer from a 350.
Posted By: Rubicon

Re: Mechanical Tachometer - 08/07/19 05:33 AM

So I was confusing the tach cable with the speedometer cable. The wheel isn't the problem it's the engine and to be honest I've never missed having a tachometer on this bike.The only purpose I can imagine is knowing you are in sixth and not trying to shift into a seventh gear that doesn't exist.I do know people have put on the digital tachs and the only complaint is slightly slow response time.
Posted By: BillV

Re: Mechanical Tachometer - 08/07/19 07:19 PM

Those little tach/hour meters are cheap but I've heard about response time issues for years. They seem somewhat crappy. At one time I was considering this.

The size seems good for our bikes. I like all the options and a stepper motor ought to give better response (no guarantee). But not waterproof is a downside and will require some sealing.

Unfortunately, I've never pursued it any further.
Posted By: BillV

Re: Mechanical Tachometer - 08/13/19 09:04 PM

I was playing with the options for a different Speedhut 2 5/8" tach and came up with this today:


Not bad!
Posted By: peejman

Re: Mechanical Tachometer - 08/15/19 06:39 PM

Car related tach's generally aren't set up to work with a single cylinder engine.
Posted By: BillV

Re: Mechanical Tachometer - 08/15/19 10:32 PM

The Speedhut instructions say that it can be set up for between .5 and 6 coil pulses per revolution (single cylinder 4 stroke to 12 cylinder 4 stroke). I think the XT is 1 PPR because of its strange wasted spark design. However I have some indication that the wasted sparks are distinctly weaker than the non-wasted so .5 PPR might be appropriate. You ought to be able to tell from whatever setting works with the Trail Tech tachs.
Posted By: peejman

Re: Mechanical Tachometer - 08/16/19 01:36 AM

Interesting. The ones I've seen just have a 4, 6, 8 switch on the back. It was fun to set it at 4 in a V8 car and shift at 11,000 rpm. smile
Posted By: Rubicon

Re: Mechanical Tachometer - 08/16/19 05:56 AM

I'm going to give my personal opinion on this for what it's worth.I have probably read the majority of posts on this thread and I've never seen someone put a mechanical tach on the XT. To be fair only about a dozen people have gone to the trouble of really modifying this bike extensively but that tells me it probably isn't going to be easy. If it were me I would just go with one like this guy did. https://www.rickramsey.net/CRF250Lmods.htm If you do a little research you will see he has meticulously modified a number of high end bikes and doesn't settle for mediocre. He called the tachometer "magic" and it's cheap and easy to install. I question his real motivation for modifying one expensive bike after another and posting it on the internet but I found I can learn a lot despite not owning any of the motorcycles he has practically redesigned. I know what you're thinking but most of his projects were on more expensive bikes.
Posted By: peejman

Re: Mechanical Tachometer - 08/16/19 02:19 PM

Why all the mods...? To each his own I guess. Some folks clearly have a lot more time and money than I do. Lucky them.

@BillV... You might also want to think about how waterproof and vibration resistant that tach is. Car stuff usually isn't meant to be out in the weather.
Posted By: Az4x4

Re: Mechanical Tachometer - 08/16/19 02:42 PM


Originally Posted By: Rubicon
..I'm going to give my personal opinion on this for what it's worth.... If it were me I would just go with one like this guy did. https://www.rickramsey.net/CRF250Lmods.htm..

If I were to install a tach on my CRF230L (and I'm not about to for what it's worth) it would be like this guy did on his CRF250L. Simple, cheap, works well enough.

If someone's heart is set on installing a tach, there's no need to hack up these old school 223cc engines trying to get a mechanical tach installed when electronic tachs like these are accurate enough for anyone's purposes and readily available.

As far as what drives this guy to reinvent bikes in his own image - your guess is as good as mine!..

Posted By: BillV

Re: Mechanical Tachometer - 08/16/19 05:55 PM

I mentioned earlier here that Speedhut says that it isn't waterproof. So some sealing would be required. I was thinking in terms of clear silicone RVT but getting a decent seal around the lens might be challenging if the tach can't be disassembled. Vibration might also be an issue but my GSXR has a stepper motor tach and works fine. It will come down to how well the unit is built and I'm not a salesman for them.

Instead of switches, the pulses per revolution setting is set electronically.

Those cheap digital tachs commonly rely on an inductive lead that is a wire wrapped around the coil wire (see the pics here). They can give erratic results due to varying spark intensity on the wasted spark. I'm fairly sure that's what sharpy was seeing in the #103492 post here. Near the end of the first link I posted some results of my fiddling around that didn't make that much sense. I now believe that my timing light's inductive lead was missing the weaker wasted spark.
Posted By: Rubicon

Re: Mechanical Tachometer - 08/16/19 06:27 PM

I would not spend a ton of time or money putting a tachometer on this bike.It's pretty easy to tell by engine behavior when to shift.The Trail tech is a fairly sophisticated product and I would be surprised if the kit for this bike doesn't use the wrap a wire around the spark plug method.
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