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Built a GP bike, TZR250 frame,CRF450X powerplant, TZ250GP suspension, wheels and brakes. Needed a Tach and there is No useable signal from the CDI or Coil in any normal way. Got a nice $100 electric tach from Jegs adjustable for 1-12 cyl.operation.Crf450X flywheel has 6 poles and drives the Tach correctly with a buffered signal from the stator windings using the 12 cylinder mode(6PPR). I wound one pole with 30 or so wraps around an unused former and fed it to several different versions of simple circuits to buffer and Square the signal coming from winding. They all worked but I kept getting Loss of calibration from somewhere. Took it around the block with no wires hooked up to do something else and tach read 9500 rpm static when I parked it. Huh, shock mounted it, problem solved, it rocks up to 10,000, at which point I suggest you might want to be lookin elsewhere.

Wouldn't it have been easier to use a Trail Tech trip computer that has a tach built in ??

Easier, yes, $400 price tag, not in my budget.

Where are you buying your parts ??

A Trail Tech Trip Computer with a tach is $130 , in fact its on sale here for $123.45

http://www.crfsonly.com/catalog/product ... ts_id/1836

Your shopping at the wrong places !

I have no use for most of the functions and a Digital Tach is useless at speed, no time to read it. Plus that thing is tiny. I need to see it at a glance traveling 120 mph down the straight with a corner coming up fast. Primary function is to check gearing on the top end. Currently geared 15/43 with 160/60 17 tire.

Yea but the tach is a graph , so basically all you have to do is know where you want to be in RPM's and glance at that spot quickly , i understand your issue , but unless you have something custom made , i dont think the automotive ones will work right , what about a OEM type from a road bike , cant you get any of them to work for your needs ??(like a GSXR tach or something similar) , i am sure you can get one on EBay cheap enough to experiment with

Unless you build some kind of Crank Trigger setup , its going to be difficult to get what you want

What are the other customs your racing against using ??

This guy is not using a tach (i think its the same type of bike)

http://cgi.ebay.com/ebaymotors/HONDA-CR ... 702wt_1069

bjborn wrote: No useable signal from the CDI or Coil in any normal way.

I simply soldered a wire to the appropriate lug of an existing coil wire.

Track tested it this last weekend at an exhibition race at the Kansas Speedway Bikers for Babies event. Works great, I only had a chance to look at it one time while riding, it was buried at 10,000 rpm in third as I shifted to fourth.