TRX250R.ORG
General => Projects => Topic started by: coops86250r on August 03, 2019, 01:05:20 AM
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Hello folks,
I mentioned in my build thread about running the new LED HPI ignition system and doing a install write-up on it. The first thing I will say is this is NOT that hard, just take your time, double and triple check your TDC and stay within what Arlen recommends for the timing which is 2.85-3.00 mm BTDC. One recommendation is to spend the money on the dial indicator set that he sells for doing this install. Many of us probably already have a dial indicator that measures in inches, the one Arlen sells measures in mm, which is also how he bases his measurements.
The first pic is going to show the base plate that the stator mounts to. It's a nice simple piece and centers up the stator very nice and snug. You'll also notice with the base plate that you have numerous mounting holes and they are also slotted to allow timing adjustments should you need/want to play with the timing a bit. I should note that from talking with Arlen he did a lot of testing with this ignition and found the sweet spot to be right between 2.85-3.00 mm BTDC. The HPI instructions say between 2-4 mm BTDC.
Here is a pic of the base plate.
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The next thing I will talk about is the counter balancer bearing retainer that is being used. If you are using the stock one you should be fine, I'm running the ESR one and it is thicker. This wouldn't allow the stator plate to sit flush to the base plate. The simple solution for me was to just sand a little off the bearing holder to create enough clearance for the stator plate to sit flush and square to the base plate. The small screw driver in the pic shows the area where I removed some meat. The amount of metal removed to create the clearance needed is very minimal but needed to be done one mine.
Here is a pic of the area where metal was removed to provide clearance for the stator plate.
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Once I was at this point it was time to set up the dial indicator and rotate the engine in a counter clockwise rotation when looking at the stator side of the motor. This is the normal rotation of the motor on the stator side and is the direction you will spin the engine when coming up to TDC. Before clamping the dial indicator into the holder and going for broke finding TDC bring it up slowly to see if you are making contact with the piston top and/or if the included extensions for the dial indicator are to long. Once you've made sure the dial indicator will read in the range you need go ahead and rotate the engine in a counter clockwise direction until you hit TDC. I backed mine off a couple of times and came back up on TDC to make sure something didn't change ormove after rotating the face of the dial indicator to zero.
Once I was confident in my TDC reading I installed the stator plate to the base using some blue loctite. At this point I just lightly snugged the screws that hold the stator plate with the wires coming from it pointing at the hole in the crankcase for the original stator wires.
The next 2 pics will show the dial indicator in the spark plug hole and the stator plate attached to the base plate.
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For those wondering, yes, that is the original grommet from my oem stator. Using an x-acto knife and doing some VERY careful cutting I was able to remove it from the oem stator and not damage the wires. I opened up the inside of the grommet so the HPI wires will fit nicely inside. Once the install is complete I will squirt some silicone down there to seal it up.
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Now it's time to get the flywheel on and start lining things up where they need to be. My flywheel was a perfect taper to match the crank but Arlen did say some don't have a perfect taper. When installing the flywheel make sure you have a decent hold of it as the stator windings and the magnet in the flywheel with want to become close friends without warning. I put the flywheel on and just used the palm of my hand to seat it lightly to the crank, noting the position of the timing notch cut into the flywheel. This allowed me to rotate the motor and get it right in the honey zone of 2.85-3.00 mm BTDC that Arlen mentioned. There are two timing marks on the stator plate to go by and it is critical that you line things up with the correct one!! With the flywheel lightly seated on the crank I rotated the engine counter clockwise until I came up on 2.85 mm BTDC. At this point I checked where the timing mark on the flywheel was in relation to the timing mark on the stator plate.
The first pic here shows the WRONG timing mark to use. The 2nd pic shows the CORRECT timing mark on the stator plate to using and align with the timing mark on the flywheel.
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I centered my crank in the middle of what Arlen recommended for timing at 2.93 mm BTDC. After double checking the flywheel held position when rotating the crank I followed Arlen's suggestions of using a 17mm socket and lightly tapping the center of the flywheel to seat it good onto the crank taper. Arlen mentioned using a impact gun to tighten up the flywheel nut but I wasn't to keen on this, I didn't want to run the risk of stripping the crank threads. I used a dead blow hammer and gave the socket a hit to seat the flywheel. From there I installed the washer that goes under the flywheel nut and put some anti-seize on the base of the nut to help when tightening. Using a flywheel/clutch holding tool I tightened the flywheel nut to the high end of factory specs. After getting the flywheel nut tightened I went back and rotated the crank back and forth a few times coming up on TDC to make sure it hadn't moved, slipped, or rotated on the crank when tightening the flywheel nut. After this checked out I brought the engine back up to my desired timing of 2.93 mm BTDC and finished aligning the timing mark on the stator plate to the timing mark on the flywheel.
This last pic shows the timing marks lined up after the flywheel and stator plate have been tightened. The screw driver tip is pointing at the timing mark cut into the flywheel.
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The last thing for me to install at this point is the flywheel weight. Arlen mentioned that some folks may have a very slight rubbing on the stator cover from the bolts that hold the flywheel weight onto the flywheel. He mentioned stacking 2 stator cover gaskets to overcome this. With my engine there isn't any contact with the stator cover when the flywheel weight is installed. I did a test fit before final assembly without any gasket and still had a little room to spare.
I'm hoping this will be a helpful install guide for anyone who decides to run this ignition. If you have any questions please don't hesitate to ask.
Thanks,
Tony
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Great write up! Thanks for taking the time to contribute
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Thanks for the write up Tony. I think it's the oem stator cover that has contact issues. My friends does and he is running a oem cover. So he hasn't added the weight yet because of this
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Happy to contribute whenever I can with some hopefully useful information.
Gene, I'm running the oem stator cover and it fits fine with the weight. Arlen sent standard 6 point metric bolts with the weight. If you have contact issues I don't see why using the button head metric bolts wouldn't be strong enough and provide the clearance needed. The height of the button head would be about half of the standard 6 point head metric bolt. That was going to be what I did had I run into issues.
Thanks gentlemen,
Tony
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Excellent! Thank you for contributing to the forum!
Loren
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Happy to contribute whenever I can with some hopefully useful information.
Gene, I'm running the oem stator cover and it fits fine with the weight. Arlen sent standard 6 point metric bolts with the weight. If you have contact issues I don't see why using the button head metric bolts wouldn't be strong enough and provide the clearance needed. The height of the button head would be about half of the standard 6 point head metric bolt. That was going to be what I did had I run into issues.
Thanks gentlemen,
Tony
this was the plans for my friends. He just never did it. So he is running without the weight still
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well done. great explanations.
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Nice write up. Thank you.
Ride report?
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This is an awesome thread. Thank you for sharing all of this info.
Got a ride report yet?
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I do not know if anyone else has noticed a trend with the effects the flywheel weight has upon the life of clutch baskets and broken gears in the transmissions. I am seeing this trend in customer engines.
Basic engineering and physics supports what I am seeing,
A heavy rotating crankshaft assembly (crankshaft and ignition flywheel) spreads the power impulse delivered to the clutch and transmission over many more degrees of crankshaft rotation than lighter rotating crankshaft assemblies.
Metals have limits on the amount of stress they can be subject to before they fatigue, crack and then have catastrophic failure. Lightweight crankshaft assemblies and the increase in the torque of the big bore kits increase the spike in stress that the clutch and transmission must experience. When a metal is stressed below a certain level the metal behaves like a spring.
A prefect spring (metal) when stretched, returns back to it.s original shape when a certain stress level is not exceeded with absolutely no long term damage. When a spring (metal) is stressed slightly beyond this certain stress level, the spring will become permanently damaged and begins to fatigue. Every time this certain stress level is exceeded, another fatigue cycle is added to the count of cycles before the metal fails. If we dramatically exceed this stress level where permanent deformation of the metal occurs, we dramatically reduce the number of cycles before catastrophic failure occurs.
In summary:
As we increase the amount of torque an engine develops and reduce the weight of the ignition flywheel....... the sooner the clutch basket tabs are damaged and transmission gears may break.
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Sorry for the lengthy time between replies folks, working some hellish hours the last few weeks.
I haven't had a chance to get any ride time, I'm still finishing up the build. I gotta fab up a small bracket to mount the new coil. I'm going to tuck it up under the gas tank on the clutch side. This will give me a nice short run to the plug and also keep the coil away from the CDI box. Realistically I'm probably a good month away from first start up with it. Still have a few loose ends to tie up to get it to my liking.
Jerry, I read your post a few times and was a bit confused by what direction you were going in regard to adding weight. The bulk of your reply to me read that adding weight is causing failures from what you are seeing but your summary implied by my reading of it that as you increase the power (torque) of your motor a lighter flywheel leads to premature clutch basket wear and possibly transmission gears breaking. Am I reading that wrong folks???
As far as the weight of the HPI unit including the flywheel weight I'm guessing it is still a tad lighter than oem. I didn't weigh the HPI flywheel and weight before putting them on. From the instructions, the flywheel weight is 280 grams. I still might pull the flywheel back off and get a weight for everything. Give me a chance to go through the set-up again lol.
Thanks for all the replies folks and I'm happy to help!
Tony
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Jerry, I read your post a few times and was a bit confused by what direction you were going in regard to adding weight. The bulk of your reply to me read that adding weight is causing failures from what you are seeing but your summary implied by my reading of it that as you increase the power (torque) of your motor a lighter flywheel leads to premature clutch basket wear and possibly transmission gears breaking. Am I reading that wrong folks???
He's saying that the more mass that the power pulse of ignition has to move, the less sharp the effect of that pulse has on the connected components, ie, the clutch and trans gears, etc.
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So, does the flywheel still use the key-way on the crank?
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No it just uses the taper fit
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As Gene said, it is a slip fit to the taper of the crank, no key. Mine was a very nice match flywheel taper to crank taper so all I really needed to do for it to hold position was just pop it with the palm of my hand.
Tony
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It wouldn't be to awful hard to key these aftermarket flywheels, but a taper bore driven up a tapered shaft is an extremely strong connection. What good is the woodruff key in your oem crank shaft alone? It is too weak to hold the flywheel by itself. It is basically there just to time your flywheel. It would take a whole lot more horse power than a 250r can produce to spin the flywheel out of time if properly seated.
Loren